/* Counting the Atoms — Minimalist Swiss */
/* Archetype: Stripe Press / Craig Mod / Works in Progress */
/* Light, generous, one typeface, nothing decorative */

@import url('https://fonts.googleapis.com/css2?family=Inter:ital,opsz,wght@0,14..32,300..700;1,14..32,300..700&display=swap');

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

:root {
  --bg: #fafaf8;
  --text: #1a1a1a;
  --text-secondary: #555;
  --text-tertiary: #999;
  --accent: #1a1a1a;
  --border: #e0e0de;
  --border-light: #ececea;
  --max-width: 860px;
  --reading-width: 720px;
}

html {
  font-size: 19px;
  scroll-behavior: smooth;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif;
  font-feature-settings: 'kern' 1, 'liga' 1, 'calt' 1;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* --- Landing page --- */

.landing {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: 80px 32px;
}

.landing-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  width: 100%;
}

.landing h1 {
  font-size: 3.2rem;
  font-weight: 700;
  line-height: 1.05;
  letter-spacing: -0.035em;
  margin-bottom: 0.25em;
  color: var(--text);
}

.landing .subtitle {
  font-size: 0.85rem;
  color: var(--text-tertiary);
  font-weight: 400;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  margin-bottom: 2em;
}

.landing .intro {
  font-size: 1.15rem;
  line-height: 1.75;
  color: var(--text-secondary);
  margin-bottom: 1.25em;
  max-width: var(--reading-width);
  font-weight: 350;
}

.landing .intro:last-child {
  margin-bottom: 2.5em;
}

.toc-landing {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: 0;
}

.toc-landing li {
  padding: 1.6em 0;
  border-top: 1px solid var(--border);
}

.toc-landing li:last-child {
  border-bottom: 1px solid var(--border);
}

.toc-landing a {
  text-decoration: none;
  color: var(--text);
  font-size: 1.15rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  display: block;
  transition: opacity 0.15s;
}

.toc-landing a:hover {
  opacity: 0.55;
}

.toc-landing .card-link {
  display: block;
}

.toc-landing .card-title {
  display: block;
  font-size: 1.15rem;
  font-weight: 600;
  letter-spacing: -0.01em;
}

.toc-landing .desc {
  display: block;
  font-size: 0.88rem;
  color: var(--text-secondary);
  margin-top: 0.4em;
  line-height: 1.55;
  font-weight: 350;
}

/* --- Essay pages --- */

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 32px;
}

.essay-header {
  padding: 120px 0 48px;
  margin-bottom: 48px;
  border-bottom: 1px solid var(--border);
}

.essay-header .series {
  font-size: 0.78rem;
  color: var(--text-tertiary);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 1.2em;
  font-weight: 500;
}

.essay-header .series a {
  color: var(--text-tertiary);
  text-decoration: none;
  transition: color 0.15s;
}

.essay-header .series a:hover {
  color: var(--text);
}

.essay-header h1 {
  font-size: 2.6rem;
  font-weight: 700;
  line-height: 1.1;
  letter-spacing: -0.03em;
  color: var(--text);
  margin-bottom: 0.3em;
}

.essay-header .subtitle {
  font-size: 1.1rem;
  color: var(--text-secondary);
  font-weight: 350;
  line-height: 1.5;
  margin-bottom: 0.8em;
}

.essay-header .meta {
  font-size: 0.82rem;
  color: var(--text-tertiary);
  font-weight: 400;
  letter-spacing: 0.02em;
}

/* Table of contents */
.essay-toc {
  margin-bottom: 3em;
  padding: 1.5em 0;
  border-bottom: 1px solid var(--border-light);
}

.essay-toc h2 {
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-tertiary);
  margin-bottom: 1em;
  font-weight: 600;
}

.essay-toc ol {
  list-style: none;
  padding: 0;
  counter-reset: toc;
}

.essay-toc li {
  counter-increment: toc;
  margin-bottom: 0.4em;
}

.essay-toc li::before {
  content: counter(toc) " ";
  color: var(--text-tertiary);
  font-size: 0.82rem;
  font-variant-numeric: tabular-nums;
  margin-right: 0.3em;
}

.essay-toc a {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.9rem;
  font-weight: 400;
  transition: color 0.15s;
}

.essay-toc a:hover {
  color: var(--text);
}

/* Essay body */
.essay-body {
  max-width: var(--reading-width);
}

.essay-body h2 {
  font-size: 1.35rem;
  font-weight: 650;
  color: var(--text);
  margin: 3em 0 0.8em;
  line-height: 1.25;
  letter-spacing: -0.015em;
}

.essay-body p {
  margin-bottom: 1.25em;
  font-weight: 370;
}

.essay-body strong {
  color: var(--text);
  font-weight: 600;
}

.essay-body em {
  font-style: italic;
}

.essay-body blockquote {
  border-left: 2px solid var(--border);
  padding-left: 1.3em;
  margin: 1.8em 0;
  color: var(--text-secondary);
  font-style: italic;
}

.essay-body a {
  color: var(--text);
  text-decoration: underline;
  text-decoration-color: var(--border);
  text-underline-offset: 3px;
  transition: text-decoration-color 0.15s;
}

.essay-body a:hover {
  text-decoration-color: var(--text);
}

.essay-body ul, .essay-body ol {
  margin: 1em 0 1.3em 1.5em;
  font-weight: 370;
}

.essay-body li {
  margin-bottom: 0.4em;
}

.essay-body hr {
  border: none;
  border-top: 1px solid var(--border-light);
  margin: 3.5em 0;
}

/* Pull quote */
.pull-quote {
  font-size: 1.25rem;
  line-height: 1.55;
  color: var(--text);
  font-weight: 500;
  letter-spacing: -0.01em;
  margin: 2.5em 0;
  padding: 1.5em 0;
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}

/* Data callout */
.data-callout {
  background: #f3f3f0;
  border-radius: 3px;
  padding: 1.3em 1.5em;
  margin: 1.8em 0;
  font-size: 0.9rem;
}

.data-callout p {
  margin-bottom: 0.5em;
}

.data-callout p:last-child {
  margin-bottom: 0;
}

/* Sources */
.sources {
  margin-top: 4em;
  padding-top: 2em;
  border-top: 1px solid var(--border);
}

.sources h2 {
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-tertiary);
  margin-bottom: 1.2em;
  font-weight: 600;
}

.sources ul {
  list-style: none;
  padding: 0;
}

.sources li {
  font-size: 0.82rem;
  color: var(--text-secondary);
  margin-bottom: 0.45em;
  line-height: 1.5;
  font-weight: 370;
}

/* Author bio */
.author-bio {
  margin-top: 3em;
  padding: 2em 0;
  border-top: 1px solid var(--border);
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.7;
  font-weight: 370;
}

/* Navigation between parts */
.essay-nav {
  margin-top: 3em;
  padding: 1.8em 0;
  border-top: 1px solid var(--border);
  display: flex;
  justify-content: space-between;
  gap: 1em;
}

.essay-nav a {
  color: var(--text);
  text-decoration: none;
  font-size: 0.88rem;
  font-weight: 550;
  letter-spacing: -0.005em;
  transition: opacity 0.15s;
}

.essay-nav a:hover {
  opacity: 0.55;
}

/* Footer */
.site-footer {
  padding: 4em 0 5em;
  text-align: center;
  font-size: 0.75rem;
  color: var(--text-tertiary);
  letter-spacing: 0.03em;
}

/* --- Responsive --- */
@media (max-width: 640px) {
  html {
    font-size: 17px;
  }

  .landing {
    padding: 60px 20px;
  }

  .landing h1 {
    font-size: 2.2rem;
  }

  .landing .intro {
    font-size: 1.05rem;
  }

  .toc-landing a {
    font-size: 1.05rem;
  }

  .essay-header {
    padding: 80px 0 32px;
  }

  .essay-header h1 {
    font-size: 1.9rem;
  }

  .container {
    padding: 0 20px;
  }

  .essay-nav {
    flex-direction: column;
  }
}

/* Landing page essay spacing */
.landing .essay-body p {
  margin-bottom: 1.25em;
}
.landing .essay-body {
  margin-bottom: 2em;
}
.landing .pull-quote {
  margin: 2em 0;
}
.landing .data-callout {
  margin: 2em 0;
}