/* ==================== DESIGN TOKENS ==================== */
:root {
  --light-color-primary: 68 114 210;
  --light-color-on-primary: 255 255 255;
  --light-color-primary-container: 221 232 254;
  --light-color-on-primary-container: 26 48 95;
  --light-color-surface: 255 255 255;
  --light-color-on-surface: 0 0 0;
  --light-color-on-surface-variant: 50 65 87;
  --light-color-surface-container-low: 248 250 252;
  --light-color-surface-container: 241 245 249;
  --light-color-surface-container-high: 227 233 241;
  --light-color-surface-container-highest: 212 221 232;
  --light-color-outline: 98 116 142;
  --light-color-outline-variant: 144 161 185;
  --light-color-shadow: 0 0 0;
  --light-color-error: 231 0 11;
  --light-color-on-error: 254 242 242;
  --light-color-error-container: 255 226 226;
  --light-color-on-error-container: 130 24 26;
  --light-color-success: 0 130 54;
  --light-color-on-success: 240 253 244;
  --light-color-success-container: 220 252 231;
  --light-color-on-success-container: 13 84 43;
  --light-color-warning-container: 254 243 198;
  --light-color-on-warning-container: 123 51 6;

  --color-primary: var(--light-color-primary);
  --color-on-primary: var(--light-color-on-primary);
  --color-primary-container: var(--light-color-primary-container);
  --color-on-primary-container: var(--light-color-on-primary-container);
  --color-surface: var(--light-color-surface);
  --color-on-surface: var(--light-color-on-surface);
  --color-on-surface-variant: var(--light-color-on-surface-variant);
  --color-surface-container-low: var(--light-color-surface-container-low);
  --color-surface-container: var(--light-color-surface-container);
  --color-surface-container-high: var(--light-color-surface-container-high);
  --color-surface-container-highest: var(--light-color-surface-container-highest);
  --color-outline: var(--light-color-outline);
  --color-outline-variant: var(--light-color-outline-variant);
  --color-shadow: var(--light-color-shadow);
  --color-error: var(--light-color-error);
  --color-on-error: var(--light-color-on-error);
  --color-error-container: var(--light-color-error-container);
  --color-on-error-container: var(--light-color-on-error-container);
  --color-success: var(--light-color-success);
  --color-on-success: var(--light-color-on-success);
  --color-success-container: var(--light-color-success-container);
  --color-on-success-container: var(--light-color-on-success-container);
  --color-warning-container: var(--light-color-warning-container);
  --color-on-warning-container: var(--light-color-on-warning-container);
}

/* ==================== RESET & BASE ==================== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: 'DM Sans', sans-serif;
  background-color: rgb(var(--color-surface-container-low));
  color: rgb(var(--color-on-surface));
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px 16px;
}

/* ==================== LAYOUT ==================== */
.quiz-wrapper {
  width: 100%;
  max-width: 600px;
}

/* ==================== CATEGORY SCREEN ==================== */
.category-header {
  margin-bottom: 28px;
  animation: fadeSlideDown 0.4s ease both;
}

.category-title {
  font-size: 26px;
  font-weight: 600;
  color: rgb(var(--color-on-surface));
  letter-spacing: -0.4px;
}

.category-subtitle {
  font-size: 14px;
  font-weight: 400;
  color: rgb(var(--color-on-surface-variant));
  margin-top: 4px;
}

.category-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
}

/* Each category card staggered in to create a cascade reveal */
.category-card {
  background-color: rgb(var(--color-surface));
  border-radius: 18px;
  padding: 22px 20px;
  cursor: pointer;
  border: 1.5px solid rgb(var(--color-surface-container-high));
  box-shadow:
    0 1px 3px rgba(var(--color-shadow), 0.06),
    0 4px 12px rgba(var(--color-shadow), 0.05);
  transition: transform 0.15s ease, box-shadow 0.15s ease, border-color 0.15s ease;
  text-align: left;
  font-family: 'DM Sans', sans-serif;
  opacity: 0;
  animation: fadeSlideUp 0.4s ease forwards;
}

.category-card:nth-child(1) { animation-delay: 0.05s; }
.category-card:nth-child(2) { animation-delay: 0.12s; }
.category-card:nth-child(3) { animation-delay: 0.19s; }
.category-card:nth-child(4) { animation-delay: 0.26s; }

.category-card:hover {
  transform: translateY(-3px);
  box-shadow:
    0 4px 12px rgba(var(--color-shadow), 0.10),
    0 8px 28px rgba(var(--color-shadow), 0.08);
  border-color: rgb(var(--color-outline-variant));
}

.category-card:active {
  transform: translateY(-1px) scale(0.99);
}

.category-icon-wrap {
  width: 48px;
  height: 48px;
  border-radius: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 24px;
  margin-bottom: 14px;
  /* background set inline per card via data-gradient */
}

.category-card-title {
  font-size: 15px;
  font-weight: 600;
  color: rgb(var(--color-on-surface));
  letter-spacing: -0.1px;
  margin-bottom: 4px;
}

.category-card-meta {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}

.category-count {
  font-size: 12px;
  font-weight: 400;
  color: rgb(var(--color-on-surface-variant));
}

.category-difficulty {
  font-size: 11px;
  font-weight: 500;
  padding: 2px 8px;
  border-radius: 99px;
}

.difficulty-beginner {
  background-color: rgb(var(--color-success-container));
  color: rgb(var(--color-on-success-container));
}

.difficulty-intermediate {
  background-color: rgb(var(--color-warning-container));
  color: rgb(var(--color-on-warning-container));
}

/* ==================== HEADER ==================== */
.quiz-header {
  margin-bottom: 24px;
  animation: fadeSlideDown 0.4s ease both;
}

.quiz-header-inner {
  display: flex;
  align-items: center;
  gap: 10px;
}

.back-btn {
  flex-shrink: 0;
  width: 34px;
  height: 34px;
  border-radius: 10px;
  background-color: rgb(var(--color-surface-container));
  border: 1.5px solid rgb(var(--color-surface-container-high));
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  color: rgb(var(--color-on-surface-variant));
  transition: background-color 0.15s ease;
  font-family: 'DM Sans', sans-serif;
}

.back-btn:hover {
  background-color: rgb(var(--color-surface-container-high));
}

.quiz-title {
  font-size: 20px;
  font-weight: 600;
  color: rgb(var(--color-on-surface));
  letter-spacing: -0.3px;
}

.quiz-subtitle {
  font-size: 13px;
  font-weight: 400;
  color: rgb(var(--color-on-surface-variant));
  margin-top: 2px;
  margin-left: 44px; /* aligns under title, past the back button */
}

/* ==================== PROGRESS ==================== */
.progress-bar-track {
  height: 6px;
  background-color: rgb(var(--color-surface-container-high));
  border-radius: 99px;
  margin-bottom: 24px;
  overflow: hidden;
  animation: fadeSlideDown 0.4s 0.05s ease both;
}

.progress-bar-fill {
  height: 100%;
  border-radius: 99px;
  transition: width 0.5s cubic-bezier(0.4, 0, 0.2, 1);
  /* gradient injected via JS to match the active quiz group's color */
}

/* ==================== QUESTION CARD ==================== */
.question-card {
  background-color: rgb(var(--color-surface));
  border-radius: 20px;
  padding: 28px;
  box-shadow:
    0 1px 3px rgba(var(--color-shadow), 0.08),
    0 4px 16px rgba(var(--color-shadow), 0.06);
  animation: fadeSlideDown 0.4s 0.1s ease both;
}

.question-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 20px;
}

.question-badge {
  font-size: 12px;
  font-weight: 500;
  color: rgb(var(--color-on-primary-container));
  background-color: rgb(var(--color-primary-container));
  padding: 4px 10px;
  border-radius: 99px;
  letter-spacing: 0.2px;
}

.question-counter {
  font-size: 13px;
  font-weight: 400;
  color: rgb(var(--color-on-surface-variant));
}

.question-text {
  font-size: 17px;
  font-weight: 500;
  line-height: 1.55;
  color: rgb(var(--color-on-surface));
  margin-bottom: 24px;
  letter-spacing: -0.1px;
}

/* ==================== CHOICES ==================== */
.choices-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
  list-style: none;
}

.choice-btn {
  display: flex;
  align-items: center;
  gap: 14px;
  width: 100%;
  padding: 14px 16px;
  background-color: rgb(var(--color-surface-container-low));
  border: 1.5px solid rgb(var(--color-outline-variant));
  border-radius: 12px;
  cursor: pointer;
  text-align: left;
  font-family: 'DM Sans', sans-serif;
  font-size: 14px;
  font-weight: 400;
  color: rgb(var(--color-on-surface));
  transition: background-color 0.15s ease, border-color 0.15s ease, transform 0.1s ease;
  -webkit-tap-highlight-color: transparent;
}

.choice-btn:hover:not(:disabled) {
  background-color: rgb(var(--color-surface-container));
  border-color: rgb(var(--color-outline));
}

.choice-btn:active:not(:disabled) { transform: scale(0.99); }
.choice-btn:disabled { cursor: default; }

.choice-label {
  flex-shrink: 0;
  width: 28px;
  height: 28px;
  border-radius: 8px;
  background-color: rgb(var(--color-surface-container-highest));
  color: rgb(var(--color-on-surface-variant));
  font-size: 12px;
  font-weight: 600;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background-color 0.2s ease, color 0.2s ease;
}

.choice-text { flex: 1; line-height: 1.45; }

.choice-icon {
  flex-shrink: 0;
  width: 20px;
  height: 20px;
  opacity: 0;
  transition: opacity 0.2s ease;
}

.choice-btn.correct {
  background-color: rgb(var(--color-success-container));
  border-color: rgb(var(--color-success));
}

.choice-btn.correct .choice-label {
  background-color: rgb(var(--color-success));
  color: rgb(var(--color-on-success));
}

.choice-btn.correct .choice-icon { opacity: 1; }

.choice-btn.wrong {
  background-color: rgb(var(--color-error-container));
  border-color: rgb(var(--color-error));
}

.choice-btn.wrong .choice-label {
  background-color: rgb(var(--color-error));
  color: rgb(var(--color-on-error));
}

.choice-btn.wrong .choice-icon { opacity: 1; }

.choice-btn.reveal-correct {
  background-color: rgb(var(--color-success-container));
  border-color: rgb(var(--color-success));
  opacity: 0.7;
}

.choice-btn.reveal-correct .choice-label {
  background-color: rgb(var(--color-success));
  color: rgb(var(--color-on-success));
}

.choice-btn.muted { opacity: 0.45; }

/* ==================== FEEDBACK BAR ==================== */
.feedback-bar {
  margin-top: 16px;
  padding: 12px 16px;
  border-radius: 10px;
  font-size: 14px;
  font-weight: 500;
  display: flex;
  align-items: center;
  gap: 8px;
  opacity: 0;
  transform: translateY(6px);
  transition: opacity 0.25s ease, transform 0.25s ease;
  pointer-events: none;
}

.feedback-bar.visible { opacity: 1; transform: translateY(0); }

.feedback-bar.correct-feedback {
  background-color: rgb(var(--color-success-container));
  color: rgb(var(--color-on-success-container));
}

.feedback-bar.wrong-feedback {
  background-color: rgb(var(--color-error-container));
  color: rgb(var(--color-on-error-container));
}

/* ==================== NEXT BUTTON ==================== */
.next-btn {
  width: 100%;
  margin-top: 20px;
  padding: 14px 20px;
  color: rgb(var(--color-on-primary));
  border: none;
  border-radius: 12px;
  font-family: 'DM Sans', sans-serif;
  font-size: 15px;
  font-weight: 500;
  cursor: pointer;
  letter-spacing: 0.1px;
  opacity: 0;
  pointer-events: none;
  transform: translateY(6px);
  transition: opacity 0.25s ease, transform 0.25s ease;
  /* background set via JS to match active quiz group's gradient */
}

.next-btn.visible {
  opacity: 1;
  pointer-events: auto;
  transform: translateY(0);
}

.next-btn:hover { opacity: 0.92; }
.next-btn:active { transform: scale(0.99); }

/* ==================== RESULTS SCREEN ==================== */
.results-card {
  background-color: rgb(var(--color-surface));
  border-radius: 20px;
  padding: 36px 28px;
  text-align: center;
  box-shadow:
    0 1px 3px rgba(var(--color-shadow), 0.08),
    0 4px 16px rgba(var(--color-shadow), 0.06);
  animation: fadeSlideDown 0.4s ease both;
}

.results-score-ring {
  width: 100px;
  height: 100px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 20px;
  /* background and box-shadow set via JS to match the active quiz group */
}

.results-score-number {
  font-size: 32px;
  font-weight: 600;
  color: rgb(var(--color-on-primary));
  line-height: 1;
}

.results-score-total {
  font-size: 14px;
  color: rgb(var(--color-on-primary));
  font-weight: 400;
}

.results-title {
  font-size: 20px;
  font-weight: 600;
  color: rgb(var(--color-on-surface));
  margin-bottom: 6px;
  letter-spacing: -0.2px;
}

.results-message {
  font-size: 14px;
  font-weight: 400;
  color: rgb(var(--color-on-surface-variant));
  margin-bottom: 28px;
  line-height: 1.5;
}

.results-stat-row {
  display: flex;
  gap: 10px;
  margin-bottom: 16px;
}

.results-stat {
  flex: 1;
  padding: 14px 12px;
  border-radius: 12px;
  text-align: center;
}

.results-stat.stat-correct { background-color: rgb(var(--color-success-container)); }
.results-stat.stat-wrong   { background-color: rgb(var(--color-error-container)); }

.results-stat-value {
  font-size: 24px;
  font-weight: 600;
  line-height: 1.1;
}

.stat-correct .results-stat-value { color: rgb(var(--color-success)); }
.stat-wrong   .results-stat-value { color: rgb(var(--color-error)); }

.results-stat-label {
  font-size: 12px;
  font-weight: 400;
  margin-top: 2px;
}

.stat-correct .results-stat-label { color: rgb(var(--color-on-success-container)); }
.stat-wrong   .results-stat-label { color: rgb(var(--color-on-error-container)); }

.results-btn-group {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-top: 24px;
}

.restart-btn {
  width: 100%;
  padding: 14px 20px;
  color: rgb(var(--color-on-primary));
  border: none;
  border-radius: 12px;
  font-family: 'DM Sans', sans-serif;
  font-size: 15px;
  font-weight: 500;
  cursor: pointer;
  transition: opacity 0.15s ease, transform 0.1s ease;
}

.restart-btn:hover  { opacity: 0.92; }
.restart-btn:active { transform: scale(0.99); }

.back-to-categories-btn {
  width: 100%;
  padding: 13px 20px;
  background-color: transparent;
  color: rgb(var(--color-on-surface-variant));
  border: 1.5px solid rgb(var(--color-outline-variant));
  border-radius: 12px;
  font-family: 'DM Sans', sans-serif;
  font-size: 15px;
  font-weight: 500;
  cursor: pointer;
  transition: background-color 0.15s ease, border-color 0.15s ease;
}

.back-to-categories-btn:hover {
  background-color: rgb(var(--color-surface-container));
  border-color: rgb(var(--color-outline));
}

/* ==================== ANIMATIONS ==================== */
@keyframes fadeSlideDown {
  from { opacity: 0; transform: translateY(-10px); }
  to   { opacity: 1; transform: translateY(0); }
}

@keyframes fadeSlideUp {
  from { opacity: 0; transform: translateY(14px); }
  to   { opacity: 1; transform: translateY(0); }
}

.question-transition-out { animation: slideOut 0.25s ease forwards; }

@keyframes slideOut {
  to { opacity: 0; transform: translateX(-20px); }
}

/* ==================== HIDDEN UTILITY ==================== */
.hidden { display: none !important; }