/* DARK MODE THEME */
:root {
  --primary: #3b82f6;
  --primary-hover: #2563eb;
  --secondary: #8b5cf6;
  --secondary-hover: #7c3aed;
  --bg: #0f172a;
  --card-bg: #1e293b;
  --text: #f8fafc;
  --text-muted: #94a3b8;
  --success: #22c55e;
  --error: #ef4444;
  --border: #334155;
}

body {
  font-family: "Helvetica Neue", Arial, "Hiragino Kaku Gothic ProN", "Hiragino Sans", Meiryo, sans-serif;
  background-color: var(--bg);
  color: var(--text);
  margin: 0;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  padding: 20px;
  box-sizing: border-box;
}

.app-container {
  width: 100%;
  max-width: 700px;
  background: var(--card-bg);
  border-radius: 16px;
  box-shadow: 0 10px 25px rgba(0,0,0,0.5);
  padding: 30px;
  border: 1px solid var(--border);
}

.screen { display: none; }
.screen.active { display: block; }

h1, h2, h3 { margin-top: 0; }

#start-screen { text-align: center; padding: 40px 0; }
#start-screen p { color: var(--text-muted); margin-bottom: 30px; }

.btn {
  display: block;
  width: 100%;
  padding: 14px;
  margin-bottom: 15px;
  border: none;
  border-radius: 8px;
  font-size: 1.1rem;
  font-weight: bold;
  cursor: pointer;
  transition: background-color 0.2s, transform 0.1s;
  color: white;
}
.btn:active { transform: scale(0.98); }
.btn.primary { background-color: var(--primary); }
.btn.primary:hover { background-color: var(--primary-hover); }
.btn.secondary { background-color: var(--secondary); }
.btn.secondary:hover { background-color: var(--secondary-hover); }

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 1px solid var(--border);
  padding-bottom: 15px;
  margin-bottom: 25px;
}

.header-left h1 { font-size: 1.2rem; margin: 0 0 5px 0; color: var(--text-muted); }
#timer-display { font-weight: bold; color: #facc15; font-size: 1.1rem; }
#timer-display.danger { color: var(--error); animation: pulse 1s infinite; }

@keyframes pulse {
  0% { opacity: 1; }
  50% { opacity: 0.5; }
  100% { opacity: 1; }
}

.score-board { font-size: 1rem; color: var(--text-muted); }

.category-badge {
  display: inline-block;
  background: #312e81;
  color: #a5b4fc;
  font-size: 0.85rem;
  font-weight: bold;
  padding: 6px 12px;
  border-radius: 20px;
  margin-bottom: 15px;
}

#question { font-size: 1.25rem; line-height: 1.5; margin-bottom: 25px; }

.option-btn {
  width: 100%;
  text-align: left;
  padding: 16px;
  margin-bottom: 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--bg);
  color: var(--text);
  font-size: 1.05rem;
  cursor: pointer;
  transition: all 0.2s;
}

.option-btn:hover:not(:disabled) {
  border-color: var(--primary);
  background: #1e293b;
}

.option-btn.correct {
  background-color: rgba(34, 197, 94, 0.2);
  border-color: var(--success);
  color: #4ade80;
}

.option-btn.wrong {
  background-color: rgba(239, 68, 68, 0.2);
  border-color: var(--error);
  color: #f87171;
}

.explanation-box {
  margin-top: 25px;
  padding: 20px;
  background: rgba(59, 130, 246, 0.1);
  border-left: 4px solid var(--primary);
  border-radius: 8px;
}
.explanation-box h3 { color: var(--primary); margin-bottom: 10px; font-size: 1.1rem; }
.explanation-box p { line-height: 1.6; margin-bottom: 20px; }

.hidden { display: none !important; }

#result-screen { text-align: center; padding: 40px 0; }
.result-score {
  background: var(--bg);
  padding: 40px 20px;
  border-radius: 12px;
  margin: 30px 0;
  border: 1px solid var(--border);
}
#final-score { font-size: 3rem; color: var(--primary); margin: 10px 0; }
#pass-status { font-size: 1.2rem; font-weight: bold; }
.pass { color: var(--success); }
.fail { color: var(--error); }