:root {
    color-scheme: dark;
    --bg: #071019;
    --panel: #0f1f2e;
    --panel-2: #163044;
    --primary: #2dd4bf;
    --primary-2: #5eead4;
    --text: #eaf6f5;
    --muted: #8fa8ab;
    --danger: #f87171;
    --success: #47d18c;
    --cell-bg: #0b1a26;
    --cell-given: #14283a;
    --box-border: rgba(255, 255, 255, 0.35);
}

* { box-sizing: border-box; }

html, body { min-height: 100%; margin: 0; -webkit-tap-highlight-color: transparent; }

body {
    display: grid;
    place-items: center;
    min-height: 100vh;
    background: radial-gradient(circle at top, #133041 0, var(--bg) 55%);
    color: var(--text);
    font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    user-select: none;
}

button {
    border: 0;
    border-radius: 8px;
    background: var(--primary);
    color: #06201c;
    cursor: pointer;
    font: inherit;
    font-weight: 800;
    transition: filter 0.15s ease;
}

button:hover:not(:disabled) { filter: brightness(1.08); }
button:focus-visible { outline: 3px solid #ffffff; outline-offset: 2px; }
button:disabled { opacity: 0.5; cursor: not-allowed; }

.game-shell {
    width: min(100%, 560px);
    min-height: 100vh;
    padding: 16px;
    display: grid;
    align-content: center;
    gap: 12px;
}

.scorebar {
    display: grid;
    grid-template-columns: repeat(4, 1fr) auto;
    gap: 10px;
    align-items: center;
    border: 1px solid rgba(255, 255, 255, 0.10);
    border-radius: 10px;
    background: rgba(15, 31, 46, 0.85);
    padding: 12px;
    backdrop-filter: blur(6px);
}

.scorebar div { display: grid; gap: 2px; }

.label {
    color: var(--muted);
    font-size: 11px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.scorebar strong {
    font-size: clamp(16px, 4.2vw, 26px);
    line-height: 1;
    font-variant-numeric: tabular-nums;
}

#restartButton { min-width: 90px; height: 40px; background: rgba(255, 255, 255, 0.08); color: var(--text); }

.board-wrap {
    position: relative;
    width: min(100%, 460px);
    margin: 0 auto;
    aspect-ratio: 1;
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: 12px;
    background: var(--panel);
    box-shadow: 0 14px 30px rgba(0, 0, 0, 0.4);
    padding: 8px;
}

.grid {
    display: grid;
    grid-template-columns: repeat(9, 1fr);
    grid-template-rows: repeat(9, 1fr);
    width: 100%;
    height: 100%;
    gap: 1px;
    background: var(--box-border);
    border: 2px solid var(--box-border);
    border-radius: 4px;
    overflow: hidden;
}

.cell {
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--cell-bg);
    color: var(--primary-2);
    font-weight: 700;
    font-size: clamp(12px, 3.6vw, 20px);
    cursor: pointer;
    position: relative;
}

.cell.given { background: var(--cell-given); color: var(--text); font-weight: 800; cursor: default; }
.cell.selected { background: color-mix(in srgb, var(--primary) 30%, var(--cell-bg)); }
.cell.peer { background: color-mix(in srgb, var(--primary) 10%, var(--cell-bg)); }
.cell.same-value:not(.given) { color: var(--primary); }
.cell.conflict { background: color-mix(in srgb, var(--danger) 35%, var(--cell-bg)); }

.cell.border-right { border-right: 2px solid var(--box-border); }
.cell.border-bottom { border-bottom: 2px solid var(--box-border); }

.numpad {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 6px;
}

.numpad button {
    height: 46px;
    background: var(--panel-2);
    color: var(--text);
    font-size: 16px;
    font-weight: 800;
}

.numpad button.erase { background: rgba(248, 113, 113, 0.18); color: var(--danger); }

.overlay {
    position: absolute;
    inset: 0;
    display: grid;
    place-content: center;
    gap: 14px;
    padding: 20px;
    text-align: center;
    background: rgba(7, 16, 25, 0.95);
    border-radius: 12px;
    backdrop-filter: blur(8px);
    z-index: 10;
}

.overlay[hidden] { display: none; }

.overlay h1 { margin: 0; font-size: clamp(24px, 6vw, 40px); line-height: 1.1; }

.overlay p { max-width: 340px; margin: 0 auto; color: var(--muted); line-height: 1.5; font-size: 13.5px; }

.overlay .stats-final {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 10px;
    max-width: 380px;
    margin: 8px auto 0;
}

.overlay .stat-card {
    background: rgba(255, 255, 255, 0.06);
    border: 1px solid rgba(255, 255, 255, 0.10);
    border-radius: 8px;
    padding: 10px 6px;
}

.overlay .stat-card .label { margin-bottom: 4px; }
.overlay .stat-card strong { font-size: 20px; color: var(--primary-2); line-height: 1; }

.overlay button { justify-self: center; min-width: 160px; height: 48px; margin-top: 6px; }

.overlay button.secondary {
    background: rgba(255, 255, 255, 0.08);
    color: var(--text);
    margin-top: 0;
    font-size: 13px;
    height: 40px;
}

@media (max-width: 720px) {
    .game-shell { align-content: start; }
    .scorebar { grid-template-columns: repeat(2, 1fr); gap: 8px; padding: 10px; }
    #restartButton { grid-column: 1 / -1; width: 100%; }
}