/* Onfleek — workplace communication field guide.
   Identity: crisp teal + chartreuse "signal" accent on cool mist; numbered chapter rail. */

:root {
  --ink: #0e1c22;
  --teal: #0f766e;
  --teal-deep: #0b5a54;
  --lime: #c3e34a;
  --paper: #ffffff;
  --mist: #f2f6f5;
  --line: #d7e2df;
  --muted: #5a6b6a;
  --radius: 14px;
  --shadow: 0 1px 2px rgba(14, 28, 34, .06), 0 10px 30px -18px rgba(14, 28, 34, .35);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: "Inter", "Segoe UI", system-ui, -apple-system, sans-serif;
  color: var(--ink);
  background: var(--mist);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--teal-deep); text-decoration: none; }
a:hover { text-decoration: underline; }

h1, h2, h3 { line-height: 1.2; letter-spacing: -0.01em; }

/* ---------- header ---------- */
.site-head {
  display: flex; align-items: center; justify-content: space-between;
  gap: 1rem; padding: 1rem clamp(1rem, 4vw, 3rem);
  background: var(--paper); border-bottom: 1px solid var(--line);
  position: sticky; top: 0; z-index: 20;
}
.brand { display: inline-flex; align-items: center; gap: .6rem; color: var(--ink); }
.brand:hover { text-decoration: none; }
.brand-mark { width: 32px; height: 32px; }
.brand-word { font-weight: 800; font-size: 1.2rem; letter-spacing: -0.02em; }
.site-nav { display: flex; gap: 1.4rem; font-size: .95rem; font-weight: 600; }
.site-nav a { color: var(--muted); }
.site-nav a:hover { color: var(--teal); text-decoration: none; }

/* ---------- layout ---------- */
main { max-width: 1120px; margin: 0 auto; padding: 0 clamp(1rem, 4vw, 3rem) 4rem; }

.eyebrow {
  margin: 0; text-transform: uppercase; letter-spacing: .14em;
  font-size: .74rem; font-weight: 700; color: var(--teal);
}
.eyebrow a { color: inherit; }

/* ---------- hero ---------- */
.hero {
  padding: clamp(2.5rem, 6vw, 5rem) 0 2.5rem;
}
.hero h1 {
  font-size: clamp(2.4rem, 6vw, 4rem); margin: .6rem 0 1rem; font-weight: 850;
}
.hero h1 em { font-style: normal; color: var(--teal); position: relative; }
.hero h1 em::after {
  content: ""; position: absolute; left: 0; right: 0; bottom: .1em; height: .28em;
  background: var(--lime); z-index: -1; border-radius: 3px;
}
.lede { font-size: 1.12rem; color: var(--muted); max-width: 46ch; }
.hero-row { display: flex; flex-wrap: wrap; gap: .8rem; margin: 1.6rem 0 2.2rem; }
.btn {
  display: inline-block; padding: .7rem 1.3rem; border-radius: 999px;
  background: var(--teal); color: #fff; font-weight: 700; font-size: .95rem;
}
.btn:hover { background: var(--teal-deep); text-decoration: none; }
.btn-ghost { background: transparent; color: var(--teal-deep); box-shadow: inset 0 0 0 1.5px var(--line); }
.btn-ghost:hover { background: var(--paper); }

.hero-stats {
  list-style: none; margin: 0; padding: 0; display: grid; gap: .6rem;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  border-top: 1px solid var(--line); padding-top: 1.4rem;
}
.hero-stats li { display: flex; align-items: baseline; gap: .6rem; }
.stat-num { font-size: 1.4rem; font-weight: 800; color: var(--teal); font-variant-numeric: tabular-nums; }
.stat-name { font-size: .9rem; color: var(--muted); font-weight: 600; }

/* ---------- chapters ---------- */
.chapters { display: grid; gap: 3rem; }
.chapter-head {
  display: grid; grid-template-columns: auto 1fr; gap: 1rem;
  align-items: start; border-top: 2px solid var(--ink); padding-top: 1rem;
}
.chapter-no {
  font-size: 2rem; font-weight: 850; color: var(--lime);
  -webkit-text-stroke: 1px var(--teal-deep); font-variant-numeric: tabular-nums;
}
.chapter-title { margin: 0 0 .25rem; font-size: 1.5rem; }
.chapter-title a { color: var(--ink); }
.chapter-intro { margin: 0; color: var(--muted); max-width: 60ch; }

/* ---------- cards ---------- */
.cards {
  display: grid; gap: 1rem; margin-top: 1.3rem;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
}
.card {
  background: var(--paper); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 1.2rem 1.2rem 1.35rem; box-shadow: var(--shadow);
  display: flex; flex-direction: column; gap: .5rem;
  transition: transform .15s ease, box-shadow .15s ease;
}
.card:hover { transform: translateY(-3px); }
.card-top { display: flex; gap: .5rem; flex-wrap: wrap; }
.tag {
  display: inline-block; font-size: .72rem; font-weight: 700; letter-spacing: .03em;
  padding: .2rem .6rem; border-radius: 999px; background: var(--mist); color: var(--muted);
  border: 1px solid var(--line);
}
.tag-level { background: var(--teal); color: #fff; border-color: var(--teal); }
.tag-dim { background: transparent; }
.card-title { margin: .2rem 0 0; font-size: 1.14rem; }
.card-title a { color: var(--ink); }
.card-goal { margin: 0; font-size: .82rem; font-weight: 700; color: var(--teal); text-transform: uppercase; letter-spacing: .05em; }
.card-desc { margin: 0; font-size: .93rem; color: var(--muted); }

/* ---------- article ---------- */
.skill { padding-top: 2.4rem; }
.skill-head { border-bottom: 1px solid var(--line); padding-bottom: 1.4rem; }
.skill-head h1 { font-size: clamp(1.9rem, 4.5vw, 3rem); margin: .5rem 0 .2rem; font-weight: 850; }
.zh { margin: 0 0 .9rem; color: var(--muted); font-size: 1.05rem; }
.tags { display: flex; gap: .5rem; flex-wrap: wrap; }

.facts {
  margin: 1.8rem 0; background: var(--paper); border: 1px solid var(--line);
  border-left: 5px solid var(--lime); border-radius: var(--radius);
  padding: 1.3rem 1.4rem; box-shadow: var(--shadow);
}
.facts-title { margin: 0 0 .8rem; font-size: .78rem; text-transform: uppercase; letter-spacing: .14em; color: var(--teal); }
.facts-list { margin: 0; display: grid; gap: .55rem; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); }
.fact { display: grid; grid-template-columns: 8.5rem 1fr; gap: .5rem; align-items: baseline; }
.fact dt { font-weight: 700; font-size: .82rem; color: var(--muted); text-transform: uppercase; letter-spacing: .04em; }
.fact dd { margin: 0; font-weight: 600; }

.prose { max-width: 68ch; }
.prose h2 {
  font-size: 1.3rem; margin: 2.4rem 0 .7rem; padding-top: .4rem;
  border-top: 1px solid var(--line);
}
.prose h2:first-child { border-top: 0; margin-top: 0; }
.prose p { margin: 0 0 1.05rem; }
.prose--narrow { max-width: 60ch; }

.related {
  margin-top: 3rem; padding-top: 1.4rem; border-top: 2px solid var(--ink);
}
.related h2 { font-size: 1.1rem; }
.related ul { list-style: none; margin: 0; padding: 0; display: flex; flex-wrap: wrap; gap: .6rem; }
.related li a {
  display: inline-block; padding: .5rem .95rem; background: var(--paper);
  border: 1px solid var(--line); border-radius: 999px; font-weight: 600; font-size: .92rem;
}
.related li a:hover { border-color: var(--teal); text-decoration: none; }

/* ---------- category ---------- */
.cat-head { padding: 2.4rem 0 .5rem; max-width: 66ch; }
.cat-head h1 { font-size: clamp(1.9rem, 4.5vw, 2.8rem); margin: .6rem 0; font-weight: 850; }
.breadcrumb { font-size: .82rem; color: var(--muted); }
.breadcrumb a { color: var(--muted); }
.empty { margin-top: 2rem; padding: 1.2rem 1.4rem; background: var(--paper); border: 1px dashed var(--line); border-radius: var(--radius); color: var(--muted); }

/* ---------- legal ---------- */
.page { padding-top: 2.6rem; }
.page-head h1 { font-size: clamp(1.8rem, 4vw, 2.6rem); margin: .55rem 0 1.4rem; font-weight: 850; }
.page-head { border-bottom: 1px solid var(--line); }

/* ---------- footer ---------- */
.site-foot {
  border-top: 1px solid var(--line); background: var(--paper);
  padding: 2rem clamp(1rem, 4vw, 3rem); display: grid; gap: .7rem;
  text-align: center; justify-items: center;
}
.foot-tag { margin: 0; color: var(--muted); font-size: .9rem; max-width: 60ch; }
.foot-nav { display: flex; gap: 1.2rem; font-size: .9rem; font-weight: 600; }
.foot-nav a { color: var(--muted); }
.fine { margin: 0; font-size: .82rem; color: var(--muted); }

@media (max-width: 620px) {
  .fact { grid-template-columns: 1fr; gap: .1rem; }
  .site-nav { gap: 1rem; font-size: .88rem; }
}