:root {
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Text", system-ui, sans-serif;
  color: #f8fafc;
  background: #0f172a;
  font-synthesis: none;
  -webkit-text-size-adjust: 100%;
  --bg: #0f172a;
  --panel: rgba(15, 23, 42, 0.94);
  --panel-2: #1e293b;
  --border: #334155;
  --muted: #cbd5e1;
  --green: #22c55e;
  --blue: #3b82f6;
  --red: #ef4444;
  --amber: #f59e0b;
  --slate: #475569;
}

* { box-sizing: border-box; }

html, body { min-height: 100%; margin: 0; }

body {
  min-height: 100dvh;
  background:
    radial-gradient(circle at 50% -20%, rgba(59, 130, 246, 0.20), transparent 48%),
    linear-gradient(150deg, #0f172a 0%, #1e293b 45%, #0f172a 100%);
  color: #f8fafc;
  overscroll-behavior: none;
  -webkit-tap-highlight-color: transparent;
  touch-action: manipulation;
}

button, input { font: inherit; }
button { -webkit-appearance: none; appearance: none; }

.app-shell {
  width: min(100%, 640px);
  min-height: 100dvh;
  margin: 0 auto;
  padding:
    max(20px, env(safe-area-inset-top))
    max(16px, env(safe-area-inset-right))
    max(24px, env(safe-area-inset-bottom))
    max(16px, env(safe-area-inset-left));
  display: flex;
  align-items: center;
}

.screen {
  width: 100%;
  background: var(--panel);
  border: 1px solid rgba(148, 163, 184, 0.12);
  border-radius: 24px;
  padding: 22px;
  box-shadow: 0 24px 70px rgba(0, 0, 0, 0.28);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
}

h1, h2, h3, p { margin-top: 0; }
h1, h2 { text-align: center; letter-spacing: -0.025em; }
h1 { font-size: clamp(2.5rem, 10vw, 4rem); margin-bottom: 10px; }
h2 { font-size: 2rem; margin-bottom: 14px; }
h3 { margin-bottom: 6px; }
p { color: var(--muted); line-height: 1.5; text-align: center; }

.subtitle { margin-bottom: 24px; }
.rules { margin: 0 auto 22px; padding-left: 20px; max-width: 380px; color: var(--muted); line-height: 1.65; }

.button {
  width: 100%;
  min-height: 54px;
  border: 0;
  border-radius: 14px;
  padding: 14px 16px;
  margin-top: 10px;
  color: #fff;
  font-weight: 750;
  font-size: 1.05rem;
  cursor: pointer;
  transition: transform 90ms ease, opacity 90ms ease;
}
.button:active { transform: scale(0.985); }
.button:disabled { opacity: 0.45; cursor: default; transform: none; }
.button-primary { background: var(--blue); }
.button-success { background: var(--green); }
.button-danger { background: var(--red); }
.button-secondary { background: var(--slate); }
.button-ghost { background: transparent; border: 1px solid var(--border); color: var(--muted); }

.difficulty-grid { display: grid; gap: 12px; margin: 20px 0; }
.difficulty-card {
  width: 100%;
  text-align: left;
  border: 1.5px solid var(--border);
  border-radius: 16px;
  padding: 16px;
  background: rgba(30, 41, 59, 0.66);
  color: #fff;
  cursor: pointer;
}
.difficulty-card h3 { font-size: 1.2rem; }
.difficulty-card p { text-align: left; margin: 0; font-size: .95rem; }
.difficulty-card.beginner { border-color: var(--green); }
.difficulty-card.intermediate { border-color: var(--amber); }
.difficulty-card.advanced { border-color: var(--red); }

.game-header { display: grid; gap: 8px; margin-bottom: 12px; }
.status-row { display: grid; grid-template-columns: repeat(3, 1fr); gap: 8px; }
.status-card {
  padding: 10px 8px;
  border-radius: 12px;
  background: rgba(51, 65, 85, 0.62);
  text-align: center;
  min-width: 0;
}
.status-label { display: block; color: #94a3b8; font-size: .72rem; text-transform: uppercase; letter-spacing: .06em; }
.status-value { display: block; margin-top: 3px; font-weight: 800; font-variant-numeric: tabular-nums; }
.time-danger { color: #fca5a5; }

.number-display {
  text-align: center;
  margin: 18px 0 14px;
  font-weight: 850;
  font-size: clamp(3.6rem, 17vw, 6rem);
  line-height: 1;
  font-variant-numeric: tabular-nums;
}
.number-display small { display: block; margin-top: 10px; font-size: 1.35rem; color: #cbd5e1; }

.answer-display, .name-input {
  width: 100%;
  border: 1.5px solid var(--border);
  border-radius: 14px;
  background: #1e293b;
  color: #fff;
  min-height: 52px;
  padding: 12px 14px;
  text-align: center;
  font-size: 1.25rem;
  font-variant-numeric: tabular-nums;
  outline: none;
}
.name-input:focus { border-color: #60a5fa; box-shadow: 0 0 0 3px rgba(59, 130, 246, .16); }

.keyboard {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 9px;
  margin: 14px 0 8px;
}
.key {
  min-height: 58px;
  border: 0;
  border-radius: 13px;
  background: var(--slate);
  color: #fff;
  font-weight: 750;
  font-size: 1.3rem;
  cursor: pointer;
}
.key:active { transform: scale(.97); }

.actions { display: grid; gap: 8px; }
.result-time { font-size: 2.2rem; color: #fff; font-weight: 850; text-align: center; margin: 10px 0 18px; font-variant-numeric: tabular-nums; }

.leaderboard-wrap { overflow-x: auto; margin: 16px 0; }
.leaderboard { width: 100%; border-collapse: collapse; font-size: .95rem; }
.leaderboard th, .leaderboard td { padding: 10px 8px; border-bottom: 1px solid var(--border); text-align: left; }
.leaderboard th { color: #93c5fd; font-size: .78rem; text-transform: uppercase; letter-spacing: .04em; }
.leaderboard td:last-child, .leaderboard th:last-child { text-align: right; font-variant-numeric: tabular-nums; }
.empty-state { padding: 18px; border: 1px dashed var(--border); border-radius: 14px; }
.record-badge { display: inline-block; margin-bottom: 10px; padding: 6px 10px; border-radius: 999px; background: rgba(34, 197, 94, .14); color: #86efac; font-weight: 750; font-size: .85rem; }
.validation { min-height: 20px; margin: 8px 0 0; color: #fca5a5; font-size: .9rem; text-align: center; }

.segmented { display: grid; grid-template-columns: repeat(3, 1fr); gap: 6px; padding: 5px; border-radius: 14px; background: #1e293b; margin: 14px 0; }
.segmented button { border: 0; border-radius: 10px; padding: 9px 5px; color: var(--muted); background: transparent; font-weight: 700; font-size: .84rem; }
.segmented button.active { color: #fff; background: var(--slate); }

.modal {
  position: fixed;
  inset: 0;
  z-index: 20;
  padding: max(20px, env(safe-area-inset-top)) 18px max(20px, env(safe-area-inset-bottom));
  background: rgba(2, 6, 23, .78);
  display: flex;
  align-items: center;
  justify-content: center;
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}
.modal[hidden] { display: none; }
.modal-card { width: min(100%, 440px); padding: 22px; border-radius: 20px; background: #0f172a; border: 1px solid var(--border); box-shadow: 0 30px 80px rgba(0,0,0,.4); }
.modal-question { font-size: 1.2rem; color: #fff; }
.answer { margin: 10px 0; border-radius: 12px; padding: 12px; font-weight: 700; text-align: center; background: rgba(51, 65, 85, .55); }
.answer-correct { color: #86efac; }
.answer-wrong { color: #fca5a5; }

.install-note { margin-top: 18px; font-size: .82rem; color: #94a3b8; }

@media (max-height: 760px) {
  .app-shell { align-items: flex-start; }
  .screen { padding: 16px; }
  .number-display { margin: 10px 0; }
  .key { min-height: 50px; }
  .button { min-height: 48px; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition: none !important; }
}

.setting-block {
  margin: 14px 0 22px;
  padding: 14px;
  border: 1px solid var(--border);
  border-radius: 16px;
  background: rgba(30, 41, 59, 0.42);
}
.setting-title {
  color: #e2e8f0;
  text-align: center;
  font-size: .86rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: .06em;
}
.difficulty-title { margin-top: 4px; }
.setting-help, .precision-note {
  margin: 8px 0 0;
  color: #94a3b8;
  font-size: .82rem;
  line-height: 1.4;
}
.segmented.two { grid-template-columns: repeat(2, 1fr); }
.mode-pill {
  width: fit-content;
  margin: 4px auto 0;
  padding: 6px 11px;
  border-radius: 999px;
  background: rgba(59, 130, 246, .12);
  border: 1px solid rgba(96, 165, 250, .28);
  color: #bfdbfe;
  font-size: .82rem;
  font-weight: 750;
}
.precision-note { text-align: center; margin: 7px 0 2px; }
.record-meta { margin-top: 2px; color: #94a3b8; font-size: .74rem; }