/* AI Education OS -- marketing landing page styles.
   Deliberately independent from web/ (the app's own React/Vite bundle):
   no shared build pipeline, no shared CSS, no shared router -- see
   deploy/nginx/nginx.conf.template's root-domain server block, which
   serves this directory as a separate static site with its own
   `location /` (no SPA fallback), so this page's routing can never be
   confused with the app's client-side routes. */

:root {
  --color-bg: #0b1220;
  --color-bg-muted: #0f1829;
  --color-surface: #141f33;
  --color-border: #243352;
  --color-text: #eef2f9;
  --color-text-muted: #aab6cc;
  --color-primary: #4f7cff;
  --color-primary-hover: #6e92ff;
  --radius: 12px;
  --max-width: 1120px;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
}

body {
  font-family:
    'Segoe UI',
    system-ui,
    -apple-system,
    Roboto,
    Helvetica,
    Arial,
    sans-serif;
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.55;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.25rem;
}

a {
  color: inherit;
}

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

/* --- Header --- */

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(11, 18, 32, 0.9);
  backdrop-filter: blur(6px);
  border-bottom: 1px solid var(--color-border);
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.9rem 1.25rem;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  text-decoration: none;
  font-weight: 700;
  font-size: 1.05rem;
}

.site-nav {
  display: none;
  gap: 1.5rem;
}

.site-nav a {
  text-decoration: none;
  color: var(--color-text-muted);
  font-size: 0.95rem;
}

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

@media (min-width: 768px) {
  .site-nav {
    display: flex;
  }
}

/* --- Buttons --- */

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  text-decoration: none;
  border-radius: var(--radius);
  font-weight: 600;
  padding: 0.55rem 1rem;
  font-size: 0.95rem;
  transition: background-color 0.15s ease, border-color 0.15s ease;
}

.button--primary {
  background: var(--color-primary);
  color: #ffffff;
}

.button--primary:hover {
  background: var(--color-primary-hover);
}

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

.button--ghost:hover {
  border-color: var(--color-primary);
}

.button--large {
  padding: 0.85rem 1.5rem;
  font-size: 1.05rem;
}

.site-nav__cta {
  display: none;
}

@media (min-width: 768px) {
  .site-nav__cta {
    display: inline-flex;
  }
}

/* --- Hero --- */

.hero {
  padding: 4.5rem 0 3.5rem;
}

.hero__inner {
  text-align: center;
  max-width: 820px;
}

.hero__title {
  font-size: clamp(1.9rem, 4vw, 3rem);
  line-height: 1.15;
  margin: 0 0 1rem;
  font-weight: 800;
}

.hero__subtitle {
  font-size: 1.1rem;
  color: var(--color-text-muted);
  margin: 0 auto 2rem;
  max-width: 680px;
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  justify-content: center;
}

/* --- Sections --- */

.section {
  padding: 4rem 0;
}

.section--muted {
  background: var(--color-bg-muted);
}

.section__title {
  font-size: clamp(1.5rem, 3vw, 2.1rem);
  margin: 0 0 0.5rem;
  text-align: center;
  font-weight: 800;
}

.section__lead {
  text-align: center;
  color: var(--color-text-muted);
  max-width: 640px;
  margin: 0 auto 2.5rem;
}

.grid {
  display: grid;
  gap: 1.25rem;
  grid-template-columns: 1fr;
}

@media (min-width: 640px) {
  .grid--3 {
    grid-template-columns: repeat(2, 1fr);
  }
  .grid--4 {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 960px) {
  .grid--3 {
    grid-template-columns: repeat(3, 1fr);
  }
  .grid--4 {
    grid-template-columns: repeat(4, 1fr);
  }
}

.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.5rem;
}

.card h3 {
  margin: 0 0 0.6rem;
  font-size: 1.05rem;
}

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

.card--audience {
  text-align: left;
}

/* --- CTA section --- */

.cta-section {
  padding: 4rem 0 5rem;
  text-align: center;
}

.cta-section__inner h2 {
  font-size: clamp(1.5rem, 3vw, 2.1rem);
  margin: 0 0 0.5rem;
  font-weight: 800;
}

.cta-section__inner p {
  color: var(--color-text-muted);
  margin: 0 0 1.75rem;
}

/* --- Footer --- */

.site-footer {
  border-top: 1px solid var(--color-border);
  padding: 1.5rem 0 2.5rem;
}

.site-footer__inner {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  align-items: center;
  text-align: center;
}

@media (min-width: 640px) {
  .site-footer__inner {
    flex-direction: row;
    justify-content: space-between;
    text-align: left;
  }
}

.brand--footer {
  font-weight: 600;
  font-size: 0.95rem;
}

.site-footer__copy {
  color: var(--color-text-muted);
  font-size: 0.85rem;
}