/* =========================================================
   LÀM SAO — hệ thống thiết kế "Cẩm nang thực hành"
   Palette:  --ink #1B2430  --paper #FFFFFF  --paper-line #E4E1D6
             --mustard #E8A93E  --teal #2F7A6F  --clay #C24E30
   Display: "Be Vietnam Pro"  |  Utility/số: "JetBrains Mono"
   ========================================================= */

:root {
  --ink: #1B2430;
  --ink-soft: #4A5568;
  --paper: #FFFFFF;
  --paper-alt: #F6F5EF;
  --paper-line: #E4E1D6;
  --mustard: #E8A93E;
  --mustard-deep: #C98A22;
  --teal: #2F7A6F;
  --teal-deep: #21584F;
  --clay: #C24E30;
  --radius-sm: 4px;
  --radius-md: 10px;
  --max-w: 1180px;
  --grid-size: 28px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: 'Be Vietnam Pro', 'Segoe UI', sans-serif;
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

.mono {
  font-family: 'JetBrains Mono', 'Courier New', monospace;
}

a { color: inherit; text-decoration: none; }
img { max-width: 100%; display: block; }

.wrap {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
}

/* ---------- grid-paper texture used behind hero & section breaks ---------- */
.grid-paper {
  background-image:
    linear-gradient(var(--paper-line) 1px, transparent 1px),
    linear-gradient(90deg, var(--paper-line) 1px, transparent 1px);
  background-size: var(--grid-size) var(--grid-size);
  background-color: var(--paper-alt);
}

/* ---------- header ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  background: var(--paper);
  border-bottom: 2px solid var(--ink);
}
.site-header .bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 0;
  gap: 20px;
}
.logo {
  display: flex;
  align-items: baseline;
  gap: 8px;
  font-weight: 800;
  font-size: 1.5rem;
  letter-spacing: -0.02em;
}
.logo .tag {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.62rem;
  font-weight: 500;
  color: var(--teal-deep);
  background: #E4F1EE;
  padding: 3px 7px;
  border-radius: var(--radius-sm);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  transform: translateY(-6px);
}
.search-box {
  flex: 1;
  max-width: 440px;
  position: relative;
}
.search-box input {
  width: 100%;
  padding: 10px 14px 10px 38px;
  border: 1.5px solid var(--paper-line);
  border-radius: 999px;
  font-family: inherit;
  font-size: 0.92rem;
  background: var(--paper-alt);
}
.search-box input:focus { outline: 2px solid var(--mustard); border-color: var(--mustard); }
.search-box svg { position: absolute; left: 13px; top: 50%; transform: translateY(-50%); width: 16px; height: 16px; opacity: 0.55; }

.nav-links { display: flex; gap: 22px; font-size: 0.92rem; font-weight: 600; }
.nav-links a { position: relative; padding: 4px 0; }
.nav-links a:hover { color: var(--teal-deep); }

.header-actions { display: flex; align-items: center; gap: 14px; }
.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 9px 18px;
  border-radius: 999px;
  font-weight: 700;
  font-size: 0.88rem;
  border: 1.5px solid var(--ink);
  cursor: pointer;
  transition: transform .15s ease, background .15s ease;
}
.btn-primary { background: var(--mustard); border-color: var(--ink); }
.btn-primary:hover { background: var(--mustard-deep); transform: translateY(-1px); }
.btn-ghost { background: transparent; }
.btn-ghost:hover { background: var(--paper-alt); }

/* ---------- hero ---------- */
.hero {
  padding: 64px 0 56px;
  border-bottom: 2px solid var(--ink);
  position: relative;
  overflow: hidden;
}
.hero .wrap { display: grid; grid-template-columns: 1.15fr 0.85fr; gap: 48px; align-items: center; }
.eyebrow {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.78rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--teal-deep);
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 18px;
}
.eyebrow::before { content: ""; width: 22px; height: 2px; background: var(--clay); display: inline-block; }
.hero h1 {
  font-size: clamp(2.1rem, 4vw, 3.4rem);
  line-height: 1.08;
  letter-spacing: -0.02em;
  margin: 0 0 20px;
  font-weight: 800;
}
.hero h1 .underline { text-decoration: underline; text-decoration-color: var(--mustard); text-decoration-thickness: 8px; text-underline-offset: -2px; }
.hero p.lede { font-size: 1.12rem; color: var(--ink-soft); max-width: 480px; margin-bottom: 28px; }
.hero-form {
  display: flex;
  gap: 10px;
  max-width: 480px;
}
.hero-form input {
  flex: 1;
  padding: 14px 16px;
  border: 2px solid var(--ink);
  border-radius: var(--radius-sm);
  font-family: inherit;
  font-size: 0.98rem;
}
.hero-stats { display: flex; gap: 28px; margin-top: 30px; }
.hero-stats .stat b { display: block; font-family: 'JetBrains Mono', monospace; font-size: 1.5rem; }
.hero-stats .stat span { font-size: 0.8rem; color: var(--ink-soft); }

/* ---------- signature element: index-card stack ---------- */
.card-stack { position: relative; height: 380px; }
.index-card {
  position: absolute;
  width: 300px;
  background: var(--paper);
  border: 2px solid var(--ink);
  border-radius: var(--radius-sm);
  padding: 18px 18px 16px;
  box-shadow: 6px 6px 0 var(--ink);
}
.index-card .num { font-family: 'JetBrains Mono', monospace; font-size: 0.72rem; color: var(--clay); font-weight: 700; }
.index-card h4 { margin: 6px 0 8px; font-size: 1.05rem; line-height: 1.3; }
.index-card p { margin: 0; font-size: 0.85rem; color: var(--ink-soft); }
.index-card.c1 { top: 0; left: 40px; transform: rotate(-4deg); z-index: 3; background: var(--paper); }
.index-card.c2 { top: 60px; left: 110px; transform: rotate(3deg); z-index: 2; background: #FFF8EA; }
.index-card.c3 { top: 130px; left: 10px; transform: rotate(-1deg); z-index: 1; background: #EEF6F4; }

/* ---------- section headers ---------- */
.section { padding: 56px 0; }
.section-head { display: flex; align-items: flex-end; justify-content: space-between; margin-bottom: 30px; gap: 20px; flex-wrap: wrap; }
.section-head h2 { font-size: 1.9rem; margin: 0; letter-spacing: -0.01em; font-weight: 800; }
.section-head .idx { font-family: 'JetBrains Mono', monospace; color: var(--clay); font-weight: 700; margin-right: 10px; }
.section-head .more { font-size: 0.88rem; font-weight: 700; color: var(--teal-deep); white-space: nowrap; }

/* ---------- category tabs (like manual dividers) ---------- */
.tab-row { display: flex; gap: 10px; flex-wrap: wrap; margin-bottom: 34px; }
.tab-chip {
  padding: 9px 16px;
  border: 1.5px solid var(--ink);
  border-radius: 999px;
  font-size: 0.86rem;
  font-weight: 700;
  background: var(--paper);
  cursor: pointer;
}
.tab-chip.active { background: var(--ink); color: var(--paper); }
.tab-chip:hover:not(.active) { background: var(--paper-alt); }

/* ---------- guide cards ---------- */
.guide-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.guide-card {
  border: 1.5px solid var(--paper-line);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: box-shadow .2s ease, transform .2s ease, border-color .2s ease;
  background: var(--paper);
}
.guide-card:hover { box-shadow: 5px 5px 0 var(--ink); transform: translate(-2px,-2px); border-color: var(--ink); }
.guide-card .thumb {
  height: 160px;
  background: var(--paper-alt);
  display: flex; align-items: center; justify-content: center;
  font-size: 2.4rem;
  border-bottom: 1.5px solid var(--paper-line);
}
.guide-card .body { padding: 16px 18px 20px; }
.guide-card .cat {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.68rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--teal-deep);
  font-weight: 700;
}
.guide-card h3 { font-size: 1.08rem; line-height: 1.35; margin: 8px 0 10px; }
.guide-card .meta { display: flex; align-items: center; gap: 12px; font-size: 0.78rem; color: var(--ink-soft); }
.guide-card .meta .steps { display: flex; align-items: center; gap: 4px; }

/* ---------- how it works strip ---------- */
.how-strip { background: var(--ink); color: var(--paper); padding: 56px 0; }
.how-strip .section-head h2 { color: var(--paper); }
.how-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }
.how-step { border: 1.5px solid rgba(255,255,255,0.18); border-radius: var(--radius-md); padding: 20px; }
.how-step .n { font-family: 'JetBrains Mono', monospace; color: var(--mustard); font-weight: 800; font-size: 1.3rem; }
.how-step h4 { margin: 10px 0 8px; font-size: 1rem; }
.how-step p { margin: 0; font-size: 0.85rem; color: #C7CDD6; }

/* ---------- newsletter / CTA banner ---------- */
.cta-banner {
  border: 2px solid var(--ink);
  border-radius: var(--radius-md);
  background: #FFF8EA;
  padding: 34px 36px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  flex-wrap: wrap;
}
.cta-banner h3 { margin: 0 0 6px; font-size: 1.3rem; }
.cta-banner p { margin: 0; color: var(--ink-soft); font-size: 0.92rem; }

/* ---------- footer ---------- */
.site-footer { border-top: 2px solid var(--ink); padding: 44px 0 30px; background: var(--paper-alt); }
.footer-grid { display: grid; grid-template-columns: 1.4fr repeat(3, 1fr); gap: 32px; margin-bottom: 34px; }
.footer-grid h5 { font-size: 0.82rem; text-transform: uppercase; letter-spacing: 0.08em; margin: 0 0 14px; font-family: 'JetBrains Mono', monospace; }
.footer-grid ul { list-style: none; padding: 0; margin: 0; display: flex; flex-direction: column; gap: 9px; font-size: 0.9rem; }
.footer-grid ul a:hover { text-decoration: underline; text-decoration-color: var(--mustard); }
.footer-bottom { display: flex; justify-content: space-between; align-items: center; padding-top: 22px; border-top: 1px solid var(--paper-line); font-size: 0.8rem; color: var(--ink-soft); flex-wrap: wrap; gap: 10px; }

/* ---------- article page ---------- */
.article-hero { padding: 40px 0 30px; border-bottom: 2px solid var(--ink); }
.breadcrumb { font-family: 'JetBrains Mono', monospace; font-size: 0.75rem; color: var(--ink-soft); margin-bottom: 16px; }
.breadcrumb a:hover { text-decoration: underline; }
.article-hero h1 { font-size: clamp(1.8rem, 3.4vw, 2.6rem); margin: 0 0 16px; font-weight: 800; letter-spacing: -0.01em; }
.article-meta { display: flex; align-items: center; gap: 18px; font-size: 0.86rem; color: var(--ink-soft); flex-wrap: wrap; }
.article-meta .pill { border: 1px solid var(--paper-line); border-radius: 999px; padding: 5px 12px; font-family: 'JetBrains Mono', monospace; font-size: 0.75rem; }

.article-layout { display: grid; grid-template-columns: 240px 1fr 260px; gap: 40px; padding: 40px 0 70px; align-items: start; }

/* left rail: step tracker (signature element) */
.step-rail { position: sticky; top: 96px; }
.step-rail .rail-title { font-family: 'JetBrains Mono', monospace; font-size: 0.72rem; text-transform: uppercase; letter-spacing: 0.08em; color: var(--ink-soft); margin-bottom: 14px; }
.step-rail ol { list-style: none; margin: 0; padding: 0; border-left: 2px solid var(--paper-line); }
.step-rail li { position: relative; padding: 0 0 22px 20px; font-size: 0.86rem; }
.step-rail li::before {
  content: "";
  position: absolute; left: -7px; top: 2px;
  width: 12px; height: 12px; border-radius: 50%;
  background: var(--paper); border: 2px solid var(--paper-line);
}
.step-rail li.done::before { background: var(--teal); border-color: var(--teal); }
.step-rail li.done a { color: var(--teal-deep); font-weight: 700; }
.step-rail li a:hover { text-decoration: underline; }

/* article body */
.article-body h2 { font-size: 1.05rem; }
.method-block { margin-bottom: 8px; }
.step-item {
  display: grid;
  grid-template-columns: 46px 1fr;
  gap: 18px;
  padding: 26px 0;
  border-bottom: 1px solid var(--paper-line);
}
.step-item .num-badge {
  width: 40px; height: 40px;
  border: 2px solid var(--ink);
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-family: 'JetBrains Mono', monospace;
  font-weight: 800;
  background: var(--mustard);
  flex-shrink: 0;
}
.step-item h3 { margin: 2px 0 10px; font-size: 1.15rem; }
.step-item p { margin: 0 0 10px; color: var(--ink-soft); }
.tip-box {
  background: #EEF6F4;
  border-left: 3px solid var(--teal);
  padding: 10px 14px;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  font-size: 0.86rem;
  margin-top: 10px;
}
.tip-box b { color: var(--teal-deep); }
.warn-box {
  background: #FBEAE5;
  border-left: 3px solid var(--clay);
  padding: 10px 14px;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  font-size: 0.86rem;
  margin-top: 10px;
}
.warn-box b { color: var(--clay); }

.feedback-box { border: 2px solid var(--ink); border-radius: var(--radius-md); padding: 24px; margin-top: 40px; text-align: center; }
.feedback-box .thumbs { display: flex; justify-content: center; gap: 14px; margin-top: 14px; }
.feedback-box button {
  border: 1.5px solid var(--ink);
  background: var(--paper);
  border-radius: 999px;
  padding: 9px 20px;
  font-weight: 700;
  cursor: pointer;
  font-size: 0.9rem;
}
.feedback-box button:hover { background: var(--paper-alt); }

/* right rail */
.side-rail .box { border: 1.5px solid var(--paper-line); border-radius: var(--radius-md); padding: 18px 20px; margin-bottom: 20px; }
.side-rail .box h5 { font-family: 'JetBrains Mono', monospace; font-size: 0.72rem; text-transform: uppercase; letter-spacing: 0.08em; margin: 0 0 12px; }
.side-rail ul { margin: 0; padding-left: 18px; font-size: 0.88rem; }
.side-rail li { margin-bottom: 8px; }
.related-link { display: block; font-size: 0.86rem; font-weight: 600; padding: 8px 0; border-bottom: 1px solid var(--paper-line); }
.related-link:hover { color: var(--teal-deep); }

/* ---------- responsive ---------- */
@media (max-width: 980px) {
  .hero .wrap { grid-template-columns: 1fr; }
  .card-stack { display: none; }
  .guide-grid { grid-template-columns: repeat(2, 1fr); }
  .how-grid { grid-template-columns: repeat(2, 1fr); }
  .article-layout { grid-template-columns: 1fr; }
  .step-rail { position: static; margin-bottom: 30px; }
  .footer-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 640px) {
  .nav-links, .search-box { display: none; }
  .guide-grid { grid-template-columns: 1fr; }
  .how-grid { grid-template-columns: 1fr; }
  .hero-stats { flex-wrap: wrap; }
  .footer-grid { grid-template-columns: 1fr; }
}

/* focus visibility for accessibility */
a:focus-visible, button:focus-visible, input:focus-visible {
  outline: 3px solid var(--mustard);
  outline-offset: 2px;
}

@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; scroll-behavior: auto !important; }
}

/* ---------- added for full-featured build ---------- */
.search-page-hero { padding: 40px 0 30px; border-bottom: 2px solid var(--ink); background: var(--paper-alt); }
.search-page-hero .hero-form { max-width: 620px; }
.result-count { font-family: 'JetBrains Mono', monospace; font-size: 0.82rem; color: var(--ink-soft); margin-bottom: 20px; }
.empty-state { text-align: center; padding: 60px 20px; color: var(--ink-soft); }
.empty-state .big { font-size: 2.4rem; margin-bottom: 10px; }
.guide-card[hidden] { display: none; }
.cat-index { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; margin-bottom: 44px; }
.cat-tile { border: 1.5px solid var(--paper-line); border-radius: var(--radius-md); padding: 22px; transition: box-shadow .2s ease, transform .2s ease, border-color .2s ease; }
.cat-tile:hover { box-shadow: 5px 5px 0 var(--ink); transform: translate(-2px,-2px); border-color: var(--ink); }
.cat-tile .ic { font-size: 1.9rem; margin-bottom: 10px; }
.cat-tile h3 { margin: 0 0 6px; font-size: 1.08rem; }
.cat-tile p { margin: 0; font-size: 0.85rem; color: var(--ink-soft); }
.cat-tile .count { font-family: 'JetBrains Mono', monospace; font-size: 0.72rem; color: var(--clay); font-weight: 700; margin-top: 10px; display: inline-block; }