:root {
    --paper: #f5f0e6; --paper-deep: #e9e1d2; --ink: #24231f; --muted: #6f6a61;
    --line: #d9d0c1; --accent: #e96345; --accent-dark: #c9472d; --board: #a99d8e;
    --board-cell: #bdb2a4; --white: #fffdf8; --radius-small: .65rem; --radius-medium: 1rem;
    --radius-large: 1.6rem; --shadow: 0 1.25rem 3.5rem rgba(74, 60, 44, .13);
}
* { box-sizing: border-box; }
.noscript-message { margin: 0; padding: .8rem 1.25rem; color: var(--white); background: var(--ink); text-align: center; }
.noscript-message a { color: #ffb09d; }
/* overscroll-behavior stops a swipe that starts on the board from chaining into
   the page's own scroll or the browser's pull-to-refresh and rubber-band. The
   board itself sets touch-action: none; this covers the chained gesture. */
html { scroll-behavior: smooth; overscroll-behavior: none; }
body {
    min-height: 100dvh; margin: 0; color: var(--ink); overscroll-behavior: none;
    background: radial-gradient(circle at 15% 7%, rgba(233,99,69,.08), transparent 24rem), linear-gradient(rgba(113,101,83,.035) 1px, transparent 1px), linear-gradient(90deg, rgba(113,101,83,.035) 1px, transparent 1px), var(--paper);
    background-size: auto, 3rem 3rem, 3rem 3rem, auto;
    font-family: "Outfit", "Avenir Next", sans-serif; -webkit-font-smoothing: antialiased;
}
button, a { -webkit-tap-highlight-color: transparent; }
a { color: inherit; }
button { font: inherit; }
.skip-link { position: fixed; z-index: 10; top: .75rem; left: .75rem; padding: .7rem 1rem; color: var(--white); background: var(--ink); border-radius: .45rem; transform: translateY(-200%); }
.skip-link:focus { transform: translateY(0); }
.site-header, footer { width: min(100% - 2rem, 78rem); margin-inline: auto; display: flex; align-items: center; justify-content: space-between; }
.site-header { padding-block: 1.4rem; }
.brand { display: inline-flex; gap: .65rem; align-items: center; font-size: 1.1rem; font-weight: 800; letter-spacing: -.035em; text-decoration: none; }
.brand img { border-radius: .55rem; }
.header-links { display: flex; gap: 1.6rem; }
.header-links a, footer a { color: var(--muted); font-size: .92rem; font-weight: 600; text-decoration-thickness: .08em; text-underline-offset: .3em; text-decoration-color: transparent; transition: color .2s ease, text-decoration-color .2s ease; }
.header-links a:hover, footer a:hover { color: var(--ink); text-decoration-color: var(--accent); }
.game-layout { width: min(100% - 2rem, 75rem); min-height: calc(100dvh - 6rem); margin-inline: auto; padding: 2rem 0 7rem; display: grid; grid-template-columns: minmax(18rem, .86fr) minmax(22rem, 32rem); gap: clamp(3rem, 9vw, 9rem); align-items: center; }
.eyebrow { margin: 0 0 1.25rem; color: var(--muted); font-size: .78rem; font-weight: 700; letter-spacing: .09em; text-transform: uppercase; }
.eyebrow span { color: var(--accent); margin-right: .45rem; }
h1, h2, p { text-wrap: pretty; }
h1 { max-width: 10ch; margin: 0; font-size: clamp(4.4rem, 9vw, 7.6rem); font-weight: 800; letter-spacing: -.075em; line-height: .82; }
h1 em { color: var(--accent); font-family: Georgia, serif; font-weight: 400; }
.intro-copy { max-width: 31rem; margin: 2rem 0 0; color: var(--muted); font-size: clamp(1.05rem, 2vw, 1.2rem); line-height: 1.65; }
.desktop-hint { margin-top: 3rem; display: flex; gap: 1rem; align-items: center; }
.desktop-hint p { margin: 0; color: var(--muted); font-size: .82rem; line-height: 1.55; }
.desktop-hint strong { color: var(--ink); font-weight: 600; }
.key-cluster { width: 5rem; display: flex; flex-direction: column; align-items: center; gap: .2rem; }
.key-cluster span { display: flex; gap: .2rem; }
kbd { width: 1.5rem; height: 1.45rem; display: grid; place-items: center; border: 1px solid var(--line); border-bottom-width: 3px; border-radius: .28rem; background: rgba(255,253,248,.7); font: 500 .7rem "DM Mono", monospace; }
kbd svg, .mobile-controls svg, .dialog-icon svg { width: 1rem; height: 1rem; fill: none; stroke: currentColor; stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; }
.game-panel { width: 100%; }
.score-row { margin-bottom: .8rem; display: grid; grid-template-columns: 1fr 1fr auto; gap: .55rem; }
.score-card { min-height: 4.2rem; padding: .65rem .9rem; border: 1px solid var(--line); border-radius: var(--radius-small); background: rgba(255,253,248,.66); }
.score-card--primary { background: var(--ink); border-color: var(--ink); color: var(--white); }
.score-card span { display: block; margin-bottom: .15rem; color: var(--muted); font-size: .68rem; font-weight: 700; letter-spacing: .08em; text-transform: uppercase; }
.score-card--primary span { color: #bdb8ae; }
.score-card strong { font: 500 clamp(1.45rem, 4vw, 1.85rem) "DM Mono", monospace; letter-spacing: -.06em; }
.game-actions { display: grid; grid-template-columns: repeat(2, 3.25rem); gap: .45rem; }
.icon-button { display: grid; place-items: center; border: 1px solid var(--line); border-radius: var(--radius-small); color: var(--ink); background: var(--white); cursor: pointer; transition: transform .2s ease, border-color .2s ease, background .2s ease; }
.icon-button svg { width: 1.35rem; height: 1.35rem; display: block; fill: none; stroke: currentColor; stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }
.icon-button svg.solid-icon, .dialog-icon svg.solid-icon { fill: currentColor; stroke: none; }
.icon-button:hover:not(:disabled) { border-color: var(--ink); transform: translateY(-2px); }
.icon-button:active:not(:disabled) { transform: translateY(1px) scale(.98); }
.icon-button:disabled { opacity: .35; cursor: not-allowed; }
.board-wrap { position: relative; }
.game-board { width: 100%; aspect-ratio: 1; display: grid; grid-template-rows: repeat(4,1fr); gap: clamp(.42rem,1.5vw,.65rem); padding: clamp(.52rem,1.8vw,.75rem); border-radius: var(--radius-medium); background: var(--board); box-shadow: var(--shadow), inset 0 1px 0 rgba(255,255,255,.28); touch-action: none; user-select: none; }
.board-row { min-height: 0; display: grid; grid-template-columns: repeat(4,1fr); gap: clamp(.42rem,1.5vw,.65rem); }
.cell { min-width: 0; min-height: 0; display: grid; place-items: center; border-radius: clamp(.42rem,1.2vw,.68rem); color: #514b43; background: var(--board-cell); font: 600 clamp(1.45rem,6vw,2.6rem) "DM Mono", monospace; letter-spacing: -.08em; box-shadow: inset 0 1px 0 rgba(255,255,255,.24); transition: background-color .18s ease, transform .18s ease; }
.cell[data-value="0"] { color: transparent; }
.cell[data-value="2"] { background: #f1e8d9; }
.cell[data-value="4"] { background: #eadbc1; }
.cell[data-value="8"] { background: #efaa73; color: #fffaf1; }
.cell[data-value="16"] { background: #e98a5f; color: #fffaf1; }
.cell[data-value="32"] { background: #e56b51; color: white; }
.cell[data-value="64"] { background: #d94c3f; color: white; }
.cell[data-value="128"] { background: #d8ad5b; color: white; font-size: clamp(1.2rem,5vw,2.2rem); }
.cell[data-value="256"] { background: #c99a40; color: white; font-size: clamp(1.2rem,5vw,2.2rem); }
.cell[data-value="512"] { background: #b27a32; color: white; font-size: clamp(1.2rem,5vw,2.2rem); }
.cell[data-value="1024"] { background: #735b49; color: white; font-size: clamp(1rem,4.2vw,1.85rem); }
.cell[data-value="2048"] { background: #24231f; color: #ffd671; font-size: clamp(1rem,4.2vw,1.85rem); box-shadow: inset 0 0 0 2px #ffd671, 0 0 1.4rem rgba(255,214,113,.35); }
.cell[data-value="4096"], .cell[data-value="8192"] { background: #171714; color: white; font-size: clamp(.9rem,3.8vw,1.65rem); }
.cell.pop { animation: pop .22s cubic-bezier(.2,.9,.3,1.35); }
@keyframes pop { 0% { transform: scale(.82); } 100% { transform: scale(1); } }
.game-message { position: absolute; inset: 0; z-index: 2; padding: 2rem; display: flex; flex-direction: column; align-items: center; justify-content: center; text-align: center; border-radius: var(--radius-medium); color: var(--white); background: rgba(36,35,31,.92); backdrop-filter: blur(.45rem); animation: fade-in .25s ease both; }
.game-message[hidden] { display: none; }
.message-kicker { margin: 0 0 .55rem; color: #f5a58f; font-size: .75rem; font-weight: 700; letter-spacing: .08em; text-transform: uppercase; }
.game-message h2 { margin: 0; font-size: clamp(2rem,7vw,3.35rem); letter-spacing: -.05em; }
.game-message > p:not(.message-kicker) { max-width: 22rem; margin: .75rem 0 1.5rem; color: #d7d2ca; }
.message-actions { display: flex; gap: .55rem; align-items: center; }
@keyframes fade-in { from { opacity: 0; } }
.button { min-height: 2.85rem; padding: .7rem 1.1rem; border: 0; border-radius: .55rem; font-weight: 700; cursor: pointer; transition: transform .2s ease, background .2s ease; }
.button:hover { transform: translateY(-1px); }
.button:active { transform: translateY(1px) scale(.98); }
.button--primary { color: white; background: var(--accent); }
.button--primary:hover { background: var(--accent-dark); }
.button--text { color: inherit; background: transparent; }
.mobile-controls { display: none; }
.status-line { min-height: 1.35rem; margin: .8rem 0 0; color: var(--muted); font-size: .78rem; text-align: center; }
.guide-section { width: min(100% - 2rem,75rem); margin: 0 auto 7rem; padding-top: 6rem; border-top: 1px solid var(--line); display: grid; grid-template-columns: .75fr 1fr; gap: clamp(3rem,8vw,8rem); }
.guide-section h2 { margin: 0; font-size: clamp(2.8rem,6vw,5rem); line-height: .95; letter-spacing: -.06em; }
.steps { margin: 0; padding: 0; list-style: none; }
.steps li { padding: 1.3rem 0; display: grid; grid-template-columns: 3rem 1fr; border-top: 1px solid var(--line); }
.steps li:last-child { border-bottom: 1px solid var(--line); }
.steps span { color: var(--accent); font: 500 .78rem "DM Mono", monospace; }
.steps strong { display: block; margin-bottom: .25rem; font-size: 1.15rem; }
.steps p { margin: 0; color: var(--muted); line-height: 1.5; }
footer { padding: 2rem 0 2.5rem; border-top: 1px solid var(--line); color: var(--muted); font-size: .85rem; }
footer p { margin: 0; }
footer div { display: flex; gap: 1.5rem; }
.confirm-dialog { width: min(calc(100% - 2rem),25rem); padding: 0; border: 0; border-radius: var(--radius-large); color: var(--ink); background: var(--white); box-shadow: 0 2rem 6rem rgba(40,33,24,.32); }
.confirm-dialog::backdrop { background: rgba(36,35,31,.55); backdrop-filter: blur(.25rem); }
.confirm-dialog form { padding: 2rem; text-align: center; }
.dialog-icon { width: 3rem; height: 3rem; margin: 0 auto 1rem; display: grid; place-items: center; border-radius: .8rem; color: var(--accent); background: #fbe2da; }
.dialog-icon svg { width: 1.35rem; height: 1.35rem; }
.confirm-dialog h2 { margin: 0; font-size: 1.55rem; letter-spacing: -.035em; }
.confirm-dialog p { margin: .6rem 0 1.5rem; color: var(--muted); line-height: 1.5; }
.dialog-actions { display: flex; justify-content: center; gap: .5rem; }
:focus-visible { outline: 3px solid rgba(233,99,69,.48); outline-offset: 3px; }
@media (max-width: 800px) {
    .site-header { padding-block: 1rem; }
    .game-layout { min-height: auto; padding: 2.8rem 0 5rem; grid-template-columns: 1fr; gap: 2.8rem; }
    .intro-panel { text-align: center; }
    h1 { max-width: none; font-size: clamp(4.3rem,20vw,6.7rem); }
    .intro-copy { margin-inline: auto; }
    .desktop-hint { display: none; }
    .game-panel { max-width: 32rem; margin-inline: auto; }
    .guide-section { grid-template-columns: 1fr; gap: 2.5rem; }
}
@media (max-width: 540px) {
    .site-header, footer, .game-layout, .guide-section { width: min(100% - 1.25rem,75rem); }
    .header-links a:first-child { display: none; }
    .game-layout { padding-top: 2rem; gap: 2.25rem; }
    .eyebrow { font-size: .7rem; }
    .intro-copy { margin-top: 1.35rem; font-size: .98rem; }
    .score-row { grid-template-columns: 1fr 1fr; }
    .game-actions { grid-column: 1 / -1; grid-template-columns: 1fr 1fr; }
    .icon-button { min-height: 2.75rem; }
    .mobile-controls { margin-top: .85rem; display: flex; flex-direction: column; align-items: center; gap: .28rem; }
    .mobile-controls span { display: flex; gap: .28rem; }
    .mobile-controls button { width: 3rem; height: 2.45rem; padding: 0; display: grid; place-items: center; border: 1px solid var(--line); border-bottom-width: 3px; border-radius: .45rem; color: var(--ink); background: var(--white); cursor: pointer; }
    .mobile-controls button:active { transform: translateY(2px); border-bottom-width: 1px; }
    .guide-section { margin-bottom: 4rem; padding-top: 4rem; }
    footer { align-items: flex-start; gap: 1.5rem; flex-direction: column; }
}
@media (prefers-reduced-motion: reduce) { *, *::before, *::after { scroll-behavior: auto !important; animation-duration: .01ms !important; transition-duration: .01ms !important; } }

.about-page { width: min(100% - 2rem, 75rem); margin-inline: auto; }
.about-hero { min-height: 72dvh; padding: clamp(5rem, 10vw, 9rem) 0 7rem; }
.about-hero h1 { max-width: 11ch; }
.about-hero > p:not(.eyebrow) { max-width: 40rem; margin: 2rem 0; color: var(--muted); font-size: 1.2rem; line-height: 1.7; }
.about-hero .button { display: inline-flex; align-items: center; text-decoration: none; }
.about-grid { padding: 6rem 0; display: grid; grid-template-columns: .75fr 1fr; gap: clamp(3rem, 8vw, 8rem); border-top: 1px solid var(--line); }
.about-grid h2, .tip-band h2 { max-width: 12ch; margin: 0; font-size: clamp(2.5rem, 5vw, 4.6rem); line-height: 1; letter-spacing: -.055em; }
.prose { color: var(--muted); font-size: 1.05rem; line-height: 1.75; }
.prose p:first-child { margin-top: 0; }
.prose a { color: var(--ink); text-underline-offset: .25em; text-decoration-color: var(--accent); }
.tip-band { margin: 1rem 0 7rem; padding: clamp(2.5rem, 7vw, 5rem); border-radius: var(--radius-large); color: var(--white); background: var(--ink); }
.tip-band h2 { max-width: 16ch; }
.tip-band > p:last-child { max-width: 45rem; margin: 1.5rem 0 0; color: #c9c4bb; font-size: 1.08rem; line-height: 1.7; }
.tip-band .eyebrow { color: #f5a58f; }
@media (max-width: 800px) { .about-grid { grid-template-columns: 1fr; gap: 2rem; } .about-hero { min-height: auto; } }
@media (max-width: 540px) { .about-page { width: min(100% - 1.25rem, 75rem); } .about-hero { padding-top: 4rem; } .about-hero h1 { font-size: clamp(3.8rem, 18vw, 5rem); } .about-grid { padding: 4rem 0; } .tip-band { margin-bottom: 4rem; } }