/* Number Link — Purple */
:root {
    --nl-accent: #9333EA; --nl-accent-light: #D8B4FE; --nl-accent-dark: #581C87;
    --nl-bg: #100820; --nl-surface: #1B0F30; --nl-surface-light: #261743;
    --nl-text: #EDE8FA; --nl-text-dim: #9F8FCC; --nl-gold: #FACC15;
    --c1: #EF4444; --c2: #3B82F6; --c3: #22C55E; --c4: #F59E0B; --c5: #EC4899; --c6: #06B6D4; --c7: #A855F7; --c8: #84CC16;
}
.nl-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(--nl-surface); border: 1px dashed var(--nl-text-dim); display: flex; align-items: center; justify-content: center; color: var(--nl-text-dim); font-size: 12px; border-radius: 8px; }
#numberlink-app { flex: 1; max-width: 560px; min-width: 320px; color: var(--nl-text); }
.screen { display: none; }
.screen.active { display: block; animation: nlFade .3s ease; }
@keyframes nlFade { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: translateY(0); } }
.nl-header { text-align: center; padding: 36px 0 24px; }
.nl-logo { display: inline-block; padding: 12px 18px; background: var(--nl-surface); border: 1px solid var(--nl-surface-light); border-radius: 12px; font-family: 'JetBrains Mono', monospace; color: var(--nl-accent-light); font-weight: 800; letter-spacing: 4px; margin-bottom: 14px; font-size: 1.4rem; }
.nl-header h1 { font-family: 'Syne', sans-serif; font-size: 2.2rem; font-weight: 800; color: var(--nl-accent-light); letter-spacing: 4px; margin: 0; text-shadow: 0 0 24px rgba(147,51,234,0.5); }
.subtitle { color: var(--nl-text-dim); font-size: 1rem; margin-top: 8px; }
.card { background: var(--nl-surface); border-radius: 14px; padding: 20px; margin-bottom: 16px; border: 1px solid var(--nl-surface-light); }
.card__title { font-family: 'Syne', sans-serif; font-size: 0.85rem; text-transform: uppercase; letter-spacing: 2px; color: var(--nl-accent-light); margin-bottom: 14px; }
.diff-grid { display: grid; grid-template-columns: repeat(5, 1fr); gap: 8px; }
.diff-btn { background: var(--nl-surface-light); border: 1.5px solid transparent; color: var(--nl-text); padding: 12px 6px; border-radius: 10px; cursor: pointer; display: flex; flex-direction: column; align-items: center; gap: 4px; font-family: 'JetBrains Mono', monospace; font-size: 0.8rem; transition: transform .12s, border-color .12s; }
.diff-btn:hover { transform: translateY(-2px); border-color: var(--nl-accent); }
.diff-btn.selected { background: linear-gradient(135deg, var(--nl-accent-dark), var(--nl-accent)); border-color: var(--nl-accent-light); }
.nl-rules { margin: 0; padding-left: 1.1rem; color: var(--nl-text-dim); line-height: 1.6; font-size: 0.92rem; }
.btn { font-family: 'DM Sans', sans-serif; font-weight: 600; border-radius: 10px; border: none; cursor: pointer; padding: 12px 22px; transition: transform .12s, box-shadow .12s; font-size: 0.95rem; }
.btn:hover { transform: translateY(-1px); }
.btn--primary { background: linear-gradient(135deg, var(--nl-accent-dark), var(--nl-accent)); color: #fff; box-shadow: 0 6px 18px rgba(147,51,234,0.4); }
.btn--outline { background: transparent; border: 1.5px solid var(--nl-accent); color: var(--nl-accent-light); }
.btn--ghost { background: transparent; color: var(--nl-text-dim); }
.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 { display: grid; grid-template-columns: repeat(4, 1fr); gap: 10px; background: var(--nl-surface); padding: 14px; border-radius: 12px; border: 1px solid var(--nl-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(--nl-text-dim); }
.hud__value { font-family: 'JetBrains Mono', monospace; font-size: 1.2rem; font-weight: 700; color: var(--nl-accent-light); }
.hud__timer { color: var(--nl-gold); }
.nl-board-area { display: flex; justify-content: center; padding: 16px 0; }
.nl-board { display: grid; gap: 2px; padding: 14px; background: var(--nl-surface); border: 1px solid var(--nl-surface-light); border-radius: 14px; user-select: none; box-shadow: 0 18px 40px rgba(0,0,0,0.45); }
.nl-cell {
    width: 60px; height: 60px;
    background: var(--nl-bg);
    border: 1px solid var(--nl-surface-light);
    border-radius: 6px;
    display: flex; align-items: center; justify-content: center;
    cursor: pointer;
    position: relative;
    transition: background 0.12s ease;
    font-family: 'JetBrains Mono', monospace;
    font-weight: 800;
    color: #fff;
    font-size: 1.05rem;
}
.nl-cell.endpoint { box-shadow: inset 0 0 0 3px rgba(255,255,255,0.4); }
.nl-cell.path { position: relative; }
.nl-cell::after {
    content: "";
    position: absolute;
    inset: 26%;
    border-radius: 4px;
    background: var(--cell-color, transparent);
    opacity: 0.35;
    pointer-events: none;
}
.nl-cell.endpoint::after { display: none; }
.nl-cell.active { box-shadow: inset 0 0 0 2px var(--nl-gold); }
.nl-board[data-size="5"] .nl-cell { width: 60px; height: 60px; }
.nl-board[data-size="6"] .nl-cell { width: 54px; height: 54px; }
.nl-board[data-size="7"] .nl-cell { width: 48px; height: 48px; }
.nl-board[data-size="8"] .nl-cell { width: 44px; height: 44px; }
.nl-board[data-size="9"] .nl-cell { width: 40px; height: 40px; }
.nl-actions { display: flex; justify-content: center; flex-wrap: wrap; gap: 10px; margin-top: 16px; }
.result-card, .lb-card { background: var(--nl-surface); border-radius: 16px; padding: 36px 28px; border: 1px solid var(--nl-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(--nl-accent-light); letter-spacing: 4px; margin: 0 0 12px; }
.result-score { font-family: 'JetBrains Mono', monospace; font-size: 3rem; font-weight: 700; color: var(--nl-gold); margin: 8px 0; }
.result-detail { color: var(--nl-text-dim); font-size: 0.95rem; margin-bottom: 18px; line-height: 1.6; }
#nickname { width: 100%; padding: 12px 14px; border-radius: 10px; background: var(--nl-bg); color: var(--nl-text); border: 1.5px solid var(--nl-surface-light); font-size: 0.95rem; margin-bottom: 12px; box-sizing: border-box; font-family: 'DM Sans', sans-serif; }
#nickname:focus { outline: none; border-color: var(--nl-accent); }
.result-actions { display: flex; gap: 10px; justify-content: center; margin-bottom: 10px; }
.lb-card h2 { font-family: 'Syne', sans-serif; color: var(--nl-accent-light); 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(--nl-bg); margin-bottom: 6px; border-radius: 8px; border: 1px solid var(--nl-surface-light); }
#leaderboard-list li::before { content: counter(lb); color: var(--nl-accent-light); font-weight: 700; margin-right: 10px; min-width: 24px; }
#leaderboard-list li:nth-child(1) { border-color: var(--nl-gold); }
#leaderboard-list .lb-score { font-family: 'JetBrains Mono', monospace; color: var(--nl-accent-light); font-weight: 600; }
@media (max-width: 900px) {
    .nl-layout { flex-direction: column; padding: 12px; }
    .ad-slot { width: 100%; }
    .ad-placeholder--vertical { width: 100%; height: 90px; }
    .nl-board[data-size] .nl-cell { width: 40px; height: 40px; font-size: 0.85rem; }
}