:root {
    --bg: #0f172a;
    --panel-bg: rgba(30, 41, 59, 0.88);
    --panel-border: rgba(255, 255, 255, 0.08);
    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --accent: #22d3ee;
}

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

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

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

/* ── Floating panel ── */
#ui-panel {
    position: absolute;
    top: 20px;
    left: 20px;
    width: 240px;
    background: var(--panel-bg);
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
    border: 1px solid var(--panel-border);
    border-radius: 16px;
    padding: 20px;
    box-shadow: 0 4px 24px rgba(0, 0, 0, 0.3);
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.back-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 13px;
    transition: color 0.2s;
}
.back-link:hover { color: var(--text-primary); }

h1 {
    font-size: 20px;
    font-weight: 600;
    color: var(--text-primary);
}

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

.section-label {
    font-size: 10px;
    font-weight: 600;
    letter-spacing: 0.09em;
    text-transform: uppercase;
    color: var(--text-secondary);
}

/* ── Number control ── */
.number-control {
    display: flex;
    align-items: center;
    gap: 10px;
}

.adjust-btn {
    width: 36px;
    height: 36px;
    border-radius: 8px;
    border: 1px solid var(--panel-border);
    background: rgba(255, 255, 255, 0.06);
    color: var(--text-primary);
    font-size: 1.2rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background 0.15s, transform 0.1s;
    user-select: none;
    flex-shrink: 0;
}
.adjust-btn:hover { background: rgba(255, 255, 255, 0.13); }
.adjust-btn:active { transform: scale(0.9); }

.number-display {
    flex: 1;
    text-align: center;
    font-size: 2rem;
    font-weight: 600;
    color: var(--text-primary);
    line-height: 1;
}

/* ── Toggle ── */
.toggle-label {
    display: flex;
    align-items: center;
    gap: 10px;
    cursor: pointer;
    user-select: none;
    font-size: 0.875rem;
    color: var(--text-secondary);
    transition: color 0.2s;
}
.toggle-label:hover { color: var(--text-primary); }

.toggle-label input[type="checkbox"] { display: none; }

.toggle-track {
    width: 44px;
    height: 24px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 12px;
    position: relative;
    flex-shrink: 0;
    transition: background 0.2s;
}
.toggle-label input:checked + .toggle-track {
    background: var(--accent);
}
.toggle-thumb {
    position: absolute;
    top: 3px;
    left: 3px;
    width: 18px;
    height: 18px;
    background: white;
    border-radius: 50%;
    transition: transform 0.2s;
    box-shadow: 0 1px 4px rgba(0, 0, 0, 0.3);
}
.toggle-label input:checked + .toggle-track .toggle-thumb {
    transform: translateX(20px);
}