:root {
  color-scheme: light;
  --brand: #075e54;
  --brand-2: #128c7e;
  --accent: #25d366;
  --surface: #ffffff;
  --background: #f4f8f7;
  --text: #14201d;
  --muted: #64736f;
  --line: #9aa8a4;
  --soft: #e4efec;
  --selected: #d5efe8;
  --peer: #edf8f5;
  --error: #ffe0e0;
  --error-text: #b00020;
  --shadow: 0 12px 34px rgba(7, 94, 84, 0.13);
}

* { box-sizing: border-box; }
html { min-height: 100%; background: var(--background); }
body {
  margin: 0;
  min-height: 100vh;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: var(--text);
  background:
    radial-gradient(circle at 10% 10%, rgba(37, 211, 102, .12), transparent 30%),
    linear-gradient(155deg, #eaf7f3, #f9fbfa 55%, #eef5f3);
}
button { font: inherit; }
button:focus-visible, a:focus-visible { outline: 3px solid #ffbf47; outline-offset: 3px; }
[hidden] { display: none !important; }

.skip-link {
  position: fixed;
  left: 1rem;
  top: -4rem;
  z-index: 100;
  background: #fff;
  color: var(--brand);
  padding: .75rem 1rem;
  border-radius: .75rem;
}
.skip-link:focus { top: 1rem; }

.app {
  width: min(100%, 720px);
  min-height: 100vh;
  margin: 0 auto;
  padding: max(12px, env(safe-area-inset-top)) 12px max(16px, env(safe-area-inset-bottom));
}
.app-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  padding: .5rem .2rem .75rem;
}
.brand { display: flex; align-items: center; gap: .75rem; }
.brand h1 { margin: 0; font-size: clamp(1.25rem, 4vw, 1.55rem); }
.brand p { margin: .12rem 0 0; color: var(--muted); font-size: .78rem; }
.logo {
  display: grid;
  place-items: center;
  width: 46px;
  height: 46px;
  border-radius: 15px;
  color: #fff;
  background: linear-gradient(145deg, var(--brand), var(--brand-2));
  font-size: 1.65rem;
  box-shadow: var(--shadow);
}
.icon-button {
  border: 0;
  min-width: 44px;
  min-height: 44px;
  border-radius: 13px;
  background: var(--surface);
  color: var(--brand);
  font-weight: 900;
  cursor: pointer;
  box-shadow: 0 5px 16px rgba(0, 0, 0, .08);
}

.card {
  margin: .25rem 0 1rem;
  padding: clamp(.85rem, 4vw, 1.3rem);
  border: 1px solid rgba(7, 94, 84, .08);
  border-radius: 24px;
  background: rgba(255, 255, 255, .96);
  box-shadow: var(--shadow);
}
.screen { display: none; }
.screen.active { display: block; }
.hero { text-align: center; padding: .45rem .3rem 1rem; }
.hero h2 { margin: .25rem 0 .4rem; font-size: clamp(1.65rem, 7vw, 2.25rem); }
.hero p { max-width: 520px; margin: 0 auto; color: var(--muted); line-height: 1.5; }
.eyebrow { color: var(--brand-2); font-size: .72rem; font-weight: 850; letter-spacing: .1em; text-transform: uppercase; }
.primary-actions { display: grid; gap: .6rem; margin-bottom: .8rem; }
.wide-button {
  width: 100%;
  min-height: 48px;
  border: 2px solid var(--brand-2);
  border-radius: 14px;
  background: #fff;
  color: var(--brand);
  font-weight: 850;
  cursor: pointer;
}
.continue-button { background: var(--brand); color: #fff; }
.share-button { border-color: var(--accent); }
.levels { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: .7rem; }
.level {
  min-height: 70px;
  border: 0;
  border-radius: 16px;
  color: #fff;
  font-weight: 900;
  cursor: pointer;
  box-shadow: 0 7px 18px rgba(0, 0, 0, .12);
  transition: transform .16s ease, filter .16s ease;
}
.level:hover { transform: translateY(-2px); filter: brightness(1.04); }
.level:active { transform: scale(.98); }
.level small { display: block; margin-top: .18rem; font-size: .7rem; font-weight: 650; opacity: .9; }
.easy { background: #239b56; }
.medium { background: #2874a6; }
.hard { background: #ca6f1e; }
.expert { background: #b03a2e; }
.pro { background: #7d3c98; }
.master { background: #273746; }
.tip { margin: 1rem 0 0; padding: .85rem; border-radius: 14px; background: #f2f8f6; color: var(--muted); font-size: .82rem; line-height: 1.45; }

.game-bar { display: flex; align-items: center; justify-content: space-between; gap: .55rem; margin-bottom: .75rem; }
.back-button { font-size: 1.25rem; }
.badge { padding: .5rem .72rem; border-radius: 999px; background: var(--soft); color: var(--brand); font-size: .82rem; font-weight: 900; }
.stats { display: flex; gap: .4rem; font-variant-numeric: tabular-nums; }
.stat { padding: .46rem .6rem; border-radius: 10px; background: #f2f6f5; color: var(--muted); font-size: .76rem; }
.board-wrap { position: relative; width: min(100%, 560px); margin: 0 auto; }
.board {
  display: grid;
  grid-template-columns: repeat(9, 1fr);
  width: 100%;
  aspect-ratio: 1;
  overflow: hidden;
  border: 3px solid #263a35;
  border-radius: 8px;
  background: #fff;
  touch-action: manipulation;
}
.cell {
  position: relative;
  display: grid;
  place-items: center;
  min-width: 0;
  border: 0;
  border-right: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  background: #fff;
  color: #116b5d;
  font-size: clamp(1.1rem, 6vw, 1.9rem);
  font-weight: 650;
  cursor: pointer;
  padding: 0;
}
.cell:nth-child(9n) { border-right: 0; }
.cell:nth-child(n + 73) { border-bottom: 0; }
.cell.box-right { border-right: 3px solid #263a35; }
.cell.box-bottom { border-bottom: 3px solid #263a35; }
.cell.given { background: #fbfdfc; color: #17231f; font-weight: 900; }
.cell.peer { background: var(--peer); }
.cell.same { background: #dcf4ed; }
.cell.selected { background: var(--selected); box-shadow: inset 0 0 0 3px var(--brand-2); }
.cell.wrong { background: var(--error); color: var(--error-text); }
.notes {
  position: absolute;
  inset: 2px;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: repeat(3, 1fr);
  color: #52716a;
  font-size: clamp(.42rem, 1.8vw, .68rem);
  font-weight: 800;
}
.notes span { display: grid; place-items: center; }
.pause-cover {
  position: absolute;
  inset: 0;
  z-index: 4;
  display: grid;
  place-items: center;
  border-radius: 7px;
  background: rgba(255, 255, 255, .96);
  text-align: center;
}
.pause-cover strong { display: block; font-size: 1.45rem; }
.pause-cover button { margin-top: .8rem; border: 0; border-radius: 12px; padding: .75rem 1rem; background: var(--brand); color: #fff; font-weight: 850; cursor: pointer; }
.toolbar { display: grid; grid-template-columns: repeat(5, 1fr); gap: .45rem; width: min(100%, 560px); margin: .8rem auto .65rem; }
.tool {
  min-height: 58px;
  padding: .5rem .15rem;
  border: 0;
  border-radius: 13px;
  background: #fff;
  color: #36534c;
  font-size: .7rem;
  font-weight: 800;
  cursor: pointer;
  box-shadow: 0 3px 12px rgba(0, 0, 0, .09);
}
.tool span { display: block; margin-bottom: .1rem; font-size: 1.15rem; }
.tool.active { background: var(--brand); color: #fff; }
.number-pad { display: grid; grid-template-columns: repeat(9, 1fr); gap: .32rem; width: min(100%, 560px); margin: 0 auto; }
.number {
  aspect-ratio: 1;
  border: 0;
  border-radius: 11px;
  background: #e4f4ef;
  color: var(--brand);
  font-size: clamp(1.05rem, 5vw, 1.7rem);
  font-weight: 900;
  cursor: pointer;
}
.number.completed { opacity: .28; }
.footer-line { margin: .65rem 0 0; color: var(--muted); text-align: center; font-size: .74rem; }

.modal {
  position: fixed;
  inset: 0;
  z-index: 20;
  display: grid;
  place-items: center;
  padding: 1.2rem;
  background: rgba(0, 0, 0, .55);
}
.modal-box { width: min(100%, 440px); padding: 1.4rem; border-radius: 22px; background: #fff; box-shadow: var(--shadow); text-align: center; }
.modal-box h2 { margin: .25rem 0; }
.modal-box p { color: var(--muted); line-height: 1.5; }
.modal-actions { display: grid; gap: .55rem; margin-top: 1rem; }
.modal-actions button { border: 0; border-radius: 13px; padding: .75rem; font-weight: 850; cursor: pointer; }
.primary { background: var(--brand); color: #fff; }
.secondary { background: #e7efed; color: #26463f; }
.danger { background: #ffe7e7; color: #9f1b1b; }
.help { text-align: left; font-size: .9rem; line-height: 1.55; }
.toast {
  position: fixed;
  left: 50%;
  bottom: calc(20px + env(safe-area-inset-bottom));
  z-index: 50;
  max-width: 90%;
  padding: .65rem .95rem;
  border-radius: 999px;
  background: #1d302b;
  color: #fff;
  opacity: 0;
  transform: translate(-50%, 30px);
  transition: .22s ease;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  pointer-events: none;
}
.toast.visible { opacity: 1; transform: translate(-50%, 0); }

@media (max-width: 430px) {
  .app { padding-left: 7px; padding-right: 7px; }
  .card { border-radius: 18px; }
  .toolbar { gap: .25rem; }
  .tool { font-size: .62rem; }
  .stat { padding: .42rem; font-size: .68rem; }
}
@media (orientation: landscape) and (max-height: 620px) {
  .app { width: min(100%, 1040px); }
  #gameScreen.card.active { display: grid; grid-template-columns: minmax(300px, 52vh) 1fr; gap: .75rem 1rem; }
  .game-bar { grid-column: 1 / -1; margin: 0; }
  .board-wrap { grid-column: 1; grid-row: 2 / 5; }
  .toolbar, .number-pad { grid-column: 2; width: 100%; }
  .toolbar { margin: 0; align-self: end; }
  .number-pad { align-self: start; }
  .footer-line { display: none; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition: none !important; }
}