/* ── Lights Out — Neon Violet Theme ── */
:root {
    --lo-accent: #7C3AED;
    --lo-accent-light: #A78BFA;
    --lo-accent-dark: #5B21B6;
    --lo-glow: rgba(167, 139, 250, 0.55);
    --lo-bg: #0B0820;
    --lo-surface: #16112E;
    --lo-surface-light: #221A40;
    --lo-text: #ECE9FA;
    --lo-text-dim: #9C8FCC;
    --lo-off: #1B1438;
    --lo-off-border: #2C2050;
    --lo-success: #34D399;
    --lo-gold: #FACC15;
    --lo-danger: #F87171;
}

/* ── Layout ── */
.lo-layout {
    display: flex;
    justify-content: center;
    gap: 20px;
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
    min-height: calc(100vh - 80px);
}
.ad-slot { width: 160px; flex-shrink: 0; }
.ad-slot--left, .ad-slot--right { display: flex; align-items: flex-start; }
.ad-placeholder--vertical {
    width: 160px; height: 600px;
    background: var(--lo-surface);
    border: 1px dashed var(--lo-text-dim);
    display: flex; align-items: center; justify-content: center;
    color: var(--lo-text-dim); font-size: 12px; border-radius: 8px;
}

#lightsout-app {
    flex: 1;
    max-width: 720px;
    min-width: 320px;
    color: var(--lo-text);
}

/* ── Screens ── */
.screen { display: none; }
.screen.active { display: block; animation: loFade 0.3s ease; }
@keyframes loFade {
    from { opacity: 0; transform: translateY(8px); }
    to { opacity: 1; transform: translateY(0); }
}

/* ── Header ── */
.lo-header {
    text-align: center;
    padding: 36px 0 24px;
}
.lo-logo { margin-bottom: 14px; }
.lo-logo-grid {
    display: inline-grid;
    grid-template-columns: repeat(3, 22px);
    gap: 4px;
    padding: 10px;
    background: var(--lo-surface);
    border-radius: 10px;
    border: 1px solid var(--lo-off-border);
}
.lo-logo-grid span {
    width: 22px; height: 22px;
    border-radius: 5px;
    background: var(--lo-off);
    transition: background 0.4s ease, box-shadow 0.4s ease;
}
.lo-logo-grid span.on {
    background: var(--lo-accent);
    box-shadow: 0 0 12px var(--lo-glow);
    animation: loPulse 2.4s ease-in-out infinite;
}
@keyframes loPulse {
    0%, 100% { box-shadow: 0 0 8px var(--lo-glow); }
    50% { box-shadow: 0 0 18px var(--lo-glow); }
}
.lo-header h1 {
    font-family: 'Syne', sans-serif;
    font-size: 2.6rem;
    font-weight: 800;
    color: var(--lo-accent-light);
    letter-spacing: 4px;
    margin: 0;
    text-shadow: 0 0 26px var(--lo-glow);
}
.subtitle {
    color: var(--lo-text-dim);
    font-size: 1rem;
    margin-top: 8px;
}

/* ── Cards ── */
.card {
    background: var(--lo-surface);
    border-radius: 14px;
    padding: 20px;
    margin-bottom: 16px;
    border: 1px solid var(--lo-surface-light);
}
.card__title {
    font-family: 'Syne', sans-serif;
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 2px;
    color: var(--lo-accent-light);
    margin-bottom: 14px;
}

/* ── Difficulty ── */
.difficulty-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
}
.diff-btn {
    background: var(--lo-surface-light);
    border: 1.5px solid transparent;
    color: var(--lo-text);
    padding: 14px 8px;
    border-radius: 10px;
    cursor: pointer;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 4px;
    transition: transform 0.15s ease, border-color 0.15s ease, background 0.15s ease;
    font-family: 'DM Sans', sans-serif;
    font-size: 0.85rem;
}
.diff-btn:hover { transform: translateY(-2px); border-color: var(--lo-accent); }
.diff-btn.selected {
    background: linear-gradient(135deg, var(--lo-accent-dark), var(--lo-accent));
    border-color: var(--lo-accent-light);
    box-shadow: 0 0 16px rgba(124, 58, 237, 0.45);
}
.diff-icon {
    font-family: 'JetBrains Mono', monospace;
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--lo-accent-light);
}
.diff-btn.selected .diff-icon { color: #fff; }
.diff-desc { font-size: 0.72rem; color: var(--lo-text-dim); }
.diff-btn.selected .diff-desc { color: rgba(255,255,255,0.85); }

/* ── Rules ── */
.lo-rules {
    margin: 0;
    padding-left: 1.1rem;
    color: var(--lo-text-dim);
    font-size: 0.92rem;
    line-height: 1.6;
}
.lo-rules li + li { margin-top: 6px; }

/* ── Buttons ── */
.btn {
    font-family: 'DM Sans', sans-serif;
    font-weight: 600;
    border-radius: 10px;
    border: none;
    cursor: pointer;
    padding: 12px 22px;
    transition: transform 0.12s ease, box-shadow 0.12s ease, background 0.15s ease;
    font-size: 0.95rem;
}
.btn:hover { transform: translateY(-1px); }
.btn--primary {
    background: linear-gradient(135deg, var(--lo-accent), var(--lo-accent-light));
    color: #fff;
    box-shadow: 0 6px 18px rgba(124, 58, 237, 0.35);
}
.btn--primary:hover { box-shadow: 0 10px 24px rgba(124, 58, 237, 0.5); }
.btn--outline {
    background: transparent;
    border: 1.5px solid var(--lo-accent);
    color: var(--lo-accent-light);
}
.btn--outline:hover { background: rgba(124, 58, 237, 0.12); }
.btn--ghost { background: transparent; color: var(--lo-text-dim); }
.btn--ghost:hover { color: var(--lo-accent-light); }
.btn--lg { padding: 16px 36px; font-size: 1.05rem; }
.btn--sm { padding: 8px 14px; font-size: 0.85rem; }

.menu-actions {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    margin-top: 18px;
}

/* ── Game HUD ── */
#game-hud {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
    background: var(--lo-surface);
    padding: 14px;
    border-radius: 12px;
    border: 1px solid var(--lo-surface-light);
    margin-bottom: 18px;
}
.hud__cell {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 2px;
}
.hud__label {
    font-size: 0.7rem;
    text-transform: uppercase;
    letter-spacing: 1.5px;
    color: var(--lo-text-dim);
}
.hud__value {
    font-family: 'JetBrains Mono', monospace;
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--lo-accent-light);
}
.hud__timer { color: var(--lo-gold); }

/* ── Board ── */
.lo-board-area {
    display: flex;
    justify-content: center;
    padding: 16px 0;
}
.lo-board {
    display: grid;
    gap: 8px;
    padding: 14px;
    background: var(--lo-surface);
    border-radius: 16px;
    border: 1px solid var(--lo-surface-light);
    box-shadow: 0 12px 36px rgba(0, 0, 0, 0.45);
}
.lo-cell {
    width: 64px;
    height: 64px;
    background: var(--lo-off);
    border: 1.5px solid var(--lo-off-border);
    border-radius: 12px;
    cursor: pointer;
    transition: transform 0.08s ease, background 0.25s ease, box-shadow 0.25s ease;
    position: relative;
    overflow: hidden;
}
.lo-cell:hover { transform: scale(0.96); }
.lo-cell.on {
    background: linear-gradient(135deg, var(--lo-accent), var(--lo-accent-light));
    border-color: var(--lo-accent-light);
    box-shadow:
        0 0 18px var(--lo-glow),
        inset 0 0 12px rgba(255, 255, 255, 0.25);
}
.lo-cell.on::after {
    content: "";
    position: absolute;
    inset: 8px;
    border-radius: 8px;
    background: radial-gradient(circle at 30% 30%, rgba(255,255,255,0.5), transparent 60%);
    pointer-events: none;
}
.lo-cell.flash {
    animation: loFlash 0.32s ease;
}
@keyframes loFlash {
    0% { transform: scale(0.85); }
    60% { transform: scale(1.08); }
    100% { transform: scale(1); }
}

/* size variants */
.lo-board[data-size="3"] .lo-cell { width: 86px; height: 86px; }
.lo-board[data-size="4"] .lo-cell { width: 74px; height: 74px; }
.lo-board[data-size="5"] .lo-cell { width: 64px; height: 64px; }
.lo-board[data-size="6"] .lo-cell { width: 54px; height: 54px; }

/* ── Actions ── */
.lo-actions {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 10px;
    margin-top: 16px;
}

/* ── Result Card ── */
.result-card, .lb-card {
    background: var(--lo-surface);
    border-radius: 16px;
    padding: 36px 28px;
    border: 1px solid var(--lo-surface-light);
    text-align: center;
    max-width: 480px;
    margin: 40px auto;
    box-shadow: 0 18px 36px rgba(0, 0, 0, 0.4);
}
.result-card h2 {
    font-family: 'Syne', sans-serif;
    font-size: 2rem;
    color: var(--lo-accent-light);
    letter-spacing: 4px;
    margin: 0 0 12px;
    text-shadow: 0 0 24px var(--lo-glow);
}
.result-score {
    font-family: 'JetBrains Mono', monospace;
    font-size: 3rem;
    font-weight: 700;
    color: var(--lo-gold);
    margin: 8px 0;
}
.result-detail {
    color: var(--lo-text-dim);
    font-size: 0.95rem;
    margin-bottom: 18px;
    line-height: 1.6;
}
#nickname {
    width: 100%;
    padding: 12px 14px;
    border-radius: 10px;
    background: var(--lo-bg);
    color: var(--lo-text);
    border: 1.5px solid var(--lo-surface-light);
    font-family: 'DM Sans', sans-serif;
    font-size: 0.95rem;
    margin-bottom: 12px;
    box-sizing: border-box;
}
#nickname:focus { outline: none; border-color: var(--lo-accent); }
.result-actions {
    display: flex;
    gap: 10px;
    justify-content: center;
    margin-bottom: 10px;
}

/* ── Leaderboard ── */
.lb-card h2 {
    font-family: 'Syne', sans-serif;
    color: var(--lo-accent-light);
    letter-spacing: 4px;
    margin-bottom: 18px;
    text-shadow: 0 0 24px var(--lo-glow);
}
#leaderboard-list {
    list-style: none;
    padding: 0;
    margin: 0 0 16px;
    text-align: left;
    counter-reset: lb;
}
#leaderboard-list li {
    counter-increment: lb;
    display: flex;
    justify-content: space-between;
    padding: 10px 14px;
    background: var(--lo-bg);
    margin-bottom: 6px;
    border-radius: 8px;
    border: 1px solid var(--lo-surface-light);
    font-family: 'DM Sans', sans-serif;
}
#leaderboard-list li::before {
    content: counter(lb);
    color: var(--lo-accent-light);
    font-weight: 700;
    margin-right: 10px;
    min-width: 24px;
}
#leaderboard-list li:nth-child(1) { border-color: var(--lo-gold); }
#leaderboard-list li:nth-child(1)::before { color: var(--lo-gold); }
#leaderboard-list .lb-score {
    font-family: 'JetBrains Mono', monospace;
    color: var(--lo-accent-light);
    font-weight: 600;
}

/* ── Responsive ── */
@media (max-width: 900px) {
    .lo-layout { flex-direction: column; padding: 12px; }
    .ad-slot { width: 100%; }
    .ad-placeholder--vertical { width: 100%; height: 90px; }
    .difficulty-grid { grid-template-columns: repeat(2, 1fr); }
    .lo-header h1 { font-size: 2rem; letter-spacing: 2px; }
    .lo-board[data-size="3"] .lo-cell { width: 74px; height: 74px; }
    .lo-board[data-size="4"] .lo-cell { width: 60px; height: 60px; }
    .lo-board[data-size="5"] .lo-cell { width: 50px; height: 50px; }
    .lo-board[data-size="6"] .lo-cell { width: 42px; height: 42px; }
    #game-hud { grid-template-columns: repeat(2, 1fr); }
}