/* Plainly — shared stylesheet
   Design intent: a reference site, not a course funnel.
   Reads like documentation you trust: serif body for long-form,
   tight sans for structure, one accent colour, generous measure. */

:root {
  --paper: #fcfcfa;
  --paper-sunk: #f4f4f0;
  --ink: #1a2029;
  --ink-soft: #4a5560;
  --ink-faint: #78838d;
  --rule: #e2e4df;
  --accent: #0b6e63;
  --accent-soft: #e6f2f0;
  --flag: #9a5b12;
  --flag-soft: #fdf3e4;

  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
  --serif: Georgia, "Iowan Old Style", "Palatino Linotype", Palatino, serif;
  --mono: ui-monospace, "SF Mono", "Cascadia Mono", Consolas, monospace;

  --measure: 34rem;
  --wide: 64rem;
}

@media (prefers-color-scheme: dark) {
  :root {
    --paper: #14181d;
    --paper-sunk: #1b2027;
    --ink: #e8eaec;
    --ink-soft: #b0b8c0;
    --ink-faint: #8a939c;
    --rule: #2b323a;
    --accent: #5fc7b8;
    --accent-soft: #17302d;
    --flag: #e0a860;
    --flag-soft: #2c2318;
  }
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--serif);
  font-size: 1.125rem;
  line-height: 1.65;
}

/* ---------- Structure ---------- */

.wrap {
  width: 100%;
  max-width: var(--wide);
  margin: 0 auto;
  padding: 0 1.5rem;
}

.prose {
  max-width: var(--measure);
}

main { padding-bottom: 5rem; }

/* ---------- Header ---------- */

.site-head {
  border-bottom: 1px solid var(--rule);
  padding: 1.1rem 0;
  margin-bottom: 3rem;
}

.site-head .wrap {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0.75rem 2rem;
}

.wordmark {
  font-family: var(--sans);
  font-weight: 700;
  font-size: 1.15rem;
  letter-spacing: -0.02em;
  color: var(--ink);
  text-decoration: none;
}

.wordmark span { color: var(--accent); }

.site-nav {
  font-family: var(--sans);
  font-size: 0.9rem;
  display: flex;
  flex-wrap: wrap;
  gap: 1.25rem;
  margin-left: auto;
}

.site-nav a {
  color: var(--ink-soft);
  text-decoration: none;
}

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

/* ---------- Typography ---------- */

h1, h2, h3 {
  font-family: var(--sans);
  letter-spacing: -0.021em;
  line-height: 1.2;
  color: var(--ink);
}

h1 {
  font-size: clamp(1.9rem, 4.5vw, 2.75rem);
  margin: 0 0 0.75rem;
}

h2 {
  font-size: 1.4rem;
  margin: 3rem 0 0.75rem;
}

h3 {
  font-size: 1.1rem;
  margin: 2rem 0 0.5rem;
}

.standfirst {
  font-size: 1.25rem;
  line-height: 1.5;
  color: var(--ink-soft);
  margin: 0 0 2rem;
  max-width: 38rem;
}

p { margin: 0 0 1.25rem; }

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

strong { font-weight: 600; }

code {
  font-family: var(--mono);
  font-size: 0.87em;
  background: var(--paper-sunk);
  padding: 0.12em 0.34em;
  border-radius: 3px;
}

ul, ol { padding-left: 1.35rem; margin: 0 0 1.25rem; }
li { margin-bottom: 0.5rem; }

.kicker {
  font-family: var(--sans);
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--accent);
  margin: 0 0 0.6rem;
}

/* ---------- Verification stamp ---------- */
/* The load-bearing element of this whole site. Every page carries one. */

.stamp {
  font-family: var(--sans);
  font-size: 0.82rem;
  color: var(--ink-faint);
  border-left: 2px solid var(--accent);
  padding: 0.15rem 0 0.15rem 0.75rem;
  margin: 0 0 2.5rem;
}

.stamp b { color: var(--ink-soft); font-weight: 600; }

/* ---------- Level tracks ---------- */

.tracks {
  display: grid;
  gap: 1rem;
  grid-template-columns: repeat(auto-fit, minmax(15rem, 1fr));
  margin: 2.5rem 0 1rem;
  padding: 0;
  list-style: none;
}

.track {
  display: flex;
  flex-direction: column;
  border: 1px solid var(--rule);
  border-radius: 6px;
  padding: 1.35rem;
  background: var(--paper);
  text-decoration: none;
  color: inherit;
  transition: border-color 0.15s ease, transform 0.15s ease;
  margin: 0;
}

.track:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
}

.track-num {
  font-family: var(--sans);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--accent);
  text-transform: uppercase;
  margin-bottom: 0.5rem;
}

.track h3 { margin: 0 0 0.4rem; font-size: 1.18rem; }

.track p {
  font-size: 0.98rem;
  color: var(--ink-soft);
  margin: 0 0 0.9rem;
  line-height: 1.5;
}

.track-you {
  font-family: var(--sans);
  font-size: 0.85rem;
  color: var(--ink-faint);
  margin-top: auto;
  border-top: 1px solid var(--rule);
  padding-top: 0.75rem;
}

/* ---------- Callouts ---------- */

.note {
  background: var(--accent-soft);
  border-radius: 6px;
  padding: 1.1rem 1.35rem;
  margin: 2rem 0;
  font-size: 1.02rem;
}

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

.note-title {
  font-family: var(--sans);
  font-weight: 700;
  font-size: 0.8rem;
  letter-spacing: 0.07em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.4rem;
}

.gap {
  background: var(--flag-soft);
  border-radius: 6px;
  padding: 1.1rem 1.35rem;
  margin: 2rem 0;
  font-size: 1.02rem;
}

.gap .note-title { color: var(--flag); }
.gap p:last-child { margin-bottom: 0; }

/* ---------- Tables ---------- */

.table-scroll {
  overflow-x: auto;
  margin: 1.5rem 0 0.75rem;
  border: 1px solid var(--rule);
  border-radius: 6px;
}

table {
  border-collapse: collapse;
  width: 100%;
  font-family: var(--sans);
  font-size: 0.92rem;
}

th, td {
  text-align: left;
  padding: 0.7rem 0.9rem;
  border-bottom: 1px solid var(--rule);
  white-space: nowrap;
}

th {
  background: var(--paper-sunk);
  font-weight: 600;
  font-size: 0.82rem;
  letter-spacing: 0.03em;
  text-transform: uppercase;
  color: var(--ink-soft);
}

tbody tr:last-child td { border-bottom: none; }

td.num { font-variant-numeric: tabular-nums; }

.unverified {
  color: var(--flag);
  font-style: italic;
  font-family: var(--serif);
}

.table-note {
  font-family: var(--sans);
  font-size: 0.85rem;
  color: var(--ink-faint);
  margin: 0 0 2rem;
}

/* ---------- Resource lists ---------- */

.resources { list-style: none; padding: 0; }

.resources li {
  border-bottom: 1px solid var(--rule);
  padding: 1.1rem 0;
  margin: 0;
}

.resources li:last-child { border-bottom: none; }

.res-name {
  font-family: var(--sans);
  font-weight: 600;
  font-size: 1.02rem;
}

.res-meta {
  font-family: var(--sans);
  font-size: 0.8rem;
  color: var(--ink-faint);
  margin-left: 0.5rem;
}

.tag {
  display: inline-block;
  font-family: var(--sans);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  padding: 0.15rem 0.45rem;
  border-radius: 3px;
  background: var(--accent-soft);
  color: var(--accent);
  margin-left: 0.4rem;
  vertical-align: 0.1em;
}

.tag.paid { background: var(--flag-soft); color: var(--flag); }

.resources p {
  font-size: 0.98rem;
  color: var(--ink-soft);
  margin: 0.35rem 0 0;
  line-height: 1.5;
}

/* ---------- Concept index ---------- */

.concept-list {
  list-style: none;
  padding: 0;
  display: grid;
  gap: 0.75rem;
  grid-template-columns: repeat(auto-fit, minmax(17rem, 1fr));
}

.concept-list li { margin: 0; }

.concept-list a {
  display: block;
  border: 1px solid var(--rule);
  border-radius: 6px;
  padding: 1rem 1.15rem;
  text-decoration: none;
  color: inherit;
  transition: border-color 0.15s ease;
  height: 100%;
}

.concept-list a:hover { border-color: var(--accent); }

.concept-list .res-name { display: block; margin-bottom: 0.2rem; }

.concept-list p { margin: 0; font-size: 0.94rem; }

.soon {
  border: 1px dashed var(--rule) !important;
  opacity: 0.62;
}

/* ---------- Footer ---------- */

.site-foot {
  border-top: 1px solid var(--rule);
  padding: 2rem 0 3rem;
  font-family: var(--sans);
  font-size: 0.88rem;
  color: var(--ink-faint);
}

.site-foot p { margin: 0 0 0.5rem; max-width: 40rem; }
.site-foot a { color: var(--ink-soft); }

/* ---------- Utilities ---------- */

.next {
  font-family: var(--sans);
  font-size: 0.95rem;
  margin-top: 3rem;
  padding-top: 1.25rem;
  border-top: 1px solid var(--rule);
}

hr {
  border: none;
  border-top: 1px solid var(--rule);
  margin: 3rem 0;
}