/* ============================================================
   Landing Page Styles
   Dario Amodei Study Guide
   ============================================================ */

html {
  scroll-behavior: smooth;
}

/* --- Hero Section --- */

.hero {
  background: linear-gradient(135deg, #0F172A 0%, #312E81 50%, #6366F1 100%);
  color: #fff;
  text-align: center;
  padding: 80px 24px;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background:
    radial-gradient(circle at 20% 80%, rgba(217, 119, 6, 0.15) 0%, transparent 50%),
    radial-gradient(circle at 80% 20%, rgba(99, 102, 241, 0.2) 0%, transparent 50%);
  pointer-events: none;
}

.hero__title {
  font-family: Georgia, "Times New Roman", serif;
  font-size: 3rem;
  font-weight: 700;
  margin: 0 0 12px;
  letter-spacing: -0.02em;
  position: relative;
}

.hero__subtitle {
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1.35rem;
  font-weight: 400;
  margin: 0 0 8px;
  opacity: 0.92;
  position: relative;
}

.hero__author {
  font-size: 1.1rem;
  margin: 0 0 4px;
  opacity: 0.85;
  position: relative;
}

.hero__meta {
  font-size: 0.95rem;
  margin: 0 0 36px;
  opacity: 0.7;
  position: relative;
}

.hero__actions {
  display: flex;
  gap: 16px;
  justify-content: center;
  flex-wrap: wrap;
  position: relative;
}

.hero .btn--primary {
  display: inline-block;
  padding: 14px 32px;
  border-radius: 8px;
  font-size: 1rem;
  font-weight: 600;
  text-decoration: none;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  cursor: pointer;
  border: none;
  background: #fff;
  color: #0F172A;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
}

.hero .btn--primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.2);
}

.hero .btn--secondary {
  display: inline-block;
  padding: 14px 32px;
  border-radius: 8px;
  font-size: 1rem;
  font-weight: 600;
  text-decoration: none;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  cursor: pointer;
  background: rgba(255, 255, 255, 0.12);
  color: #fff;
  border: 2px solid rgba(255, 255, 255, 0.4);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

.hero .btn--secondary:hover {
  transform: translateY(-2px);
  background: rgba(255, 255, 255, 0.22);
  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.15);
}

/* --- Sections --- */

.section {
  padding: 64px 24px;
  max-width: 1200px;
  margin: 0 auto;
}

.section__heading {
  font-family: Georgia, "Times New Roman", serif;
  font-size: 2rem;
  font-weight: 700;
  text-align: center;
  margin: 0 0 8px;
  color: #1E293B;
}

.section__description {
  text-align: center;
  color: #64748B;
  margin: 0 0 40px;
  font-size: 1.05rem;
}

.section__heading::after {
  content: "";
  display: block;
  width: 48px;
  height: 3px;
  background: linear-gradient(90deg, #0F172A, #6366F1);
  margin: 12px auto 0;
  border-radius: 2px;
}

/* MOL section accent */
.section--mol .section__heading::after {
  background: linear-gradient(90deg, #0F172A, #D97706);
}

/* AOT section accent */
.section--aot .section__heading::after {
  background: linear-gradient(90deg, #0F172A, #6366F1);
}

/* GPT-3 section accent */
.section--gpt3 .section__heading::after {
  background: linear-gradient(90deg, #0F172A, #0D9488);
}

/* --- Grid --- */

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 24px;
}

.grid--2 {
  grid-template-columns: repeat(auto-fill, minmax(400px, 1fr));
}

/* --- Essay Cards --- */

.essay-card {
  background: #fff;
  border-radius: 12px;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.08), 0 2px 8px rgba(0, 0, 0, 0.04);
  padding: 32px 28px;
  border-top: 4px solid transparent;
  text-decoration: none;
  color: inherit;
  display: block;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.essay-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1), 0 8px 24px rgba(0, 0, 0, 0.08);
  text-decoration: none;
  color: inherit;
}

.essay-card--mol {
  border-top-color: #D97706;
}

.essay-card--aot {
  border-top-color: #6366F1;
}

.essay-card__icon {
  font-size: 2.5rem;
  margin: 0 0 16px;
  display: block;
}

.essay-card__title {
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1.4rem;
  font-weight: 700;
  margin: 0 0 8px;
  color: #1E293B;
}

.essay-card__author {
  font-size: 0.9rem;
  color: #94A3B8;
  margin: 0 0 12px;
  font-weight: 500;
}

.essay-card__desc {
  font-size: 0.95rem;
  color: #64748B;
  line-height: 1.6;
  margin: 0 0 16px;
}

.essay-card__meta {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

.essay-card__badge {
  display: inline-flex;
  align-items: center;
  padding: 0.125em 0.625em;
  font-size: 0.75rem;
  font-weight: 600;
  border-radius: 9999px;
  white-space: nowrap;
}

.essay-card--mol .essay-card__badge {
  background-color: #FFFBEB;
  color: #92400E;
}

.essay-card--aot .essay-card__badge {
  background-color: #EEF2FF;
  color: #3730A3;
}

.essay-card--gpt3 {
  border-top-color: #0D9488;
}

.essay-card--gpt3 .essay-card__badge {
  background-color: #F0FDFA;
  color: #115E59;
}

/* --- Chapter/Section Cards --- */

.chapter-card {
  background: #fff;
  border-radius: 10px;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.08), 0 2px 8px rgba(0, 0, 0, 0.04);
  padding: 24px 24px 24px 20px;
  border-left: 4px solid transparent;
  text-decoration: none;
  color: inherit;
  display: block;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.chapter-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1), 0 8px 24px rgba(0, 0, 0, 0.08);
  text-decoration: none;
  color: inherit;
}

.chapter-card__number {
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin: 0 0 4px;
  opacity: 0.6;
}

.chapter-card__title {
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1.2rem;
  font-weight: 700;
  margin: 0 0 8px;
  color: #1E293B;
}

.chapter-card__desc {
  font-size: 0.92rem;
  color: #64748B;
  margin: 0 0 12px;
  line-height: 1.5;
}

.chapter-card__pages {
  font-size: 0.8rem;
  color: #94A3B8;
  font-weight: 500;
}

/* Chapter border colors — MOL sections (amber palette) */
.chapter-card--mol-1 { border-left-color: #D97706; }
.chapter-card--mol-2 { border-left-color: #F59E0B; }
.chapter-card--mol-3 { border-left-color: #FBBF24; }
.chapter-card--mol-4 { border-left-color: #B45309; }
.chapter-card--mol-5 { border-left-color: #92400E; }

/* Chapter border colors — AOT sections (indigo palette) */
.chapter-card--aot-1 { border-left-color: #6366F1; }
.chapter-card--aot-2 { border-left-color: #818CF8; }
.chapter-card--aot-3 { border-left-color: #A5B4FC; }
.chapter-card--aot-4 { border-left-color: #4F46E5; }
.chapter-card--aot-5 { border-left-color: #3730A3; }

/* Chapter border colors — GPT-3 sections (teal palette) */
.chapter-card--gpt3-1 { border-left-color: #0D9488; }
.chapter-card--gpt3-2 { border-left-color: #14B8A6; }
.chapter-card--gpt3-3 { border-left-color: #2DD4BF; }
.chapter-card--gpt3-4 { border-left-color: #0F766E; }
.chapter-card--gpt3-5 { border-left-color: #115E59; }

/* Generic chapter colors (numbered fallback) */
.chapter-card--1 { border-left-color: #D97706; }
.chapter-card--2 { border-left-color: #6366F1; }
.chapter-card--3 { border-left-color: #059669; }
.chapter-card--4 { border-left-color: #2563EB; }
.chapter-card--5 { border-left-color: #DC2626; }
.chapter-card--6 { border-left-color: #0891B2; }
.chapter-card--7 { border-left-color: #7C3AED; }
.chapter-card--8 { border-left-color: #DB2777; }

/* --- Simulator Cards --- */

.simulator-card {
  background: #fff;
  border-radius: 10px;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.08), 0 2px 8px rgba(0, 0, 0, 0.04);
  padding: 28px 24px;
  border-top: 4px solid transparent;
  text-decoration: none;
  color: inherit;
  display: block;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.simulator-card:hover {
  transform: scale(1.02);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1), 0 8px 24px rgba(0, 0, 0, 0.08);
  text-decoration: none;
  color: inherit;
}

.simulator-card__icon {
  font-size: 2rem;
  margin: 0 0 12px;
  display: block;
}

.simulator-card__title {
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1.15rem;
  font-weight: 700;
  margin: 0 0 8px;
  color: #1E293B;
}

.simulator-card__desc {
  font-size: 0.92rem;
  color: #64748B;
  line-height: 1.5;
  margin: 0;
}

/* Simulator border-top colors */
.simulator-card--blue    { border-top-color: #2563EB; }
.simulator-card--amber   { border-top-color: #D97706; }
.simulator-card--purple  { border-top-color: #6366F1; }
.simulator-card--green   { border-top-color: #059669; }
.simulator-card--rose    { border-top-color: #E11D48; }
.simulator-card--indigo  { border-top-color: #4F46E5; }
.simulator-card--teal    { border-top-color: #0D9488; }

/* --- Feature Highlights --- */

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

.feature-item {
  text-align: center;
  padding: 24px 16px;
}

.feature-item__icon {
  font-size: 2rem;
  margin-bottom: 12px;
  display: block;
}

.feature-item__title {
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1.05rem;
  font-weight: 700;
  margin: 0 0 8px;
  color: #1E293B;
}

.feature-item__desc {
  font-size: 0.9rem;
  color: #64748B;
  line-height: 1.5;
  margin: 0;
}

/* --- Footer --- */

.footer {
  text-align: center;
  padding: 32px 24px;
  color: #94A3B8;
  font-size: 0.9rem;
  border-top: 1px solid #E2E8F0;
}

.footer a {
  color: #64748B;
  text-decoration: none;
  transition: color 0.2s ease;
}

.footer a:hover {
  color: #1E293B;
  text-decoration: underline;
}

/* --- Divider --- */

.divider {
  border: none;
  border-top: 1px solid #E2E8F0;
  margin: 0;
}

/* --- Responsive --- */

@media (max-width: 640px) {
  .hero {
    padding: 56px 20px;
  }

  .hero__title {
    font-size: 2rem;
  }

  .hero__subtitle {
    font-size: 1.1rem;
  }

  .grid {
    grid-template-columns: 1fr;
  }

  .grid--2 {
    grid-template-columns: 1fr;
  }

  .section {
    padding: 48px 16px;
  }

  .section__heading {
    font-size: 1.6rem;
  }

  .essay-card {
    padding: 24px 20px;
  }

  .essay-card__title {
    font-size: 1.2rem;
  }

  .feature-grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 400px) {
  .feature-grid {
    grid-template-columns: 1fr;
  }
}