/* CSS Custom Properties */
:root {
  --color-bg: #0f0b0a;
  --color-surface: #1a1412;
  --color-surface-2: #241b18;
  --color-border: #2e2520;
  --color-primary: #e5482e;
  --color-primary-hover: #c93a22;
  --color-accent: #f0b429;
  --color-text: #f5f1ea;
  --color-text-muted: #a89e92;
  --color-success: #22c55e;
  --color-error: #ff2d55;
  --font-sans: "Inter", system-ui, -apple-system, sans-serif;
  --font-mono: "JetBrains Mono", "Fira Code", monospace;
  --font-hanzi: "Kaiti SC", "STKaiti", "KaiTi", "Noto Serif SC", serif;
  --radius: 8px;
  --radius-lg: 12px;
  --max-width: 1100px;
}

/* Reset */
*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

/* The hidden attribute must win over component display rules (e.g. flex/inline-block). */
[hidden] {
  display: none !important;
}

body {
  font-family: var(--font-sans);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

/* Typography, fluid with clamp() */
h1 {
  font-size: clamp(2rem, 5vw, 3.5rem);
  font-weight: 700;
  line-height: 1.1;
  letter-spacing: -0.02em;
}

h2 {
  font-size: clamp(1.5rem, 3vw, 2.25rem);
  font-weight: 600;
  line-height: 1.2;
  text-align: center;
  margin-bottom: 1rem;
}

h3 {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

/* Utility */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
}

.fu {
  color: var(--color-accent);
}

/* Buttons */
.btn {
  display: inline-block;
  padding: 0.75rem 1.5rem;
  border-radius: 6px;
  text-decoration: none;
  font-weight: 500;
  font-size: 1rem;
  transition: all 0.2s ease;
  cursor: pointer;
}

.btn:hover {
  opacity: 0.85;
  transform: translateY(-1px);
}

.btn-primary {
  background: var(--color-primary);
  color: #fff;
}

.btn-primary:hover {
  background: var(--color-primary-hover);
  opacity: 1;
  transform: translateY(-1px);
}

.btn-secondary {
  background: transparent;
  color: var(--color-text);
  border: 1px solid var(--color-border);
}

.btn-small {
  padding: 0.5rem 1rem;
  font-size: 0.875rem;
}

/* Coming soon pill */
.coming-soon-pill {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  border-radius: 999px;
  border: 1px solid var(--color-border);
  background: var(--color-surface);
  font-weight: 600;
  font-size: 1rem;
  color: var(--color-text);
  cursor: default;
}

.pill-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--color-accent);
  box-shadow: 0 0 12px var(--color-accent);
  animation: pulseDot 1.8s ease-in-out infinite;
}

.nav-pill {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.4rem 0.875rem;
  border-radius: 999px;
  border: 1px solid var(--color-border);
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--color-text);
}

.nav-pill .pill-dot {
  width: 6px;
  height: 6px;
}

/* Navigation */
.nav {
  border-bottom: 1px solid var(--color-border);
  padding: 1rem 0;
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(15, 11, 10, 0.85);
  backdrop-filter: blur(12px);
}

.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-brand {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-weight: 700;
  font-size: 1.25rem;
  text-decoration: none;
  color: var(--color-text);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 1.5rem;
}

.nav-links a {
  text-decoration: none;
  color: var(--color-text-muted);
  font-size: 0.9375rem;
}

.nav-links a:hover {
  color: var(--color-text);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 4px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}

.nav-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--color-text);
}

/* Hero */
.hero {
  position: relative;
  padding: 5rem 0 4.5rem;
  overflow: hidden;
}

.hero-glow {
  position: absolute;
  pointer-events: none;
  border-radius: 50%;
  filter: blur(80px);
  z-index: 0;
}

.hero-glow-primary {
  top: -180px;
  right: -120px;
  width: 560px;
  height: 560px;
  background: rgba(229, 72, 46, 0.18);
}

.hero-glow-accent {
  bottom: -220px;
  left: -160px;
  width: 480px;
  height: 480px;
  background: rgba(240, 180, 41, 0.1);
}

.hero-grid {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: 1.05fr 1fr;
  gap: 3.5rem;
  align-items: center;
}

.hero-copy {
  max-width: 560px;
  min-width: 0;
}

.hero-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 0.625rem;
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-text-muted);
  margin-bottom: 1.25rem;
}

.eyebrow-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--color-accent);
  box-shadow: 0 0 12px var(--color-accent);
  animation: pulseDot 1.8s ease-in-out infinite;
}

@keyframes pulseDot {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.35; }
}

.hero-headline {
  font-size: clamp(2.5rem, 6vw, 4.5rem);
  font-weight: 700;
  line-height: 1.04;
  letter-spacing: -0.025em;
  color: var(--color-text);
  margin: 0 0 1.25rem;
}

.hl-primary { color: var(--color-primary); }
.hl-accent { color: var(--color-accent); }

.hero-subtitle {
  margin: 0 0 1.75rem;
  font-size: clamp(1rem, 1.4vw, 1.0625rem);
  line-height: 1.6;
  color: var(--color-text-muted);
  max-width: 520px;
}

.hero-actions {
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
  margin-bottom: 0.75rem;
  align-items: center;
}

/* Waitlist */
.waitlist {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  flex: 1 1 320px;
}
.waitlist-input {
  flex: 1 1 200px;
  min-width: 0;
  padding: 0.75rem 1rem;
  border-radius: 6px;
  border: 1px solid var(--color-border);
  background: var(--color-surface);
  color: var(--color-text);
  font-family: var(--font-sans);
  font-size: 1rem;
}
.waitlist-input::placeholder {
  color: var(--color-text-muted);
}
.waitlist-input:focus {
  outline: none;
  border-color: var(--color-primary);
}
.waitlist-submit {
  white-space: nowrap;
}
.waitlist-note {
  margin-bottom: 1.25rem;
  font-size: 0.8125rem;
  color: var(--color-text-muted);
}
.waitlist-msg {
  margin-bottom: 1.25rem;
  font-size: 0.9375rem;
  font-weight: 500;
}
.waitlist-msg.success {
  color: var(--color-success);
}
.waitlist-msg.error {
  color: var(--color-error);
}

.hero-meta {
  display: flex;
  align-items: center;
  gap: 0.875rem;
  font-size: 0.8125rem;
  color: var(--color-text-muted);
  flex-wrap: wrap;
}

.meta-item {
  display: inline-flex;
  align-items: center;
  gap: 0.375rem;
}

.meta-check {
  color: var(--color-accent);
}

.meta-pip {
  width: 3px;
  height: 3px;
  border-radius: 50%;
  background: currentColor;
  opacity: 0.5;
}

/* Hero card, quick-test teaser */
.hero-card {
  position: relative;
  background: linear-gradient(180deg, var(--color-surface) 0%, var(--color-surface-2) 100%);
  border: 1px solid var(--color-border);
  border-radius: 20px;
  padding: 1.75rem;
  box-shadow: 0 40px 80px -40px rgba(0, 0, 0, 0.8);
  min-width: 0;
  overflow: hidden;
}

.hero-card::before {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: 20px;
  pointer-events: none;
  box-shadow: inset 0 0 0 1px rgba(229, 72, 46, 0.08);
}

.hero-card-head {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 0.75rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--color-border);
  font-size: 0.6875rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-text-muted);
  font-weight: 500;
  min-width: 0;
}

.card-tag {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}

.card-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--color-accent);
  box-shadow: 0 0 10px var(--color-accent);
}

.card-score {
  text-transform: none;
  letter-spacing: normal;
  font-size: 0.8125rem;
  color: var(--color-text-muted);
  font-family: var(--font-mono);
}

.quiz-body {
  padding: 1.25rem 0 0.25rem;
}

.quiz-hanzi {
  font-family: var(--font-hanzi);
  font-size: clamp(2.25rem, 4.5vw, 3rem);
  line-height: 1.2;
  color: var(--color-text);
}

.quiz-pinyin {
  font-style: italic;
  color: var(--color-text-muted);
  font-size: 0.9375rem;
  margin-bottom: 0.875rem;
}

.quiz-question {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  margin-bottom: 0.75rem;
}

.quiz-choices {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.choice {
  font-family: var(--font-mono);
  font-size: 1rem;
  font-weight: 600;
  padding: 0.5rem 1.125rem;
  border-radius: 999px;
  background: transparent;
  border: 1px solid var(--color-border);
  color: var(--color-text);
  cursor: pointer;
  transition: border-color 0.15s, color 0.15s, background 0.15s, transform 0.15s;
}

.choice:hover:not(:disabled) {
  border-color: var(--color-text-muted);
  transform: translateY(-1px);
}

.choice:disabled {
  cursor: default;
  opacity: 0.55;
}

.choice.correct {
  background: rgba(34, 197, 94, 0.15);
  border-color: var(--color-success);
  color: var(--color-success);
  opacity: 1;
}

.choice.wrong {
  background: rgba(255, 45, 85, 0.12);
  border-color: var(--color-error);
  color: var(--color-error);
  opacity: 1;
}

.quiz-explain {
  margin-top: 1rem;
  padding-top: 1rem;
  border-top: 1px solid var(--color-border);
  font-size: 0.875rem;
  color: var(--color-text-muted);
  line-height: 1.55;
}

.quiz-explain strong {
  color: var(--color-text);
}

.quiz-next {
  margin-top: 0.875rem;
}

.hero-card-hint {
  margin: 1rem 0 0;
  font-size: 0.75rem;
  color: var(--color-text-muted);
  text-align: center;
}

@media (prefers-reduced-motion: reduce) {
  .eyebrow-dot,
  .pill-dot {
    animation: none;
  }
}

/* Section subtitle */
.section-subtitle {
  text-align: center;
  color: var(--color-text-muted);
  max-width: 640px;
  margin: 0.75rem auto 0;
  font-size: 1rem;
}

/* Features */
.features {
  padding: 4rem 0;
  background: var(--color-surface);
}

.features-grid {
  margin-top: 2.5rem;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1.5rem;
}

.feature-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 8px;
  padding: 2rem;
  transition: all 0.2s ease;
}

.feature-card:hover {
  transform: translateY(-1px);
}

.feature-icon {
  color: var(--color-accent);
  margin-bottom: 1rem;
}

.feature-card p {
  color: var(--color-text-muted);
  font-size: 0.9375rem;
}

.feature-card .hanzi {
  font-family: var(--font-hanzi);
  font-style: normal;
  color: var(--color-text);
}

/* How it works */
.how-it-works {
  padding: 4rem 0;
}

.steps-grid {
  margin-top: 2.5rem;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.25rem;
}

.step {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 1.75rem 1.5rem;
  text-align: left;
  position: relative;
}

.step-number {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: var(--color-surface-2);
  border: 1px solid var(--color-border);
  color: var(--color-accent);
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 0.9375rem;
  margin-bottom: 0.875rem;
}

.step h3 {
  font-size: 1.0625rem;
  margin-bottom: 0.375rem;
}

.step p {
  color: var(--color-text-muted);
  font-size: 0.9375rem;
  margin: 0;
}

.how-extras {
  margin-top: 2rem;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.5rem;
  max-width: 720px;
  margin-left: auto;
  margin-right: auto;
}

.extra-chip {
  font-size: 0.8125rem;
  padding: 0.375rem 0.75rem;
  border-radius: 999px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  color: var(--color-text-muted);
}

/* FAQ */
.faq {
  padding: 4rem 0;
  background: var(--color-surface);
}

.faq h2 {
  margin-bottom: 2rem;
}

.faq details {
  border: 1px solid var(--color-border);
  border-radius: 8px;
  padding: 1rem 1.25rem;
  margin-bottom: 0.75rem;
  background: var(--color-bg, transparent);
}

.faq summary {
  cursor: pointer;
  font-weight: 600;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.faq summary::-webkit-details-marker {
  display: none;
}

.faq summary::after {
  content: "+";
  font-size: 1.25rem;
  color: var(--color-text-muted);
  margin-left: 1rem;
}

.faq details[open] summary::after {
  content: "−";
}

.faq details p {
  margin-top: 0.75rem;
  color: var(--color-text-muted);
  line-height: 1.6;
}

/* Footer */
.footer {
  border-top: 1px solid var(--color-border);
  padding: 3rem 0 1.5rem;
  margin-top: 4rem;
}

.footer-content {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  flex-wrap: wrap;
  gap: 2rem;
}

.footer-brand p {
  color: var(--color-text-muted);
  margin-top: 0.25rem;
  font-size: 0.875rem;
}

.footer-links {
  display: flex;
  gap: 1.5rem;
}

.footer-links a {
  text-decoration: none;
  color: var(--color-text-muted);
  font-size: 0.875rem;
}

.footer-links a:hover {
  color: var(--color-text);
}

.footer-bottom {
  margin-top: 2rem;
  padding-top: 1rem;
  border-top: 1px solid var(--color-border);
}

.footer-bottom p {
  color: var(--color-text-muted);
  font-size: 0.8125rem;
}

/* Mobile responsive */
@media (max-width: 768px) {
  .nav-toggle {
    display: flex;
  }

  .nav-links {
    display: none;
    position: absolute;
    top: 60px;
    left: 0;
    right: 0;
    background: var(--color-surface);
    flex-direction: column;
    padding: 1rem 1.5rem;
    border-bottom: 1px solid var(--color-border);
  }

  .nav-links.active {
    display: flex;
  }

  .nav-container {
    position: relative;
  }

  .hero {
    padding: 3rem 0 2.5rem;
  }

  .hero-grid {
    grid-template-columns: 1fr;
    gap: 2.5rem;
  }

  .hero-copy {
    max-width: 100%;
  }

  .hero-card {
    padding: 1.5rem 1.25rem;
  }

  .hero-card-head {
    flex-wrap: wrap;
  }

  .choice {
    font-size: 0.875rem;
    padding: 0.4375rem 0.875rem;
  }
}

/* Post cards (blog index + homepage blog preview) */
.post-card {
  display: block;
  padding: 1.5rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background: var(--color-surface);
  text-decoration: none;
  color: inherit;
  transition: border-color 0.15s, transform 0.15s;
}

.post-card:hover {
  border-color: var(--color-primary);
  transform: translateY(-2px);
}

.post-card h3 {
  font-size: 1.05rem;
  margin-bottom: 0.5rem;
  color: var(--color-text);
}

.post-card p {
  color: var(--color-text-muted);
  font-size: 0.95rem;
  line-height: 1.55;
  margin: 0;
}

/* Blog preview section (homepage) */
.blog-preview {
  padding: 5rem 0;
}

.blog-preview-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1rem;
  margin-top: 2rem;
}

.blog-preview-all {
  margin-top: 1.5rem;
  text-align: center;
}

.blog-preview-all a {
  color: var(--color-accent);
  text-decoration: none;
  font-weight: 500;
}

.blog-preview-all a:hover {
  color: var(--color-primary);
}