:root {
  --primary-color: #2563eb;
  --secondary-color: #64748b;
  --bg-color: #f8fafc;
  --card-bg: #ffffff;
  --text-color: #1e293b;
  --error-color: #ef4444;
  --success-color: #22c55e;
}

body {
  font-family: 'Pretendard', -apple-system, BlinkMacSystemFont, system-ui, Roboto, sans-serif;
  background-color: var(--bg-color);
  color: var(--text-color);
  margin: 0;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
}

.container {
  width: 100%;
  max-width: 600px;
  padding: 20px;
}

header {
  text-align: center;
  margin-bottom: 30px;
  position: relative;
}

h1 {
  font-size: 2.5rem;
  margin: 0;
  color: var(--primary-color);
}

.subtitle {
  color: var(--secondary-color);
  margin-top: 5px;
}

#progress-indicator {
  margin-top: 15px;
  font-weight: 600;
  color: var(--primary-color);
  background: #dbeafe;
  display: inline-block;
  padding: 4px 12px;
  border-radius: 20px;
  font-size: 0.9rem;
}

#timer-container {
  margin-top: 15px;
  font-size: 2rem;
  font-weight: bold;
}

#timer.warning {
  color: var(--error-color);
  animation: blink 1s infinite;
}

@keyframes blink {
  50% { opacity: 0.7; }
}

.card {
  background: var(--card-bg);
  padding: 25px;
  border-radius: 16px;
  box-shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  margin-bottom: 20px;
  transition: transform 0.2s;
}

#question-text {
  font-size: 1.25rem;
  line-height: 1.6;
  margin: 0;
  font-weight: 500;
}

#answer-input {
  width: 100%;
  height: 120px;
  border: 1px solid #e2e8f0;
  border-radius: 8px;
  padding: 12px;
  font-size: 1rem;
  resize: none;
  box-sizing: border-box;
  margin-bottom: 15px;
  font-family: inherit;
}

#answer-input:focus {
  outline: none;
  border-color: var(--primary-color);
}

.primary-btn {
  width: 100%;
  padding: 14px;
  border: none;
  border-radius: 8px;
  background-color: var(--primary-color);
  color: white;
  font-size: 1.1rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.2s;
}

.primary-btn:hover:not(:disabled) {
  background-color: #1d4ed8;
}

.primary-btn:disabled {
  background-color: #94a3b8;
  cursor: not-allowed;
}

.hidden {
  display: none;
}

.error-text {
  color: var(--error-color);
  font-weight: bold;
}

#ai-response-section h3 {
  margin-top: 0;
  color: var(--primary-color);
  font-size: 1.1rem;
}

#ai-response-text {
  line-height: 1.6;
  margin-bottom: 0;
}

#session-end-section {
  text-align: center;
}

#session-end-section h2 {
  color: var(--primary-color);
  margin-top: 0;
}