:root {
  --bg: #f4efe6;
  --ink: #11201c;
  --card: #fffdf8;
  --accent: #ff6b2d;
  --accent-soft: #ffe0d2;
  --teal: #1f7a6b;
  --line: #d7cfc3;
  --nav-h: 60px;
}

html {
  scroll-behavior: smooth;
}

/* Skip to content */
.skip-link {
  position: absolute;
  top: -100%;
  left: 1rem;
  background: var(--ink);
  color: #fff;
  padding: 0.5rem 1rem;
  border-radius: 0 0 0.5rem 0.5rem;
  font-weight: 700;
  font-size: 0.88rem;
  z-index: 1000;
  text-decoration: none;
  transition: top 120ms ease;
}

.skip-link:focus {
  top: 0;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Manrope", sans-serif;
  color: var(--ink);
  background:
    radial-gradient(circle at 8% 14%, #fff5d8 0, transparent 35%),
    radial-gradient(circle at 88% 6%, #d7f1ec 0, transparent 33%),
    var(--bg);
  line-height: 1.5;
  position: relative;
  overflow-x: hidden;
}

header,
main,
footer {
  position: relative;
  z-index: 1;
}

/* Reading progress bar */
.progress-bar {
  position: fixed;
  top: 0;
  left: 0;
  width: 0%;
  height: 3px;
  background: linear-gradient(90deg, var(--accent), var(--teal));
  z-index: 200;
  transition: width 80ms linear;
  border-radius: 0 2px 2px 0;
}

/* Back-to-top button */
.back-to-top {
  position: fixed;
  bottom: 1.5rem;
  right: 1.5rem;
  width: 2.6rem;
  height: 2.6rem;
  border-radius: 50%;
  background: var(--ink);
  color: #fff;
  border: none;
  font-size: 1.1rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  pointer-events: none;
  transform: translateY(8px);
  transition: opacity 200ms ease, transform 200ms ease, background 150ms ease;
  z-index: 100;
  box-shadow: 0 4px 14px rgba(17, 32, 28, 0.22);
}

.back-to-top.visible {
  opacity: 1;
  pointer-events: auto;
  transform: translateY(0);
}

.back-to-top:hover {
  background: var(--teal);
}

.hero {
  padding: 1.25rem clamp(1rem, 4vw, 3rem) 4rem;
}

.hero-compact {
  padding-bottom: 2rem;
}

.top-nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 2.5rem;
  position: sticky;
  top: 0;
  z-index: 50;
  background: transparent;
  padding: 0.6rem 0;
  transition: background 200ms ease, box-shadow 200ms ease;
}

.top-nav.scrolled {
  background: rgba(244, 239, 230, 0.92);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  box-shadow: 0 1px 0 var(--line);
  margin-bottom: 0;
  padding: 0.6rem clamp(1rem, 4vw, 3rem);
  margin-left: calc(-1 * clamp(1rem, 4vw, 3rem));
  margin-right: calc(-1 * clamp(1rem, 4vw, 3rem));
}

.brand {
  font-family: "Space Grotesk", sans-serif;
  font-weight: 700;
  letter-spacing: 0.02em;
  color: var(--ink);
  text-decoration: none;
}

.brand:hover {
  color: var(--teal);
}

.nav-link {
  color: var(--ink);
  text-decoration: none;
  font-weight: 600;
  font-size: 0.9rem;
  border-bottom: 2px solid transparent;
  transition: color 150ms ease, border-color 150ms ease;
}

.nav-link:hover {
  color: var(--teal);
  border-color: var(--accent);
}

.hero-content {
  max-width: 760px;
  animation: rise 650ms ease;
}

.eyebrow {
  display: inline-block;
  background: var(--accent-soft);
  color: var(--accent);
  padding: 0.35rem 0.75rem;
  border-radius: 999px;
  font-weight: 700;
  font-size: 0.82rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

h1 {
  font-family: "Space Grotesk", sans-serif;
  font-size: clamp(2rem, 6vw, 3.9rem);
  line-height: 1.08;
  margin: 0.75rem 0;
  letter-spacing: -0.02em;
}

.hero p {
  font-size: clamp(1rem, 2.3vw, 1.2rem);
  max-width: 62ch;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1.25rem;
}

.level-tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 0.55rem;
  margin-top: 0.95rem;
}

.level-tab {
  border: 1.5px solid #d9cdbf;
  background: #fff8ef;
  color: #29403a;
  border-radius: 999px;
  padding: 0.45rem 1rem;
  font-weight: 700;
  font-size: 0.88rem;
  cursor: pointer;
  transition: background 150ms ease, border-color 150ms ease, color 150ms ease;
}

.level-tab:hover:not(.is-active) {
  background: #f5ede0;
  border-color: #b8a99a;
}

.level-tab.is-active {
  background: var(--teal);
  color: #ffffff;
  border-color: var(--teal);
  box-shadow: 0 2px 8px rgba(31, 122, 107, 0.3);
}

.btn {
  text-decoration: none;
  font-weight: 700;
  border-radius: 0.7rem;
  padding: 0.78rem 1.25rem;
  font-size: 0.95rem;
  letter-spacing: 0.01em;
  transition: transform 160ms ease, box-shadow 160ms ease;
}

.btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 18px rgba(0,0,0,0.12);
}

.btn-primary {
  background: var(--accent);
  color: white;
  box-shadow: 0 2px 8px rgba(255, 107, 45, 0.3);
}

.btn-secondary {
  background: white;
  color: var(--ink);
  border: 1.5px solid var(--line);
}

.section {
  padding: 0 1rem 3rem;
  max-width: 1080px;
  margin: 0 auto;
}

.section-head h2 {
  font-family: "Space Grotesk", sans-serif;
  margin-bottom: 0.25rem;
  font-size: clamp(1.45rem, 4vw, 2.2rem);
  letter-spacing: -0.02em;
}

.section-head p {
  margin-top: 0;
  color: #4a5e58;
  font-size: 1.02rem;
}

.cards {
  display: grid;
  gap: 1rem;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  margin-top: 1rem;
}

.topic-card {
  display: flex;
  flex-direction: column;
  height: 100%;
}

.topic-card ul {
  margin-bottom: 0.5rem;
}

.topic-card .card-link {
  margin-top: auto;
  align-self: flex-start;
}

.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 1.2rem;
  padding: 1.25rem;
  box-shadow: 0 4px 16px rgba(17, 32, 28, 0.06);
  opacity: 0;
  transform: translateY(10px);
  animation: fadeInUp 500ms forwards;
  transition: box-shadow 200ms ease, transform 200ms ease;
}

.card:hover {
  box-shadow: 0 8px 28px rgba(17, 32, 28, 0.1);
  transform: translateY(-2px);
}

.card {
  cursor: default;
}

.topic-card {
  cursor: pointer;
}

.topic-card:focus-within {
  outline: 2px solid var(--teal);
  outline-offset: 2px;
}

.card h3 {
  margin-top: 0;
  margin-bottom: 0.55rem;
  font-family: "Space Grotesk", sans-serif;
}

.card-title-row {
  display: flex;
  align-items: center;
  gap: 0.65rem;
}

.card-topic-icon {
  width: 2rem;
  height: 2rem;
  flex: 0 0 auto;
}

.card-title-row h3 {
  margin: 0;
}

.card p {
  margin-top: 0;
}

.card li strong {
  display: inline-block;
  margin-bottom: 0.15rem;
}

.badge {
  display: inline-block;
  font-size: 0.72rem;
  font-weight: 700;
  color: var(--teal);
  background: #e3f4f0;
  padding: 0.22rem 0.6rem;
  border-radius: 999px;
  margin-bottom: 0.55rem;
  letter-spacing: 0.03em;
  text-transform: uppercase;
}

.card-link {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  margin-top: 0.45rem;
  text-decoration: none;
  font-weight: 700;
  font-size: 0.9rem;
  color: var(--teal);
  border-bottom: 2px solid transparent;
  transition: color 150ms ease, border-color 150ms ease;
}

.card-link::after {
  content: "→";
  transition: transform 150ms ease;
}

.card-link:hover {
  color: #155e52;
  border-color: var(--teal);
}

.card-link:hover::after {
  transform: translateX(3px);
}

.roadmap {
  margin-top: 1rem;
}

.roadmap-list {
  margin: 0;
  padding-left: 1.15rem;
  display: grid;
  gap: 0.5rem;
}

.roadmap-list li {
  padding: 0.3rem 0.4rem;
  background: rgba(255, 255, 255, 0.55);
  border: 1px solid #e4d8ca;
  border-radius: 0.4rem;
}

.cta {
  text-align: center;
  background: linear-gradient(140deg, #fff4df, #def2ec);
  border: 1px solid #ddd4c4;
  border-radius: 1.2rem;
  padding: 2.5rem 1.5rem;
}

.note {
  border-radius: 1rem;
  padding: 1.1rem 1.25rem;
  border: 1px solid #d9d0c4;
  margin-bottom: 1rem;
}

.note h3 {
  margin: 0 0 0.35rem;
  font-family: "Space Grotesk", sans-serif;
}

.note p {
  margin: 0;
}

.note-action {
  background: #eaf6f3;
  border-color: #b2ddd6;
}

.note-warning {
  background: #fff6ec;
  border-color: #f5d8aa;
}

.quiz-shell {
  background:
    radial-gradient(circle at 9% 16%, rgba(255, 238, 184, 0.7), transparent 30%),
    radial-gradient(circle at 88% 12%, rgba(191, 240, 232, 0.8), transparent 36%),
    rgba(255, 255, 255, 0.82);
  border: 2px solid #d7cdc0;
  border-radius: 1rem;
  padding: 1rem 1rem 1.1rem;
}

.quiz-question {
  border: 2px solid #ded4c8;
  border-radius: 0.8rem;
  padding: 0.85rem;
  margin: 0 0 0.8rem;
  background: #fffcf7;
  transition: border-color 170ms ease, box-shadow 170ms ease, transform 170ms ease;
}

.quiz-question legend {
  font-weight: 700;
  padding: 0 0.3rem;
  color: var(--ink);
  font-size: 0.97rem;
  line-height: 1.4;
}

.quiz-option {
  display: flex;
  align-items: flex-start;
  gap: 0.45rem;
  margin-top: 0.45rem;
  padding: 0.42rem 0.5rem;
  border-radius: 0.55rem;
  border: 1px solid transparent;
}

.quiz-option:hover {
  background: #fff3e1;
  border-color: #f5d8ac;
}

.quiz-option input {
  margin-top: 0.18rem;
  accent-color: #ff7f50;
}

.quiz-option span {
  font-weight: 500;
  font-size: 0.95rem;
  color: #1e3530;
}

.quiz-meta {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 0.8rem;
  margin-bottom: 0.95rem;
  flex-wrap: wrap;
}

.quiz-progress-wrap {
  min-width: min(100%, 290px);
  flex: 1 1 290px;
}

.quiz-progress-label {
  margin: 0 0 0.3rem;
  font-size: 0.93rem;
  color: #264740;
  font-weight: 700;
}

.quiz-progress-track {
  position: relative;
  height: 0.8rem;
  border-radius: 999px;
  overflow: hidden;
  background: #f5e6d3;
  border: 1px solid #e5d0b2;
}

.quiz-progress-fill {
  display: block;
  height: 100%;
  border-radius: inherit;
  background: linear-gradient(90deg, #ff8a65, #ffca28, #5ad2c7);
  transition: width 220ms ease;
}

.quiz-score-chips {
  display: flex;
  gap: 0.45rem;
  flex-wrap: wrap;
}

.quiz-chip {
  display: inline-flex;
  align-items: center;
  padding: 0.3rem 0.58rem;
  font-size: 0.76rem;
  border-radius: 999px;
  background: #eaf6f3;
  color: #165249;
  border: 1px solid #b9e0d6;
  font-weight: 700;
}

.quiz-chip-best {
  background: #fff5c8;
  border-color: #ecd376;
  color: #765f13;
}

.quiz-question-correct {
  border-color: #56b186;
  box-shadow: 0 0 0 3px rgba(86, 177, 134, 0.13);
}

.quiz-question-wrong {
  border-color: #e17d63;
  box-shadow: 0 0 0 3px rgba(225, 125, 99, 0.14);
}

.quiz-answer-note {
  margin: 0.62rem 0 0;
  font-size: 0.9rem;
  font-weight: 600;
  color: #4c5f5a;
}

.quiz-result {
  margin-top: 1rem;
  border-top: 1px dashed #cdbfae;
  padding-top: 0.8rem;
}

.quiz-result ul {
  padding-left: 1.1rem;
  margin-bottom: 0;
}

.info-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1rem;
}

.reference-list {
  margin: 0;
  padding-left: 1.1rem;
}

.reference-list li {
  margin-bottom: 0.45rem;
}

.reference-list a {
  color: #0f6559;
  font-weight: 600;
}

.reference-list a:hover {
  color: #0a4a40;
}

footer {
  text-align: center;
  font-size: 0.92rem;
  padding: 2rem 1.2rem 1.5rem;
  color: #4a5e58;
  border-top: 1px solid var(--line);
  margin-top: 1rem;
}

.ai-note {
  margin-top: 0.3rem;
  font-size: 0.78rem;
  color: #7a8e89;
  opacity: 0.9;
}

@keyframes rise {
  from {
    opacity: 0;
    transform: translateY(8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeInUp {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Focus ring */
*:focus-visible {
  outline: 2px solid var(--teal);
  outline-offset: 3px;
  border-radius: 3px;
}

.btn:focus-visible {
  outline-offset: 4px;
}

@media (max-width: 640px) {
  .hero {
    padding-bottom: 2.4rem;
  }

  .top-nav {
    margin-bottom: 1.8rem;
  }

  .quiz-shell {
    padding: 0.85rem;
  }

  .quiz-option {
    padding: 0.38rem 0.42rem;
  }

  .back-to-top {
    bottom: 1rem;
    right: 1rem;
  }
}

/* =========================================
   TEEN-FRIENDLY VISUAL ENHANCEMENTS
   ========================================= */

.topic-hero-badge {
  font-size: clamp(3.5rem, 10vw, 5.5rem);
  line-height: 1;
  margin-bottom: 0.5rem;
  display: block;
  animation: badge-bounce 0.7s cubic-bezier(0.34, 1.56, 0.64, 1) both;
}

@keyframes badge-bounce {
  0%   { transform: scale(0.4) rotate(-15deg); opacity: 0; }
  70%  { transform: scale(1.08) rotate(3deg); }
  100% { transform: scale(1)    rotate(0deg); opacity: 1; }
}

.topic-tagline {
  font-size: 1rem;
  color: var(--teal);
  font-weight: 600;
  margin: 0 0 0.75rem;
  font-style: italic;
  opacity: 0.9;
}

.fun-fact-card {
  background: linear-gradient(135deg, #fffbe6 0%, #fff3cd 100%);
  border: 2px solid #ffc947;
  border-radius: 1.25rem;
  padding: 1.1rem 1.4rem 1.1rem 1.2rem;
  margin: 1.75rem 0 0.25rem;
  position: relative;
  overflow: hidden;
}

.fun-fact-card::after {
  content: '✨';
  position: absolute;
  top: 0.25rem;
  right: 0.85rem;
  font-size: 2rem;
  opacity: 0.3;
  transform: rotate(18deg);
  pointer-events: none;
}

.fun-fact-card h4 {
  margin: 0 0 0.35rem;
  color: #b45309;
  font-size: 0.76rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.1em;
}

.fun-fact-card p {
  margin: 0;
  color: #78350f;
  font-size: 0.96rem;
  font-weight: 500;
  line-height: 1.65;
}

.module-icon {
  font-size: 1.9rem;
  display: block;
  margin-bottom: 0.4rem;
  line-height: 1;
}

.real-world-tip {
  display: flex;
  gap: 0.75rem;
  align-items: flex-start;
  background: rgba(31, 122, 107, 0.07);
  border-left: 3px solid var(--teal);
  border-radius: 0 0.75rem 0.75rem 0;
  padding: 0.85rem 1.1rem;
  margin-top: 1.5rem;
  font-size: 0.93rem;
  color: #1a4a40;
  line-height: 1.6;
}

.real-world-tip-icon {
  font-size: 1.4rem;
  flex-shrink: 0;
  line-height: 1.3;
}

.real-world-tip strong {
  display: block;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--teal);
  margin-bottom: 0.25rem;
  font-weight: 800;
}