/* ---------- Fonts (self-hosted latin subsets from Google Fonts, SIL OFL 1.1; see fonts/) ---------- */
@font-face {
    font-family: 'Space Grotesk';
    font-style: normal;
    font-weight: 400 700; /* variable font: one file for 400, 500 and 700 */
    font-display: swap;
    src: url(fonts/space-grotesk-latin.woff2) format('woff2');
    unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}
@font-face {
    font-family: 'Unbounded';
    font-style: normal;
    font-weight: 700 900; /* variable font: one file for 700 and 900 */
    font-display: swap;
    src: url(fonts/unbounded-latin.woff2) format('woff2');
    unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}

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

:root {
    --bg: #0e0e12;
    --ink: #f3f1ea;
    --ink-soft: #a6a3b0;
    --ink-faint: #6e6c79;
    --glass: rgba(255, 255, 255, 0.05);
    --glass-line: rgba(255, 255, 255, 0.1);
    --chip: rgba(255, 255, 255, 0.05);
    --surface: #1a1a22;
    --surface-line: #34343f;
    --edge: #000;
    --edge-tile: rgba(0, 0, 0, 0.85);
    --board-bg: #1c1c25;
    --cell-bg: #272732;
    --accent: #c6f35a;
    --accent-ink: #11140a;
    --accent-text: #c6f35a;
    --pop-shadow: #8b7bff;
    --board-shadow: #c6f35a;
    --danger: #ff4d6d;
    --overlay: rgba(12, 12, 16, 0.74);
    --glow-a: rgba(198, 243, 90, 0.12);
    --glow-b: rgba(139, 123, 255, 0.16);

    --font-ui: "Space Grotesk", system-ui, -apple-system, "Segoe UI", sans-serif;
    --font-display: "Unbounded", "Arial Black", system-ui, sans-serif;
    --slide: 110ms;
    --board-size: min(calc(100vw - 32px), 480px);

    color-scheme: dark;
}

@media (prefers-color-scheme: light) {
    :root {
        --bg: #f3efe6;
        --ink: #16161c;
        --ink-soft: #55535e;
        --ink-faint: #8a8794;
        --glass: rgba(255, 255, 255, 0.6);
        --glass-line: rgba(22, 22, 28, 0.12);
        --chip: rgba(22, 22, 28, 0.05);
        --surface: #fffdf8;
        --surface-line: #16161c;
        --edge: #16161c;
        --board-bg: #e4ddcf;
        --cell-bg: #d4cbba;
        --accent-text: #4c7500;
        --pop-shadow: #16161c;
        --board-shadow: #16161c;
        --overlay: rgba(243, 239, 230, 0.8);
        --glow-a: rgba(150, 200, 40, 0.2);
        --glow-b: rgba(139, 123, 255, 0.16);

        color-scheme: light;
    }
}

html {
    -webkit-text-size-adjust: 100%;
}

body {
    margin: 0;
    min-height: 100vh;
    min-height: 100svh;
    display: flex;
    flex-direction: column;
    align-items: center;
    /* No top padding: the NX Gaming bar sits flush at the top and handles the safe area. */
    padding: 0 16px max(20px, env(safe-area-inset-bottom));
    background-color: var(--bg);
    background-image:
        radial-gradient(60vmax 40vmax at 10% -10%, var(--glow-a), transparent 60%),
        radial-gradient(50vmax 40vmax at 110% 110%, var(--glow-b), transparent 60%);
    background-attachment: fixed;
    color: var(--ink);
    font-family: var(--font-ui);
    -webkit-tap-highlight-color: transparent;
}

button {
    touch-action: manipulation;
}

[hidden] {
    display: none !important;
}

:focus-visible {
    outline: 2px solid var(--accent-text);
    outline-offset: 2px;
}

.app {
    width: var(--board-size);
    display: flex;
    flex-direction: column;
    gap: 16px;
}

/* ---------- NX Gaming bar ----------
   Shared by the hub (nesturex.com/nx-gaming) and every game page: keep the copies
   identical. Always dark, whatever the page theme, because the logo's white letters
   vanish on light backgrounds. */
.nxg-bar {
    box-sizing: content-box;
    height: 52px;
    padding: env(safe-area-inset-top, 0px) clamp(16px, 3vw, 40px) 0;
    display: flex; align-items: center; justify-content: space-between; gap: 12px;
    background: rgba(11, 16, 32, 0.92);
    border-bottom: 1px solid rgba(255, 255, 255, 0.08);
    -webkit-backdrop-filter: blur(10px);
    backdrop-filter: blur(10px);
    color: #fff;
    color-scheme: dark;
}
.nxg-bar__logo {
    display: inline-flex; align-items: center;
    min-height: 44px;
    border-radius: 8px;
}
.nxg-bar__logo img { display: block; width: auto; height: 28px; }
.nxg-bar__all {
    display: inline-flex; align-items: center; gap: 8px;
    min-height: 44px;
    padding: 0 16px;
    border-radius: 999px;
    border: 1px solid rgba(255, 255, 255, 0.14);
    background: rgba(255, 255, 255, 0.08);
    -webkit-backdrop-filter: blur(8px);
    backdrop-filter: blur(8px);
    color: #fff;
    font: 600 14px/1 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
    letter-spacing: 0.01em;
    text-decoration: none;
    white-space: nowrap;
    transition: background 0.2s, border-color 0.2s;
}
.nxg-bar__all:hover { background: rgba(255, 255, 255, 0.14); border-color: rgba(255, 255, 255, 0.24); }
.nxg-bar__all svg { flex: none; width: 16px; height: 16px; }
.nxg-bar__logo:focus-visible,
.nxg-bar__all:focus-visible { outline: 2px solid #5b9cf0; outline-offset: 2px; }
@media (max-width: 760px) {
    .nxg-bar { height: 48px; }
    .nxg-bar__logo img { height: 24px; }
}
/* Very narrow phones: icon-only button (the link keeps its aria-label). */
@media (max-width: 359px) {
    .nxg-bar__all { padding: 0 13px; }
    .nxg-bar__all span { display: none; }
}
/* ---------- /NX Gaming bar ---------- */

/* Full width across the centred column, flush with the top of the page. */
body > .nxg-bar {
    align-self: stretch;
    margin: 0 -16px 20px;
}

/* header */

.top {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    padding-top: 8px;
}

.logo {
    margin: 0;
    padding: 0.28em 0.4em;
    font-family: var(--font-display);
    font-weight: 900;
    font-size: clamp(28px, 9vw, 44px);
    line-height: 1;
    letter-spacing: -0.04em;
    color: var(--accent-ink);
    background: var(--accent);
    border: 2px solid var(--edge);
    border-radius: 12px;
    box-shadow: 4px 4px 0 var(--pop-shadow);
    transform: rotate(-2deg);
}

.scores {
    display: flex;
    gap: 8px;
}

.score-box {
    position: relative;
    min-width: 76px;
    padding: 8px 12px;
    text-align: center;
    background: var(--glass);
    border: 1px solid var(--glass-line);
    border-radius: 12px;
    -webkit-backdrop-filter: blur(12px);
    backdrop-filter: blur(12px);
}

.score-box .label {
    display: block;
    font-size: 11px;
    font-weight: 700;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--ink-soft);
}

.score-box .value {
    display: block;
    margin-top: 2px;
    font-family: var(--font-display);
    font-weight: 700;
    font-size: 20px;
    font-variant-numeric: tabular-nums;
}

.score-add {
    position: absolute;
    left: 50%;
    top: 40%;
    font-family: var(--font-display);
    font-weight: 700;
    font-size: 16px;
    color: var(--accent-text);
    pointer-events: none;
    animation: float-up 700ms ease-out forwards;
}

@keyframes float-up {
    from { opacity: 1; transform: translate(-50%, 0); }
    to { opacity: 0; transform: translate(-50%, -40px); }
}

/* toolbar */

.toolbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 10px;
}

.sizes {
    display: inline-flex;
    gap: 2px;
    padding: 3px;
    background: var(--glass);
    border: 1px solid var(--glass-line);
    border-radius: 11px;
}

.sizes button {
    padding: 9px 10px;
    font: 600 13px/1 var(--font-ui);
    color: var(--ink-soft);
    background: transparent;
    border: 0;
    border-radius: 8px;
    cursor: pointer;
}

.sizes button:hover {
    color: var(--ink);
}

.sizes button[aria-checked="true"] {
    color: var(--bg);
    background: var(--ink);
}

.actions {
    display: flex;
    gap: 8px;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 10px 14px;
    font: 700 14px/1 var(--font-ui);
    color: var(--ink);
    background: var(--surface);
    border: 2px solid var(--surface-line);
    border-radius: 10px;
    box-shadow: 3px 3px 0 var(--edge);
    cursor: pointer;
    transition: transform 80ms, box-shadow 80ms, background-color 120ms;
}

.btn:hover {
    transform: translate(-1px, -1px);
    box-shadow: 4px 4px 0 var(--edge);
}

.btn:active {
    transform: translate(3px, 3px);
    box-shadow: 0 0 0 var(--edge);
}

.btn:disabled {
    opacity: 0.4;
    cursor: not-allowed;
    transform: none;
    box-shadow: 3px 3px 0 var(--edge);
}

.btn-accent {
    color: var(--accent-ink);
    background: var(--accent);
    border-color: var(--edge);
    box-shadow: 3px 3px 0 var(--pop-shadow);
}

.btn-accent:hover {
    box-shadow: 4px 4px 0 var(--pop-shadow);
}

.btn-accent:active {
    box-shadow: 0 0 0 var(--pop-shadow);
}

.btn.is-confirm {
    color: #fff;
    background: var(--danger);
}

.badge {
    display: inline-grid;
    place-items: center;
    min-width: 18px;
    height: 18px;
    padding: 0 5px;
    font-size: 11px;
    color: var(--bg);
    background: var(--ink);
    border-radius: 9px;
}

/* board */

.board-wrap {
    --n: 4;
    --gap: calc(var(--board-size) * 0.2 / (var(--n) + 4));
    --cell: calc((var(--board-size) - 4px - var(--gap) * (var(--n) + 1)) / var(--n));

    position: relative;
    width: var(--board-size);
    aspect-ratio: 1;
    background: var(--board-bg);
    border: 2px solid var(--edge);
    border-radius: 16px;
    box-shadow: 6px 6px 0 var(--board-shadow);
    touch-action: none;
    -webkit-user-select: none;
    user-select: none;
}

.grid,
.tiles {
    position: absolute;
    inset: var(--gap);
}

.grid {
    display: grid;
    grid-template-columns: repeat(var(--n), 1fr);
    grid-template-rows: repeat(var(--n), 1fr);
    gap: var(--gap);
}

.cell {
    background: var(--cell-bg);
    border-radius: min(10px, calc(var(--cell) * 0.14));
}

.tile {
    position: absolute;
    top: 0;
    left: 0;
    z-index: 1;
    width: var(--cell);
    height: var(--cell);
    transform: translate(
        calc(var(--c) * (var(--cell) + var(--gap))),
        calc(var(--r) * (var(--cell) + var(--gap)))
    );
    transition: transform var(--slide) ease-in-out;
}

.tile-merged { z-index: 2; }
.tile-gone { z-index: 0; }

.tile-inner {
    display: grid;
    place-items: center;
    width: 100%;
    height: 100%;
    font-family: var(--font-display);
    font-weight: 900;
    font-size: calc(var(--cell) * 0.4);
    line-height: 1;
    letter-spacing: -0.04em;
    font-variant-numeric: tabular-nums;
    color: var(--t-ink, #3a332b);
    background: var(--t-bg, #ede7dd);
    border: 2px solid var(--edge-tile);
    border-radius: min(10px, calc(var(--cell) * 0.14));
    box-shadow: inset 0 calc(var(--cell) * -0.06) 0 rgba(0, 0, 0, 0.16);
}

.tile[data-len="3"] .tile-inner { font-size: calc(var(--cell) * 0.33); }
.tile[data-len="4"] .tile-inner { font-size: calc(var(--cell) * 0.26); }
.tile[data-len="5"] .tile-inner { font-size: calc(var(--cell) * 0.21); }

.tile[data-v="2"]    { --t-bg: #ede7dd; --t-ink: #3a332b; }
.tile[data-v="4"]    { --t-bg: #f2dcb8; --t-ink: #3a332b; }
.tile[data-v="8"]    { --t-bg: #ffb86b; --t-ink: #2a1606; }
.tile[data-v="16"]   { --t-bg: #ff8f5a; --t-ink: #2a1004; }
.tile[data-v="32"]   { --t-bg: #ff6b5a; --t-ink: #fff; }
.tile[data-v="64"]   { --t-bg: #ff4d6d; --t-ink: #fff; }
.tile[data-v="128"]  { --t-bg: #ffd84d; --t-ink: #2a2204; }
.tile[data-v="256"]  { --t-bg: #c6f35a; --t-ink: #11140a; }
.tile[data-v="512"]  { --t-bg: #5af2b0; --t-ink: #06261a; }
.tile[data-v="1024"] { --t-bg: #4dd6ff; --t-ink: #04202a; }
.tile[data-v="2048"] { --t-bg: #8b7bff; --t-ink: #fff; }
.tile[data-v="4096"] { --t-bg: #e05aff; --t-ink: #fff; }
.tile[data-v="8192"] { --t-bg: #111116; --t-ink: #c6f35a; }

.tile[data-v="2048"] .tile-inner,
.tile[data-v="4096"] .tile-inner {
    box-shadow:
        inset 0 calc(var(--cell) * -0.06) 0 rgba(0, 0, 0, 0.16),
        0 0 calc(var(--cell) * 0.35) rgba(139, 123, 255, 0.6);
}

.tile[data-v="8192"] .tile-inner {
    border-color: #c6f35a;
    box-shadow: 0 0 calc(var(--cell) * 0.35) rgba(198, 243, 90, 0.5);
}

.tile-new .tile-inner {
    animation: appear 160ms ease-out var(--slide) backwards;
}

.tile-merged .tile-inner {
    animation: pop 200ms ease-out var(--slide) backwards;
}

@keyframes appear {
    from { opacity: 0; transform: scale(0.4); }
    to { opacity: 1; transform: scale(1); }
}

@keyframes pop {
    0% { transform: scale(0); }
    60% { transform: scale(1.15); }
    100% { transform: scale(1); }
}

/* a little bump when a move does nothing */
.nudge-left  { --nx: -6px; --ny: 0; animation: nudge 180ms ease-out; }
.nudge-right { --nx: 6px;  --ny: 0; animation: nudge 180ms ease-out; }
.nudge-up    { --nx: 0; --ny: -6px; animation: nudge 180ms ease-out; }
.nudge-down  { --nx: 0; --ny: 6px;  animation: nudge 180ms ease-out; }

@keyframes nudge {
    40% { translate: var(--nx) var(--ny); }
}

/* overlay */

.overlay {
    position: absolute;
    inset: 0;
    z-index: 5;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 24px;
    text-align: center;
    background: var(--overlay);
    border-radius: 14px;
    -webkit-backdrop-filter: blur(6px);
    backdrop-filter: blur(6px);
    animation: fade 260ms ease-out;
}

.overlay[hidden] {
    display: none;
}

.overlay-kicker {
    margin: 0;
    font-size: 12px;
    font-weight: 700;
    letter-spacing: 0.14em;
    text-transform: uppercase;
    color: var(--accent-text);
}

.overlay-title {
    margin: 8px 0;
    font-family: var(--font-display);
    font-weight: 900;
    font-size: clamp(32px, 10vw, 52px);
    letter-spacing: -0.04em;
}

.overlay-text {
    max-width: 30ch;
    margin: 0 0 20px;
    color: var(--ink-soft);
    line-height: 1.5;
}

.overlay-actions {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 10px;
}

@keyframes fade {
    from { opacity: 0; }
}

/* below the board */

.subbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    margin-top: 4px;
}

.hint {
    margin: 0;
    font-size: 13px;
    line-height: 1.8;
    color: var(--ink-soft);
}

kbd {
    display: inline-block;
    min-width: 20px;
    margin: 0 1px;
    padding: 1px 5px;
    font: 600 11px/1.5 var(--font-ui);
    text-align: center;
    color: var(--ink);
    background: var(--chip);
    border: 1px solid var(--glass-line);
    border-bottom-width: 2px;
    border-radius: 5px;
}

.hint-touch {
    display: none;
}

@media (hover: none) and (pointer: coarse) {
    .hint-keys { display: none; }
    .hint-touch { display: inline; }
}

.icon-btns {
    display: flex;
    flex-shrink: 0;
    gap: 8px;
}

.icon-btn {
    display: grid;
    place-items: center;
    width: 40px;
    height: 40px;
    padding: 0;
    color: var(--ink);
    background: var(--glass);
    border: 1px solid var(--glass-line);
    border-radius: 10px;
    cursor: pointer;
    -webkit-backdrop-filter: blur(12px);
    backdrop-filter: blur(12px);
    transition: border-color 120ms;
}

.icon-btn:hover {
    border-color: var(--ink-faint);
}

.icon-btn svg {
    width: 20px;
    height: 20px;
}

#sound .off { display: none; }
#sound[aria-pressed="false"] .on { display: none; }
#sound[aria-pressed="false"] .off { display: block; }

.how {
    margin-top: 12px;
    padding: 20px 22px;
    background: var(--glass);
    border: 1px solid var(--glass-line);
    border-radius: 16px;
    -webkit-backdrop-filter: blur(12px);
    backdrop-filter: blur(12px);
}

.how h2 {
    margin: 0 0 10px;
    font-family: var(--font-display);
    font-weight: 700;
    font-size: 16px;
}

.how ol {
    margin: 0;
    padding-left: 20px;
}

.how li {
    margin-bottom: 4px;
    line-height: 1.6;
    color: var(--ink-soft);
}

.how strong {
    color: var(--ink);
}

.tip {
    margin: 12px 0 0;
    font-size: 14px;
    color: var(--accent-text);
}

footer {
    margin-top: 32px;
    font-size: 13px;
    color: var(--ink-faint);
    text-align: center;
}

footer a {
    color: var(--accent-text);
    text-underline-offset: 3px;
}

footer a:hover {
    color: var(--ink);
}

/* stats dialog */

dialog {
    width: min(calc(100vw - 32px), 400px);
    padding: 22px;
    color: var(--ink);
    background: var(--surface);
    border: 2px solid var(--edge);
    border-radius: 16px;
    box-shadow: 6px 6px 0 var(--board-shadow);
}

dialog::backdrop {
    background: rgba(0, 0, 0, 0.5);
    -webkit-backdrop-filter: blur(4px);
    backdrop-filter: blur(4px);
}

.dialog-head {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 16px;
}

.dialog-head h2 {
    margin: 0;
    font-family: var(--font-display);
    font-weight: 700;
    font-size: 20px;
}

.dialog-head form {
    margin: 0;
}

.stat-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 10px;
}

.stat {
    padding: 12px 14px;
    background: var(--chip);
    border: 1px solid var(--glass-line);
    border-radius: 12px;
}

.stat b {
    display: block;
    font-family: var(--font-display);
    font-size: 22px;
}

.stat span {
    font-size: 13px;
    color: var(--ink-soft);
}

dialog h3 {
    margin: 20px 0 6px;
    font-size: 12px;
    font-weight: 700;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--ink-soft);
}

.bests {
    margin: 0;
    padding: 0;
    list-style: none;
}

.bests li {
    display: flex;
    justify-content: space-between;
    padding: 9px 0;
    border-bottom: 1px solid var(--glass-line);
}

.bests li:last-child {
    border-bottom: 0;
}

.bests b {
    font-variant-numeric: tabular-nums;
}

/* share dialog */

dialog {
    max-height: calc(100dvh - 32px);
    overflow-y: auto;
}

.share-dialog {
    width: min(calc(100vw - 32px), 440px);
}

.share-preview {
    position: relative;
    aspect-ratio: 1;
    overflow: hidden;
    background: var(--chip);
    border: 1px solid var(--glass-line);
    border-radius: 12px;
}

.share-preview img {
    display: block;
    width: 100%;
    height: 100%;
}

.share-preview.is-loading::after {
    content: "Making your card…";
    position: absolute;
    inset: 0;
    display: grid;
    place-items: center;
    font-size: 14px;
    color: var(--ink-soft);
    animation: pulse 1s ease-in-out infinite alternate;
}

@keyframes pulse {
    from { opacity: 0.4; }
}

.share-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-top: 16px;
}

.share-actions .btn {
    flex: 1 1 auto;
    justify-content: center;
    white-space: nowrap;
}

.share-links {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 10px;
    margin-top: 12px;
}

/* Same chunky style as .btn, in each platform's brand colours */
.social {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 11px 12px;
    font: 700 14px/1 var(--font-ui);
    color: #fff;
    text-decoration: none;
    white-space: nowrap;
    background: var(--social-bg);
    border: 2px solid var(--edge);
    border-radius: 10px;
    box-shadow: 3px 3px 0 var(--edge);
    cursor: pointer;
    transition: transform 80ms, box-shadow 80ms, filter 120ms;
}

.social:hover {
    filter: brightness(1.08);
    transform: translate(-1px, -1px);
    box-shadow: 4px 4px 0 var(--edge);
}

.social:active {
    transform: translate(3px, 3px);
    box-shadow: 0 0 0 var(--edge);
}

.social svg {
    flex: none;
    width: 18px;
    height: 18px;
}

.social-wa { --social-bg: #25d366; color: #052e16; }
.social-fb { --social-bg: #1877f2; }
.social-x { --social-bg: #000; }
.social-link { --social-bg: var(--surface); color: var(--ink); border-color: var(--surface-line); }

/* X is black-on-black in dark mode, so give it a visible edge there */
@media (prefers-color-scheme: dark) {
    .social-x { border-color: #3a3a46; }
}

.share-status {
    min-height: 1.4em;
    margin: 12px 0 0;
    font-size: 13px;
    color: var(--accent-text);
}

.noscript {
    text-align: center;
}

@media (max-width: 440px) {
    .sizes,
    .actions { flex: 1 1 100%; }
    .sizes button,
    .actions .btn { flex: 1; justify-content: center; }
}

@media (max-width: 380px) {
    .score-box { min-width: 64px; padding: 6px 8px; }
    .score-box .value { font-size: 17px; }
}

@media (prefers-reduced-motion: reduce) {
    .tile { transition: none; }
    .tile-inner,
    .board-wrap,
    .overlay,
    .score-add,
    .share-preview::after { animation: none !important; }
}