/* ── Piano Tiles — Slate Mono Theme ── */
:root {
    --pt-accent: #1C1917;
    --pt-accent-light: #44403C;
    --pt-bg: #FAFAF9;
    --pt-surface: #FFFFFF;
    --pt-surface-alt: #F5F5F4;
    --pt-text: #1C1917;
    --pt-text-dim: #78716C;
    --pt-border: #E7E5E4;
    --pt-success: #16A34A;
    --pt-gold: #F59E0B;
    --pt-danger: #DC2626;
    --pt-tile: #1C1917;
    --pt-glow: rgba(28, 25, 23, 0.35);
}

/* ── Layout ── */
.pt-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(--pt-surface);
    border: 1px dashed var(--pt-text-dim);
    display: flex; align-items: center; justify-content: center;
    color: var(--pt-text-dim); font-size: 12px; border-radius: 8px;
}

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

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

/* ── Header ── */
.pt-header { text-align: center; padding: 36px 0 24px; }
.pt-logo {
    display: inline-flex;
    gap: 2px;
    background: var(--pt-surface);
    padding: 10px;
    border-radius: 10px;
    margin-bottom: 14px;
    border: 1px solid var(--pt-border);
    align-items: flex-start;
}
.key { width: 14px; height: 56px; border-radius: 0 0 4px 4px; }
.key--white { background: #FAFAF9; border: 1px solid var(--pt-border); border-top: none; }
.key--black { background: var(--pt-tile); width: 10px; height: 40px; margin: 0 -6px; z-index: 2; position: relative; }
.pt-header h1 {
    font-family: 'Syne', sans-serif;
    font-size: 2.6rem;
    font-weight: 800;
    color: var(--pt-tile);
    letter-spacing: 4px;
    margin: 0;
}
.subtitle { color: var(--pt-text-dim); font-size: 1rem; margin-top: 8px; }

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

/* ── Difficulty ── */
.difficulty-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
}
.diff-btn {
    background: var(--pt-surface-alt);
    border: 1.5px solid transparent;
    color: var(--pt-text);
    padding: 14px 8px;
    border-radius: 10px;
    cursor: pointer;
    display: flex; flex-direction: column; align-items: center; gap: 4px;
    transition: transform 0.15s, border-color 0.15s, background 0.15s;
    font-family: 'DM Sans', sans-serif;
    font-size: 0.85rem;
}
.diff-btn:hover { transform: translateY(-2px); border-color: var(--pt-tile); }
.diff-btn.selected {
    background: var(--pt-tile);
    border-color: var(--pt-tile);
    color: #fff;
}
.diff-icon { font-size: 1rem; font-weight: 700; }
.diff-desc { font-size: 0.72rem; color: var(--pt-text-dim); }
.diff-btn.selected .diff-desc { color: rgba(255,255,255,0.8); }

/* ── Rules ── */
.pt-rules {
    margin: 0; padding-left: 1.1rem;
    color: var(--pt-text-dim);
    font-size: 0.92rem; line-height: 1.6;
}
.pt-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, box-shadow 0.12s, background 0.15s;
    font-size: 0.95rem;
}
.btn:hover { transform: translateY(-1px); }
.btn--primary {
    background: var(--pt-tile);
    color: #fff;
    box-shadow: 0 6px 18px var(--pt-glow);
}
.btn--primary:hover { box-shadow: 0 10px 24px var(--pt-glow); }
.btn--outline {
    background: transparent;
    border: 1.5px solid var(--pt-tile);
    color: var(--pt-tile);
}
.btn--outline:hover { background: rgba(28,25,23,0.08); }
.btn--ghost { background: transparent; color: var(--pt-text-dim); }
.btn--ghost:hover { color: var(--pt-tile); }
.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;
}

/* ── HUD ── */
#game-hud {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
    background: var(--pt-surface);
    padding: 14px;
    border-radius: 12px;
    border: 1px solid var(--pt-border);
    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(--pt-text-dim);
}
.hud__value {
    font-family: 'JetBrains Mono', monospace;
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--pt-tile);
}
.hud__timer { color: var(--pt-gold); }

/* ── Stage ── */
.pt-stage-wrap {
    position: relative;
    width: 400px;
    max-width: 100%;
    margin: 0 auto;
    background: var(--pt-surface);
    border-radius: 16px;
    border: 1px solid var(--pt-border);
    overflow: hidden;
    box-shadow: 0 12px 36px rgba(0,0,0,0.15);
    touch-action: manipulation;
}
#pt-canvas {
    display: block;
    width: 100%;
    height: auto;
    aspect-ratio: 400/640;
}
.pt-touch-overlay {
    position: absolute; inset: 0;
    display: grid; grid-template-columns: repeat(4, 1fr);
}
.pt-lane { cursor: pointer; user-select: none; -webkit-tap-highlight-color: transparent; }
.pt-lane:active { background: rgba(28,25,23,0.08); }

.pt-actions { display: flex; justify-content: center; margin-top: 16px; }

/* ── Result ── */
.result-card, .lb-card {
    background: var(--pt-surface);
    border-radius: 16px;
    padding: 36px 28px;
    border: 1px solid var(--pt-border);
    text-align: center;
    max-width: 480px;
    margin: 40px auto;
    box-shadow: 0 18px 36px rgba(0,0,0,0.12);
}
.result-card h2 {
    font-family: 'Syne', sans-serif;
    font-size: 2rem;
    color: var(--pt-tile);
    letter-spacing: 4px;
    margin: 0 0 12px;
}
.result-score {
    font-family: 'JetBrains Mono', monospace;
    font-size: 3rem;
    font-weight: 700;
    color: var(--pt-gold);
    margin: 8px 0;
}
.result-detail {
    color: var(--pt-text-dim);
    font-size: 0.95rem;
    margin-bottom: 18px;
    line-height: 1.6;
}
#nickname {
    width: 100%;
    padding: 12px 14px;
    border-radius: 10px;
    background: var(--pt-bg);
    color: var(--pt-text);
    border: 1.5px solid var(--pt-border);
    font-family: 'DM Sans', sans-serif;
    font-size: 0.95rem;
    margin-bottom: 12px;
    box-sizing: border-box;
}
#nickname:focus { outline: none; border-color: var(--pt-tile); }
.result-actions { display: flex; gap: 10px; justify-content: center; margin-bottom: 10px; }

/* ── Leaderboard ── */
.lb-card h2 {
    font-family: 'Syne', sans-serif;
    color: var(--pt-tile);
    letter-spacing: 4px;
    margin-bottom: 18px;
}
#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(--pt-surface-alt);
    margin-bottom: 6px;
    border-radius: 8px;
    border: 1px solid var(--pt-border);
    font-family: 'DM Sans', sans-serif;
}
#leaderboard-list li::before {
    content: counter(lb);
    color: var(--pt-tile);
    font-weight: 700;
    margin-right: 10px;
    min-width: 24px;
}
#leaderboard-list li:nth-child(1) { border-color: var(--pt-gold); }
#leaderboard-list li:nth-child(1)::before { color: var(--pt-gold); }
#leaderboard-list .lb-score {
    font-family: 'JetBrains Mono', monospace;
    color: var(--pt-tile);
    font-weight: 600;
}

/* ── Responsive ── */
@media (max-width: 900px) {
    .pt-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); }
    .pt-header h1 { font-size: 2rem; letter-spacing: 2px; }
    .pt-stage-wrap { width: 100%; max-width: 400px; }
}