@import url('https://fonts.googleapis.com/css2?family=Spectral:wght@400;600;700&family=IBM+Plex+Sans:wght@400;500;600;700&display=swap');

:root {
  --paper: #f6f1ea;
  --ink: #111418;
  --muted: #6f6a64;
  --accent: #7c5cff;
  --accent-secondary: #5c8cff;
  --accent-weak: #ece8ff;
  --accent-gradient: linear-gradient(135deg, #7c5cff 0%, #5c8cff 100%);
  --line: #e3dbcf;
  --card: #fffdf8;
  --shadow: 0 20px 50px rgba(17, 20, 24, 0.12);
  --max-width: 1120px;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: 'IBM Plex Sans', system-ui, -apple-system, sans-serif;
  color: var(--ink);
  background: var(--paper);
  line-height: 1.6;
}

body::before {
  content: '';
  position: fixed;
  inset: 0;
  background-image:
    radial-gradient(1200px 700px at 80% -10%, rgba(124, 92, 255, 0.14), transparent 60%),
    repeating-linear-gradient(90deg, rgba(17, 20, 24, 0.04), rgba(17, 20, 24, 0.04) 1px, transparent 1px, transparent 36px);
  pointer-events: none;
  z-index: -1;
}

.page {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 32px 24px 80px;
}

.site-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 0 28px;
  border-bottom: 1px solid var(--line);
}

.logo {
  font-family: 'Spectral', serif;
  font-weight: 700;
  font-size: 24px;
  text-decoration: none;
  color: var(--ink);
}

.lang-switcher a {
  margin-left: 10px;
  text-decoration: none;
  color: var(--muted);
  font-size: 14px;
  font-weight: 600;
}

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

.hero {
  display: grid;
  gap: 32px;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  align-items: center;
  padding: 48px 0 36px;
}

.hero-title {
  font-family: 'Spectral', serif;
  font-size: clamp(36px, 4vw, 56px);
  line-height: 1.1;
  margin: 0 0 18px;
}

.hero-subtitle {
  font-size: 18px;
  color: var(--muted);
  margin: 0 0 24px;
}

.cta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.button {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 18px;
  border-radius: 999px;
  font-weight: 600;
  text-decoration: none;
  border: 1px solid var(--accent);
  color: var(--accent);
  background: transparent;
}

.button.primary {
  background: var(--accent-gradient);
  border-color: transparent;
  color: #fff;
}

.trust-strip {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 16px;
  padding: 20px;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 16px;
  box-shadow: var(--shadow);
}

.section {
  padding: 56px 0 0;
}

.section-title {
  font-family: 'Spectral', serif;
  font-size: 28px;
  margin-bottom: 18px;
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 18px;
}

.feature-card {
  padding: 18px;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 16px;
}

.paper-card {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 20px;
  padding: 24px;
  box-shadow: var(--shadow);
}

.paper-header {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 12px;
}

.paper-title {
  font-family: 'Spectral', serif;
  font-weight: 600;
}

.paper-meta {
  font-size: 12px;
  color: var(--muted);
}

.paper-paragraph {
  margin: 0 0 16px;
  color: var(--muted);
}

.paper-formula {
  font-family: 'IBM Plex Sans', system-ui, sans-serif;
  background: var(--accent-weak);
  padding: 10px 14px;
  border-radius: 10px;
  margin-bottom: 14px;
}

.formula-image {
  width: 100%;
  height: 120px;
  object-fit: cover;
  object-position: center;
  border-radius: 10px;
  border: 1px solid var(--line);
  background: #fff;
  margin-bottom: 14px;
}

.paper-translation .label {
  display: inline-block;
  text-transform: uppercase;
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--accent);
  margin-bottom: 6px;
}

.screenshots {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 18px;
}

.screenshot-card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 12px;
  box-shadow: var(--shadow);
}

.screenshot-card img {
  width: 100%;
  height: auto;
  display: block;
  border-radius: 12px;
}

.screenshot-card figcaption {
  margin-top: 8px;
  font-size: 13px;
  color: var(--muted);
}

.footer {
  margin-top: 64px;
  padding-top: 24px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 14px;
}

.reveal {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}

.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

@media (max-width: 720px) {
  .cta-row {
    flex-direction: column;
    align-items: stretch;
  }
  .button {
    justify-content: center;
  }
}