/* =============================================================
   The AI Alternatives Project — style.css
   Design reference: Brookings / RAND research aesthetic
   ============================================================= */

/* 1. Reset */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

/* 2. Custom Properties */
:root {
  --color-navy:    #1a2744;
  --color-slate:   #3d4f6e;
  --color-ink:     #2c2c2c;
  --color-muted:   #6b7a96;
  --color-bg:      #f8f7f4;
  --color-white:   #ffffff;
  --color-accent:  #c0722a;
  --color-rule:    #dcd8d0;

  --font-display:  'Playfair Display', Georgia, serif;
  --font-body:     'Inter', system-ui, sans-serif;

  --space-1:  8px;
  --space-2:  16px;
  --space-3:  24px;
  --space-4:  32px;
  --space-5:  48px;
  --space-6:  64px;
  --space-7:  96px;

  --max-width: 1100px;
  --prose-width: 680px;
}

/* 3. Base */
html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-body);
  font-size: 17px;
  line-height: 1.7;
  color: var(--color-ink);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3 {
  font-family: var(--font-display);
  line-height: 1.2;
  color: var(--color-navy);
}

h1 { font-size: clamp(2rem, 4vw, 3rem); font-weight: 700; }
h2 { font-size: clamp(1.5rem, 3vw, 2rem); font-weight: 700; }
h3 { font-size: 1.125rem; font-weight: 400; }

p { max-width: var(--prose-width); }

a {
  color: var(--color-accent);
  text-decoration: none;
}
a:hover { text-decoration: underline; }

ul { list-style: none; }

/* 4. Layout */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-4);
}

.section {
  padding: var(--space-7) 0;
}

.section--alt {
  background-color: var(--color-white);
}

.section-label {
  display: block;
  font-family: var(--font-body);
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: var(--space-2);
}

.section-header {
  margin-bottom: var(--space-5);
  border-bottom: 1px solid var(--color-rule);
  padding-bottom: var(--space-3);
}

.section-header p {
  margin-top: var(--space-2);
  color: var(--color-muted);
  font-size: 1rem;
}

/* 5. Navigation */
.nav {
  background-color: var(--color-navy);
  position: sticky;
  top: 0;
  z-index: 100;
  border-bottom: 1px solid rgba(255,255,255,0.08);
}

.nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
}

.nav__wordmark {
  font-family: var(--font-body);
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--color-white);
  letter-spacing: 0.02em;
  text-decoration: none;
  white-space: nowrap;
}

.nav__wordmark span {
  color: rgba(255,255,255,0.45);
  font-weight: 400;
}

.nav__links {
  display: flex;
  gap: var(--space-4);
}

.nav__links a {
  color: rgba(255,255,255,0.7);
  font-size: 0.8125rem;
  font-weight: 500;
  letter-spacing: 0.02em;
  text-decoration: none;
  transition: color 0.15s ease;
}

.nav__links a:hover {
  color: var(--color-white);
  text-decoration: none;
}

/* 6. Hero */
.hero {
  background-color: var(--color-white);
  padding: var(--space-7) 0;
  border-bottom: 1px solid var(--color-rule);
}

.hero__eyebrow {
  font-family: var(--font-body);
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: var(--space-3);
}

.hero__headline {
  max-width: 820px;
  margin-bottom: var(--space-3);
}

.hero__subhead {
  max-width: 620px;
  font-size: 1.0625rem;
  color: var(--color-muted);
  margin-bottom: var(--space-5);
  line-height: 1.75;
}

.hero__meta {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  flex-wrap: wrap;
}

.cta-button {
  display: inline-block;
  padding: 10px 24px;
  border: 1.5px solid var(--color-accent);
  color: var(--color-accent);
  font-family: var(--font-body);
  font-size: 0.8125rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  text-decoration: none;
  transition: background-color 0.15s ease, color 0.15s ease;
}
.cta-button:hover {
  background-color: var(--color-accent);
  color: var(--color-white);
  text-decoration: none;
}

.hero__affiliation {
  font-size: 0.8125rem;
  color: var(--color-muted);
}

.hero__affiliation a {
  color: var(--color-slate);
  font-weight: 500;
}

/* 7. Two-column and three-column layouts */
.two-col {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-6);
  align-items: start;
}

.three-col {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-3);
}

/* 8. Data Card */
.data-card {
  background-color: var(--color-bg);
  border: 1px solid var(--color-rule);
  padding: var(--space-4);
}

.data-card__title {
  font-family: var(--font-body);
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-muted);
  margin-bottom: var(--space-3);
}

.metric-item {
  padding: var(--space-2) 0;
  border-bottom: 1px solid var(--color-rule);
}
.metric-item:last-child { border-bottom: none; }

.metric-item__label {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--color-slate);
  margin-bottom: 2px;
}

.metric-item__value {
  font-size: 0.8125rem;
  color: var(--color-muted);
  font-style: italic;
}

/* 9. Method Cards */
.method-card {
  background-color: var(--color-white);
  border: 1px solid var(--color-rule);
  padding: var(--space-4);
}

.method-card__number {
  font-family: var(--font-display);
  font-size: 2rem;
  color: var(--color-rule);
  line-height: 1;
  margin-bottom: var(--space-2);
}

.method-card h3 {
  font-family: var(--font-body);
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--color-navy);
  margin-bottom: var(--space-2);
}

.method-card p {
  font-size: 0.9rem;
  color: var(--color-muted);
  line-height: 1.65;
}

/* 10. Scope List */
.scope-intro {
  margin-bottom: var(--space-4);
  color: var(--color-muted);
}

.scope-list li {
  padding: var(--space-2) 0;
  padding-left: var(--space-3);
  border-bottom: 1px solid var(--color-rule);
  position: relative;
  font-size: 0.9375rem;
  color: var(--color-ink);
}
.scope-list li:first-child { border-top: 1px solid var(--color-rule); }

.scope-list li::before {
  content: '—';
  position: absolute;
  left: 0;
  color: var(--color-muted);
}

/* 11. Dataset Section */
.dataset-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-5);
  align-items: start;
}

.dataset-block h3 {
  font-family: var(--font-body);
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-navy);
  margin-bottom: var(--space-2);
}

.dataset-block p {
  font-size: 0.9375rem;
  color: var(--color-muted);
  margin-bottom: var(--space-3);
  line-height: 1.7;
}

.divider {
  width: 32px;
  height: 2px;
  background-color: var(--color-accent);
  margin-bottom: var(--space-3);
}

/* 12. Email Form */
.email-form {
  display: flex;
  gap: 0;
  max-width: 420px;
  margin-top: var(--space-3);
}

.email-form input[type="email"] {
  flex: 1;
  padding: 10px 14px;
  border: 1px solid var(--color-rule);
  border-right: none;
  background-color: var(--color-white);
  font-family: var(--font-body);
  font-size: 0.875rem;
  color: var(--color-ink);
  outline: none;
  transition: border-color 0.15s;
}

.email-form input[type="email"]:focus {
  border-color: var(--color-slate);
}

.email-form input[type="email"]::placeholder {
  color: var(--color-muted);
}

.email-form button {
  padding: 10px 20px;
  background-color: var(--color-navy);
  color: var(--color-white);
  border: 1px solid var(--color-navy);
  font-family: var(--font-body);
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  cursor: pointer;
  transition: background-color 0.15s;
}

.email-form button:hover {
  background-color: var(--color-slate);
  border-color: var(--color-slate);
}

.w-form-done {
  margin-top: var(--space-2);
  font-size: 0.875rem;
  color: var(--color-slate);
  font-weight: 500;
}

.w-form-fail {
  margin-top: var(--space-2);
  font-size: 0.875rem;
  color: var(--color-accent);
}

/* 13. Contact Section */
.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-6);
}

.contact-block h3 {
  font-family: var(--font-body);
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--color-navy);
  margin-bottom: var(--space-2);
}

.contact-block p {
  font-size: 0.9rem;
  color: var(--color-muted);
  line-height: 1.7;
}

.contact-block a {
  font-weight: 500;
}

/* 14. Footer */
.footer {
  background-color: var(--color-navy);
  color: rgba(255,255,255,0.55);
  padding: var(--space-5) 0;
  border-top: 3px solid var(--color-accent);
}

.footer__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--space-3);
}

.footer__brand {
  font-size: 0.875rem;
  color: rgba(255,255,255,0.85);
  font-weight: 500;
}

.footer__brand span {
  color: rgba(255,255,255,0.4);
  font-weight: 400;
}

.footer__links {
  display: flex;
  gap: var(--space-4);
}

.footer__links a {
  font-size: 0.8125rem;
  color: rgba(255,255,255,0.55);
  text-decoration: none;
  transition: color 0.15s;
}
.footer__links a:hover { color: rgba(255,255,255,0.9); text-decoration: none; }

.footer__copy {
  width: 100%;
  font-size: 0.75rem;
  color: rgba(255,255,255,0.3);
  margin-top: var(--space-2);
  padding-top: var(--space-2);
  border-top: 1px solid rgba(255,255,255,0.08);
}

/* 15. Responsive */
@media (max-width: 768px) {
  :root {
    --space-7: 56px;
    --space-6: 40px;
  }

  .nav__links {
    display: none;
  }

  .two-col,
  .three-col,
  .dataset-grid,
  .contact-grid {
    grid-template-columns: 1fr;
  }

  .footer__inner {
    flex-direction: column;
    align-items: flex-start;
  }

  .footer__links {
    flex-wrap: wrap;
    gap: var(--space-2);
  }

  .email-form {
    flex-direction: column;
  }

  .email-form input[type="email"] {
    border-right: 1px solid var(--color-rule);
    border-bottom: none;
  }

  .email-form button {
    width: 100%;
  }
}