/* ========================================
   Realtime Whiteboard — Clean Light UI
   ======================================== */
:root {
    --primary: #2563EB;
    --primary-hover: #1D4ED8;
    --primary-light: #DBEAFE;
    --secondary: #3B82F6;
    --accent: #DBEAFE;
    --bg: #FFFFFF;
    --bg-ui: #F8FAFC;
    --bg-hover: #F1F5F9;
    --border: #E2E8F0;
    --border-hover: #CBD5E1;
    --text: #1E293B;
    --text-secondary: #64748B;
    --text-muted: #94A3B8;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 4px 16px rgba(0, 0, 0, 0.1);
    --radius: 12px;
    --radius-sm: 8px;
    --font: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --transition: 0.2s ease;
}

/* Dark Mode */
[data-theme="dark"] {
    --bg: #1a1a2e;
    --bg-ui: #16213e;
    --bg-hover: #1f2b47;
    --border: #2d3a5a;
    --border-hover: #3d4f7a;
    --text: #E2E8F0;
    --text-secondary: #94A3B8;
    --text-muted: #64748B;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 4px 16px rgba(0, 0, 0, 0.4);
    --primary-light: rgba(37, 99, 235, 0.2);
}

[data-theme="dark"] canvas {
    background: #1e1e2f;
}

*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: var(--font);
    background: var(--bg);
    color: var(--text);
    overflow: hidden;
    height: 100vh;
}

/* Layout */
.app-container {
    display: grid;
    grid-template-columns: 54px 1fr;
    grid-template-rows: 48px 1fr;
    height: 100vh;
}

/* Toolbar — Left */
.toolbar {
    grid-row: 1 / -1;
    grid-column: 1;
    background: var(--bg-ui);
    border-right: 1px solid var(--border);
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 0.5rem 0;
    gap: 0.25rem;
    z-index: 10;
}

.toolbar-group {
    display: flex;
    flex-direction: column;
    gap: 2px;
    width: 100%;
    padding: 0 4px;
}

.toolbar-divider {
    height: 1px;
    width: 70%;
    background: var(--border);
    margin: 0.3rem 0;
}

.tool-btn,
.action-btn {
    width: 42px;
    height: 38px;
    display: flex;
    align-items: center;
    justify-content: center;
    border: none;
    background: transparent;
    border-radius: var(--radius-sm);
    font-size: 1rem;
    cursor: pointer;
    transition: all var(--transition);
    color: var(--text-secondary);
}

.tool-btn:hover,
.action-btn:hover {
    background: var(--bg-hover);
}

.tool-btn.active {
    background: var(--primary-light);
    color: var(--primary);
    box-shadow: inset 0 0 0 1.5px var(--primary);
}

/* Top Bar */
.top-bar {
    grid-row: 1;
    grid-column: 2;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 1rem;
    background: var(--bg-ui);
    border-bottom: 1px solid var(--border);
    z-index: 10;
    gap: 0.75rem;
}

.top-left {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.app-title {
    font-weight: 700;
    font-size: 0.85rem;
    color: var(--text);
}

.zoom-level {
    font-size: 0.72rem;
    color: var(--text-muted);
    background: var(--bg-hover);
    padding: 0.15rem 0.45rem;
    border-radius: 4px;
    font-weight: 600;
}

.top-center {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.color-row {
    display: flex;
    gap: 4px;
    align-items: center;
}

.color-swatch {
    width: 22px;
    height: 22px;
    border-radius: 50%;
    border: 2px solid transparent;
    cursor: pointer;
    transition: all var(--transition);
}

.color-swatch:hover {
    transform: scale(1.15);
}

.color-swatch.active {
    border-color: var(--primary);
    box-shadow: 0 0 0 2px var(--primary-light);
}

input[type="color"] {
    width: 22px;
    height: 22px;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    padding: 0;
}

.brush-controls {
    display: flex;
    align-items: center;
    gap: 0.4rem;
    font-size: 0.75rem;
    color: var(--text-secondary);
}

.brush-controls input[type="range"] {
    width: 70px;
    accent-color: var(--primary);
}

.brush-controls span {
    font-weight: 600;
    min-width: 16px;
    color: var(--primary);
}

.top-right {
    display: flex;
    gap: 0.35rem;
}

.btn-sm {
    padding: 0.3rem 0.6rem;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    background: transparent;
    font-family: var(--font);
    font-size: 0.75rem;
    cursor: pointer;
    transition: all var(--transition);
    color: var(--text-secondary);
}

.btn-sm:hover {
    background: var(--bg-hover);
    border-color: var(--border-hover);
    color: var(--text);
}

/* Canvas */
.canvas-area {
    grid-row: 2;
    grid-column: 2;
    position: relative;
    overflow: hidden;
    background: var(--bg);
    cursor: crosshair;
}

canvas {
    display: block;
    background: var(--bg);
}

.stickies-layer {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    pointer-events: none;
}

/* Sticky Notes */
.sticky-note {
    position: absolute;
    width: 180px;
    min-height: 100px;
    padding: 0.6rem;
    background: #FEF3C7;
    border: 1px solid #F59E0B;
    border-radius: var(--radius-sm);
    box-shadow: var(--shadow-lg);
    font-family: var(--font);
    font-size: 0.8rem;
    pointer-events: all;
    cursor: grab;
    user-select: none;
    display: flex;
    flex-direction: column;
}

.sticky-note .sticky-content {
    flex: 1;
    outline: none;
    min-height: 60px;
    line-height: 1.4;
    color: #92400E;
}

.sticky-note .sticky-close {
    align-self: flex-end;
    background: none;
    border: none;
    cursor: pointer;
    font-size: 0.8rem;
    opacity: 0.5;
}

.sticky-note .sticky-close:hover {
    opacity: 1;
}

/* Room Panel */
.room-panel {
    position: fixed;
    right: 0;
    top: 0;
    bottom: 0;
    width: 280px;
    background: var(--bg-ui);
    border-left: 1px solid var(--border);
    padding: 1rem;
    overflow-y: auto;
    z-index: 20;
    box-shadow: var(--shadow-lg);
    transition: transform 0.3s ease;
}

.room-panel.hidden {
    transform: translateX(100%);
}

.room-panel h3 {
    font-size: 0.95rem;
    font-weight: 700;
    margin-bottom: 0.75rem;
}

.room-panel h4 {
    font-size: 0.8rem;
    font-weight: 600;
    margin-bottom: 0.35rem;
    color: var(--text-secondary);
}

.room-section {
    margin-bottom: 0.75rem;
}

.room-section label {
    display: block;
    font-size: 0.75rem;
    font-weight: 500;
    color: var(--text-secondary);
    margin-bottom: 0.25rem;
}

.room-section input[type="text"],
.room-section textarea {
    width: 100%;
    padding: 0.4rem 0.6rem;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    font-family: var(--font);
    font-size: 0.8rem;
    background: var(--bg);
    color: var(--text);
    outline: none;
    transition: border-color var(--transition);
    resize: vertical;
}

.room-section input:focus,
.room-section textarea:focus {
    border-color: var(--primary);
}

.join-row {
    display: flex;
    flex-direction: column;
    gap: 0.35rem;
}

.room-code-row {
    display: flex;
    align-items: center;
    gap: 0.35rem;
    margin-top: 0.35rem;
}

.room-code {
    font-family: monospace;
    font-size: 0.75rem;
    background: var(--bg-hover);
    padding: 0.2rem 0.5rem;
    border-radius: 4px;
    word-break: break-all;
}

.btn-primary {
    width: 100%;
    padding: 0.5rem;
    border: none;
    border-radius: var(--radius-sm);
    background: var(--primary);
    color: white;
    font-family: var(--font);
    font-size: 0.8rem;
    font-weight: 600;
    cursor: pointer;
    transition: background var(--transition);
}

.btn-primary:hover {
    background: var(--primary-hover);
}

.btn-xs {
    padding: 0.25rem 0.5rem;
    border: 1px solid var(--border);
    border-radius: 4px;
    background: transparent;
    font-size: 0.72rem;
    cursor: pointer;
    color: var(--text-secondary);
}

.btn-xs:hover {
    background: var(--bg-hover);
}

.users-list {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
}

.user-item {
    font-size: 0.78rem;
    padding: 0.3rem 0.5rem;
    background: var(--bg-hover);
    border-radius: 4px;
    color: var(--text-secondary);
}

.user-item.self {
    color: var(--primary);
    font-weight: 600;
}

/* Toast */
.toast {
    position: fixed;
    bottom: 1.5rem;
    left: 50%;
    transform: translateX(-50%) translateY(20px);
    padding: 0.55rem 1rem;
    background: var(--bg-ui);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    color: var(--text);
    font-size: 0.8rem;
    font-weight: 500;
    box-shadow: var(--shadow-lg);
    opacity: 0;
    transition: all 0.3s ease;
    z-index: 100;
    pointer-events: none;
}

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

.hidden {
    display: none !important;
}

/* Responsive */
@media (max-width: 640px) {
    .app-container {
        grid-template-columns: 44px 1fr;
    }

    .tool-btn,
    .action-btn {
        width: 36px;
        height: 34px;
        font-size: 0.85rem;
    }

    .top-center {
        display: none;
    }

    .room-panel {
        width: 240px;
    }
}