:root {
  --primary: #d9a441;
  --primary-dark: #c28f34;
  --accent: #2f6a54;
  --accent-dark: #1f4a3d;
  --ink-on-gold: #4a3413;
  --success: #16a34a;
  --danger: #dc2626;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  font-family: 'Karla', sans-serif;
  background: radial-gradient(circle at top, var(--accent) 0%, var(--accent-dark) 70%);
  color: #eef0ea;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
}

.wrap {
  width: 100%;
  max-width: 480px;
  position: relative;
}

.back-link {
  position: absolute;
  top: -44px;
  left: 0;
  color: #eef0ea;
  text-decoration: none;
  font-size: 14px;
  opacity: 0.8;
}
.back-link:hover { opacity: 1; }

.screen {
  background: rgba(255, 255, 255, 0.06);
  border: 1px solid rgba(217, 164, 65, 0.35);
  border-radius: 20px;
  padding: 32px 28px;
  text-align: center;
  backdrop-filter: blur(6px);
}
.hidden { display: none; }

.title {
  font-family: 'Bitter', serif;
  font-size: 26px;
  margin: 0 0 8px;
  color: var(--primary);
}

.subtitle {
  font-size: 14px;
  opacity: 0.85;
  margin: 0 0 22px;
  line-height: 1.5;
}

.difficulty-row {
  display: flex;
  gap: 8px;
  justify-content: center;
  margin-bottom: 20px;
}

.diff-btn {
  flex: 1;
  padding: 10px 0;
  border-radius: 10px;
  border: 2px solid rgba(217, 164, 65, 0.4);
  background: transparent;
  color: #eef0ea;
  font-weight: 700;
  cursor: pointer;
  transition: all 0.15s ease;
}
.diff-btn.selected,
.diff-btn:hover {
  background: var(--primary);
  border-color: var(--primary);
  color: var(--ink-on-gold);
}

.primary-btn {
  background: var(--primary);
  color: var(--ink-on-gold);
  border: none;
  border-radius: 12px;
  padding: 14px 32px;
  font-size: 16px;
  font-weight: 800;
  cursor: pointer;
  box-shadow: 0 4px 0 0 var(--primary-dark);
  transition: transform 0.1s ease;
}
.primary-btn:hover { filter: brightness(1.08); }
.primary-btn:active { transform: translateY(3px); box-shadow: 0 1px 0 0 var(--primary-dark); }

.best-score {
  margin: 16px 0 0;
  font-size: 13px;
  opacity: 0.7;
}

.hud {
  display: flex;
  justify-content: space-between;
  margin-bottom: 12px;
}
.hud-item { display: flex; flex-direction: column; align-items: center; flex: 1; }
.hud-label { font-size: 11px; opacity: 0.7; text-transform: uppercase; letter-spacing: 0.05em; }
.hud-value { font-family: 'JetBrains Mono', monospace; font-size: 20px; font-weight: 700; color: var(--primary); }
#lives.hud-value { font-family: inherit; font-size: 16px; }

.timer-track {
  height: 8px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.12);
  overflow: hidden;
  margin-bottom: 24px;
}
.timer-fill {
  height: 100%;
  width: 100%;
  background: linear-gradient(90deg, var(--accent), var(--primary));
}

.problem-card {
  background: rgba(0, 0, 0, 0.18);
  border-radius: 16px;
  padding: 28px 20px;
}

.problem {
  font-family: 'JetBrains Mono', monospace;
  font-size: 32px;
  font-weight: 700;
  margin-bottom: 22px;
  color: #fff;
}

.answer-row {
  display: flex;
  gap: 10px;
}

.answer-btn {
  flex: 1;
  padding: 16px 8px;
  border-radius: 12px;
  border: none;
  font-size: 15px;
  font-weight: 800;
  cursor: pointer;
  transition: transform 0.1s ease, filter 0.15s ease;
}
.answer-btn:hover { filter: brightness(1.1); }
.answer-btn:active { transform: translateY(2px); }
.false-btn { background: rgba(220, 38, 38, 0.85); color: #fff; }
.true-btn { background: rgba(22, 163, 74, 0.9); color: #fff; }

.feedback {
  height: 20px;
  margin-top: 14px;
  font-weight: 700;
  font-size: 14px;
}
.feedback.correct { color: #7be3a0; }
.feedback.wrong { color: #ff9b9b; }

.result-card { margin-bottom: 24px; }
.result-row {
  display: flex;
  justify-content: space-between;
  padding: 10px 4px;
  border-bottom: 1px dashed rgba(217, 164, 65, 0.3);
  font-size: 15px;
}
.result-row strong { color: var(--primary); font-family: 'JetBrains Mono', monospace; }