:root {
  --bg-primary: #0a0a0f;
  --bg-secondary: #14141f;
  --bg-tertiary: #1e1e2e;
  --text-primary: #ffffff;
  --text-secondary: #a0a0b0;
  --text-muted: #606070;
  --accent: #00d4ff;
  --accent-secondary: #00ff88;
  --danger: #ff4466;
  --focus-ring: #00d4ff;
  --focus-glow: rgba(0, 212, 255, 0.4);
  --radius-md: 12px;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html, body {
  width: 600px; height: 600px; overflow: hidden;
  background: #000;
  color: var(--text-primary);
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  font-variant-numeric: tabular-nums;
}

#app { width: 100%; height: 100%; position: relative; }

.screen {
  width: 100%; height: 100%;
  position: absolute; top: 0; left: 0;
  display: flex; flex-direction: column;
  padding: 32px;
}

.screen.hidden { display: none; }

.focusable {
  transition: border-color 0.15s ease, box-shadow 0.15s ease, background-color 0.15s ease;
  border: 2px solid transparent;
  cursor: pointer;
  outline: none;
}

.focusable:focus {
  border-color: var(--focus-ring);
  box-shadow: 0 0 20px var(--focus-glow);
}

.hidden { display: none !important; }

/* ===== HOME ===== */
.home-title {
  font-size: 64px;
  font-weight: 800;
  letter-spacing: 4px;
  color: var(--accent);
  text-align: center;
  margin-top: 24px;
  text-shadow: 0 0 24px rgba(0, 212, 255, 0.35);
}

.home-sub {
  text-align: center;
  color: var(--text-secondary);
  font-size: 20px;
  margin-top: 8px;
  letter-spacing: 1px;
}

.home-best {
  margin: 32px auto 0;
  padding: 16px 28px;
  background: var(--bg-secondary);
  border-radius: var(--radius-md);
  text-align: center;
  border: 2px solid var(--bg-tertiary);
  min-width: 280px;
}

.best-label {
  font-size: 14px;
  color: var(--text-muted);
  letter-spacing: 2px;
}

.best-row {
  font-size: 32px;
  font-weight: 700;
  margin-top: 4px;
  color: var(--text-primary);
}

.best-score { color: var(--accent-secondary); }
.best-sep { color: var(--text-muted); margin: 0 12px; }
.best-time { color: var(--text-primary); }

.home-actions {
  margin-top: auto;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.btn {
  background: var(--bg-secondary);
  color: var(--text-primary);
  font-size: 22px;
  font-weight: 700;
  letter-spacing: 2px;
  padding: 0 24px;
  height: 88px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  border: 2px solid var(--bg-tertiary);
  font-family: inherit;
}

.btn-primary {
  background: var(--accent);
  color: #001218;
  border-color: var(--accent);
}

.btn-primary.focusable:focus {
  box-shadow: 0 0 28px var(--focus-glow);
}

.btn-ghost {
  background: transparent;
  color: var(--text-secondary);
  font-size: 16px;
  height: 56px;
  letter-spacing: 1.5px;
}

/* ===== GAME ===== */
#game { padding: 20px 24px; }

.hud {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  align-items: center;
  background: var(--bg-secondary);
  border-radius: var(--radius-md);
  padding: 12px 18px;
  border: 1px solid var(--bg-tertiary);
}

.hud-cell { display: flex; flex-direction: column; }
.hud-center { align-items: center; }
.hud-right { align-items: flex-end; }

.hud-label {
  font-size: 12px;
  color: var(--text-muted);
  letter-spacing: 2px;
}

.hud-value {
  font-size: 26px;
  font-weight: 700;
  color: var(--text-primary);
  margin-top: 2px;
}

.hud-time { color: var(--accent); }
.hud-time.warn { color: var(--danger); }
.hud-correct { color: var(--accent-secondary); }

.progress-bar {
  margin-top: 10px;
  height: 6px;
  background: var(--bg-secondary);
  border-radius: 3px;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--accent), var(--accent-secondary));
  transition: width 0.25s ease;
}

.problem {
  flex: 0 0 auto;
  margin: 24px 0 22px;
  text-align: center;
  font-size: 80px;
  font-weight: 800;
  letter-spacing: 3px;
  color: var(--text-primary);
  min-height: 110px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.problem.flash-good { color: var(--accent-secondary); }
.problem.flash-bad { color: var(--danger); }

.answers {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  flex: 1 1 auto;
}

.answer-btn {
  background: var(--bg-secondary);
  border: 2px solid var(--bg-tertiary);
  color: var(--text-primary);
  font-size: 40px;
  font-weight: 700;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: inherit;
  min-height: 88px;
}

.answer-btn.correct {
  background: rgba(0, 255, 136, 0.18);
  border-color: var(--accent-secondary);
  color: var(--accent-secondary);
}

.answer-btn.wrong {
  background: rgba(255, 68, 102, 0.18);
  border-color: var(--danger);
  color: var(--danger);
}

.game-foot {
  text-align: center;
  color: var(--text-muted);
  font-size: 13px;
  letter-spacing: 1.5px;
  margin-top: 10px;
}

/* ===== RESULT ===== */
#result { justify-content: flex-start; }

.result-title {
  text-align: center;
  font-size: 56px;
  font-weight: 800;
  letter-spacing: 4px;
  color: var(--accent);
  margin-top: 8px;
  text-shadow: 0 0 24px rgba(0, 212, 255, 0.35);
}

.result-grid {
  margin-top: 24px;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
}

.result-cell {
  background: var(--bg-secondary);
  border: 1px solid var(--bg-tertiary);
  border-radius: var(--radius-md);
  padding: 16px 18px;
}

.result-label {
  font-size: 13px;
  color: var(--text-muted);
  letter-spacing: 2px;
}

.result-value {
  font-size: 34px;
  font-weight: 800;
  color: var(--text-primary);
  margin-top: 4px;
}

.result-value.accent { color: var(--accent-secondary); }

.result-badge {
  margin-top: 18px;
  text-align: center;
  font-size: 18px;
  font-weight: 700;
  letter-spacing: 2px;
  color: var(--accent-secondary);
  min-height: 24px;
}

.result-actions {
  margin-top: auto;
  display: flex;
  flex-direction: column;
  gap: 12px;
}