:root {
  --bg: #faf8f4;
  --bg-alt: #f0ece4;
  --fg: #1a1a1a;
  --fg-muted: #5c5c5c;
  --accent: #c8553d;
  --accent-light: #e8744e;
  --navy: #1e2d3d;
  --cream: #faf8f4;
  --gold: #d4a843;
  --card-bg: #ffffff;
  --font-display: 'Syne', sans-serif;
  --font-body: 'DM Sans', sans-serif;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  background: var(--bg);
  color: var(--fg);
  font-family: var(--font-body);
  font-size: 18px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

/* ===== HERO ===== */
.hero {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  padding: 80px 24px 60px;
  text-align: center;
  background: var(--navy);
  color: #ffffff;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -30%;
  width: 80%;
  height: 200%;
  background: radial-gradient(ellipse, rgba(200, 85, 61, 0.15) 0%, transparent 60%);
  pointer-events: none;
}

.hero-inner {
  max-width: 800px;
  position: relative;
  z-index: 1;
}

.hero-badge {
  display: inline-block;
  padding: 8px 20px;
  border: 1px solid rgba(255,255,255,0.2);
  border-radius: 100px;
  font-family: var(--font-body);
  font-size: 14px;
  font-weight: 500;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  margin-bottom: 40px;
  color: rgba(255,255,255,0.7);
}

.hero h1 {
  font-family: var(--font-display);
  font-size: clamp(3rem, 8vw, 6rem);
  font-weight: 800;
  line-height: 1.05;
  letter-spacing: -0.03em;
  margin-bottom: 24px;
}

.hero h1 .accent {
  color: var(--accent);
  font-style: italic;
}

.lede {
  font-size: clamp(1.1rem, 2.5vw, 1.35rem);
  color: rgba(255,255,255,0.65);
  max-width: 560px;
  margin: 0 auto;
  line-height: 1.6;
}

.hero-visual {
  margin-top: 60px;
  position: relative;
  z-index: 1;
}

.sock-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  max-width: 280px;
  margin: 0 auto;
}

.sock-item {
  width: 80px;
  height: 80px;
  border-radius: 16px;
  background: rgba(255,255,255,0.08);
  border: 1px solid rgba(255,255,255,0.12);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 24px;
  color: rgba(255,255,255,0.3);
  transition: all 0.3s ease;
}

.sock-item.ninth {
  background: var(--accent);
  border-color: var(--accent);
  color: #ffffff;
  box-shadow: 0 0 30px rgba(200, 85, 61, 0.4);
}

.sock-caption {
  margin-top: 20px;
  font-size: 14px;
  color: rgba(255,255,255,0.4);
  font-style: italic;
}

/* ===== PROBLEM ===== */
.problem {
  padding: 120px 24px;
  background: var(--bg);
}

.problem-inner {
  max-width: 900px;
  margin: 0 auto;
  text-align: center;
}

.problem h2 {
  font-family: var(--font-display);
  font-size: clamp(2rem, 5vw, 3rem);
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: 60px;
  letter-spacing: -0.02em;
}

.strikethrough {
  text-decoration: line-through;
  color: var(--fg-muted);
}

.problem-cards {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  margin-bottom: 48px;
}

.card {
  background: var(--card-bg);
  border: 1px solid rgba(0,0,0,0.06);
  border-radius: 20px;
  padding: 40px 28px;
  text-align: center;
  transition: transform 0.2s ease;
}

.card:hover {
  transform: translateY(-4px);
}

.card-number {
  font-family: var(--font-display);
  font-size: 3.5rem;
  font-weight: 800;
  color: var(--navy);
  line-height: 1;
  margin-bottom: 12px;
}

.card-text {
  font-size: 15px;
  color: var(--fg-muted);
  line-height: 1.5;
}

.problem-footnote {
  font-size: 15px;
  color: var(--fg-muted);
  font-style: italic;
}

/* ===== SOLUTION ===== */
.solution {
  padding: 120px 24px;
  background: var(--bg-alt);
}

.solution-inner {
  max-width: 1000px;
  margin: 0 auto;
  text-align: center;
}

.solution-label {
  font-family: var(--font-display);
  font-size: 13px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--accent);
  margin-bottom: 20px;
}

.solution h2 {
  font-family: var(--font-display);
  font-size: clamp(2rem, 5vw, 3rem);
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: 64px;
  letter-spacing: -0.02em;
}

.features-row {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px;
  text-align: left;
}

.feature {
  padding: 36px 28px;
  background: var(--card-bg);
  border-radius: 20px;
  border: 1px solid rgba(0,0,0,0.04);
}

.feature-icon {
  font-size: 20px;
  color: var(--accent);
  margin-bottom: 16px;
}

.feature h3 {
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 10px;
}

.feature p {
  font-size: 15px;
  color: var(--fg-muted);
  line-height: 1.6;
}

/* ===== MATH ===== */
.math {
  padding: 120px 24px;
  background: var(--navy);
  color: #ffffff;
  position: relative;
  overflow: hidden;
}

.math::after {
  content: '';
  position: absolute;
  bottom: -40%;
  left: -20%;
  width: 60%;
  height: 180%;
  background: radial-gradient(ellipse, rgba(212, 168, 67, 0.1) 0%, transparent 60%);
  pointer-events: none;
}

.math-inner {
  max-width: 800px;
  margin: 0 auto;
  text-align: center;
  position: relative;
  z-index: 1;
}

.math h2 {
  font-family: var(--font-display);
  font-size: clamp(1.8rem, 4vw, 2.5rem);
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: 40px;
  letter-spacing: -0.02em;
}

.math-equation {
  font-family: var(--font-display);
  font-size: clamp(4rem, 10vw, 7rem);
  font-weight: 800;
  color: var(--gold);
  line-height: 1;
  margin-bottom: 24px;
  letter-spacing: -0.04em;
}

.math-subtext {
  font-size: 1.1rem;
  color: rgba(255,255,255,0.6);
  max-width: 480px;
  margin: 0 auto 48px;
  line-height: 1.6;
}

.math-aside {
  padding-top: 32px;
  border-top: 1px solid rgba(255,255,255,0.1);
}

.math-aside p {
  font-size: 15px;
  color: rgba(255,255,255,0.4);
  font-style: italic;
}

/* ===== CLOSING ===== */
.closing {
  padding: 140px 24px;
  background: var(--bg);
  text-align: center;
}

.closing-inner {
  max-width: 700px;
  margin: 0 auto;
}

.closing h2 {
  font-family: var(--font-display);
  font-size: clamp(2.2rem, 5vw, 3.5rem);
  font-weight: 800;
  line-height: 1.1;
  margin-bottom: 24px;
  letter-spacing: -0.03em;
}

.closing p {
  font-size: 1.1rem;
  color: var(--fg-muted);
  line-height: 1.7;
  max-width: 560px;
  margin: 0 auto;
}

/* ===== FOOTER ===== */
.site-footer {
  padding: 48px 24px;
  background: var(--navy);
  color: rgba(255,255,255,0.4);
  text-align: center;
}

.footer-brand {
  font-family: var(--font-display);
  font-size: 1.5rem;
  font-weight: 800;
  color: #ffffff;
  margin-bottom: 8px;
}

.footer-tagline {
  font-size: 14px;
  font-style: italic;
}

/* ===== RESPONSIVE ===== */
@media (max-width: 768px) {
  .problem-cards {
    grid-template-columns: 1fr;
    gap: 16px;
  }

  .features-row {
    grid-template-columns: 1fr;
    gap: 16px;
  }

  .sock-grid {
    max-width: 240px;
  }

  .sock-item {
    width: 68px;
    height: 68px;
    font-size: 20px;
  }

  .hero {
    padding: 60px 20px 48px;
    min-height: auto;
  }

  .problem,
  .solution,
  .math,
  .closing {
    padding: 80px 20px;
  }

  .card {
    padding: 28px 20px;
  }

  .feature {
    padding: 28px 20px;
  }
}