:root {
  --bg: #0b1021;
  --surface: #111832;
  --surface-alt: #1c2645;
  --text: #f6f7fb;
  --muted: #b5bddb;
  --accent: #5d8bfd;
  --accent-alt: #64d2ff;
  --info: #9c7bff;
  --danger: #ff6f6f;
  --success: #4cd7a3;
  --radius: 16px;
  --shadow: 0 20px 45px rgba(6, 10, 40, 0.35);
  --font-body: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'PingFang SC',
    'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  --font-display: 'Space Grotesk', 'Inter', sans-serif;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
  background: radial-gradient(circle at top left, #1f2959, #080d1c 55%);
  color: var(--text);
  font-family: var(--font-body);
  line-height: 1.6;
}

a {
  color: inherit;
  text-decoration: none;
}

a:hover,
a:focus {
  color: var(--accent-alt);
}

img {
  max-width: 100%;
  display: block;
}

.container {
  width: min(1160px, 92vw);
  margin: 0 auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(8, 13, 28, 0.9);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.05);
}

.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 16px;
  padding: 20px 0;
}

.brand {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.2rem;
  letter-spacing: 0.04em;
}

.primary-nav {
  display: flex;
  gap: 24px;
  font-weight: 500;
}

.primary-nav a {
  position: relative;
  padding: 6px 0;
}

.primary-nav a::after {
  content: '';
  position: absolute;
  left: 0;
  bottom: -6px;
  width: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--accent), var(--accent-alt));
  transition: width 0.3s ease;
}

.primary-nav a[aria-current='page'] {
  color: var(--accent);
}

.primary-nav a[aria-current='page']::after {
  width: 100%;
}

.primary-nav a:focus::after,
.primary-nav a:hover::after {
  width: 100%;
}

.language-switcher {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-left: 24px;
  flex-shrink: 0;
}

.lang-toggle {
  background: rgba(255, 255, 255, 0.08);
  border: 1px solid transparent;
  border-radius: 999px;
  color: var(--text);
  cursor: pointer;
  font-size: 0.85rem;
  padding: 6px 14px;
  transition: background 0.3s ease, border-color 0.3s ease, color 0.3s ease;
}

.lang-toggle:hover,
.lang-toggle:focus-visible {
  background: rgba(255, 255, 255, 0.15);
}

.lang-toggle:focus-visible {
  outline: 2px solid var(--accent-alt);
  outline-offset: 2px;
}

.lang-toggle[aria-pressed='true'] {
  background: linear-gradient(90deg, var(--accent), var(--accent-alt));
  color: #0b1021;
}

.lang-toggle[aria-pressed='true']:hover,
.lang-toggle[aria-pressed='true']:focus-visible {
  background: linear-gradient(90deg, var(--accent-alt), var(--accent));
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 6px;
  background: transparent;
  border: none;
  cursor: pointer;
}

.nav-toggle span {
  display: block;
  width: 26px;
  height: 2px;
  background: var(--text);
}

.hero {
  padding: 120px 0 80px;
}

.hero__grid {
  display: grid;
  gap: 48px;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  align-items: center;
}

.hero__eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 0.9rem;
  text-transform: uppercase;
  letter-spacing: 0.2em;
  color: var(--accent-alt);
}

.hero__eyebrow::before {
  content: '';
  display: inline-block;
  width: 36px;
  height: 1px;
  background: var(--accent-alt);
}

.hero h1 {
  font-family: var(--font-display);
  font-size: clamp(2.6rem, 3.6vw + 1.2rem, 3.8rem);
  line-height: 1.1;
  margin: 16px 0 24px;
}

.hero__description {
  max-width: 520px;
  color: var(--muted);
  font-size: 1.05rem;
  margin-bottom: 32px;
}

.hero__actions {
  display: flex;
  gap: 16px;
  margin-bottom: 32px;
}

.hero__stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
  gap: 20px;
  color: var(--muted);
}

.hero__stats dt {
  font-family: var(--font-display);
  font-size: 1.4rem;
  color: var(--text);
}

.hero__panel-card {
  padding: 28px;
  border-radius: var(--radius);
  background: linear-gradient(160deg, rgba(35, 47, 97, 0.75), rgba(18, 26, 52, 0.95));
  box-shadow: var(--shadow);
  border: 1px solid rgba(255, 255, 255, 0.06);
}

.hero__panel-card h2 {
  margin: 0 0 20px;
  font-family: var(--font-display);
}

.hero__note {
  margin-top: 12px;
  font-size: 0.85rem;
  color: var(--muted);
}

.section {
  padding: 96px 0;
}

.section--muted {
  background: rgba(12, 18, 36, 0.72);
}

.section__header {
  margin-bottom: 40px;
  max-width: 640px;
}

.section__header h2 {
  font-family: var(--font-display);
  font-size: clamp(2rem, 2.8vw + 1rem, 2.6rem);
  margin-bottom: 16px;
}

.section__header p {
  color: var(--muted);
}

.card {
  background: rgba(13, 19, 41, 0.72);
  border-radius: var(--radius);
  border: 1px solid rgba(255, 255, 255, 0.05);
  padding: 28px;
  box-shadow: 0 24px 48px rgba(7, 11, 26, 0.45);
  display: flex;
  flex-direction: column;
  gap: 24px;
  transition: transform 0.3s ease, border-color 0.3s ease;
}

.card:hover,
.card:focus-within {
  transform: translateY(-6px);
  border-color: rgba(100, 210, 255, 0.3);
}

.card__header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
}

.tag {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.25rem 0.75rem;
  border-radius: 999px;
  font-size: 0.75rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  background: rgba(93, 139, 253, 0.16);
  color: var(--accent-alt);
}

.tag--info {
  background: rgba(156, 123, 255, 0.16);
  color: #c9a7ff;
}

.tag--accent {
  background: rgba(76, 215, 163, 0.16);
  color: var(--success);
}

.calculator-grid,
.conversion-grid,
.advanced-grid {
  display: grid;
  gap: 28px;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
}

.form {
  display: grid;
  gap: 16px;
}

.form--inline {
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  align-items: end;
}

.form__group {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.superscore-inputs {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

label {
  font-weight: 500;
}

input,
select,
textarea {
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: 12px;
  background: rgba(5, 9, 24, 0.8);
  padding: 12px 14px;
  color: var(--text);
  font: inherit;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

input:focus,
select:focus,
textarea:focus {
  border-color: var(--accent-alt);
  outline: none;
  box-shadow: 0 0 0 3px rgba(100, 210, 255, 0.2);
}

textarea {
  resize: vertical;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 20px;
  border-radius: 12px;
  font-weight: 600;
  letter-spacing: 0.02em;
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform 0.2s ease, box-shadow 0.2s ease, background 0.2s ease;
}

.btn--primary {
  background: linear-gradient(135deg, var(--accent), var(--accent-alt));
  box-shadow: 0 10px 30px rgba(100, 210, 255, 0.35);
}

.btn--primary:hover,
.btn--primary:focus {
  transform: translateY(-2px);
}

.btn--ghost {
  background: transparent;
  border-color: rgba(255, 255, 255, 0.25);
  color: var(--muted);
}

.btn--ghost:hover,
.btn--ghost:focus {
  border-color: var(--accent-alt);
  color: var(--accent-alt);
}

.btn--block {
  width: 100%;
}

.result {
  border-radius: 12px;
  padding: 18px;
  background: rgba(15, 22, 44, 0.7);
  border: 1px dashed rgba(255, 255, 255, 0.1);
  color: var(--muted);
  min-height: 64px;
  font-size: 0.95rem;
}

.result strong {
  color: var(--text);
  font-size: 1.1rem;
}

.result__sub {
  margin-top: 6px;
  font-size: 0.85rem;
  color: var(--muted);
}

.result__hint {
  margin-top: 12px;
  font-size: 0.85rem;
  color: var(--muted);
}

.percentile {
  display: grid;
  gap: 8px;
  padding: 20px;
  border-radius: 12px;
  background: rgba(16, 27, 58, 0.8);
  border: 1px solid rgba(100, 210, 255, 0.25);
}

.percentile::before {
  content: '90th Percentile';
  font-family: var(--font-display);
  font-size: 1.4rem;
}

.list {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 12px;
}

.list--links a {
  color: var(--accent-alt);
  font-weight: 500;
}

.prediction {
  display: grid;
  gap: 6px;
  padding: 16px 20px;
  border-radius: 12px;
  border: 1px solid rgba(76, 215, 163, 0.4);
  background: rgba(14, 27, 35, 0.6);
}

.prediction__label {
  text-transform: uppercase;
  font-size: 0.75rem;
  letter-spacing: 0.2em;
  color: var(--success);
}

.prediction__value {
  font-family: var(--font-display);
  font-size: 1.8rem;
}

.resources {
  display: grid;
  gap: 40px;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  align-items: start;
}

.feedback {
  background: rgba(15, 19, 39, 0.85);
  padding: 24px;
  border-radius: var(--radius);
  border: 1px solid rgba(255, 255, 255, 0.05);
}

.form__hint {
  font-size: 0.8rem;
  color: var(--muted);
}

.roadmap {
  display: grid;
  gap: 24px;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
}

.roadmap__item {
  padding: 24px;
  border-radius: var(--radius);
  border: 1px solid rgba(255, 255, 255, 0.08);
  background: rgba(12, 18, 36, 0.8);
  position: relative;
}

.roadmap__item::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: var(--radius);
  border: 1px solid rgba(93, 139, 253, 0.35);
  opacity: 0;
  transition: opacity 0.3s ease;
}

.roadmap__item:hover::before {
  opacity: 1;
}

.roadmap__item h3 {
  margin: 0 0 12px;
  font-family: var(--font-display);
}

.roadmap__item time {
  display: inline-block;
  margin-bottom: 12px;
  color: var(--accent-alt);
  font-weight: 600;
}

.site-footer {
  padding: 60px 0 36px;
  background: rgba(5, 8, 20, 0.95);
  border-top: 1px solid rgba(255, 255, 255, 0.05);
}

.footer__grid {
  display: grid;
  gap: 36px;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
}

.footer__note {
  text-align: center;
  color: var(--muted);
  margin-top: 32px;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}

@media (max-width: 720px) {
  .primary-nav {
    position: absolute;
    inset: 72px 16px auto;
    flex-direction: column;
    padding: 20px;
    border-radius: var(--radius);
    background: rgba(12, 18, 36, 0.96);
    border: 1px solid rgba(255, 255, 255, 0.05);
    transform: translateY(-20px);
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s ease, transform 0.3s ease;
  }

  .primary-nav.is-open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
  }

  .nav-toggle {
    display: flex;
  }

  .language-switcher {
    margin-left: auto;
    order: 3;
    gap: 8px;
  }

  .lang-toggle {
    padding: 6px 12px;
  }

  .hero {
    padding-top: 96px;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}