/* Paint.NET Pro Dark UI Theme - Ultra Responsive Header, Large Icons & Resizable Panels */
:root {
    --bg-main: #141820;
    --bg-header: #0d1117;
    --bg-panel: #181f2b;
    --bg-panel-dark: #0f131a;
    --border-color: #2b3548;
    --border-focus: #00ADEF;
    --text-primary: #e6edf3;
    --text-secondary: #94a3b8;
    --accent-blue: #00ADEF;
    --accent-blue-hover: #38bdf8;
    --accent-green: #2ecc71;
    --accent-red: #e74c3c;
    --accent-purple: #9b59b6;
    --canvas-shadow: 0 4px 30px rgba(0, 0, 0, 0.7);
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    user-select: none;
}

body, html {
    width: 100%;
    height: 100%;
    overflow: hidden;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background-color: var(--bg-main);
    color: var(--text-primary);
}

/* === ВЕРХНИЙ БАР (HEADER) — АДАПТИВНЫЙ И КОМПАКТНЫЙ === */
.app-header {
    height: 40px;
    background-color: var(--bg-header);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: flex-start;
    padding: 0 4px;
    gap: 4px;
    z-index: 100;
    overflow-x: auto;
    overflow-y: hidden;
    scrollbar-width: thin;
    scrollbar-color: rgba(56, 189, 248, 0.4) transparent;
}
.app-header::-webkit-scrollbar {
    height: 3px;
}
.app-header::-webkit-scrollbar-thumb {
    background: rgba(56, 189, 248, 0.4);
    border-radius: 2px;
}
.app-header::-webkit-scrollbar-track {
    background: transparent;
}

.logo-area {
    display: flex;
    align-items: center;
    gap: 4px;
    font-weight: 700;
    font-size: 12px;
    white-space: nowrap;
    flex-shrink: 0;
}

.logo-icon {
    font-size: 15px;
}

.header-section {
    display: flex;
    align-items: center;
    gap: 3px;
    background: var(--bg-panel);
    padding: 2px 4px;
    border-radius: 4px;
    border: 1px solid var(--border-color);
    flex-shrink: 0;
}

/* БЫСТРЫЕ ИНСТРУМЕНТЫ И ЦВЕТА В ШАПКЕ */
.header-quick-tools {
    gap: 3px;
    padding: 2px 4px;
}
.header-tool-btn {
    width: 24px;
    height: 24px;
    min-height: 24px !important;
    padding: 1px !important;
    font-size: 13px !important;
    border-radius: 3px;
    background: #141923;
    border: 1.5px solid var(--border-color);
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    transition: all 0.15s ease;
}
.header-tool-btn:hover {
    background: #252e3e;
    border-color: var(--accent-blue);
    transform: scale(1.1);
}
.header-tool-btn.active {
    background: rgba(0, 173, 239, 0.25);
    border-color: var(--accent-blue);
    box-shadow: 0 0 6px rgba(0, 173, 239, 0.4);
}

.btn-expand-canvas {
    background: #0d233a;
    border: 1.5px solid #0284c7;
    color: #38bdf8;
    font-weight: 700;
    font-size: 11px !important;
    padding: 2px 7px !important;
    height: 24px;
    min-height: 24px !important;
    border-radius: 4px;
    display: inline-flex;
    align-items: center;
    gap: 2px;
    cursor: pointer;
    transition: all 0.15s ease;
    white-space: nowrap;
}
.btn-expand-canvas:hover {
    background: #0284c7;
    color: #ffffff;
    border-color: #38bdf8;
    box-shadow: 0 0 8px rgba(56, 189, 248, 0.4);
    transform: translateY(-1px);
}
.btn-expand-canvas:active {
    transform: translateY(1px);
}

.header-vdivider {
    width: 1px;
    height: 18px;
    background: #334155;
    margin: 0 2px;
}

.header-color-btn {
    width: 22px;
    height: 22px;
    border-radius: 4px;
    border: 1.5px solid #2b3548;
    cursor: pointer;
    transition: transform 0.12s ease, border-color 0.12s ease, box-shadow 0.12s ease;
    flex-shrink: 0;
}
.header-color-btn:hover {
    transform: scale(1.18);
    border-color: #ffffff;
}
.header-color-btn.active {
    border-color: #ffffff;
    box-shadow: 0 0 6px #ffffff;
    transform: scale(1.1);
}

.header-right-toggle {
    margin-left: auto;
    flex-shrink: 0;
}

.section-label {
    font-size: 11px;
    color: var(--text-secondary);
    font-weight: 500;
    white-space: nowrap;
}

.sheet-indicator {
    font-size: 12px;
    font-weight: 700;
    padding: 0 3px;
    color: #ffffff;
    white-space: nowrap;
}

/* КНОПКИ ШАПКИ */
.btn {
    background: #202735;
    color: var(--text-primary);
    border: 1px solid var(--border-color);
    padding: 2px 6px;
    border-radius: 4px;
    font-size: 11px;
    cursor: pointer;
    font-weight: 500;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 3px;
    transition: all 0.15s ease;
    white-space: nowrap;
    height: 25px;
}

.btn:hover {
    background: #2d384c;
    border-color: #4a5c7c;
    color: #ffffff;
}

.btn:active {
    transform: translateY(1px);
}

.btn-icon {
    padding: 2px 5px;
}

/* ГРУППА МАСШТАБИРОВАНИЯ (ЗУМ / ЛУПА) */
.zoom-group {
    display: flex;
    align-items: center;
    gap: 3px;
}

.zoom-select {
    width: 68px;
    font-size: 11px;
    font-weight: 600;
    padding: 3px 4px;
    background: #18202d;
    color: #e2e8f0;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    height: 28px;
    cursor: pointer;
}

.zoom-select:focus {
    border-color: var(--accent-blue);
    outline: none;
}

.cursor-zoom-in {
    cursor: zoom-in !important;
}

.cursor-zoom-out {
    cursor: zoom-out !important;
}

.btn-toggle-panel {
    background: #1e2636;
    font-size: 11px;
    font-weight: 600;
    border-color: #384863;
    color: var(--accent-blue);
    padding: 4px 8px;
}
.btn-toggle-panel:hover {
    background: #28374e;
    border-color: var(--accent-blue);
}

.btn-primary {
    background: #0984e3;
    border-color: #00ADEF;
    color: #ffffff;
    font-weight: 600;
}
.btn-primary:hover {
    background: #00ADEF;
}

.btn-accent {
    background: #27ae60;
    border-color: #2ecc71;
    color: #ffffff;
}
.btn-accent:hover {
    background: #2ecc71;
}

.btn-danger {
    background: #c0392b;
    border-color: #e74c3c;
    color: #ffffff;
}
.btn-danger:hover {
    background: #e74c3c;
}

.btn-history {
    background: #1c2432;
    border-color: #2c3a50;
    font-size: 11px;
    font-weight: 600;
    padding: 4px 8px;
    transition: all 0.15s ease;
}
.btn-history:hover:not(:disabled) {
    background: #253348;
    border-color: var(--accent-blue);
    color: #ffffff;
}
.btn-history:disabled, .btn-history.disabled {
    opacity: 0.4;
    cursor: not-allowed;
    border-color: #1e2634;
    background: #151a24;
    color: var(--text-secondary);
}

/* КНОПКА ЗАПИСИ ВИДЕО */
.btn-record {
    background: #2d1820;
    border-color: #c0392b;
    color: #ffffff;
    font-weight: 600;
    display: inline-flex;
    align-items: center;
    gap: 5px;
}
.btn-record:hover {
    background: #c0392b;
    box-shadow: 0 0 8px rgba(231, 76, 60, 0.4);
}
.btn-record.recording {
    background: #e74c3c;
    animation: pulse-red 1.5s infinite;
}
.rec-dot {
    width: 7px;
    height: 7px;
    background: #e74c3c;
    border-radius: 50%;
    display: inline-block;
}
.btn-record.recording .rec-dot {
    background: #ffffff;
}
.record-timer {
    font-size: 11px;
    font-weight: 700;
    color: #e74c3c;
    font-family: monospace;
    padding: 0 3px;
}

@keyframes pulse-red {
    0% { box-shadow: 0 0 0 0 rgba(231, 76, 60, 0.7); }
    70% { box-shadow: 0 0 0 6px rgba(231, 76, 60, 0); }
    100% { box-shadow: 0 0 0 0 rgba(231, 76, 60, 0); }
}

.btn-export {
    background: #34495e;
    border-color: #4b6584;
    font-weight: 600;
}
.btn-export:hover {
    background: #4b6584;
}

.btn-pdf {
    background: #8e44ad;
    border-color: #9b59b6;
    color: #ffffff;
    font-weight: 600;
}
.btn-pdf:hover {
    background: #9b59b6;
    box-shadow: 0 0 8px rgba(155, 89, 182, 0.4);
}

.custom-select {
    background: #0f131a;
    color: #ffffff;
    border: 1px solid var(--border-color);
    padding: 2px 4px;
    border-radius: 3px;
    font-size: 11px;
    outline: none;
    cursor: pointer;
    height: 24px;
}

.toggle-switch {
    position: relative;
    display: inline-block;
    width: 24px;
    height: 14px;
}
.toggle-switch input { opacity: 0; width: 0; height: 0; }
.slider {
    position: absolute; cursor: pointer; top: 0; left: 0; right: 0; bottom: 0;
    background-color: #4b5563;
    transition: .2s;
    border-radius: 14px;
}
.slider:before {
    position: absolute; content: ""; height: 10px; width: 10px; left: 2px; bottom: 2px;
    background-color: white;
    transition: .2s;
    border-radius: 50%;
}
input:checked + .slider { background-color: var(--accent-green); }
input:checked + .slider:before { transform: translateX(10px); }

.folder-status-badge {
    font-size: 10px;
    padding: 2px 5px;
    background: #242c3b;
    color: #a0aec0;
    border-radius: 3px;
    max-width: 80px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    border: 1px solid #3e4a5e;
}
.folder-status-badge.active {
    background: rgba(46, 204, 113, 0.2);
    color: #2ecc71;
    border-color: #2ecc71;
}

/* === РАБОЧАЯ ОБЛАСТЬ (WORKSPACE) === */
.app-workspace {
    display: flex;
    height: calc(100vh - 44px);
    width: 100%;
    position: relative;
    overflow: hidden;
}

/* СВОРАЧИВАЕМЫЕ ЛЕВАЯ И ПРАВАЯ ПАНЕЛИ С ИЗМЕНЯЕМОЙ ШИРИНОЙ (RESIZABLE) */
.toolbar-panel, .sidebar-panel {
    background-color: var(--bg-panel);
    border-color: var(--border-color);
    padding: 8px;
    display: flex;
    flex-direction: column;
    gap: 7px;
    overflow-y: auto;
    z-index: 20;
    position: relative;
    flex-shrink: 0;
    transition: transform 0.2s cubic-bezier(0.16, 1, 0.3, 1), opacity 0.2s ease;
}

/* Начальная удобная ширина */
.toolbar-panel {
    width: 165px;
    min-width: 130px;
    max-width: 380px;
    border-right: 1px solid var(--border-color);
}
.toolbar-panel.collapsed {
    transform: translateX(-100%);
    width: 0 !important;
    min-width: 0 !important;
    max-width: 0 !important;
    padding: 0 !important;
    margin: 0 !important;
    border: none !important;
    opacity: 0;
    pointer-events: none;
}

.sidebar-panel {
    width: 215px;
    min-width: 170px;
    max-width: 480px;
    border-left: 1px solid var(--border-color);
}
.sidebar-panel.collapsed {
    transform: translateX(100%);
    width: 0 !important;
    min-width: 0 !important;
    max-width: 0 !important;
    padding: 0 !important;
    margin: 0 !important;
    border: none !important;
    opacity: 0;
    pointer-events: none;
}

/* РАЗДЕЛИТЕЛИ ДЛЯ РЕЗИЗА (RESIZE HANDLES) */
.resize-handle {
    position: absolute;
    top: 0;
    bottom: 0;
    width: 6px;
    cursor: col-resize;
    z-index: 50;
    transition: background 0.15s ease;
}
.resize-handle:hover, .resize-handle.active {
    background: var(--accent-blue);
}
.resize-handle-left {
    right: 0;
}
.resize-handle-right {
    left: 0;
}

.panel-close-x {
    background: none;
    border: none;
    color: var(--text-secondary);
    font-size: 13px;
    cursor: pointer;
    padding: 2px 4px;
    border-radius: 3px;
}
.panel-close-x:hover {
    color: #ffffff;
    background: var(--accent-red);
}

.panel-header {
    font-size: 11px;
    font-weight: 700;
    text-transform: uppercase;
    color: var(--text-secondary);
    letter-spacing: 0.5px;
    margin-bottom: 2px;
}

.d-flex-between {
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.stroke-val-badge {
    background: #0f131a;
    color: var(--accent-blue);
    font-size: 11px;
    padding: 1px 5px;
    border-radius: 4px;
    font-weight: bold;
    border: 1px solid #2b3548;
}

.badge {
    background: var(--accent-blue);
    color: #ffffff;
    font-size: 10px;
    padding: 1px 5px;
    border-radius: 10px;
    font-weight: bold;
}

.panel-divider {
    height: 1px;
    background: var(--border-color);
    margin: 3px 0;
}

/* БОЛЬШИЕ КНОПКИ ИНСТРУМЕНТОВ РИСОВАНИЯ */
.tools-grid-large {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(64px, 1fr));
    gap: 5px;
}

/* БОЛЬШИЕ КНОПКИ ГЕОМЕТРИЧЕСКИХ ФИГУР */
.shapes-grid-large {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(80px, 1fr));
    gap: 5px;
}

.tool-btn {
    background: #10151f;
    border: 1.5px solid var(--border-color);
    color: var(--text-primary);
    padding: 6px 3px;
    border-radius: 5px;
    cursor: pointer;
    text-align: center;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 2px;
    position: relative;
    transition: all 0.15s ease;
    min-height: 48px;
}

.tool-icon {
    font-size: 18px;
    line-height: 1;
}

.tool-name {
    font-size: 10.5px;
    font-weight: 600;
    color: #cbd5e1;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    max-width: 100%;
}

.tool-hotkey {
    position: absolute;
    top: 2px;
    right: 3px;
    font-size: 8.5px;
    font-weight: 700;
    color: var(--accent-blue);
    opacity: 0.8;
}

.tool-btn:hover {
    background: #222c3d;
    border-color: var(--accent-blue);
    transform: translateY(-1px);
}

.tool-btn.active {
    background: rgba(0, 173, 239, 0.22);
    border-color: var(--accent-blue);
    box-shadow: 0 0 8px rgba(0, 173, 239, 0.35);
}
.tool-btn.active .tool-name {
    color: #ffffff;
    font-weight: 700;
}

/* СЕТКА ВЫБОРА ФОНА */
.bg-selector-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3px;
}
.bg-btn {
    background: #10151f;
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    padding: 5px 3px;
    border-radius: 4px;
    font-size: 10.5px;
    cursor: pointer;
    text-align: center;
    font-weight: 500;
}
.bg-btn:hover { background: #222c3d; border-color: #4a5c7c; }
.bg-btn.active {
    background: rgba(0, 173, 239, 0.2);
    border-color: var(--accent-blue);
    color: var(--accent-blue);
    font-weight: 600;
}

.range-control input[type="range"] {
    width: 100%;
    accent-color: var(--accent-blue);
    cursor: pointer;
    height: 5px;
}

/* === ХОЛСТ (VIEWPORT) === */
.canvas-viewport {
    flex-grow: 1;
    background: #090c10;
    display: flex;
    align-items: flex-start;
    justify-content: center;
    overflow-y: auto;
    overflow-x: auto;
    position: relative;
    padding: 10px;
    min-width: 0;
}

.canvas-container {
    position: relative;
    width: 100%;
    max-width: 1920px;
    aspect-ratio: 1920 / 1080;
    box-shadow: var(--canvas-shadow);
    border-radius: 4px;
    overflow: hidden;
    background: #ffffff;
    flex-shrink: 0;
    transform: translateZ(0);
    will-change: transform;
}

.canvas-container canvas {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    cursor: crosshair;
    touch-action: none;
    user-select: none;
    -webkit-user-select: none;
    transform: translateZ(0);
    backface-visibility: hidden;
}

#bgCanvas { z-index: 1; pointer-events: none; }
#mainCanvas { z-index: 2; pointer-events: none; }
#previewCanvas { z-index: 3; pointer-events: auto; }

/* ПЛАВАЮЩИЕ КНОПКИ РАЗВОРАЧИВАНИЯ */
.floating-unhide-btn {
    position: absolute;
    top: 10px;
    background: rgba(22, 27, 36, 0.9);
    border: 1.5px solid var(--accent-blue);
    color: var(--accent-blue);
    padding: 6px 10px;
    border-radius: 5px;
    cursor: pointer;
    z-index: 30;
    backdrop-filter: blur(5px);
    display: none;
    box-shadow: 0 4px 14px rgba(0,0,0,0.6);
    font-size: 11px;
    font-weight: 600;
    transition: transform 0.15s ease, background 0.15s ease;
}
.floating-unhide-btn:hover {
    background: var(--accent-blue);
    color: #ffffff;
    transform: scale(1.06);
}
.float-left-btn { left: 10px; }
.float-right-btn { right: 10px; }

.canvas-text-overlay {
    position: absolute;
    z-index: 10;
    background: rgba(24, 29, 38, 0.95);
    border: 2px dashed var(--accent-blue);
    color: #ffffff;
    font-family: 'Segoe UI', Arial, sans-serif;
    font-size: 24px;
    padding: 4px 8px;
    outline: none;
    resize: both;
    overflow: hidden;
}

/* ПЛАВАЮЩИЙ И МАСШТАБИРУЕМЫЙ СКРИНШОТ */
.image-floating-wrapper {
    position: absolute;
    z-index: 25;
    border: 2px dashed var(--accent-blue);
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.7);
    cursor: move;
    user-select: none;
    touch-action: none;
}

.image-floating-img {
    width: 100%;
    height: 100%;
    display: block;
    pointer-events: none;
    object-fit: contain;
    image-rendering: -webkit-optimize-contrast;
    image-rendering: high-quality;
    background: transparent;
}

.image-control-bar {
    position: absolute;
    top: -36px;
    left: 0;
    display: flex;
    gap: 6px;
    background: rgba(15, 19, 26, 0.95);
    padding: 3px 6px;
    border-radius: 4px;
    border: 1px solid var(--border-color);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.6);
    pointer-events: auto;
}

.btn-xs {
    font-size: 10px;
    padding: 2px 6px;
    height: 22px;
}

/* 4 УГЛОВЫХ МАРКЕРА ИЗМЕНЕНИЯ РАЗМЕРА */
.img-resize-handle {
    position: absolute;
    width: 12px;
    height: 12px;
    background: #ffffff;
    border: 2px solid var(--accent-blue);
    border-radius: 2px;
    box-shadow: 0 0 4px rgba(0, 0, 0, 0.5);
    z-index: 26;
}

.handle-tl { top: -6px; left: -6px; cursor: nwse-resize; }
.handle-tr { top: -6px; right: -6px; cursor: nesw-resize; }
.handle-bl { bottom: -6px; left: -6px; cursor: nesw-resize; }
.handle-br { bottom: -6px; right: -6px; cursor: nwse-resize; }

.img-resize-handle:hover {
    background: var(--accent-blue);
    transform: scale(1.3);
}

/* === ПАЛИТРА И СПИСОК ЛИСТОВ (СПРАВА) === */
.color-picker-box {
    display: flex;
    flex-direction: column;
    gap: 5px;
}

.current-color-preview {
    display: flex;
    align-items: center;
    gap: 6px;
    background: #0f131a;
    padding: 3px 6px;
    border-radius: 4px;
    border: 1px solid var(--border-color);
}
.current-color-preview input[type="color"] {
    width: 24px;
    height: 24px;
    border: none;
    background: none;
    cursor: pointer;
    border-radius: 3px;
}
#primaryColorHex {
    font-size: 11px;
    font-family: monospace;
    font-weight: 700;
}

.preset-colors-palette {
    display: grid;
    grid-template-columns: repeat(6, 1fr);
    gap: 4px;
}
.color-chip {
    height: 22px;
    border-radius: 3px;
    border: 1.5px solid #2b3548;
    cursor: pointer;
    transition: transform 0.1s ease, border-color 0.1s ease;
}
.color-chip:hover {
    transform: scale(1.15);
    border-color: #ffffff;
}
.color-chip.active {
    border-color: #ffffff;
    box-shadow: 0 0 5px #ffffff;
}

/* СПИСОК МИНИАТЮР ЛИСТОВ */
.sheets-thumbnails-list {
    flex-grow: 1;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: 5px;
    padding-right: 2px;
    max-height: 200px;
}

.sheet-thumb-card {
    background: #0f131a;
    border: 1.5px solid var(--border-color);
    border-radius: 4px;
    padding: 3px;
    cursor: pointer;
    transition: all 0.15s ease;
    display: flex;
    flex-direction: column;
    gap: 2px;
}
.sheet-thumb-card:hover {
    border-color: #4b5563;
    background: #19202c;
}
.sheet-thumb-card.active {
    border-color: var(--accent-blue);
    background: rgba(0, 173, 239, 0.15);
    box-shadow: 0 0 6px rgba(0, 173, 239, 0.3);
}
.sheet-thumb-img, .sheet-thumb-canvas {
    width: 100%;
    aspect-ratio: 16 / 9;
    background: #ffffff;
    border-radius: 2px;
    object-fit: cover;
    border: 1px solid #262f3f;
    display: block;
}
.sheet-thumb-title {
    font-size: 10px;
    font-weight: 600;
    color: var(--text-secondary);
    display: flex;
    justify-content: space-between;
}

.single-export-actions {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4px;
    margin-top: auto;
}
.btn-sm {
    font-size: 10px;
    padding: 4px 2px;
}

/* УВЕДОМЛЕНИЯ (TOAST) */
.toast-popup {
    position: fixed;
    bottom: 20px;
    left: 50%;
    transform: translateX(-50%) translateY(80px);
    background: #1e293b;
    color: #ffffff;
    padding: 8px 16px;
    border-radius: 6px;
    font-size: 12px;
    font-weight: 600;
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.5);
    border: 1px solid var(--accent-blue);
    transition: transform 0.3s cubic-bezier(0.16, 1, 0.3, 1), opacity 0.3s ease;
    opacity: 0;
    z-index: 9999;
    pointer-events: none;
}
.toast-popup.show {
    transform: translateX(-50%) translateY(0);
    opacity: 1;
}

/* ЗАГОЛОВКИ ПОДРАЗДЕЛОВ ФИГУР */
.shapes-sub-header {
    font-size: 11px;
    font-weight: 700;
    color: var(--accent-blue);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin: 4px 0 2px 2px;
}

/* КНОПКИ КАЛЬКУЛЯТОРА И ИИ В ШАПКЕ */
.btn-calc {
    background: linear-gradient(135deg, #1e293b 0%, #334155 100%);
    border: 1.5px solid #475569;
    color: #f8fafc;
    font-size: 11px;
    padding: 3px 8px;
    font-weight: 600;
    border-radius: 4px;
}
.btn-calc:hover {
    background: #475569;
    border-color: #38bdf8;
    box-shadow: 0 0 8px rgba(56, 189, 248, 0.3);
}

.btn-ai-solve {
    background: linear-gradient(135deg, #0284c7 0%, #0369a1 100%);
    border: 1.5px solid #38bdf8;
    color: #ffffff;
    font-size: 11px;
    padding: 3px 8px;
    font-weight: 700;
    border-radius: 4px;
    box-shadow: 0 0 8px rgba(2, 132, 199, 0.4);
}
.btn-ai-solve:hover {
    background: linear-gradient(135deg, #0ea5e9 0%, #0284c7 100%);
    box-shadow: 0 0 12px rgba(14, 165, 233, 0.6);
    transform: translateY(-1px);
}

.btn-ai-similar {
    background: linear-gradient(135deg, #7c3aed 0%, #6d28d9 100%);
    border: 1.5px solid #a78bfa;
    color: #ffffff;
    font-size: 11px;
    padding: 3px 8px;
    font-weight: 700;
    border-radius: 4px;
    box-shadow: 0 0 8px rgba(124, 58, 237, 0.4);
}
.btn-ai-similar:hover {
    background: linear-gradient(135deg, #8b5cf6 0%, #7c3aed 100%);
    box-shadow: 0 0 12px rgba(139, 92, 246, 0.6);
    transform: translateY(-1px);
}

.btn-purple {
    background: #7c3aed;
    color: #ffffff;
    border: 1px solid #a78bfa;
}
.btn-purple:hover {
    background: #8b5cf6;
}

/* МОДАЛЬНЫЕ ОКНА (OVERLAYS & WINDOWS) */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.75);
    z-index: 10000;
    display: flex;
    align-items: center;
    justify-content: center;
    animation: fadeIn 0.15s ease;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.modal-window {
    background: #181f2b;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    box-shadow: 0 15px 35px rgba(0, 0, 0, 0.8);
    display: flex;
    flex-direction: column;
    overflow: hidden;
    max-height: 90vh;
}

.modal-header {
    background: #0f131a;
    padding: 8px 14px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-size: 13px;
    font-weight: 700;
    border-bottom: 1px solid var(--border-color);
}
.ai-modal-header {
    border-bottom: 2px solid var(--accent-blue);
}
.ai-modal-header-purple {
    border-bottom: 2px solid #a78bfa;
}

.modal-close-btn {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    font-size: 16px;
    cursor: pointer;
    line-height: 1;
}
.modal-close-btn:hover {
    color: #ef4444;
}

.modal-footer {
    padding: 10px 14px;
    background: #0f131a;
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: flex-end;
    gap: 8px;
}

/* ==========================================================================
   1. ПЛАВАЮЩИЙ ИНЖЕНЕРНЫЙ КАЛЬКУЛЯТОР & ДРОБИ
   ========================================================================== */
.floating-calc-window {
    position: fixed;
    top: 55px;
    right: 230px;
    width: 380px;
    background: #121824;
    border: 1.5px solid #3b82f6;
    border-radius: 10px;
    box-shadow: 0 16px 40px rgba(0, 0, 0, 0.85);
    z-index: 1000;
    display: flex;
    flex-direction: column;
    overflow: hidden;
    user-select: none;
    animation: fadeIn 0.15s ease;
}

.floating-calc-header {
    background: #090d14;
    padding: 8px 12px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-size: 12.5px;
    font-weight: 700;
    border-bottom: 1px solid var(--border-color);
    cursor: move;
}

.calc-drag-handle {
    display: flex;
    align-items: center;
    gap: 6px;
    color: #60a5fa;
    cursor: move;
}

.calc-body {
    padding: 12px;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.calc-display-container {
    background: #090d14;
    border: 1.5px solid var(--border-color);
    border-radius: 8px;
    padding: 8px 10px;
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.calc-expr-input {
    width: 100%;
    background: transparent;
    border: none;
    outline: none;
    color: #ffffff;
    font-size: 16px;
    font-family: 'Consolas', 'Courier New', monospace;
    font-weight: 600;
}

.calc-results-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 10px;
    border-top: 1px dashed #222d3d;
    padding-top: 4px;
}

.calc-exact-badge {
    color: #38bdf8;
    font-size: 18px;
    font-weight: 700;
    font-family: 'Cambria Math', 'Segoe UI Math', serif;
    display: inline-flex;
    align-items: center;
    gap: 4px;
    min-height: 38px;
    white-space: nowrap;
}

.calc-math-whole {
    font-size: 19px;
    font-weight: 700;
    color: #38bdf8;
    margin-right: 2px;
}

.calc-math-frac {
    display: inline-flex;
    flex-direction: column;
    vertical-align: middle;
    text-align: center;
    font-size: 12px;
    line-height: 1;
    margin: 0 2px;
}

.calc-math-num {
    display: block;
    border-bottom: 2px solid #38bdf8;
    padding-bottom: 1px;
    color: #38bdf8;
    font-weight: 700;
}

.calc-math-den {
    display: block;
    padding-top: 2px;
    color: #38bdf8;
    font-weight: 700;
}

.calc-decimal-badge {
    color: #94a3b8;
    font-size: 13px;
    font-family: monospace;
    white-space: nowrap;
}

.calc-quick-fractions-bar {
    display: flex;
    gap: 4px;
    background: #0f1521;
    padding: 4px 6px;
    border-radius: 6px;
    border: 1px solid #1e293b;
    overflow-x: auto;
}

.calc-quick-btn {
    background: #1e293b;
    border: 1px solid #334155;
    color: #cbd5e1;
    border-radius: 4px;
    padding: 3px 8px;
    font-size: 11.5px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.1s;
    white-space: nowrap;
}
.calc-quick-btn:hover {
    background: #2563eb;
    color: #ffffff;
}

.calc-grid {
    display: grid;
    grid-template-columns: repeat(6, 1fr);
    gap: 5px;
}

.calc-btn {
    height: 34px;
    border-radius: 5px;
    border: 1px solid #233044;
    background: #1a2232;
    color: #e2e8f0;
    font-size: 12px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.1s ease;
    display: flex;
    align-items: center;
    justify-content: center;
}

.calc-btn:hover {
    background: #2b3952;
    border-color: #38bdf8;
    transform: scale(1.03);
}
.calc-btn:active {
    transform: scale(0.97);
}

.calc-fn {
    background: #141c2b;
    color: #38bdf8;
    font-size: 11.5px;
    border-color: #1e293b;
}
.calc-fn:hover {
    background: #1e293b;
    color: #7dd3fc;
}
.calc-op {
    background: #1e3a8a;
    color: #dbeafe;
    font-weight: 700;
    font-size: 15px;
    border-color: #2563eb;
}
.calc-op:hover {
    background: #2563eb;
    color: #ffffff;
}
.calc-num {
    background: #1e293b;
    font-weight: 700;
    font-size: 15px;
    color: #f8fafc;
    border-color: #334155;
}
.calc-num:hover {
    background: #334155;
    color: #38bdf8;
    border-color: #38bdf8;
}
.calc-clear {
    background: #991b1b;
    color: #fee2e2;
    font-weight: 700;
    font-size: 13px;
    border-color: #b91c1c;
}
.calc-clear:hover {
    background: #dc2626;
    color: #ffffff;
}
.calc-backspace {
    background: #7f1d1d;
    color: #fca5a5;
    font-weight: 700;
    font-size: 14px;
    border-color: #991b1b;
}
.calc-backspace:hover {
    background: #b91c1c;
    color: #ffffff;
}
.calc-equals {
    background: #059669;
    color: #ffffff;
    font-weight: 700;
    font-size: 13.5px;
    border-color: #10b981;
}
.calc-equals:hover {
    background: #10b981;
    box-shadow: 0 0 10px rgba(16, 185, 129, 0.4);
}

.calc-insert-board {
    background: #0284c7;
    color: #ffffff;
    font-weight: 700;
    font-size: 13px;
    height: 36px;
    margin-top: 2px;
    border-color: #38bdf8;
}
.calc-insert-board:hover {
    background: #0369a1;
    box-shadow: 0 0 10px rgba(56, 189, 248, 0.3);
}

/* ==========================================================================
   2. ОБЩИЕ СТИЛИ ДЛЯ ПЛАВАЮЩИХ МАТЕМАТИЧЕСКИХ ОКОН (ГРАФИКИ И РЕШАТЕЛЬ)
   ========================================================================== */
.floating-math-window {
    position: fixed;
    top: 50px;
    left: 220px;
    width: 920px;
    max-width: calc(100vw - 40px);
    max-height: calc(100vh - 65px);
    background: #121824;
    border: 2px solid var(--accent-blue);
    border-radius: 12px;
    box-shadow: 0 20px 50px rgba(0, 0, 0, 0.9);
    z-index: 1005;
    display: flex;
    flex-direction: column;
    overflow: hidden;
    user-select: none;
    animation: fadeIn 0.15s ease-out;
}

.floating-math-header {
    background: #090d14;
    padding: 10px 16px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-size: 14px;
    font-weight: 700;
    border-bottom: 1.5px solid var(--border-color);
    cursor: move;
}

.math-drag-handle {
    color: #38bdf8;
    display: flex;
    align-items: center;
    gap: 8px;
    cursor: move;
}

.math-header-actions {
    display: flex;
    align-items: center;
    gap: 8px;
}

.btn-math-icon {
    background: #1e293b;
    border: 1px solid #334155;
    color: #cbd5e1;
    border-radius: 4px;
    padding: 3px 8px;
    font-size: 11px;
    cursor: pointer;
}
.btn-math-icon:hover {
    background: #334155;
    color: #ffffff;
}

/* ==========================================================================
   3. ГРАФИЧЕСКИЙ КАЛЬКУЛЯТОР & ИССЛЕДОВАНИЕ СВОЙСТВ
   ========================================================================== */
.graph-window-body {
    padding: 14px;
    display: flex;
    flex-direction: column;
    gap: 12px;
    background: #101622;
}

.graph-input-toolbar {
    display: flex;
    flex-direction: column;
    gap: 8px;
    background: #090d14;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 10px 12px;
}

.graph-formula-group {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-wrap: wrap;
}

.graph-fn-label {
    font-size: 14px;
    font-weight: 700;
    color: #38bdf8;
    font-family: 'Cambria Math', serif;
    white-space: nowrap;
}

.graph-formula-input {
    flex-grow: 1;
    min-width: 220px;
    background: #182232;
    border: 1.5px solid #2d3d54;
    border-radius: 6px;
    padding: 7px 12px;
    color: #ffffff;
    font-size: 14px;
    font-family: 'Consolas', monospace;
    outline: none;
    font-weight: bold;
}
.graph-formula-input:focus {
    border-color: #38bdf8;
}

.graph-presets-select {
    width: 210px;
    font-size: 11.5px;
}

.btn-build-graph {
    font-weight: 700;
    padding: 7px 14px;
    white-space: nowrap;
}

.graph-range-controls {
    display: flex;
    align-items: center;
    gap: 14px;
    font-size: 12px;
    color: #94a3b8;
    flex-wrap: wrap;
}

.graph-range-num {
    width: 50px;
    background: #182232;
    border: 1px solid #2d3d54;
    border-radius: 4px;
    padding: 2px 5px;
    color: #ffffff;
    font-size: 12px;
    text-align: center;
}

.graph-checkbox-label {
    display: flex;
    align-items: center;
    gap: 4px;
    cursor: pointer;
    color: #e2e8f0;
}

.graph-content-layout {
    display: grid;
    grid-template-columns: 500px 1fr;
    gap: 12px;
    min-height: 380px;
}

.graph-canvas-container {
    position: relative;
    background: #06090e;
    border: 1.5px solid var(--border-color);
    border-radius: 8px;
    overflow: hidden;
    display: flex;
    align-items: center;
    justify-content: center;
}

#graphCanvas {
    width: 100%;
    height: 100%;
    display: block;
    cursor: crosshair;
}

.graph-coord-badge {
    position: absolute;
    bottom: 8px;
    right: 8px;
    background: rgba(15, 23, 42, 0.88);
    color: #38bdf8;
    border: 1px solid #0284c7;
    border-radius: 4px;
    padding: 3px 8px;
    font-size: 11.5px;
    font-family: monospace;
    font-weight: 700;
    pointer-events: none;
}

.graph-properties-panel {
    background: #090d14;
    border: 1.5px solid var(--border-color);
    border-radius: 8px;
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.properties-header {
    background: #0d131f;
    padding: 8px 12px;
    font-size: 12.5px;
    font-weight: 700;
    color: #38bdf8;
    border-bottom: 1px solid var(--border-color);
}

.properties-scroll-body {
    padding: 10px;
    overflow-y: auto;
    max-height: 340px;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.prop-card-item {
    background: #131b28;
    border: 1px solid #233147;
    border-left: 3.5px solid var(--accent-blue);
    border-radius: 4px;
    padding: 6px 10px;
    display: flex;
    flex-direction: column;
    gap: 2px;
}

.prop-card-title {
    font-size: 11px;
    font-weight: 700;
    color: #94a3b8;
    text-transform: uppercase;
    letter-spacing: 0.3px;
}

.prop-card-val {
    font-size: 13px;
    color: #f1f5f9;
    font-weight: 600;
}
.prop-card-val.math-val {
    color: #38bdf8;
    font-family: 'Cambria Math', serif;
}

.graph-footer-actions, .solver-footer-actions {
    display: flex;
    align-items: center;
    justify-content: flex-end;
    gap: 10px;
    border-top: 1px solid var(--border-color);
    padding-top: 10px;
}

/* ==========================================================================
   4. РЕШАТЕЛЬ УРАВНЕНИЙ, СИСТЕМ И НЕРАВЕНСТВ (1–11 КЛАСС)
   ========================================================================== */
.solver-window-body {
    padding: 14px;
    display: flex;
    flex-direction: column;
    gap: 10px;
    background: #101622;
    overflow: hidden;
    flex: 1;
    min-height: 0;
}

.solver-tabs-nav {
    display: flex;
    gap: 6px;
    border-bottom: 1.5px solid var(--border-color);
    padding-bottom: 8px;
    flex-shrink: 0;
}

.solver-tab-btn {
    background: #182232;
    border: 1px solid #2d3d54;
    color: #94a3b8;
    border-radius: 6px;
    padding: 6px 14px;
    font-size: 12.5px;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.15s;
}
.solver-tab-btn.active, .solver-tab-btn:hover {
    background: #2563eb;
    color: #ffffff;
    border-color: #3b82f6;
}

.solver-symbols-bar {
    display: flex;
    gap: 4px;
    background: #090d14;
    padding: 5px 8px;
    border-radius: 6px;
    border: 1px solid var(--border-color);
    overflow-x: auto;
    flex-shrink: 0;
}

.sym-btn {
    background: #162030;
    border: 1px solid #2b3a50;
    color: #7dd3fc;
    border-radius: 4px;
    padding: 3px 8px;
    font-size: 12px;
    font-weight: 700;
    cursor: pointer;
    white-space: nowrap;
}
.sym-btn:hover {
    background: #0284c7;
    color: #ffffff;
}

.solver-presets-row {
    display: flex;
    flex-shrink: 0;
}

.solver-presets-select {
    width: 100%;
    font-size: 12.5px;
}

.solver-input-row {
    display: flex;
    gap: 10px;
    flex-shrink: 0;
}

.solver-textarea {
    flex-grow: 1;
    min-height: 48px;
    max-height: 70px;
    background: #090d14;
    border: 1.5px solid var(--border-color);
    border-radius: 6px;
    padding: 8px 12px;
    color: #ffffff;
    font-size: 14px;
    font-family: 'Consolas', monospace;
    font-weight: bold;
    outline: none;
    resize: vertical;
}
.solver-textarea:focus {
    border-color: var(--accent-blue);
}

.btn-solve-execute {
    width: 180px;
    font-size: 13.5px;
    font-weight: 700;
    flex-shrink: 0;
}

.solver-solution-area {
    flex: 1;
    min-height: 180px;
    max-height: calc(100vh - 360px);
    overflow-y: auto;
    background: #090d14;
    border: 1.5px solid var(--border-color);
    border-radius: 8px;
    padding: 14px;
    display: flex;
    flex-direction: column;
    gap: 10px;
    scrollbar-width: thin;
    scrollbar-color: #2563eb #090d14;
}

.solver-solution-area::-webkit-scrollbar {
    width: 8px;
}
.solver-solution-area::-webkit-scrollbar-track {
    background: #090d14;
    border-radius: 4px;
}
.solver-solution-area::-webkit-scrollbar-thumb {
    background: #2563eb;
    border-radius: 4px;
}
.solver-solution-area::-webkit-scrollbar-thumb:hover {
    background: #3b82f6;
}

.solver-placeholder {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100%;
    min-height: 180px;
    color: var(--text-secondary);
    text-align: center;
    gap: 10px;
    font-size: 13px;
}

.solver-icon-large {
    font-size: 38px;
}

/* ОКНА ИИ АГЕНТА */
.ai-modal-window {
    width: 760px;
    max-width: 95vw;
}
.ai-modal-body {
    padding: 14px;
    display: flex;
    flex-direction: column;
    gap: 10px;
}
.ai-prompt-bar {
    display: flex;
    align-items: center;
    gap: 8px;
    background: #0f131a;
    padding: 8px 10px;
    border-radius: 6px;
    border: 1px solid var(--border-color);
}
.ai-prompt-bar label {
    font-size: 11px;
    font-weight: 600;
    color: var(--text-secondary);
    white-space: nowrap;
}

.ai-task-text-bar {
    display: flex;
    flex-direction: column;
    gap: 4px;
    background: #0f131a;
    padding: 8px 10px;
    border-radius: 6px;
    border: 1px solid var(--border-color);
}
.ai-task-text-bar label {
    font-size: 11px;
    font-weight: 600;
    color: #38bdf8;
}
.ai-custom-textarea {
    width: 100%;
    min-height: 48px;
    max-height: 90px;
    background: #181f2b;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    padding: 6px 10px;
    color: #ffffff;
    font-size: 12px;
    font-family: inherit;
    outline: none;
    resize: vertical;
}
.ai-custom-textarea:focus {
    border-color: var(--accent-blue);
}

.ai-input {
    flex-grow: 1;
    background: #181f2b;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    padding: 5px 10px;
    color: #ffffff;
    font-size: 12px;
    outline: none;
}
.ai-input:focus {
    border-color: var(--accent-blue);
}
.ai-content-area {
    min-height: 280px;
    max-height: 55vh;
    overflow-y: auto;
    background: #090d14;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    padding: 16px;
    font-size: 13px;
    line-height: 1.6;
    color: #f1f5f9;
    user-select: text;
}
.ai-placeholder {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100%;
    min-height: 240px;
    color: var(--text-secondary);
    text-align: center;
    gap: 12px;
}
.ai-icon-large {
    font-size: 40px;
}
.ai-step-card {
    background: #141b27;
    border-left: 3px solid var(--accent-blue);
    padding: 10px 14px;
    margin-bottom: 10px;
    border-radius: 0 6px 6px 0;
}
.ai-step-title {
    font-weight: 700;
    color: var(--accent-blue);
    font-size: 13px;
    margin-bottom: 4px;
}
.ai-answer-box {
    background: rgba(46, 204, 113, 0.12);
    border: 1.5px solid #2ecc71;
    border-radius: 6px;
    padding: 12px 16px;
    margin-top: 12px;
    font-weight: 700;
    color: #4ade80;
    font-size: 14px;
}
.ai-task-card {
    background: #141b27;
    border: 1px solid #334155;
    border-radius: 6px;
    padding: 12px 14px;
    margin-bottom: 12px;
}
.ai-task-card h4 {
    color: #c084fc;
    margin-bottom: 8px;
    font-size: 18px;
}

/* КОНТЕКСТНОЕ МЕНЮ (ПРАВЫЙ КЛИК ПО КАРТИНКЕ / ХОЛСТУ) */
.custom-context-menu {
    position: fixed;
    z-index: 10005;
    background: #18202c;
    border: 1.5px solid var(--accent-blue);
    border-radius: 7px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.75);
    padding: 5px;
    min-width: 220px;
    display: flex;
    flex-direction: column;
    gap: 2px;
    animation: fadeIn 0.12s ease-out;
}

.context-menu-header {
    font-size: 10px;
    font-weight: 700;
    text-transform: uppercase;
    color: var(--accent-blue);
    padding: 4px 8px;
    letter-spacing: 0.5px;
}

.context-menu-item {
    background: transparent;
    border: none;
    color: #f1f5f9;
    padding: 7px 10px;
    border-radius: 4px;
    font-size: 12px;
    text-align: left;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 8px;
    transition: background 0.12s ease, transform 0.08s ease;
}

.context-menu-item:hover {
    background: #253346;
    color: #38bdf8;
    transform: translateX(2px);
}

.context-menu-item.ctx-danger {
    color: #fca5a5;
}
.context-menu-item.ctx-danger:hover {
    background: #451a1a;
    color: #ef4444;
}

.ctx-icon {
    font-size: 14px;
}

.context-menu-divider {
    height: 1px;
    background: var(--border-color);
    margin: 4px 0;
}

/* Toast popup notification */
.toast-popup {
    position: fixed;
    bottom: 24px;
    left: 50%;
    transform: translateX(-50%) translateY(50px);
    background: #0f172a;
    color: #f8fafc;
    padding: 10px 20px;
    border-radius: 8px;
    font-size: 13px;
    font-weight: 600;
    box-shadow: 0 10px 25px rgba(0,0,0,0.5);
    border: 1px solid #38bdf8;
    z-index: 10000;
    pointer-events: none;
    opacity: 0;
    transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
}

.toast-popup.show {
    opacity: 1;
    transform: translateX(-50%) translateY(0);
}

/* === МОДАЛЫ ИИ: ОБЕРТКА И ПРАВАЯ ВЕРТИКАЛЬНАЯ ПАНЕЛЬ ДЕЙСТВИЙ === */
.ai-modal-wrapper {
    display: flex;
    align-items: flex-start;
    gap: 14px;
    max-width: 98vw;
    animation: fadeIn 0.18s ease-out;
}

.ai-modal-window {
    width: 960px;
    max-width: calc(98vw - 160px);
}

.ai-modal-sidebar {
    display: flex;
    flex-direction: column;
    gap: 6px;
    padding-top: 1px;
    width: 118px;
    flex-shrink: 0;
}

.btn-sidebar-action {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 6px 9px;
    border-radius: 6px;
    font-size: 12px;
    font-weight: 600;
    cursor: pointer;
    border: none;
    outline: none;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.35);
    transition: all 0.12s cubic-bezier(0.16, 1, 0.3, 1);
    text-align: left;
    user-select: none;
}

.btn-sidebar-action:hover {
    transform: translateY(-1px) scale(1.02);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.5);
}

.btn-sidebar-action:active {
    transform: translateY(1px) scale(0.98);
}

.btn-sidebar-icon {
    font-size: 14px;
    flex-shrink: 0;
}

.btn-sidebar-text {
    line-height: 1.2;
}

/* Кнопка Вставить на новый лист */
.btn-sidebar-paste {
    background: linear-gradient(135deg, #0284c7 0%, #0369a1 100%);
    color: #ffffff;
    border: 1px solid #38bdf8;
}
.btn-sidebar-paste:hover {
    background: linear-gradient(135deg, #0ea5e9 0%, #0284c7 100%);
    border-color: #7dd3fc;
}

.btn-sidebar-purple {
    background: linear-gradient(135deg, #7c3aed 0%, #6d28d9 100%);
    color: #ffffff;
    border: 1px solid #c084fc;
}
.btn-sidebar-purple:hover {
    background: linear-gradient(135deg, #8b5cf6 0%, #7c3aed 100%);
    border-color: #e9d5ff;
}

/* Кнопка Копировать */
.btn-sidebar-copy {
    background: #1e293b;
    color: #f1f5f9;
    border: 1px solid #475569;
}
.btn-sidebar-copy:hover {
    background: #334155;
    border-color: #94a3b8;
    color: #38bdf8;
}

/* Кнопки DeepSeek и Алиса в боковой панели модалов */
.btn-sidebar-deepseek {
    background: linear-gradient(135deg, #1e3a8a 0%, #0c4a6e 100%);
    color: #ffffff;
    border: 1px solid #38bdf8;
}
.btn-sidebar-deepseek:hover {
    background: linear-gradient(135deg, #0284c7 0%, #1e40af 100%);
    border-color: #7dd3fc;
    box-shadow: 0 0 10px rgba(56, 189, 248, 0.4);
}

.btn-sidebar-alice {
    background: linear-gradient(135deg, #701a75 0%, #4c0519 100%);
    color: #ffffff;
    border: 1px solid #f472b6;
}
.btn-sidebar-alice:hover {
    background: linear-gradient(135deg, #a21caf 0%, #831843 100%);
    border-color: #fbcfe8;
    box-shadow: 0 0 10px rgba(244, 114, 182, 0.4);
}

/* Кнопки DeepSeek и Алиса в шапке */
.btn-deepseek {
    background: linear-gradient(135deg, #1e3a8a 0%, #172554 100%);
    border: 1.5px solid #38bdf8;
    color: #ffffff;
    font-weight: 700;
}
.btn-deepseek:hover {
    background: linear-gradient(135deg, #2563eb 0%, #1d4ed8 100%);
    box-shadow: 0 0 10px rgba(56, 189, 248, 0.5);
    transform: translateY(-1px);
}

.btn-alice {
    background: linear-gradient(135deg, #6b21a8 0%, #3b0764 100%);
    border: 1.5px solid #c084fc;
    color: #ffffff;
    font-weight: 700;
}
.btn-alice:hover {
    background: linear-gradient(135deg, #7e22ce 0%, #6b21a8 100%);
    box-shadow: 0 0 10px rgba(192, 132, 252, 0.5);
    transform: translateY(-1px);
}

/* Кнопка Закрыть */
.btn-sidebar-close {
    background: #271418;
    color: #fca5a5;
    border: 1px solid #7f1d1d;
    margin-top: 4px;
}
.btn-sidebar-close:hover {
    background: #450a0a;
    color: #fee2e2;
    border-color: #ef4444;
}

/* === КРАСИВОЕ ОФОРМЛЕНИЕ МАТЕМАТИЧЕСКИХ ВЫРАЖЕНИЙ (ДРОБИ, КОРНИ, СТЕПЕНИ) === */
.ai-content-area {
    min-height: 400px;
    max-height: 72vh;
    overflow-y: auto;
    background: #090d14;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 24px;
    font-size: 28px;
    line-height: 2.1;
    color: #f8fafc;
    user-select: text;
}

.math-expr {
    display: inline-flex;
    align-items: center;
    vertical-align: middle;
    font-family: "Cambria Math", "KaTeX_Main", "Times New Roman", serif;
    font-size: 1.3em;
    color: #38bdf8;
    background: rgba(56, 189, 248, 0.12);
    padding: 4px 12px;
    border-radius: 6px;
    border: 1.5px solid rgba(56, 189, 248, 0.4);
    letter-spacing: 0.02em;
    margin: 3px 6px;
    white-space: nowrap;
    font-weight: 700;
}

sup {
    font-size: 0.65em;
    vertical-align: super;
    line-height: 0;
    position: relative;
    top: -0.45em;
    font-weight: 700;
    margin-left: 1px;
}

sub {
    font-size: 0.65em;
    vertical-align: sub;
    line-height: 0;
    position: relative;
    bottom: -0.25em;
    font-weight: 700;
    margin-left: 1px;
}

/* ОБЫКНОВЕННАЯ ВЕРТИКАЛЬНАЯ ДРОБЬ С ЧЕТКОЙ ГОРИЗОНТАЛЬНОЙ ЛИНИЕЙ */
.math-frac {
    display: inline-flex;
    flex-direction: column;
    vertical-align: middle;
    text-align: center;
    padding: 0 7px;
    margin: 0 5px;
    font-size: 0.96em;
}

.math-num {
    display: block;
    border-bottom: 3px solid currentColor;
    padding-bottom: 2px;
    line-height: 1.15;
    text-align: center;
}

.math-den {
    display: block;
    padding-top: 4px;
    line-height: 1.15;
    text-align: center;
}

/* ПОЛНЫЙ КВАДРАТНЫЙ КОРЕНЬ С ЗНАКОМ И СПЛОШНОЙ ВЕРХНЕЙ КРЫШЕЙ */
.math-sqrt {
    display: inline-flex;
    align-items: stretch;
    vertical-align: middle;
    margin: 0 5px;
    position: relative;
}

.math-sqrt-sign {
    font-size: 1.5em;
    line-height: 0.95;
    margin-right: -1px;
    font-style: normal;
    display: inline-flex;
    align-items: center;
    font-weight: 400;
    transform: translateY(1px);
}

.math-sqrt-body {
    border-top: 3px solid currentColor;
    padding-top: 3px;
    padding-left: 6px;
    padding-right: 8px;
    display: inline-flex;
    align-items: center;
    margin-top: 2px;
}

.ai-step-card {
    background: #141c2b;
    border: 1.5px solid #2e3d56;
    border-left: 6px solid var(--accent-blue);
    border-radius: 8px;
    padding: 22px 28px;
    margin-bottom: 20px;
    color: #ffffff;
    font-size: 28px;
    line-height: 2.1;
}

.ai-step-title {
    font-size: 29px;
    font-weight: 700;
    color: #38bdf8;
    margin-bottom: 14px;
    display: flex;
    align-items: center;
    gap: 10px;
}

.ai-answer-box {
    background: rgba(34, 197, 94, 0.18);
    border: 2.5px solid #22c55e;
    border-radius: 8px;
    padding: 22px 28px;
    margin-top: 20px;
    color: #4ade80;
    font-size: 29px;
    font-weight: 700;
}

.ai-task-card {
    background: #141c2b;
    border: 1.5px solid #2e3d56;
    border-radius: 8px;
    padding: 24px 30px;
    margin-bottom: 22px;
    color: #ffffff;
}

.ai-task-card h4 {
    color: #c084fc;
    font-size: 29px;
    font-weight: 700;
    margin-bottom: 16px;
}

.ai-task-card p {
    margin: 14px 0;
    font-size: 28px;
    line-height: 2.1;
    color: #ffffff;
}

/* ==========================================================================
   21. БАЗА ЗНАНИЙ, ФОРМУЛ И ЗАДАНИЙ (5–11 КЛАССЫ)
   ========================================================================== */
.btn-theory {
    background: linear-gradient(135deg, #7c3aed 0%, #6d28d9 100%);
    border: 1.5px solid #a78bfa;
    color: #ffffff;
    font-weight: 700;
    font-size: 11.5px;
    padding: 3px 8px;
    border-radius: 4px;
    cursor: pointer;
    transition: all 0.15s ease;
    display: inline-flex;
    align-items: center;
    gap: 4px;
    white-space: nowrap;
}
.btn-theory:hover {
    background: linear-gradient(135deg, #8b5cf6 0%, #7c3aed 100%);
    border-color: #c4b5fd;
    box-shadow: 0 0 10px rgba(167, 139, 250, 0.5);
    transform: translateY(-1px);
}

.kb-modal-window {
    width: 1060px;
    max-width: 96vw;
    height: 85vh;
    max-height: 880px;
    background: #0f1622;
    border: 1.5px solid #8b5cf6;
    border-radius: 10px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.9);
    display: flex;
    flex-direction: column;
    overflow: hidden;
    color: #e2e8f0;
}

.kb-modal-header {
    background: #090d14;
    padding: 12px 18px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    border-bottom: 1.5px solid #8b5cf6;
    gap: 16px;
    flex-shrink: 0;
}

.kb-header-title {
    font-size: 16px;
    font-weight: 700;
    color: #c4b5fd;
    display: flex;
    align-items: center;
    gap: 8px;
}

.kb-search-input {
    background: #182234;
    border: 1.5px solid #334155;
    border-radius: 6px;
    padding: 6px 12px;
    color: #ffffff;
    font-size: 13px;
    outline: none;
    width: 280px;
    transition: all 0.2s;
}
.kb-search-input:focus {
    border-color: #a78bfa;
    box-shadow: 0 0 8px rgba(167, 139, 250, 0.3);
}

.kb-grades-bar {
    display: flex;
    gap: 6px;
    background: #090d14;
    padding: 8px 18px;
    border-bottom: 1px solid #1e293b;
    overflow-x: auto;
    flex-shrink: 0;
}

.kb-subtopics-bar {
    display: flex;
    gap: 6px;
    background: #0d1420;
    padding: 6px 18px;
    border-bottom: 1px solid #1e293b;
    overflow-x: auto;
    flex-shrink: 0;
    flex-wrap: wrap;
}

.kb-subtopic-chip {
    background: #182234;
    border: 1px solid #283548;
    color: #cbd5e1;
    padding: 3px 10px;
    border-radius: 12px;
    font-size: 11.5px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.15s ease;
    white-space: nowrap;
}
.kb-subtopic-chip:hover {
    background: #2563eb;
    color: #ffffff;
    border-color: #38bdf8;
}
.kb-subtopic-chip.active {
    background: #7c3aed;
    color: #ffffff;
    border-color: #a78bfa;
}

.kb-grade-btn {
    background: #141c2b;
    border: 1px solid #283548;
    color: #94a3b8;
    padding: 6px 14px;
    border-radius: 6px;
    font-size: 12.5px;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.15s ease;
    white-space: nowrap;
}
.kb-grade-btn:hover {
    background: #1e293b;
    color: #c4b5fd;
    border-color: #8b5cf6;
}
.kb-grade-btn.active {
    background: #7c3aed;
    color: #ffffff;
    border-color: #a78bfa;
    box-shadow: 0 0 10px rgba(124, 58, 237, 0.4);
}

.kb-body {
    flex: 1 1 auto;
    min-height: 0;
    max-height: calc(85vh - 120px);
    overflow-y: auto !important;
    overflow-x: hidden;
    padding: 16px 20px;
    display: block;
    -webkit-overflow-scrolling: touch;
    scroll-behavior: smooth;
}

.kb-body::-webkit-scrollbar {
    width: 10px;
}
.kb-body::-webkit-scrollbar-track {
    background: #090d14;
    border-radius: 5px;
}
.kb-body::-webkit-scrollbar-thumb {
    background: #475569;
    border-radius: 5px;
    border: 2px solid #090d14;
}
.kb-body::-webkit-scrollbar-thumb:hover {
    background: #8b5cf6;
}

.kb-topic-card {
    background: #141c2b;
    border: 1.5px solid #233147;
    border-radius: 8px;
    overflow: hidden;
    transition: border-color 0.2s;
    margin-bottom: 14px;
}
.kb-topic-card:hover {
    border-color: #8b5cf6;
}
.kb-topic-card.collapsed .kb-topic-body {
    display: none;
}

.kb-topic-header {
    background: #0d1420;
    padding: 10px 16px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    border-bottom: 1px solid #1e293b;
    cursor: pointer;
    user-select: none;
    transition: background 0.15s ease;
}
.kb-topic-header:hover {
    background: #182234;
}

.kb-topic-title {
    font-size: 15px;
    font-weight: 700;
    color: #38bdf8;
    display: flex;
    align-items: center;
    gap: 8px;
}

.kb-chevron {
    font-size: 13px;
    color: #94a3b8;
    transition: transform 0.2s ease;
    display: inline-block;
}
.kb-topic-card.collapsed .kb-chevron {
    transform: rotate(-90deg);
}

.kb-topic-body {
    padding: 14px 16px;
    display: flex;
    flex-direction: column;
    gap: 14px;
}

.kb-section-title {
    font-size: 13px;
    font-weight: 700;
    color: #a78bfa;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: 6px;
    display: flex;
    align-items: center;
    gap: 6px;
}

.kb-theory-list {
    display: flex;
    flex-direction: column;
    gap: 6px;
    font-size: 13.5px;
    line-height: 1.6;
    color: #e2e8f0;
}

.kb-theory-item {
    background: #0f1622;
    padding: 8px 12px;
    border-radius: 6px;
    border-left: 3px solid #38bdf8;
}

.kb-formulas-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 8px;
}

.kb-formula-box {
    background: #090d14;
    border: 1px solid #2e3d56;
    border-radius: 6px;
    padding: 8px 12px;
    font-size: 14px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 8px;
}

.kb-examples-list {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.kb-example-card {
    background: #0f1726;
    border: 1px solid #233147;
    border-radius: 6px;
    padding: 10px 14px;
    font-size: 13px;
    line-height: 1.5;
}

.kb-example-task {
    font-weight: 700;
    color: #f8fafc;
    margin-bottom: 6px;
}

.kb-example-sol {
    color: #cbd5e1;
    background: #090d14;
    padding: 8px 10px;
    border-radius: 4px;
    margin-bottom: 6px;
    white-space: pre-wrap;
}

.kb-example-ans {
    color: #4ade80;
    font-weight: 700;
}

.kb-practice-list {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.kb-practice-item {
    background: #0d1420;
    border: 1px solid #1e293b;
    border-radius: 6px;
    padding: 8px 12px;
    font-size: 13px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
}

.kb-action-btns {
    display: flex;
    align-items: center;
    gap: 6px;
    flex-shrink: 0;
}

.kb-act-btn {
    background: #1e293b;
    border: 1px solid #334155;
    color: #cbd5e1;
    border-radius: 4px;
    padding: 4px 8px;
    font-size: 11.5px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.15s ease;
    white-space: nowrap;
}
.kb-act-btn:hover {
    background: #2563eb;
    color: #ffffff;
    border-color: #38bdf8;
}
.kb-act-solve {
    background: #064e3b;
    color: #6ee7b7;
    border-color: #059669;
}
.kb-act-solve:hover {
    background: #059669;
    color: #ffffff;
}
.kb-act-board {
    background: #0369a1;
    color: #bae6fd;
    border-color: #0284c7;
}
.kb-act-board:hover {
    background: #0284c7;
    color: #ffffff;
}