:root {
  color-scheme: dark;
  --background: #07131d;
  --surface: #0d1d29;
  --surface-raised: #122635;
  --surface-soft: #0a1822;
  --text: #edf6f8;
  --muted: #9fb3bd;
  --line: rgba(196, 224, 231, 0.16);
  --accent: #68e0bd;
  --accent-strong: #95f1d5;
  --blue: #71b7ff;
  --orange: #ffb067;
  --radius: 22px;
  --shadow: 0 24px 70px rgba(0, 0, 0, 0.28);
  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;
  min-width: 320px;
  background:
    radial-gradient(circle at 15% 0%, rgba(60, 141, 169, 0.16), transparent 34rem),
    radial-gradient(circle at 85% 12%, rgba(74, 210, 170, 0.10), transparent 30rem),
    var(--background);
  color: var(--text);
  line-height: 1.65;
}

a {
  color: inherit;
}

a:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 4px;
  border-radius: 6px;
}

.skip-link {
  position: fixed;
  top: 1rem;
  left: 1rem;
  z-index: 20;
  padding: 0.75rem 1rem;
  background: var(--accent);
  color: #03251d;
  font-weight: 800;
  transform: translateY(-160%);
}

.skip-link:focus {
  transform: translateY(0);
}

.site-header {
  width: min(1180px, calc(100% - 2rem));
  margin: 0 auto;
  padding: 1.35rem 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid var(--line);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.75rem;
  text-decoration: none;
  font-weight: 800;
  letter-spacing: -0.02em;
}

.brand-mark {
  display: grid;
  grid-template-columns: repeat(4, 6px);
  gap: 3px;
  align-items: end;
  width: 34px;
  height: 24px;
  padding: 4px;
  border: 1px solid rgba(104, 224, 189, 0.55);
  border-radius: 7px;
}

.brand-mark span {
  display: block;
  border-radius: 3px;
  background: var(--accent);
}

.brand-mark span:nth-child(1) { height: 35%; }
.brand-mark span:nth-child(2) { height: 55%; }
.brand-mark span:nth-child(3) { height: 75%; }
.brand-mark span:nth-child(4) { height: 100%; }

nav {
  display: flex;
  gap: 1.4rem;
}

nav a {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.95rem;
  font-weight: 700;
}

nav a:hover {
  color: var(--text);
}

nav a[aria-current="page"] {
  color: var(--accent);
}

main,
footer {
  width: min(1180px, calc(100% - 2rem));
  margin-inline: auto;
}

.hero {
  min-height: 660px;
  display: grid;
  grid-template-columns: minmax(0, 1.1fr) minmax(360px, 0.9fr);
  gap: clamp(2rem, 6vw, 6rem);
  align-items: center;
  padding: 6.5rem 0 7rem;
}

.eyebrow {
  margin: 0 0 0.8rem;
  color: var(--accent);
  font-size: 0.78rem;
  font-weight: 850;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

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

h1,
h2,
h3 {
  line-height: 1.12;
}

h1 {
  max-width: 820px;
  margin: 0;
  font-size: clamp(3rem, 7vw, 5.8rem);
  letter-spacing: -0.065em;
}

h2 {
  margin: 0;
  font-size: clamp(2rem, 4vw, 3.4rem);
  letter-spacing: -0.045em;
}

h3 {
  margin: 0;
  font-size: 1.45rem;
  letter-spacing: -0.025em;
}

.hero-summary {
  max-width: 700px;
  margin: 1.7rem 0 0;
  color: var(--muted);
  font-size: clamp(1.05rem, 2vw, 1.25rem);
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.9rem;
  margin-top: 2.2rem;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 50px;
  padding: 0.8rem 1.2rem;
  border: 1px solid transparent;
  border-radius: 999px;
  text-decoration: none;
  font-weight: 800;
  transition: transform 160ms ease, border-color 160ms ease, background 160ms ease;
}

.button:hover {
  transform: translateY(-2px);
}

.button-primary {
  background: var(--accent);
  color: #04251e;
}

.button-primary:hover {
  background: var(--accent-strong);
}

.button-secondary {
  border-color: var(--line);
  background: rgba(255, 255, 255, 0.035);
  color: var(--text);
}

.button-secondary:hover {
  border-color: rgba(104, 224, 189, 0.55);
}

.hero-visual {
  position: relative;
  min-height: 420px;
  display: grid;
  place-items: center;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 34px;
  background:
    linear-gradient(145deg, rgba(255, 255, 255, 0.045), rgba(255, 255, 255, 0.015)),
    var(--surface-soft);
  box-shadow: var(--shadow);
}

.hero-visual::before,
.hero-visual::after {
  content: "";
  position: absolute;
  width: 280px;
  height: 280px;
  border-radius: 50%;
  filter: blur(18px);
}

.hero-visual::before {
  top: -130px;
  right: -100px;
  background: rgba(104, 224, 189, 0.13);
}

.hero-visual::after {
  bottom: -160px;
  left: -100px;
  background: rgba(113, 183, 255, 0.12);
}

.cell-shell {
  position: relative;
  z-index: 1;
  width: min(330px, 76%);
  height: 184px;
  display: flex;
  align-items: center;
  padding: 20px 28px;
  border: 2px solid rgba(224, 245, 247, 0.6);
  border-radius: 30px;
  background: rgba(3, 16, 24, 0.74);
  box-shadow: inset 0 0 0 10px rgba(255, 255, 255, 0.025);
}

.cell-shell::after {
  content: "";
  position: absolute;
  top: 50%;
  right: -18px;
  width: 17px;
  height: 66px;
  transform: translateY(-50%);
  border-radius: 0 8px 8px 0;
  background: rgba(224, 245, 247, 0.58);
}

.cell-layers {
  width: 100%;
  height: 100%;
  display: grid;
  grid-template-columns: 0.38fr 1.35fr 0.4fr 1.35fr 0.38fr;
  gap: 7px;
}

.layer {
  border-radius: 7px;
}

.collector { background: linear-gradient(#d8e6eb, #8da5af); }
.electrode-negative { background: linear-gradient(#66747b, #27363e); }
.separator { background: linear-gradient(#f5f1cf, #b9b591); }
.electrode-positive { background: linear-gradient(#6fb69b, #225c4b); }

.terminal {
  position: absolute;
  top: 50%;
  z-index: 2;
  display: grid;
  place-items: center;
  width: 38px;
  height: 38px;
  transform: translateY(-50%);
  border-radius: 50%;
  color: #06131c;
  font-size: 1.5rem;
  font-weight: 900;
}

.terminal-negative {
  left: 9px;
  background: #bccbd1;
}

.terminal-positive {
  right: 9px;
  background: var(--accent);
}

.visual-caption {
  position: absolute;
  z-index: 2;
  bottom: 2.2rem;
  display: flex;
  gap: 0.7rem;
  align-items: center;
  color: var(--muted);
  font-size: 0.88rem;
  font-weight: 800;
}

.visual-caption span:nth-child(even) {
  color: var(--accent);
}

.section {
  padding: 6rem 0;
  border-top: 1px solid var(--line);
}

.section-heading {
  display: grid;
  grid-template-columns: 1fr minmax(280px, 0.62fr);
  gap: 3rem;
  align-items: end;
  margin-bottom: 2.4rem;
}

.section-heading > p {
  margin: 0;
  color: var(--muted);
}

.section-heading.compact {
  grid-template-columns: 1fr;
}

.module-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1rem;
}

.module-card {
  min-height: 430px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  padding: 1.45rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: linear-gradient(150deg, rgba(255, 255, 255, 0.045), rgba(255, 255, 255, 0.015));
  transition: transform 180ms ease, border-color 180ms ease, background 180ms ease;
}

.module-card.available:hover {
  transform: translateY(-5px);
  border-color: rgba(104, 224, 189, 0.45);
  background: linear-gradient(150deg, rgba(104, 224, 189, 0.08), rgba(255, 255, 255, 0.018));
}

.module-card.planned {
  opacity: 0.72;
}

.module-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 4rem;
}

.part-number {
  color: var(--accent);
  font-size: 1.1rem;
  font-weight: 900;
  letter-spacing: 0.08em;
}

.status {
  padding: 0.35rem 0.62rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--muted);
  font-size: 0.72rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.format {
  margin: 0 0 0.7rem;
  color: var(--blue);
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.07em;
  text-transform: uppercase;
}

.module-card p:not(.format):not(.launch-note),
.wide-card p,
.principle-grid p,
.closing p {
  color: var(--muted);
}

.module-card h3 + p {
  margin-bottom: 0;
}

.card-action {
  display: inline-flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 2rem;
  padding-top: 1rem;
  border-top: 1px solid var(--line);
  color: var(--accent);
  text-decoration: none;
  font-weight: 850;
}

.card-action:hover {
  color: var(--accent-strong);
}

.card-action.muted {
  color: var(--muted);
}

.launch-note {
  margin: 0.55rem 0 0;
  color: var(--muted);
  font-size: 0.78rem;
}

.text-link {
  display: inline-flex;
  gap: 0.6rem;
  margin-top: 1.6rem;
  color: var(--accent);
  text-decoration: none;
  font-weight: 800;
}

.text-link-secondary {
  margin-left: 1.4rem;
  color: var(--blue);
}

.wide-card {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 2rem;
  align-items: center;
  padding: 2rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
}

.wide-card p {
  max-width: 740px;
  margin-bottom: 0;
}

.principle-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1rem;
}

.principle-grid article {
  padding: 1.6rem 0;
  border-top: 1px solid var(--line);
}

.principle-number {
  display: block;
  margin-bottom: 2rem;
  color: var(--accent);
  font-weight: 900;
}

.closing {
  margin: 5rem 0;
  padding: clamp(2.5rem, 6vw, 5rem);
  border: 1px solid var(--line);
  border-radius: 30px;
  background:
    radial-gradient(circle at 90% 0%, rgba(104, 224, 189, 0.16), transparent 25rem),
    var(--surface-raised);
  box-shadow: var(--shadow);
}

.closing h2 {
  max-width: 760px;
}

.closing p:not(.eyebrow) {
  max-width: 690px;
  margin-bottom: 1.7rem;
}

.guide-hero {
  min-height: 620px;
  display: grid;
  grid-template-columns: minmax(0, 1.25fr) minmax(320px, 0.75fr);
  gap: clamp(2rem, 6vw, 6rem);
  align-items: center;
  padding: 6rem 0;
}

.guide-hero h1 {
  font-size: clamp(3rem, 6vw, 5.2rem);
}

.chapter-status {
  padding: 2rem;
  border: 1px solid var(--line);
  border-radius: 28px;
  background:
    radial-gradient(circle at 100% 0%, rgba(104, 224, 189, 0.14), transparent 18rem),
    var(--surface);
  box-shadow: var(--shadow);
}

.chapter-status > strong {
  display: block;
  font-size: clamp(1.6rem, 4vw, 2.4rem);
  line-height: 1.15;
  letter-spacing: -0.04em;
}

.progress-track {
  height: 10px;
  margin: 1.5rem 0 1.8rem;
  overflow: hidden;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.08);
}

.progress-track span {
  display: block;
  width: 100%;
  height: 100%;
  border-radius: inherit;
  background: linear-gradient(90deg, var(--blue), var(--accent));
}

.chapter-status dl {
  margin: 0;
}

.chapter-status dl div {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.75rem 0;
  border-top: 1px solid var(--line);
}

.chapter-status dt {
  color: var(--muted);
}

.chapter-status dd {
  margin: 0;
  text-align: right;
  font-weight: 800;
}

.question-path {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 1rem;
  padding: 0;
  list-style: none;
}

.question-path li {
  padding: 1.4rem;
  border-top: 1px solid var(--line);
}

.question-path span {
  color: var(--accent);
  font-weight: 900;
}

.question-path p {
  margin: 1.4rem 0 0;
  color: var(--muted);
}

.question-path strong {
  display: block;
  margin-bottom: 0.45rem;
  color: var(--text);
}

.study-sequence {
  display: grid;
  gap: 1rem;
}

.study-step {
  display: grid;
  grid-template-columns: 150px minmax(0, 1fr);
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: linear-gradient(150deg, rgba(255, 255, 255, 0.04), rgba(255, 255, 255, 0.012));
}

.study-step-deeper {
  border-color: rgba(113, 183, 255, 0.28);
  background: linear-gradient(150deg, rgba(113, 183, 255, 0.07), rgba(255, 255, 255, 0.012));
}

.study-step-number {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  padding: 1.7rem;
  border-right: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.018);
}

.study-step-number span {
  color: var(--muted);
  font-size: 0.75rem;
  font-weight: 850;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.study-step-number strong {
  color: var(--accent);
  font-size: 2.5rem;
  line-height: 1;
}

.study-step-copy {
  padding: 1.7rem;
}

.study-step-copy > p:not(.format):not(.launch-note),
.study-prompts p {
  color: var(--muted);
}

.study-prompts {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1rem;
  margin-top: 1.5rem;
}

.study-prompts p {
  margin: 0;
  padding: 1rem;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: rgba(0, 0, 0, 0.12);
}

.study-prompts strong {
  color: var(--text);
}

.checkpoint-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1rem;
}

.checkpoint-grid article {
  min-height: 250px;
  padding: 1.6rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
}

.checkpoint-grid p {
  color: var(--muted);
}

.guide-closing {
  margin-bottom: 0;
}

footer {
  min-height: 120px;
  display: flex;
  justify-content: space-between;
  gap: 2rem;
  align-items: center;
  padding: 2rem 0;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.9rem;
}

footer div {
  display: flex;
  gap: 1rem;
}

footer a {
  color: var(--text);
  text-decoration: none;
}

@media (max-width: 920px) {
  .hero,
  .guide-hero {
    grid-template-columns: 1fr;
    padding-top: 4.5rem;
  }

  .hero-visual {
    min-height: 360px;
  }

  .module-grid,
  .principle-grid,
  .question-path {
    grid-template-columns: 1fr;
  }

  .module-card {
    min-height: 360px;
  }

  .section-heading {
    grid-template-columns: 1fr;
    gap: 1.2rem;
  }
}

@media (max-width: 640px) {
  .site-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 1rem;
  }

  nav {
    width: 100%;
    gap: 0.75rem;
    flex-wrap: wrap;
    justify-content: flex-start;
  }

  h1 {
    font-size: clamp(2.8rem, 14vw, 4.2rem);
  }

  .hero {
    min-height: auto;
    padding-bottom: 5rem;
  }

  .hero-actions,
  .hero-actions .button {
    width: 100%;
  }

  .text-link-secondary {
    margin-left: 0;
  }

  .hero-visual {
    min-height: 320px;
  }

  .cell-shell {
    width: 82%;
    height: 155px;
  }

  .visual-caption {
    gap: 0.38rem;
    font-size: 0.72rem;
  }

  .section {
    padding: 4.5rem 0;
  }

  .wide-card {
    grid-template-columns: 1fr;
  }

  .study-step {
    grid-template-columns: 1fr;
  }

  .study-step-number {
    min-height: 110px;
    border-right: 0;
    border-bottom: 1px solid var(--line);
  }

  .study-prompts,
  .checkpoint-grid {
    grid-template-columns: 1fr;
  }

  .wide-card .button {
    width: 100%;
  }

  footer {
    align-items: flex-start;
    flex-direction: column;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    transition-duration: 0.01ms !important;
  }
}