:root {
  --bg-top: #0f172a;
  --bg-bottom: #1e293b;
  --surface: rgba(248, 250, 252, 0.95);
  --surface-border: rgba(15, 23, 42, 0.08);
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --option-bg: #ffffff;
  --option-border: #cbd5e1;
  --option-hover: #e2e8f0;
  --accent: #0ea5a4;
  --accent-strong: #0f766e;
  --disabled: #94a3b8;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 24px;
  font-family: "Segoe UI", "SF Pro Text", "Helvetica Neue", sans-serif;
  color: var(--text-primary);
  background:
    radial-gradient(circle at 20% 20%, rgba(14, 165, 164, 0.25), transparent 45%),
    radial-gradient(circle at 80% 10%, rgba(56, 189, 248, 0.2), transparent 40%),
    linear-gradient(160deg, var(--bg-top), var(--bg-bottom));
}

#quiz-container {
  width: min(100%, 640px);
  background: var(--surface);
  border: 1px solid var(--surface-border);
  border-radius: 18px;
  padding: 28px;
  box-shadow: 0 20px 50px rgba(2, 6, 23, 0.32);
  backdrop-filter: blur(4px);
}

#question-text {
  margin: 0 0 20px;
  font-size: clamp(1.1rem, 1.5vw, 1.35rem);
  line-height: 1.45;
  font-weight: 700;
  letter-spacing: 0.01em;
}

#options-container {
  display: grid;
  gap: 12px;
}

#options-container button {
  width: 100%;
  border: 1px solid var(--option-border);
  border-radius: 12px;
  padding: 12px 14px;
  background: var(--option-bg);
  color: var(--text-primary);
  font-size: 0.98rem;
  text-align: left;
  cursor: pointer;
  transition: transform 0.16s ease, background-color 0.16s ease, border-color 0.16s ease;
}

#options-container button:hover:not(:disabled) {
  transform: translateY(-1px);
  background: var(--option-hover);
  border-color: #94a3b8;
}

#options-container button:disabled {
  cursor: not-allowed;
  opacity: 0.92;
}

.button-container {
  display: flex;
  gap: 10px;
  margin-top: 20px;
}

button {
  border: 0;
  border-radius: 10px;
  padding: 10px 16px;
  font-size: 0.96rem;
  font-weight: 600;
}

button:focus-visible {
  outline: 3px solid rgba(14, 165, 164, 0.35);
  outline-offset: 2px;
}

#next-button,
#replay-button {
  color: #f8fafc;
  background: linear-gradient(135deg, var(--accent), var(--accent-strong));
  cursor: pointer;
}

#next-button:hover:not(:disabled),
#replay-button:hover {
  filter: brightness(1.06);
}

#next-button:disabled {
  background: var(--disabled);
  cursor: not-allowed;
}

@media (max-width: 600px) {
  body {
    padding: 14px;
  }

  #quiz-container {
    padding: 18px;
    border-radius: 14px;
  }

  #question-text {
    font-size: 1.02rem;
  }

  .button-container {
    flex-direction: column;
  }

  .button-container button {
    width: 100%;
  }
}