:root {
    --bg: #0f172a;
    --panel-bg: rgba(30, 41, 59, 0.7);
    --panel-border: rgba(255, 255, 255, 0.1);
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --accent: #3b82f6;
    --accent-hover: #2563eb;
    --font-family: 'Inter', sans-serif;
}

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

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

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

#ui-panel {
    position: absolute;
    top: 20px;
    left: 20px;
    width: 260px;
    background: var(--panel-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid var(--panel-border);
    border-radius: 16px;
    padding: 20px;
    box-shadow: 0 4px 24px rgba(0, 0, 0, 0.2);
    display: flex;
    flex-direction: column;
    gap: 12px;
    max-height: calc(100vh - 40px);
    overflow-y: auto;
}

.back-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 14px;
    display: inline-flex;
    align-items: center;
    gap: 4px;
    transition: color 0.2s;
}

.back-link:hover {
    color: var(--accent);
}

h1 {
    font-size: 18px;
    font-weight: 600;
    color: var(--text-primary);
}

hr {
    border: none;
    height: 1px;
    background-color: var(--panel-border);
    width: 100%;
}

.section-label {
    font-size: 11px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--text-secondary);
}

.tool-group {
    display: flex;
    gap: 6px;
}

.tool-btn {
    flex: 1;
    background: rgba(255, 255, 255, 0.06);
    border: 1px solid var(--panel-border);
    border-radius: 8px;
    padding: 8px 4px;
    color: var(--text-secondary);
    font-size: 16px;
    cursor: pointer;
    transition: background 0.2s, border-color 0.2s, color 0.2s;
}

.tool-btn:hover {
    background: rgba(255, 255, 255, 0.12);
    color: var(--text-primary);
}

.tool-btn.active {
    background: var(--accent);
    border-color: var(--accent);
    color: white;
}

.mirror-controls {
    display: flex;
    gap: 6px;
    flex-wrap: wrap;
}

.text-btn {
    background: rgba(255, 255, 255, 0.08);
    border: 1px solid var(--panel-border);
    border-radius: 8px;
    padding: 8px 14px;
    color: var(--text-primary);
    font-weight: 500;
    font-family: var(--font-family);
    cursor: pointer;
    transition: background 0.2s, border-color 0.2s;
    font-size: 13px;
}

.text-btn:hover {
    background: rgba(255, 255, 255, 0.14);
    border-color: rgba(255, 255, 255, 0.2);
}

.text-btn.small {
    padding: 6px 10px;
    font-size: 12px;
    flex: 1;
}

.text-btn.full-width {
    width: 100%;
    text-align: center;
}

.text-btn.primary {
    background: linear-gradient(135deg, #8b5cf6, #ec4899);
    border-color: transparent;
    color: white;
    font-weight: 600;
    font-size: 15px;
    padding: 10px 14px;
}

.text-btn.primary:hover {
    box-shadow: 0 0 16px 4px rgba(139, 92, 246, 0.5);
    background: linear-gradient(135deg, #7c3aed, #db2777);
}

@keyframes button-pulse {
    0%, 100% { box-shadow: 0 0 8px 2px rgba(236, 72, 153, 0.7); }
    50%       { box-shadow: 0 0 28px 8px rgba(139, 92, 246, 0.9); }
}

.text-btn.primary.animating {
    animation: button-pulse 0.6s ease-in-out infinite;
}

.hint {
    font-size: 12px;
    color: var(--text-secondary);
    line-height: 1.5;
    min-height: 18px;
}

.toggle-row {
    display: flex;
    align-items: center;
    gap: 8px;
    cursor: pointer;
    user-select: none;
}

.toggle-row input[type="checkbox"] {
    appearance: none;
    -webkit-appearance: none;
    width: 32px;
    height: 18px;
    border-radius: 9px;
    background: rgba(255, 255, 255, 0.12);
    border: 1px solid var(--panel-border);
    position: relative;
    cursor: pointer;
    transition: background 0.2s, border-color 0.2s;
    flex-shrink: 0;
}

.toggle-row input[type="checkbox"]::after {
    content: '';
    position: absolute;
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: var(--text-secondary);
    top: 2px;
    left: 2px;
    transition: left 0.2s, background 0.2s;
}

.toggle-row input[type="checkbox"]:checked {
    background: var(--accent);
    border-color: var(--accent);
}

.toggle-row input[type="checkbox"]:checked::after {
    left: 16px;
    background: white;
}

.toggle-label-text {
    font-size: 13px;
    color: var(--text-secondary);
    transition: color 0.2s;
}

.toggle-row:has(input:checked) .toggle-label-text {
    color: var(--text-primary);
}

/* Scrollbar */
#ui-panel::-webkit-scrollbar {
    width: 4px;
}

#ui-panel::-webkit-scrollbar-track {
    background: transparent;
}

#ui-panel::-webkit-scrollbar-thumb {
    background: rgba(255, 255, 255, 0.1);
    border-radius: 4px;
}