/* ── RESET ─────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

/* ── VARIABLES ──────────────────────────────── */
:root {
  --white:        #FFFFFF;
  --anthracite:   #2D2E2E;
  --anthracite-2: #252626;
  --blue:         #4589FF;
  --gray-light:   #F4F4F4;
  --gray-border:  #E0E0E0;
  --gray-mid:     #8D8D8D;
  --font:         'IBM Plex Sans', sans-serif;
  --mono:         'IBM Plex Mono', monospace;
  --max-w:        1200px;
  --text-w:       680px;
}

html { scroll-behavior: smooth; }

body {
  font-family: var(--font);
  background: var(--anthracite);
  color: var(--anthracite);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

main {
  background: var(--white);
  flex: 1;
}

.wrap {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 48px;
}

/* ── ANIMATIONS ─────────────────────────────── */
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(20px); }
  to   { opacity: 1; transform: translateY(0); }
}

.reveal {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.65s ease, transform 0.65s ease;
}

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

/* ── ACCENT LINE ─────────────────────────────── */
.page-top-line {
  height: 3px;
  background: var(--blue);
}

/* ── NAVIGATION ──────────────────────────────── */
nav {
  background: var(--anthracite);
  padding: 22px 0;
}

nav .wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  font-size: 14px;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--white);
  text-decoration: none;
}

.nav-btn {
  font-family: var(--font);
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  padding: 10px 24px;
  background: transparent;
  color: rgba(255,255,255,0.65);
  border: 1px solid rgba(255,255,255,0.22);
  border-radius: 0;
  cursor: pointer;
  transition: color 0.15s, border-color 0.15s, background 0.15s;
  text-decoration: none;
  display: inline-block;
}

.nav-btn:hover {
  color: var(--white);
  border-color: rgba(255,255,255,0.55);
  background: rgba(255,255,255,0.06);
}

/* ── HERO ────────────────────────────────────── */
.hero {
  background: var(--anthracite);
  padding: 96px 0 120px;
  text-align: center;
  position: relative;
  overflow: hidden;
}

/* Background image overlay — keeps text readable over any photo */
.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background: rgba(45,46,46,0.78);
  pointer-events: none;
  z-index: 0;
}

/* Subtle noise texture */
.hero::after {
  content: '';
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='400' height='400'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.8' numOctaves='4' stitchTiles='stitch'/%3E%3CfeColorMatrix type='saturate' values='0'/%3E%3C/filter%3E%3Crect width='400' height='400' filter='url(%23n)' opacity='1'/%3E%3C/svg%3E");
  opacity: 0.04;
}

.hero .wrap { position: relative; z-index: 1; }

.hero-eyebrow {
  display: inline-block;
  font-size: 10px;
  font-weight: 500;
  letter-spacing: 0.28em;
  text-transform: uppercase;
  color: var(--blue);
  margin-bottom: 36px;
  animation: fadeUp 0.55s ease forwards;
  opacity: 0;
}

.hero h1 {
  font-size: clamp(38px, 5vw, 64px);
  font-weight: 700;
  letter-spacing: -0.025em;
  line-height: 1.08;
  color: var(--white);
  max-width: 880px;
  margin: 0 auto 28px;
  animation: fadeUp 0.55s 0.1s ease forwards;
  opacity: 0;
}

.hero-sub {
  font-size: 19px;
  font-weight: 300;
  line-height: 1.65;
  color: rgba(255,255,255,0.58);
  max-width: 520px;
  margin: 0 auto 52px;
  animation: fadeUp 0.55s 0.2s ease forwards;
  opacity: 0;
}

.hero-btns {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  animation: fadeUp 0.55s 0.3s ease forwards;
  opacity: 0;
  white-space: balance;
}

/* ── BUTTONS ─────────────────────────────────── */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font);
  font-size: 13px;
  font-weight: 500;
  letter-spacing: 0.07em;
  text-transform: uppercase;
  padding: 16px 32px;
  border-radius: 0;
  border: none;
  cursor: pointer;
  text-decoration: none;
  transition: opacity 0.15s, transform 0.1s;
}

.btn:hover  { opacity: 0.82; }
.btn:active { transform: scale(0.985); }

.btn-white { background: var(--white);      color: var(--anthracite); }
.btn-blue  { background: var(--blue);       color: var(--white); }
.btn-gray  { background: var(--gray-light); color: var(--anthracite); }
.btn-dark  { background: var(--anthracite); color: var(--white); }

/* ── TRUST BAR ───────────────────────────────── */
.trust-bar {
  background: var(--anthracite-2);
  border-top: 1px solid rgba(255,255,255,0.05);
  border-bottom: 1px solid rgba(255,255,255,0.05);
  padding: 20px 0;
}

.trust-label {
  display: block;
  text-align: center;
  font-size: 9px;
  font-weight: 500;
  letter-spacing: 0.3em;
  text-transform: uppercase;
  color: rgba(255,255,255,0.3);
  margin-bottom: 16px;
}

.trust-logos {
  display: flex;
  align-items: center;
  justify-content: space-around;
}

.trust-logo {
  width: 64px;
  height: 64px;
  flex: 0 0 64px;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0.4;
  transition: opacity 0.2s;
}

.trust-logo:hover { opacity: 0.7; }

.trust-logo svg {
  width: 36px;
  height: 36px;
}

/* ── CONTENT ─────────────────────────────────── */
.content {
  padding: 96px 0 72px;
}

.text-col {
  max-width: var(--text-w);
  margin: 0 auto;
}

.content-block {
  padding: 52px 0;
}

.content-block:first-child { padding-top: 0; }
.content-block:last-child  { padding-bottom: 0; }

/* ── SECTION NUM ─────────────────────────────── */
.section-num {
  font-family: var(--mono);
  font-size: 10px;
  font-weight: 400;
  letter-spacing: 0.18em;
  color: var(--gray-mid);
  text-transform: uppercase;
  display: block;
  margin-bottom: 20px;
}

.content-block h2 {
  font-size: 28px;
  font-weight: 600;
  letter-spacing: -0.015em;
  line-height: 1.22;
  color: var(--anthracite);
  margin-bottom: 22px;
}

.content-block p {
  font-size: 17px;
  font-weight: 400;
  line-height: 1.75;
  color: #4A4A4A;
}

.content-block p + p { margin-top: 16px; }

.content-btns {
  display: flex;
  gap: 12px;
  margin-top: 32px;
}

/* ── MATH CALLOUT ────────────────────────────── */
.math-callout {
  background: var(--gray-light);
  border-left: 3px solid var(--blue);
  padding: 32px 36px;
  margin-top: 24px;
}

.math-callout p {
  font-size: 16px;
  line-height: 1.7;
  color: #4A4A4A;
}

.math-figure {
  display: block;
  font-size: 52px;
  font-weight: 700;
  letter-spacing: -0.03em;
  color: var(--blue);
  line-height: 1;
  margin: 20px 0 10px;
}

.math-label {
  display: block;
  font-size: 13px;
  font-weight: 500;
  letter-spacing: 0.02em;
  color: var(--gray-mid);
  margin-bottom: 20px;
}

.math-equation {
  font-family: var(--mono);
  font-size: 13px;
  color: var(--gray-mid);
  letter-spacing: 0.04em;
}

/* ── FOOTER ──────────────────────────────────── */
footer {
  background: var(--anthracite);
  padding: 32px 0;
}

footer .wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.footer-logo {
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: rgba(255,255,255,0.45);
}

.footer-copy {
  font-size: 12px;
  color: rgba(255,255,255,0.28);
  letter-spacing: 0.02em;
}

/* ── PROSE (blog posts) ──────────────────────── */
.prose h1, .prose h2, .prose h3 {
  font-weight: 600;
  letter-spacing: -0.015em;
  line-height: 1.25;
  margin: 48px 0 16px;
  color: var(--anthracite);
}

.prose h1 { font-size: 36px; margin-top: 0; }
.prose h2 { font-size: 26px; }
.prose h3 { font-size: 20px; }

.prose p {
  font-size: 17px;
  line-height: 1.75;
  color: #4A4A4A;
  margin-bottom: 24px;
}

.prose ul, .prose ol {
  padding-left: 24px;
  margin-bottom: 24px;
}

.prose li {
  font-size: 17px;
  line-height: 1.75;
  color: #4A4A4A;
  margin-bottom: 8px;
}

.prose strong { font-weight: 600; color: var(--anthracite); }

.prose a { color: var(--blue); text-decoration: underline; text-underline-offset: 3px; }

.prose code {
  font-family: var(--mono);
  font-size: 14px;
  background: var(--gray-light);
  padding: 2px 6px;
}

.prose pre {
  background: var(--anthracite);
  padding: 24px;
  overflow-x: auto;
  margin-bottom: 24px;
}

.prose pre code {
  background: none;
  color: rgba(255,255,255,0.85);
  font-size: 14px;
  padding: 0;
}

.prose blockquote {
  border-left: 3px solid var(--blue);
  padding: 4px 0 4px 24px;
  margin: 32px 0;
}

.prose blockquote p { color: var(--gray-mid); font-style: italic; }

.prose hr {
  border: none;
  border-top: 1px solid var(--gray-border);
  margin: 48px 0;
}

/* ── RESPONSIVE ──────────────────────────────── */
@media (max-width: 900px) {
  .wrap { padding: 0 28px; }

  .hero { padding: 72px 0 88px; }

  .trust-logos {
    flex-wrap: wrap;
    justify-content: center;
    gap: 12px;
  }

  .trust-logo { flex: 0 0 calc(25% - 10px); }

  .content { padding: 72px 0 56px; }

  .math-figure { font-size: 40px; }
}

@media (max-width: 600px) {
  .hero-btns, .content-btns {
    flex-direction: column;
    align-items: stretch;
  }

  .trust-logo { flex: 0 0 calc(33% - 10px); }

  footer .wrap {
    flex-direction: column;
    gap: 8px;
    text-align: center;
  }
}