:root {
  --bg: #0d1017;
  --bg-soft: #141a24;
  --line: #1f2937;
  --text: #e6edf6;
  --muted: #8b98ab;
  --accent: #43d9ad;
  --accent-2: #5b8cff;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: radial-gradient(1200px 700px at 20% -10%, #16263a 0%, var(--bg) 55%) fixed;
  color: var(--text);
  font-family: "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  -webkit-text-size-adjust: 100%;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

.top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 16px 20px;
  border-bottom: 1px solid var(--line);
  background: rgba(13, 16, 23, .72);
  backdrop-filter: blur(8px);
  position: sticky;
  top: 0;
  z-index: 10;
}

.brand { display: flex; align-items: center; gap: 10px; color: var(--text); }
.brand:hover { text-decoration: none; }
.brand__logo { width: 28px; height: 28px; }
.brand__text { font-weight: 700; letter-spacing: .12em; text-transform: uppercase; font-size: 15px; }

.nav { display: flex; gap: 18px; font-size: 14px; }
.nav a { color: var(--muted); }
.nav a:hover { color: var(--text); text-decoration: none; }

.wrap {
  max-width: 900px;
  margin: 0 auto;
  padding: 24px 16px 8px;
  display: grid;
  grid-template-columns: minmax(0, 1fr) 240px;
  gap: 24px;
  align-items: start;
}

.board-col { display: flex; flex-direction: column; align-items: center; gap: 14px; }

.board {
  position: relative;
  border-radius: 14px;
  padding: 10px;
  background: linear-gradient(180deg, #161d28, #10151d);
  border: 1px solid var(--line);
  box-shadow: 0 24px 60px rgba(0, 0, 0, .45), inset 0 1px 0 rgba(255, 255, 255, .04);
}

#board {
  display: block;
  border-radius: 8px;
  background: #0a0e14;
  touch-action: none;
  width: min(300px, 78vw, 40vh);
  height: auto;
  aspect-ratio: 1 / 2;
}

.overlay {
  position: absolute;
  inset: 10px;
  border-radius: 8px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 10px;
  text-align: center;
  padding: 20px;
  background: rgba(8, 11, 16, .86);
  backdrop-filter: blur(3px);
  transition: opacity .18s ease;
}
.overlay.hidden { opacity: 0; pointer-events: none; }
.overlay h2 { margin: 0; font-size: 22px; letter-spacing: .08em; text-transform: uppercase; }
.overlay p { margin: 0; color: var(--muted); font-size: 14px; line-height: 1.5; max-width: 240px; }

.btn {
  appearance: none;
  border: 1px solid var(--line);
  background: var(--bg-soft);
  color: var(--text);
  font: inherit;
  font-size: 14px;
  padding: 11px 22px;
  border-radius: 10px;
  cursor: pointer;
  transition: transform .06s ease, background .15s ease;
}
.btn:hover { background: #1b2431; }
.btn:active { transform: translateY(1px); }
.btn--primary {
  background: linear-gradient(180deg, #4be3b7, #33c39a);
  border-color: transparent;
  color: #06231b;
  font-weight: 700;
  letter-spacing: .06em;
  text-transform: uppercase;
}

.panel { display: flex; flex-direction: column; gap: 10px; }

.stat {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  padding: 11px 14px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--bg-soft);
}
.stat__label { color: var(--muted); font-size: 12px; letter-spacing: .1em; text-transform: uppercase; }
.stat__value { font-variant-numeric: tabular-nums; font-size: 18px; font-weight: 600; }

.next {
  display: flex;
  flex-direction: column;
  gap: 8px;
  align-items: center;
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--bg-soft);
}
#next { background: #0a0e14; border-radius: 8px; }

.hint {
  border: 1px dashed var(--line);
  border-radius: 12px;
  padding: 12px 14px;
  color: var(--muted);
  font-size: 12.5px;
  line-height: 1.55;
}
.hint p { margin: 0 0 8px; }
.hint p:last-child { margin-bottom: 0; }
.hint b { color: var(--text); font-weight: 600; }

.touch { display: none; gap: 10px; grid-template-columns: repeat(4, 1fr); width: min(400px, 92vw); }
.tbtn {
  appearance: none;
  border: 1px solid var(--line);
  background: var(--bg-soft);
  color: var(--text);
  font-size: 18px;
  padding: 14px 0;
  border-radius: 12px;
  cursor: pointer;
  touch-action: manipulation;
  user-select: none;
}
.tbtn:active { background: #223044; }
.tbtn--wide { grid-column: span 2; font-size: 13px; letter-spacing: .1em; }

.foot {
  max-width: 900px;
  margin: 28px auto 0;
  padding: 20px 16px 32px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 13px;
  line-height: 1.6;
}
.foot p { margin: 0 0 8px; }
.foot__links { font-size: 12.5px; }

.page { max-width: 720px; margin: 0 auto; padding: 32px 16px 48px; line-height: 1.65; }
.page h1 { font-size: 26px; letter-spacing: .02em; margin: 0 0 16px; }
.page h2 { font-size: 18px; margin: 26px 0 8px; }
.page p, .page li { color: #c3cddb; }
.page ul { padding-left: 20px; }

@media (max-width: 760px) {
  .wrap { grid-template-columns: minmax(0, 1fr); gap: 18px; padding-top: 16px; }
  .panel { flex-direction: row; flex-wrap: wrap; gap: 8px; }
  .stat { flex: 1 1 calc(50% - 8px); }
  .next { flex: 1 1 100%; flex-direction: row; justify-content: space-between; }
  .hint { flex: 1 1 100%; }
  .touch { display: grid; }
  .nav { font-size: 13px; gap: 12px; }
}