:root {
  --ink: #07152f;
  --muted: #556173;
  --paper: #f7f9f7;
  --line: rgba(7, 21, 47, 0.14);
  --blue: #075fbd;
  --teal: #008b92;
  --green: #4f832e;
  --orange: #c96500;
  --violet: #5a3b99;
  --white: #ffffff;
  --shadow: 0 22px 70px rgba(7, 21, 47, 0.12);
  font-family:
    Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
    sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
}

a {
  color: inherit;
  text-decoration: none;
}

.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding: 18px clamp(18px, 4vw, 56px);
  color: var(--white);
  transition:
    background 180ms ease,
    box-shadow 180ms ease,
    color 180ms ease;
}

.site-header[data-elevated="true"] {
  color: var(--ink);
  background: rgba(255, 255, 255, 0.9);
  box-shadow: 0 1px 24px rgba(7, 21, 47, 0.11);
  backdrop-filter: blur(18px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-size: 18px;
  font-weight: 800;
  letter-spacing: 0;
}

.brand-mark {
  width: 28px;
  height: 28px;
  border: 2px solid currentColor;
  border-radius: 50%;
  background:
    radial-gradient(circle at 50% 50%, currentColor 0 9%, transparent 10%),
    radial-gradient(circle at 26% 38%, currentColor 0 8%, transparent 9%),
    radial-gradient(circle at 72% 32%, currentColor 0 8%, transparent 9%),
    radial-gradient(circle at 72% 72%, currentColor 0 8%, transparent 9%),
    radial-gradient(circle at 30% 75%, currentColor 0 8%, transparent 9%);
}

.nav {
  display: flex;
  align-items: center;
  gap: 8px;
}

.nav a {
  min-height: 38px;
  display: inline-flex;
  align-items: center;
  padding: 0 13px;
  border-radius: 999px;
  color: inherit;
  font-size: 14px;
  font-weight: 700;
}

.nav a:hover,
.nav a:focus-visible {
  background: rgba(255, 255, 255, 0.16);
  outline: none;
}

.site-header[data-elevated="true"] .nav a:hover,
.site-header[data-elevated="true"] .nav a:focus-visible {
  background: rgba(7, 21, 47, 0.08);
}

.hero {
  position: relative;
  min-height: 94vh;
  display: grid;
  align-items: end;
  overflow: hidden;
  isolation: isolate;
  background:
    linear-gradient(120deg, rgba(4, 20, 48, 0.96), rgba(0, 88, 124, 0.58)),
    #07152f;
}

.droplet-canvas,
.hero-overlay {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
}

.droplet-canvas {
  z-index: -2;
}

.hero-overlay {
  z-index: -1;
  background:
    linear-gradient(180deg, rgba(7, 21, 47, 0.1), rgba(7, 21, 47, 0.72)),
    radial-gradient(circle at 74% 30%, rgba(255, 255, 255, 0.18), transparent 34%);
}

.hero-inner {
  width: min(1120px, calc(100% - 36px));
  margin: 0 auto;
  padding: 140px 0 132px;
  color: var(--white);
}

.eyebrow {
  margin: 0 0 12px;
  color: var(--orange);
  font-size: 14px;
  font-weight: 850;
  text-transform: uppercase;
  letter-spacing: 0;
}

.hero .eyebrow {
  color: #ffb35c;
}

h1,
h2,
h3,
p {
  overflow-wrap: anywhere;
}

h1 {
  max-width: 900px;
  margin: 0;
  font-size: clamp(64px, 13vw, 162px);
  line-height: 0.82;
  letter-spacing: 0;
}

h2 {
  margin: 0;
  font-size: clamp(34px, 6vw, 76px);
  line-height: 0.96;
  letter-spacing: 0;
}

h3 {
  margin: 0;
  font-size: 24px;
  line-height: 1.1;
}

.hero-copy {
  max-width: 760px;
  margin: 28px 0 0;
  color: rgba(255, 255, 255, 0.86);
  font-size: clamp(20px, 3vw, 34px);
  line-height: 1.18;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 36px;
}

.button {
  min-height: 48px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0 18px;
  border: 1px solid rgba(255, 255, 255, 0.38);
  border-radius: 999px;
  font-weight: 800;
}

.button.primary {
  color: var(--ink);
  background: var(--white);
}

.button.secondary {
  color: var(--white);
  background: rgba(255, 255, 255, 0.08);
}

.hero-signal {
  position: absolute;
  left: 50%;
  bottom: 26px;
  width: min(1120px, calc(100% - 36px));
  transform: translateX(-50%);
  display: grid;
  grid-template-columns: 1fr auto 1fr auto 1fr;
  align-items: center;
  gap: 12px;
  padding-top: 20px;
  border-top: 1px solid rgba(255, 255, 255, 0.24);
  color: rgba(255, 255, 255, 0.86);
  font-size: 14px;
  font-weight: 750;
}

.hero-signal strong {
  color: #ffb35c;
  font-size: 20px;
}

.section {
  width: min(1120px, calc(100% - 36px));
  margin: 0 auto;
  padding: 92px 0;
}

.section-heading {
  display: grid;
  grid-template-columns: minmax(260px, 0.9fr) minmax(280px, 1.1fr);
  gap: 42px;
  align-items: end;
  margin-bottom: 42px;
}

.section-heading.compact {
  display: block;
  max-width: 840px;
}

.intro-grid {
  display: grid;
  grid-template-columns: minmax(280px, 0.82fr) minmax(320px, 1fr);
  gap: 28px;
}

.statement {
  padding: clamp(28px, 4vw, 48px);
  color: var(--white);
  background: var(--ink);
}

.statement p {
  margin: 0;
  font-size: clamp(26px, 4vw, 44px);
  line-height: 1.05;
  font-weight: 850;
}

.text-stack {
  display: grid;
  align-content: center;
  gap: 18px;
  color: var(--muted);
  font-size: 20px;
  line-height: 1.55;
}

.text-stack p {
  margin: 0;
}

.foundation-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}

.concept-panel {
  min-height: 260px;
  display: grid;
  align-content: space-between;
  gap: 26px;
  padding: 28px;
  color: var(--white);
}

.concept-panel.blue {
  background: var(--blue);
}

.concept-panel.green {
  background: var(--green);
}

.concept-panel.orange {
  background: var(--orange);
}

.panel-number {
  width: 46px;
  height: 46px;
  display: inline-grid;
  place-items: center;
  border: 1px solid rgba(255, 255, 255, 0.45);
  border-radius: 50%;
  font-weight: 850;
}

.concept-panel p,
.process-display p,
.comparison p,
.vocab-card p,
.faq-panel p,
.reference-copy p {
  margin: 0;
  line-height: 1.45;
}

.process-layout {
  display: grid;
  grid-template-columns: 360px minmax(0, 1fr);
  gap: 18px;
  margin-top: 38px;
}

.process-controls {
  display: grid;
  gap: 8px;
}

.process-step {
  min-height: 64px;
  padding: 0 18px;
  border: 1px solid var(--line);
  border-radius: 8px;
  color: var(--ink);
  background: var(--white);
  text-align: left;
  font: inherit;
  font-weight: 800;
  cursor: pointer;
}

.process-step span {
  color: var(--teal);
  margin-right: 8px;
}

.process-step.active {
  color: var(--white);
  background: var(--ink);
  border-color: var(--ink);
}

.process-step.active span {
  color: #69cfd2;
}

.process-display {
  min-height: 352px;
  padding: clamp(28px, 4vw, 52px);
  color: var(--white);
  background: linear-gradient(135deg, #07152f, #0b6e77);
  box-shadow: var(--shadow);
}

.process-display h3 {
  margin-bottom: 14px;
  font-size: clamp(34px, 5vw, 64px);
}

.process-display p:last-child {
  max-width: 640px;
  color: rgba(255, 255, 255, 0.86);
  font-size: 22px;
}

.process-visual {
  width: 100%;
  height: 74px;
  margin-bottom: 38px;
  background:
    radial-gradient(circle at 5% 50%, #ffffff 0 5px, transparent 6px),
    radial-gradient(circle at 17% 32%, rgba(255, 255, 255, 0.78) 0 4px, transparent 5px),
    radial-gradient(circle at 29% 62%, rgba(255, 255, 255, 0.72) 0 4px, transparent 5px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.85), transparent);
  background-size: 100% 100%;
}

.comparison {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
}

.comparison-column {
  padding: 30px;
  border: 1px solid var(--line);
  background: var(--white);
}

.comparison-column.accent {
  color: var(--white);
  background: var(--teal);
  border-color: var(--teal);
}

.comparison-column h3 {
  margin-bottom: 20px;
}

.comparison-column p {
  padding: 14px 0;
  border-top: 1px solid currentColor;
}

.vocab-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
  margin-top: 38px;
}

.vocab-card {
  min-height: 230px;
  padding: 22px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--white);
}

.vocab-icon {
  width: 48px;
  height: 48px;
  display: grid;
  place-items: center;
  margin-bottom: 18px;
  border-radius: 8px;
  color: var(--white);
  background: var(--blue);
  font-weight: 900;
}

.vocab-card:nth-child(2n) .vocab-icon {
  background: var(--violet);
}

.vocab-card:nth-child(3n) .vocab-icon {
  background: var(--teal);
}

.vocab-card:nth-child(4n) .vocab-icon {
  background: var(--orange);
}

.vocab-card:nth-child(5n) .vocab-icon {
  background: var(--green);
}

.vocab-card h3 {
  margin-bottom: 6px;
}

.part-of-speech {
  display: block;
  margin-bottom: 18px;
  color: var(--muted);
  font-weight: 750;
}

.vocab-card p {
  color: #273144;
}

.example {
  display: block;
  margin-top: 14px;
  color: var(--blue);
  font-weight: 750;
}

.tag-list {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  padding: 0;
  margin: 0;
  list-style: none;
}

.tag-list li {
  min-height: 42px;
  display: inline-flex;
  align-items: center;
  padding: 0 15px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--white);
  font-weight: 750;
}

.faq-list {
  display: grid;
  gap: 10px;
}

.faq-item {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--white);
}

.faq-question {
  width: 100%;
  min-height: 66px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 0 20px;
  border: 0;
  color: var(--ink);
  background: transparent;
  font: inherit;
  font-weight: 850;
  text-align: left;
  cursor: pointer;
}

.faq-question::after {
  content: "+";
  width: 32px;
  height: 32px;
  flex: 0 0 32px;
  display: grid;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 50%;
  color: var(--teal);
  font-size: 22px;
}

.faq-item.open .faq-question::after {
  content: "-";
}

.faq-panel {
  display: none;
  padding: 0 20px 22px;
  color: var(--muted);
  font-size: 18px;
}

.faq-item.open .faq-panel {
  display: block;
}

.reference-section {
  display: grid;
  grid-template-columns: 0.8fr 1.2fr;
  gap: 32px;
  align-items: center;
}

.reference-copy p:last-child {
  margin-top: 18px;
  color: var(--muted);
  font-size: 19px;
}

.reference-image {
  margin: 0;
  border: 1px solid var(--line);
  border-radius: 8px;
  overflow: hidden;
  box-shadow: var(--shadow);
  background: var(--white);
}

.reference-image img {
  display: block;
  width: 100%;
  height: auto;
}

.site-footer {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 16px;
  padding: 30px clamp(18px, 4vw, 56px);
  color: var(--white);
  background: var(--ink);
  font-weight: 800;
}

.site-footer p {
  margin: 0;
}

@media (max-width: 860px) {
  .site-header {
    align-items: flex-start;
  }

  .nav {
    display: none;
  }

  .hero {
    min-height: 88vh;
  }

  .hero-inner {
    padding: 120px 0 146px;
  }

  .hero-signal {
    grid-template-columns: 1fr;
    gap: 7px;
  }

  .hero-signal strong {
    display: none;
  }

  .section {
    padding: 70px 0;
  }

  .section-heading,
  .intro-grid,
  .foundation-grid,
  .process-layout,
  .comparison,
  .vocab-grid,
  .reference-section {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 520px) {
  .hero-actions,
  .button {
    width: 100%;
  }

  .process-step {
    min-height: 58px;
  }

  .vocab-card {
    min-height: auto;
  }
}