/* ===========================================================
   AI4Teachers — vibrant & warm, BLUE family
   Display: Fraunces (soft serif) · Body: Plus Jakarta Sans
   Language toggle: single source of truth on <html>.
   html.lang-en hides .t-zh · html.lang-zh hides .t-en
   =========================================================== */

:root {
  --ink:    #0f1d36;
  --ink-2:  #3a4a66;
  --muted:  #6b7a93;
  --bg:     #ffffff;
  --bg-tint:#f2f8ff;
  --line:   #e5eefb;
  --line-2: #d6e4f8;

  /* vivid blue-family palette */
  --blue:   #2563eb;
  --blue2:  #3b82f6;
  --sky:    #0ea5e9;
  --cyan:   #06b6d4;
  --teal:   #14b8a6;

  --grad-brand: linear-gradient(135deg, #2563eb, #06b6d4);
  --grad-blue:  linear-gradient(135deg, #1d4ed8, #3b82f6);
  --grad-sky:   linear-gradient(135deg, #0284c7, #22d3ee);
  --grad-teal:  linear-gradient(135deg, #0891b2, #14b8a6);

  --maxw: 1120px;
  --r-sm: 12px; --r: 18px; --r-lg: 26px;
  --sh-sm: 0 2px 8px rgba(30,80,170,.08);
  --sh:    0 14px 40px rgba(30,90,180,.15);
  --sh-glow: 0 16px 40px rgba(37,99,235,.30);

  --zh: 'PingFang TC','Apple LiGothic Medium','Microsoft JhengHei',sans-serif;
  --sans: 'Plus Jakarta Sans', var(--zh);
  --display: 'Fraunces', Georgia, var(--zh);
  --mono: 'JetBrains Mono', ui-monospace, monospace;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }

html.lang-en .t-zh { display: none !important; }
html.lang-zh .t-en { display: none !important; }
.t-zh { font-family: var(--zh); }

body {
  margin: 0;
  font-family: var(--sans);
  font-size: 19px;
  line-height: 1.72;
  color: var(--ink-2);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
img { max-width: 100%; display: block; }
a { color: var(--blue); text-underline-offset: 3px; }

h1, h2, h3, h4 {
  font-family: var(--display); color: var(--ink); line-height: 1.1;
  font-weight: 600; font-optical-sizing: auto; letter-spacing: -.01em; margin: 0;
}
html.lang-zh h1, html.lang-zh h2, html.lang-zh h3 { font-weight: 700; }

.wrap { max-width: var(--maxw); margin: 0 auto; padding: 0 28px; }

.kicker {
  display: inline-block;
  font-family: var(--sans); font-size: 13px; font-weight: 800;
  letter-spacing: .12em; text-transform: uppercase;
  background: var(--grad-brand); -webkit-background-clip: text; background-clip: text;
  color: transparent;
}
.gx { background: var(--grad-brand); -webkit-background-clip: text; background-clip: text; color: transparent; }

/* ===================== Header ===================== */
.site-header {
  position: sticky; top: 0; z-index: 60;
  background: rgba(255,255,255,.78);
  backdrop-filter: saturate(180%) blur(16px);
  -webkit-backdrop-filter: saturate(180%) blur(16px);
  border-bottom: 1px solid var(--line);
}
.nav { max-width: var(--maxw); margin: 0 auto; display: flex; align-items: center; gap: 18px; padding: 14px 28px; }
.brand { display: inline-flex; align-items: center; gap: 10px; font-family: var(--display); font-weight: 600; font-size: 20px; color: var(--ink); text-decoration: none; }
.brand-mark {
  width: 32px; height: 32px; border-radius: 9px;
  background: url('favicon.svg') center / 100% 100% no-repeat;
  font-size: 0; line-height: 0; color: transparent;
  box-shadow: var(--sh-sm);
}
.nav-right { margin-left: auto; display: flex; align-items: center; gap: 4px; }
.nav-right a { color: var(--ink-2); text-decoration: none; font-size: 15px; font-weight: 600; padding: 8px 14px; border-radius: 10px; transition: .15s; }
.nav-right a:hover { color: var(--blue); background: var(--bg-tint); }
.nav-right a.cta { color: #fff; background: var(--grad-brand); box-shadow: var(--sh-sm); }
.nav-right a.cta:hover { color: #fff; filter: brightness(1.06); }

.lang-seg { display: inline-flex; background: var(--bg-tint); border: 1px solid var(--line-2); border-radius: 999px; padding: 3px; margin-left: 8px; }
.lang-seg button { border: 0; background: transparent; cursor: pointer; font-family: var(--sans); font-weight: 700; font-size: 13px; color: var(--muted); padding: 5px 13px; border-radius: 999px; line-height: 1; transition: .15s; }
.lang-seg button:hover { color: var(--blue); }
html.lang-en .lang-seg button[data-lang="en"],
html.lang-zh .lang-seg button[data-lang="zh"] { background: var(--grad-brand); color: #fff; box-shadow: var(--sh-sm); }

/* ===================== Buttons ===================== */
.btn { display: inline-flex; align-items: center; gap: 8px; font-family: var(--sans); font-weight: 700; font-size: 16px; padding: 14px 26px; border-radius: 14px; text-decoration: none; cursor: pointer; border: 2px solid transparent; transition: transform .08s, filter .15s, box-shadow .2s; white-space: nowrap; }
.btn:active { transform: translateY(1px); }
.btn-primary { background: var(--grad-brand); color: #fff; box-shadow: var(--sh-glow); }
.btn-primary:hover { color: #fff; filter: brightness(1.07); }
.btn-accent { background: var(--grad-teal); color: #fff; box-shadow: 0 16px 40px rgba(8,145,178,.28); }
.btn-accent:hover { color: #fff; filter: brightness(1.06); }
.btn-ghost { background: #fff; color: var(--blue); border-color: var(--line-2); }
.btn-ghost:hover { border-color: var(--blue); background: var(--bg-tint); }

/* ===================== Hero ===================== */
.hero { position: relative; overflow: hidden; padding: 92px 0 100px; }
.hero::before {
  content: ""; position: absolute; inset: 0; z-index: -1;
  background:
    radial-gradient(46% 42% at 82% 2%,  rgba(59,130,246,.26), transparent 70%),
    radial-gradient(40% 40% at 6% 8%,   rgba(14,165,233,.22), transparent 70%),
    radial-gradient(52% 50% at 60% 108%, rgba(6,182,212,.20), transparent 70%),
    radial-gradient(40% 40% at 98% 80%, rgba(20,184,166,.16), transparent 70%),
    #fbfdff;
}
.hero-grid { display: grid; grid-template-columns: 1.05fr .95fr; gap: 56px; align-items: center; }
.hero h1 { font-size: clamp(42px, 5.6vw, 66px); margin: 20px 0 22px; line-height: 1.04; letter-spacing: -.02em; }
.hero h1 .soft { background: var(--grad-brand); -webkit-background-clip: text; background-clip: text; color: transparent; }
.hero .lead { font-size: clamp(18px, 2.1vw, 21px); color: var(--ink-2); max-width: 520px; margin: 0 0 32px; line-height: 1.62; }
.hero-actions { display: flex; gap: 14px; flex-wrap: wrap; }

/* browser window mockup */
.window { background: #fff; border: 1px solid var(--line-2); border-radius: 20px; box-shadow: var(--sh); overflow: hidden; transform: rotate(.6deg); }
.window-bar { display: flex; align-items: center; gap: 14px; padding: 13px 16px; background: var(--grad-brand); }
.dots { display: flex; gap: 7px; }
.dots i { width: 11px; height: 11px; border-radius: 50%; display: block; background: rgba(255,255,255,.55); }
.url { flex: 1; background: rgba(255,255,255,.22); border-radius: 8px; padding: 6px 12px; font-family: var(--mono); font-size: 12px; color: #fff; display: flex; align-items: center; gap: 7px; }
.url svg { width: 12px; height: 12px; color: #fff; }
.window-body { padding: 30px 28px 34px; background: linear-gradient(180deg, #fff, #f4faff); }
.mini-kicker { font-family: var(--sans); font-weight: 800; font-size: 10.5px; letter-spacing: .12em; text-transform: uppercase; color: var(--sky); }
.window-body h4 { font-size: 26px; margin: 8px 0 10px; }
.window-body p { margin: 0; font-size: 13.5px; color: var(--muted); line-height: 1.6; }
.window-body .pill { display: inline-block; margin-top: 16px; background: var(--grad-teal); color: #fff; font-family: var(--sans); font-weight: 700; font-size: 12px; padding: 8px 15px; border-radius: 9px; }
.window-body .row { display: flex; gap: 8px; margin-top: 18px; }
.window-body .chip { height: 9px; border-radius: 5px; }
.window-body .chip:nth-child(1){ background: #bfdbfe; } .window-body .chip:nth-child(2){ background: #a5f3fc; } .window-body .chip:nth-child(3){ background: #99f6e4; }

/* ===================== Sections ===================== */
section.block { padding: 100px 0; }
section.block.soft { background: linear-gradient(180deg, var(--bg-tint), #fff); border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.section-head { max-width: 700px; margin-bottom: 50px; }
.section-head h2 { font-size: clamp(32px, 4.2vw, 46px); margin: 14px 0 14px; letter-spacing: -.02em; }
.section-head p { font-size: 19px; color: var(--muted); margin: 0; }

/* feature cards — each its own blue-family color */
.grid { display: grid; gap: 22px; }
.cols-3 { grid-template-columns: repeat(3, 1fr); }
.feature { position: relative; background: #fff; border: 1px solid var(--line); border-radius: var(--r-lg); padding: 34px 30px; overflow: hidden; transition: box-shadow .22s, transform .22s, border-color .22s; }
.feature::before { content: ""; position: absolute; inset: 0 0 auto 0; height: 5px; background: var(--c, var(--grad-brand)); }
.feature:hover { transform: translateY(-5px); box-shadow: var(--card-glow, var(--sh)); border-color: transparent; }
.feature .ic { width: 54px; height: 54px; border-radius: 16px; background: var(--c, var(--grad-brand)); color: #fff; display: grid; place-items: center; margin-bottom: 22px; box-shadow: var(--sh-sm); }
.feature .ic svg { width: 26px; height: 26px; }
.feature h3 { font-size: 22px; margin-bottom: 10px; }
.feature p { margin: 0; color: var(--ink-2); font-size: 16.5px; line-height: 1.62; }
.f-blue { --c: var(--grad-blue); --card-glow: 0 18px 44px rgba(37,99,235,.22); }
.f-sky  { --c: var(--grad-sky);  --card-glow: 0 18px 44px rgba(14,165,233,.22); }
.f-teal { --c: var(--grad-teal); --card-glow: 0 18px 44px rgba(20,184,166,.22); }

/* about */
.about { max-width: 760px; }
.mono-badge { width: 76px; height: 76px; border-radius: 20px; background: var(--grad-brand); box-shadow: var(--sh); display: grid; place-items: center; font-family: var(--display); font-weight: 600; font-size: 30px; color: #fff; margin-bottom: 26px; }
.about p { font-size: 20px; line-height: 1.74; color: var(--ink-2); }
.about p + p { margin-top: 16px; }
.about p strong { color: var(--blue); }
.tags { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 28px; }
.tag { font-family: var(--sans); font-size: 14px; font-weight: 700; padding: 8px 16px; border-radius: 999px; color: #fff; }
.tag:nth-child(1){ background: var(--grad-blue); } .tag:nth-child(2){ background: var(--grad-sky); } .tag:nth-child(3){ background: var(--grad-teal); }

/* lesson teaser */
.lesson-card { display: flex; align-items: center; gap: 28px; background: #fff; border: 1px solid var(--line-2); border-radius: var(--r-lg); padding: 32px; box-shadow: var(--sh-sm); text-decoration: none; color: inherit; transition: box-shadow .22s, transform .22s; flex-wrap: wrap; }
.lesson-card:hover { box-shadow: var(--sh); transform: translateY(-3px); }
.lesson-tag { flex: 0 0 auto; font-family: var(--display); font-weight: 600; font-size: 14px; color: #fff; background: var(--grad-brand); border-radius: 16px; padding: 18px 20px; text-align: center; line-height: 1.3; box-shadow: var(--sh-sm); }
.lesson-card .meta { flex: 1 1 280px; }
.lesson-card h3 { font-size: 24px; margin-bottom: 8px; }
.lesson-card p { margin: 0; color: var(--muted); font-size: 16.5px; }
.level { display: inline-block; font-family: var(--sans); font-size: 12px; font-weight: 800; letter-spacing: .06em; text-transform: uppercase; color: #fff; background: var(--grad-teal); padding: 5px 12px; border-radius: 8px; margin-bottom: 10px; }
.arrow { flex: 0 0 auto; color: var(--blue); }

/* ===================== Lesson page ===================== */
.lesson-hero { padding: 64px 0 8px; background: linear-gradient(180deg, var(--bg-tint), #fff); border-bottom: 1px solid var(--line); }
.crumb { font-family: var(--sans); font-weight: 600; font-size: 14px; color: var(--muted); margin-bottom: 18px; }
.crumb a { color: var(--blue); text-decoration: none; }
.lesson-hero h1 { font-size: clamp(34px, 4.8vw, 50px); margin-bottom: 16px; letter-spacing: -.02em; }
.lesson-hero .lead { font-size: 20px; color: var(--ink-2); max-width: 700px; margin: 0; line-height: 1.6; }
.goals { margin: 30px 0 56px; padding: 30px 32px; background: #fff; border: 1px solid var(--line); border-radius: var(--r); box-shadow: var(--sh-sm); border-top: 5px solid transparent; background-image: linear-gradient(#fff,#fff), var(--grad-brand); background-origin: border-box; background-clip: padding-box, border-box; }
.goals h3 { font-size: 13px; font-family: var(--sans); font-weight: 800; letter-spacing: .1em; text-transform: uppercase; color: var(--blue); margin-bottom: 16px; }
.goals ul { margin: 0; padding: 0; list-style: none; }
.goals li { position: relative; padding: 10px 0 10px 34px; font-size: 18px; color: var(--ink-2); border-top: 1px solid var(--line); }
.goals li:first-child { border-top: 0; }
.goals li::before { content: ""; position: absolute; left: 0; top: 17px; width: 18px; height: 18px; border-radius: 6px; background: var(--grad-brand); }
.goals li b { color: #fff; position: absolute; left: 0; top: 13px; width: 18px; text-align: center; font-family: var(--sans); font-size: 11px; font-weight: 800; z-index: 1; }

.part { padding: 64px 0; border-bottom: 1px solid var(--line); }
.part:last-of-type { border-bottom: none; }
.part h2 { font-size: clamp(28px, 3.8vw, 38px); margin: 10px 0 10px; letter-spacing: -.02em; }
.part > .intro { color: var(--muted); font-size: 19px; margin: 0 0 34px; max-width: 720px; }

/* steps */
ol.steps { list-style: none; counter-reset: s; margin: 0; padding: 0; }
ol.steps > li { position: relative; counter-increment: s; padding: 0 0 30px 64px; }
ol.steps > li::before { content: counter(s); position: absolute; left: 0; top: -2px; width: 42px; height: 42px; border-radius: 13px; background: var(--grad-brand); color: #fff; font-family: var(--display); font-weight: 600; font-size: 18px; display: grid; place-items: center; box-shadow: var(--sh-sm); }
ol.steps > li::after { content: ""; position: absolute; left: 20px; top: 48px; bottom: 4px; width: 2px; background: linear-gradient(var(--line-2), transparent); }
ol.steps > li:last-child::after { display: none; }
.step-t { display: block; font-family: var(--display); font-weight: 600; font-size: 20px; color: var(--ink); margin-bottom: 5px; }
.step-d { color: var(--ink-2); font-size: 17px; line-height: 1.6; }

code { font-family: var(--mono); background: var(--bg-tint); border: 1px solid var(--line-2); padding: 2px 7px; border-radius: 7px; font-size: .85em; color: var(--blue); }
pre { background: #0c1b33; color: #e6f2ff; border-radius: 14px; padding: 18px 20px; overflow-x: auto; font-family: var(--mono); font-size: 14px; line-height: 1.6; box-shadow: var(--sh-sm); }
pre code { background: none; border: 0; color: inherit; padding: 0; }

.callout { display: flex; gap: 14px; align-items: flex-start; background: linear-gradient(135deg, #eff6ff, #ecfeff); border: 1px solid var(--line-2); border-radius: var(--r); padding: 20px 24px; margin: 24px 0; font-size: 17px; color: var(--ink-2); }
.callout svg { flex: 0 0 auto; width: 24px; height: 24px; color: var(--sky); margin-top: 1px; }
.callout strong { font-family: var(--display); font-weight: 600; color: var(--ink); }

.shot { margin: 22px 0 0; border: 2px dashed var(--line-2); border-radius: var(--r); background: var(--bg-tint); color: var(--muted); min-height: 134px; display: grid; place-items: center; text-align: center; font-family: var(--sans); font-weight: 600; font-size: 14px; padding: 24px; }

.checklist { background: linear-gradient(135deg, #eef6ff, #ecfdff); border: 1px solid var(--line-2); border-radius: var(--r-lg); padding: 36px 38px; }
.checklist h3 { font-size: 23px; margin-bottom: 18px; }
.checklist ul { list-style: none; margin: 0; padding: 0; }
.checklist li { position: relative; font-size: 17.5px; color: var(--ink-2); padding: 10px 0 10px 38px; }
.checklist li svg { position: absolute; left: 0; top: 12px; width: 24px; height: 24px; color: #fff; background: var(--grad-brand); border-radius: 7px; padding: 4px; }
.lesson-foot { display: flex; justify-content: space-between; gap: 16px; padding: 44px 0; flex-wrap: wrap; }

/* ===================== Contact ===================== */
.contact-hero { padding: 96px 0 90px; text-align: center; position: relative; overflow: hidden; }
.contact-hero::before { content: ""; position: absolute; inset: 0; z-index: -1; background: radial-gradient(50% 60% at 50% 0%, rgba(59,130,246,.18), transparent 70%), radial-gradient(40% 50% at 80% 60%, rgba(6,182,212,.16), transparent 70%), #fff; }
.contact-hero h1 { font-size: clamp(40px, 6vw, 60px); margin-bottom: 16px; letter-spacing: -.02em; }
.contact-hero .lead { font-size: 20px; color: var(--ink-2); max-width: 540px; margin: 0 auto; line-height: 1.6; }
.contact-card { max-width: 520px; margin: 44px auto 0; background: #fff; border: 1px solid var(--line-2); border-radius: var(--r-lg); padding: 46px 40px; box-shadow: var(--sh); text-align: center; }
.contact-card .mono-badge { margin: 0 auto 24px; width: 90px; height: 90px; font-size: 34px; }
.contact-card .name { font-family: var(--display); font-size: 27px; font-weight: 600; color: var(--ink); margin-bottom: 6px; }
.contact-card .role { color: var(--muted); font-size: 16px; margin-bottom: 28px; }
.contact-mail { display: inline-flex; align-items: center; gap: 9px; font-family: var(--mono); font-size: 15.5px; color: var(--ink); background: var(--bg-tint); border: 1px solid var(--line-2); padding: 12px 18px; border-radius: 12px; text-decoration: none; margin-bottom: 28px; }
.contact-mail:hover { border-color: var(--blue); }
.contact-mail svg { width: 16px; height: 16px; color: var(--sky); }

/* ===================== Footer ===================== */
.site-footer { border-top: 1px solid var(--line); padding: 44px 0; color: var(--muted); font-size: 14px; }
.site-footer .wrap { display: flex; justify-content: space-between; gap: 14px; flex-wrap: wrap; align-items: center; }
.site-footer .brand { font-size: 16px; }
.site-footer a { color: var(--blue); text-decoration: none; }
.site-footer a:hover { text-decoration: underline; }

/* ===================== Responsive ===================== */
@media (max-width: 900px) {
  .hero-grid { grid-template-columns: 1fr; gap: 44px; }
  .hero { padding: 64px 0 76px; }
  .window { transform: none; }
  .cols-3 { grid-template-columns: 1fr; }
  section.block { padding: 74px 0; }
}
@media (max-width: 560px) {
  body { font-size: 18px; }
  .wrap { padding: 0 20px; }
  .nav { gap: 8px; padding: 12px 18px; }
  .nav-right a:not(.cta) { display: none; }
  .about p { font-size: 18px; }
  ol.steps > li { padding-left: 56px; }
  .contact-card { padding: 36px 24px; }
  .modes { grid-template-columns: 1fr; }
}

/* ===================== Lesson 2: mode cards + comparison ===================== */
.modes { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; margin-top: 8px; }
.mode { background: #fff; border: 1px solid var(--line-2); border-radius: var(--r-lg); overflow: hidden; box-shadow: var(--sh-sm); display: flex; flex-direction: column; }
.mode-head { padding: 26px 28px; color: #fff; }
.mode.is-nonagent .mode-head { background: var(--grad-sky); }
.mode.is-agent .mode-head { background: var(--grad-blue); }
.mode-head .lbl { font-family: var(--sans); font-weight: 800; font-size: 12px; letter-spacing: .1em; text-transform: uppercase; opacity: .92; }
.mode-head h3 { color: #fff; font-size: 25px; margin: 7px 0 8px; }
.mode-head p { margin: 0; font-size: 14.5px; opacity: .96; line-height: 1.5; }
.mode-body { padding: 26px 28px; flex: 1; }
.mode-body h4 { font-family: var(--sans); font-weight: 800; font-size: 12px; letter-spacing: .08em; text-transform: uppercase; color: var(--blue); margin: 0 0 8px; }
.mode-body h4:not(:first-child) { margin-top: 22px; }
.mode-body p { margin: 0; font-size: 16px; color: var(--ink-2); line-height: 1.6; }
.plist { list-style: none; margin: 8px 0 0; padding: 0; }
.plist li { position: relative; padding: 5px 0 5px 28px; font-size: 15.5px; color: var(--ink-2); line-height: 1.5; }
.plist li::before { position: absolute; left: 2px; top: 5px; font-weight: 800; font-family: var(--sans); }
.plist li.y::before { content: "✓"; color: var(--teal); }
.plist li.n::before { content: "–"; color: var(--muted); }

.cmp-wrap { overflow-x: auto; margin-top: 8px; border: 1px solid var(--line-2); border-radius: var(--r); -webkit-overflow-scrolling: touch; }
.cmp { width: 100%; border-collapse: collapse; font-size: 15.5px; min-width: 580px; }
.cmp th, .cmp td { text-align: left; padding: 14px 18px; border-bottom: 1px solid var(--line); vertical-align: top; }
.cmp thead th { background: var(--bg-tint); font-family: var(--sans); font-weight: 800; color: var(--ink); font-size: 14px; }
.cmp thead th:first-child { background: #fff; }
.cmp tbody th { font-weight: 700; color: var(--ink); font-family: var(--sans); width: 30%; }
.cmp tbody td { color: var(--ink-2); }
.cmp tr:last-child th, .cmp tr:last-child td { border-bottom: 0; }
.cmp .agentcol { background: rgba(37,99,235,.04); }

/* ===================== Course nav (inline table of contents) ===================== */
.course-nav { display: flex; flex-wrap: wrap; gap: 8px; margin: 0 0 24px; }
.course-nav a { display: inline-flex; align-items: center; gap: 9px; font-family: var(--sans); font-weight: 600; font-size: 14px; color: var(--ink-2); background: #fff; border: 1px solid var(--line-2); border-radius: 999px; padding: 7px 16px 7px 8px; text-decoration: none; transition: .15s; }
.course-nav a .n { width: 22px; height: 22px; border-radius: 50%; background: var(--bg-tint); color: var(--blue); display: grid; place-items: center; font-family: var(--mono); font-size: 12px; font-weight: 600; flex: 0 0 auto; }
.course-nav a:hover { border-color: var(--blue); color: var(--ink); }
.course-nav a.active { background: var(--grad-brand); color: #fff; border-color: transparent; box-shadow: var(--sh-sm); }
.course-nav a.active .n { background: rgba(255,255,255,.25); color: #fff; }

/* lessons index (table of contents page) */
.toc-list { display: grid; gap: 20px; }
.toc-more { margin-top: 30px; color: var(--muted); font-size: 16px; display: inline-flex; align-items: center; gap: 8px; }
.toc-more .dot { width: 8px; height: 8px; border-radius: 50%; background: var(--grad-brand); }

/* icon tag variant of the lesson-card number tile (teaching-resources) */
.lesson-tag.icon { width: 78px; height: 78px; padding: 0; display: grid; place-items: center; }
.lesson-tag.icon svg { width: 34px; height: 34px; }
.cols-2 { grid-template-columns: 1fr 1fr; }
@media (max-width: 760px){ .cols-2 { grid-template-columns: 1fr; } }
/* track heading on the contents page */
.track-head { display: flex; align-items: center; gap: 14px; margin: 0 0 26px; }
.track-head .num { width: 34px; height: 34px; border-radius: 10px; background: var(--grad-brand); color: #fff; display: grid; place-items: center; font-family: var(--display); font-weight: 600; font-size: 16px; flex: 0 0 auto; }
.track-head h2 { font-size: clamp(26px, 3.4vw, 34px); margin: 0; }
.track-head .sub { color: var(--muted); font-size: 16px; margin-left: 2px; }
.prompt-label { font-family: var(--sans); font-weight: 800; font-size: 12px; letter-spacing: .08em; text-transform: uppercase; color: var(--blue); margin: 26px 0 8px; }
