:root {
  --paper: #f3ede2;
  --paper-2: #ece3d4;
  --ink: #211e1a;
  --ink-soft: #5b5347;
  --rust: #b8402e;
  --gold: #b07d2b;
  --teal: #3f6f4e;
  --line: #d8cfbe;
  --shadow: 0 1px 0 rgba(0, 0, 0, .04), 0 18px 40px -28px rgba(40, 30, 20, .5);
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: 24px;
}

body {
  min-width: 320px;
  padding-bottom: 84px;
  background: var(--paper);
  color: var(--ink);
  font-family: "Spline Sans", system-ui, sans-serif;
  font-size: 17px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  background-image: radial-gradient(circle at 12% 8%, rgba(184, 64, 46, .05), transparent 38%), radial-gradient(circle at 88% 92%, rgba(63, 111, 78, .05), transparent 42%);
}

a {
  color: var(--rust);
}

a:focus-visible,
summary:focus-visible {
  outline: 3px solid var(--gold);
  outline-offset: 4px;
}

.simple-shell {
  width: min(100% - 44px, 1040px);
  margin: 0 auto;
}

.hero {
  padding: 72px 0 52px;
  border-bottom: 3px solid var(--rust);
}

.kicker,
.section-label,
.nav-small {
  color: var(--rust);
  font-family: "JetBrains Mono", ui-monospace, monospace;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: .22em;
  text-transform: uppercase;
}

.kicker {
  margin-bottom: 20px;
}

.hero h1 {
  max-width: 12ch;
  margin-bottom: 24px;
  font-family: "Fraunces", Georgia, serif;
  font-size: clamp(42px, 8vw, 82px);
  font-weight: 900;
  letter-spacing: -.035em;
  line-height: .94;
}

.hero h1 em {
  color: var(--rust);
  font-weight: 500;
}

.lede {
  max-width: 62ch;
  color: var(--ink-soft);
  font-size: 19px;
  line-height: 1.6;
}

.hero .meta {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 30px;
}

.hero .meta span,
.hero .meta a {
  display: inline-flex;
  align-items: center;
  border: 1px solid var(--line);
  border-radius: 30px;
  background: var(--paper-2);
  color: var(--ink-soft);
  font-family: "JetBrains Mono", ui-monospace, monospace;
  font-size: 12px;
  line-height: 1.2;
  padding: 7px 13px;
  text-decoration: none;
}

.hero .meta a {
  border-color: var(--rust);
  color: var(--rust);
  font-weight: 700;
  transition: background .2s ease, color .2s ease, transform .2s ease;
}

.hero .meta a:hover {
  background: var(--rust);
  color: var(--paper);
  transform: translateY(-1px);
}

.section-list {
  padding-top: 12px;
}

.simple-section {
  min-height: 15rem;
  margin: 0;
  padding: 54px 0 58px;
  scroll-margin-top: 20px;
  border-bottom: 1px solid var(--line);
}

.simple-section:last-of-type {
  border-bottom: 0;
}

.sec-head {
  display: flex;
  align-items: flex-start;
  gap: 18px;
}

.sec-num {
  flex: none;
  margin-top: 7px;
  border-radius: 8px;
  background: var(--rust);
  box-shadow: 0 3px 10px rgba(184, 64, 46, .3);
  color: #fff;
  font-family: "JetBrains Mono", ui-monospace, monospace;
  font-size: 14px;
  font-weight: 700;
  line-height: 1;
  padding: 7px 11px;
}

.simple-section h2 {
  font-family: "Fraunces", Georgia, serif;
  font-size: clamp(29px, 4vw, 42px);
  font-weight: 600;
  letter-spacing: -.02em;
  line-height: 1.05;
}

/* Reusable content components for the next scaffold phase. */
.step-card,
.flow-diagram,
.istilah,
.ilustrasi-frame,
.tanya {
  border: 1px solid var(--line);
  border-radius: 14px;
  background: var(--paper-2);
  box-shadow: var(--shadow);
}

.step-card {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 16px;
  padding: 20px 22px;
}

.step-card + .step-card {
  margin-top: 12px;
}

.step-card .step-number {
  color: var(--rust);
  font-family: "JetBrains Mono", ui-monospace, monospace;
  font-weight: 700;
}

.flow-diagram {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  align-items: center;
  gap: 12px;
  padding: 22px;
}

.flow-diagram .flow-node {
  min-height: 76px;
  display: grid;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--paper);
  color: var(--ink);
  font-family: "JetBrains Mono", ui-monospace, monospace;
  font-size: 13px;
  text-align: center;
}

.flow-diagram .flow-arrow {
  color: var(--rust);
  font-family: "JetBrains Mono", ui-monospace, monospace;
  text-align: center;
}

.istilah {
  overflow: hidden;
}

.istilah summary {
  cursor: pointer;
  list-style: none;
  padding: 16px 20px;
  color: var(--teal);
  font-family: "JetBrains Mono", ui-monospace, monospace;
  font-weight: 700;
}

.istilah summary::-webkit-details-marker {
  display: none;
}

.istilah summary::before {
  content: "+";
  display: inline-block;
  width: 1.2em;
  color: var(--rust);
}

.istilah[open] summary::before {
  content: "−";
}

.istilah p {
  padding: 0 20px 18px;
  color: var(--ink-soft);
}

.ilustrasi-frame {
  min-height: 240px;
  display: grid;
  place-items: center;
  padding: 18px;
  background: var(--paper);
  border-style: dashed;
  color: var(--ink-soft);
  font-family: "JetBrains Mono", ui-monospace, monospace;
  font-size: 12px;
  text-align: center;
}

.tanya {
  padding: 24px;
  border-left: 5px solid var(--gold);
}

.tanya strong {
  font-family: "Fraunces", Georgia, serif;
  font-size: 22px;
}

.bfp-footer {
  margin-top: 54px;
  padding: 22px 0 0;
  border-top: 2px solid var(--rust);
  color: var(--ink-soft);
  font-family: "JetBrains Mono", ui-monospace, monospace;
  font-size: 11.5px;
  letter-spacing: .06em;
  line-height: 1.8;
}

.bfp-footer a {
  color: var(--rust);
  font-weight: 700;
  text-decoration: none;
}

.chapter-nav {
  position: fixed;
  z-index: 10;
  right: 0;
  bottom: 0;
  left: 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  padding: 12px clamp(16px, 4vw, 48px);
  border-top: 1.5px solid var(--line);
  background: rgba(243, 237, 226, .9);
  box-shadow: 0 -8px 32px -16px rgba(40, 30, 20, .18);
  backdrop-filter: blur(14px);
  font-family: "JetBrains Mono", ui-monospace, monospace;
}

.nav-back,
.nav-indicator {
  color: var(--ink-soft);
  font-size: 12px;
  text-decoration: none;
}

.nav-back:hover {
  color: var(--rust);
}

.nav-indicator {
  border: 1.5px solid var(--rust);
  border-radius: 40px;
  padding: 8px 15px;
  color: var(--rust);
  font-weight: 700;
  text-transform: uppercase;
  transition: background .2s ease, color .2s ease;
}

.nav-indicator:hover {
  background: var(--rust);
  color: var(--paper);
}

@media (max-width: 640px) {
  .simple-shell {
    width: min(100% - 32px, 1040px);
  }

  .hero {
    padding-top: 58px;
  }

  .hero h1 {
    max-width: 10ch;
  }

  .lede {
    font-size: 17px;
  }

  .simple-section {
    min-height: 12rem;
    padding: 42px 0 46px;
  }

  .flow-diagram {
    grid-template-columns: 1fr;
  }

  .flow-diagram .flow-arrow {
    transform: rotate(90deg);
  }

  .chapter-nav {
    padding: 10px 12px;
  }
}

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

  *,
  *::before,
  *::after {
    transition-duration: .01ms !important;
  }
}

.ilustrasi {
  margin: 26px 0;
}

.ilustrasi img {
  display: block;
  width: 100%;
  height: auto;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: #fff;
}

.ilustrasi figcaption {
  margin-top: 10px;
  font-family: "JetBrains Mono", monospace;
  font-size: 12px;
  color: var(--ink-soft);
  text-align: center;
}

.step-card pre {
  overflow-x: auto;
}