:root {
  --bg: #07070d;
  --bg-subtle: #0e0e18;
  --bg-card: #13131f;
  --fg: #e8e8ed;
  --fg-muted: #8a8a9a;
  --accent: #e8a838;
  --accent-glow: rgba(232, 168, 56, 0.15);
  --border: #1e1e2e;
  --font-display: 'Space Grotesk', sans-serif;
  --font-body: 'DM Sans', sans-serif;
}

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

html { font-size: 16px; scroll-behavior: smooth; }

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

/* ---- Hero ---- */
.hero {
  min-height: 90vh;
  display: flex;
  align-items: center;
  padding: 6rem 2rem 4rem;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -40%;
  right: -20%;
  width: 60vw;
  height: 60vw;
  background: radial-gradient(circle, var(--accent-glow) 0%, transparent 70%);
  pointer-events: none;
}

.hero-inner {
  max-width: 780px;
  margin: 0 auto;
  position: relative;
  z-index: 1;
}

.hero-tag {
  font-family: var(--font-display);
  font-size: 0.8rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--accent);
  margin-bottom: 1.5rem;
}

.hero h1 {
  font-family: var(--font-display);
  font-size: clamp(2.4rem, 6vw, 4.2rem);
  font-weight: 700;
  line-height: 1.1;
  margin-bottom: 1.5rem;
  letter-spacing: -0.02em;
}

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

.hero-sub {
  font-size: 1.15rem;
  color: var(--fg-muted);
  max-width: 540px;
  margin-bottom: 3rem;
  line-height: 1.7;
}

.hero-stat {
  display: flex;
  align-items: center;
  gap: 1.2rem;
  flex-wrap: wrap;
  padding: 1.8rem 2rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 12px;
}

.stat-item { text-align: center; }

.stat-number {
  display: block;
  font-family: var(--font-display);
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.stat-label {
  display: block;
  font-size: 0.8rem;
  color: var(--fg-muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-top: 0.2rem;
}

.stat-divider {
  font-family: var(--font-display);
  font-size: 1.5rem;
  color: var(--fg-muted);
}

.stat-item.highlight .stat-number {
  color: var(--accent);
  font-size: 2.4rem;
}

/* ---- Section Label ---- */
.section-label {
  font-family: var(--font-display);
  font-size: 0.75rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.2em;
  color: var(--accent);
  margin-bottom: 2.5rem;
}

/* ---- Problem ---- */
.problem {
  padding: 6rem 2rem;
  background: var(--bg-subtle);
}

.problem-inner {
  max-width: 960px;
  margin: 0 auto;
}

.problem-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
}

.problem-card {
  padding: 2rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 10px;
}

.problem-icon {
  font-family: var(--font-display);
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--fg-muted);
  margin-bottom: 1rem;
  letter-spacing: 0.05em;
}

.problem-card h3 {
  font-family: var(--font-display);
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 0.8rem;
  line-height: 1.3;
}

.problem-card p {
  font-size: 0.9rem;
  color: var(--fg-muted);
  line-height: 1.6;
}

/* ---- How ---- */
.how {
  padding: 6rem 2rem;
}

.how-inner {
  max-width: 640px;
  margin: 0 auto;
}

.steps {
  display: flex;
  flex-direction: column;
  gap: 0;
}

.step {
  display: flex;
  gap: 1.5rem;
  align-items: flex-start;
}

.step-num {
  font-family: var(--font-display);
  font-size: 1.8rem;
  font-weight: 700;
  color: var(--accent);
  min-width: 2.5rem;
  line-height: 1;
  padding-top: 0.2rem;
}

.step-content h3 {
  font-family: var(--font-display);
  font-size: 1.15rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

.step-content p {
  font-size: 0.95rem;
  color: var(--fg-muted);
  line-height: 1.7;
}

.step-line {
  width: 2px;
  height: 2rem;
  background: var(--border);
  margin-left: 1.2rem;
}

/* ---- Math ---- */
.math {
  padding: 6rem 2rem;
  background: var(--bg-subtle);
}

.math-inner {
  max-width: 800px;
  margin: 0 auto;
}

.math-comparison {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 2rem;
  align-items: stretch;
}

.math-col {
  padding: 2rem;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--bg-card);
}

.math-col.old {
  opacity: 0.7;
}

.math-col.new {
  border-color: var(--accent);
  box-shadow: 0 0 30px var(--accent-glow);
}

.math-header {
  font-family: var(--font-display);
  font-size: 0.8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  margin-bottom: 1.2rem;
  color: var(--fg-muted);
}

.math-col.new .math-header {
  color: var(--accent);
}

.math-detail {
  font-size: 0.9rem;
  color: var(--fg-muted);
  margin-bottom: 0.5rem;
  line-height: 1.5;
}

.math-result {
  font-family: var(--font-display);
  font-size: 1.5rem;
  font-weight: 700;
  margin-top: 1.2rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
}

.math-col.new .math-result {
  color: var(--accent);
}

.math-note {
  display: block;
  font-size: 0.75rem;
  font-weight: 400;
  color: var(--fg-muted);
  margin-top: 0.3rem;
}

.math-vs {
  font-family: var(--font-display);
  font-size: 0.8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--fg-muted);
  align-self: center;
}

/* ---- Closing ---- */
.closing {
  padding: 8rem 2rem;
  text-align: center;
}

.closing-inner {
  max-width: 600px;
  margin: 0 auto;
}

.closing h2 {
  font-family: var(--font-display);
  font-size: clamp(1.6rem, 4vw, 2.4rem);
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: 1.5rem;
  letter-spacing: -0.01em;
}

.closing p {
  font-size: 1.05rem;
  color: var(--fg-muted);
  line-height: 1.7;
}

/* ---- Footer ---- */
.site-footer {
  padding: 2.5rem 2rem;
  border-top: 1px solid var(--border);
  text-align: center;
}

.footer-inner {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 0.6rem;
  font-size: 0.8rem;
  color: var(--fg-muted);
}

.footer-brand {
  font-family: var(--font-display);
  font-weight: 600;
  color: var(--fg);
}

/* ---- Responsive ---- */
@media (max-width: 768px) {
  .hero { min-height: auto; padding: 4rem 1.5rem 3rem; }
  .hero-stat { flex-direction: column; gap: 0.8rem; padding: 1.5rem; }
  .stat-divider { display: none; }
  .problem-grid { grid-template-columns: 1fr; }
  .math-comparison { grid-template-columns: 1fr; gap: 1rem; }
  .math-vs { text-align: center; }
  .problem, .how, .math, .closing { padding: 4rem 1.5rem; }
}

@media (max-width: 480px) {
  .hero h1 { font-size: 1.8rem; }
  .step { gap: 1rem; }
}