/* Mindmatrix learning course
   Design rules held here on purpose:
   - accent is MM orange #ff671d, never yellow or gold
   - no text-transform: uppercase anywhere
   - no coloured bands, bars or borders inside cards
   - one accent per surface; colour marks meaning, not decoration */

:root {
  --blue:        #346fe2;
  --blue-dark:   #2456c0;
  --blue-soft:   #e7eefc;
  --accent:      #ff671d;
  --accent-soft: #fff1e9;
  --navy:        #0a083b;
  --navy-2:      #082471;

  --ink:      #14161c;
  --ink-2:    #3d4350;
  --ink-3:    #6b7280;
  --ink-4:    #9aa1ad;

  --paper:    #ffffff;
  --canvas:   #f6f7f9;
  --line:     #e4e7ec;
  --line-2:   #eef0f4;

  --ok:       #12805c;
  --ok-soft:  #e7f5f0;
  --bad:      #b3261e;
  --bad-soft: #fdecea;

  --font-ui:      'IBM Plex Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-display: 'Poppins', 'IBM Plex Sans', -apple-system, 'Segoe UI', sans-serif;

  --topbar-h: 60px;
  --side-w:   304px;
  --radius:   12px;
  --shadow:   0 1px 2px rgba(16,24,40,.05), 0 1px 3px rgba(16,24,40,.06);
  --shadow-2: 0 4px 14px rgba(16,24,40,.09), 0 1px 3px rgba(16,24,40,.05);
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
html { -webkit-text-size-adjust: 100%; scroll-padding-top: calc(var(--topbar-h) + 16px); }

/* An author `display` rule outranks the user agent's [hidden] rule, so .btn's
   inline-flex was showing buttons the engine had hidden. Restore the intent. */
[hidden] { display: none !important; }

body {
  font-family: var(--font-ui);
  font-size: 16px;
  line-height: 1.62;
  color: var(--ink);
  background: var(--canvas);
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4 { font-family: var(--font-display); line-height: 1.25; margin: 0; font-weight: 600; letter-spacing: -.012em; }
p { margin: 0 0 1em; }
a { color: var(--blue); text-decoration-color: rgba(52,111,226,.35); text-underline-offset: 2px; }
a:hover { text-decoration-color: currentColor; }
b, strong { font-weight: 600; color: var(--ink); }
svg { stroke: currentColor; stroke-width: 1.9; stroke-linecap: round; stroke-linejoin: round; fill: none; }

.skip {
  position: absolute; left: -9999px; top: 0; z-index: 100;
  background: var(--navy); color: #fff; padding: 10px 16px; border-radius: 0 0 8px 0;
}
.skip:focus { left: 0; }

:focus-visible { outline: 2px solid var(--blue); outline-offset: 2px; border-radius: 4px; }

/* ---------------------------------------------------------------- top bar */

.topbar {
  position: fixed; inset: 0 0 auto 0; height: var(--topbar-h); z-index: 40;
  display: flex; align-items: center; gap: 14px;
  padding: 0 18px 0 14px;
  background: rgba(255,255,255,.9);
  backdrop-filter: saturate(1.6) blur(10px);
  border-bottom: 1px solid var(--line);
}

.brand { display: flex; align-items: center; gap: 10px; text-decoration: none; color: inherit; min-width: 0; }
.brand-mark {
  width: 34px; height: 34px; flex: none; border-radius: 9px;
  background: var(--navy); color: #fff;
  display: grid; place-items: center;
}
.brand-mark svg { width: 21px; height: 21px; stroke-width: 2.2; }
.brand-text { display: flex; flex-direction: column; line-height: 1.15; min-width: 0; }
.brand-text b { font-family: var(--font-display); font-size: 15.5px; font-weight: 600; letter-spacing: -.01em; }
.brand-text i { font-style: normal; font-size: 11.5px; color: var(--ink-3); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }

.topbar-right { margin-left: auto; display: flex; align-items: center; gap: 14px; }

.progress-pill { position: relative; width: 38px; height: 38px; display: grid; place-items: center; }
.progress-pill .ring { width: 38px; height: 38px; transform: rotate(-90deg); position: absolute; inset: 0; }
.ring circle { fill: none; stroke-width: 3.2; }
.ring-bg { stroke: var(--line); }
.ring-fg {
  stroke: var(--blue); stroke-linecap: round;
  stroke-dasharray: 97.4; stroke-dashoffset: 97.4;
  transition: stroke-dashoffset .5s cubic-bezier(.4,0,.2,1);
}
.progress-pill.done .ring-fg { stroke: var(--ok); }
.progress-pill .pct { font-size: 10.5px; font-weight: 600; color: var(--ink-2); font-feature-settings: 'tnum'; }

.lang-switch { display: flex; background: var(--canvas); border: 1px solid var(--line); border-radius: 9px; padding: 3px; gap: 2px; }
.lang-switch button {
  font: inherit; font-size: 13px; font-weight: 500; color: var(--ink-3);
  background: none; border: 0; border-radius: 6px; padding: 5px 11px; cursor: pointer;
  transition: background .15s, color .15s;
}
.lang-switch button:hover { color: var(--ink); }
.lang-switch button.on { background: var(--paper); color: var(--ink); box-shadow: var(--shadow); }

.icon-btn {
  width: 38px; height: 38px; flex: none; display: none; place-items: center;
  background: none; border: 1px solid var(--line); border-radius: 9px; color: var(--ink-2); cursor: pointer;
}
.icon-btn svg { width: 19px; height: 19px; }
.icon-btn:hover { background: var(--canvas); }

/* ---------------------------------------------------------------- layout */

.shell { display: flex; padding-top: var(--topbar-h); min-height: 100vh; }

.sidebar {
  position: fixed; top: var(--topbar-h); bottom: 0; left: 0; width: var(--side-w); z-index: 30;
  background: var(--paper); border-right: 1px solid var(--line);
  display: flex; flex-direction: column; overflow: hidden;
}
.sidebar-head { padding: 18px 20px 12px; border-bottom: 1px solid var(--line-2); }
.sh-title { font-family: var(--font-display); font-size: 13px; font-weight: 600; color: var(--ink-2); letter-spacing: .01em; }
.sh-meta { font-size: 12px; color: var(--ink-3); margin-top: 3px; }

.track-list { flex: 1; overflow-y: auto; padding: 10px 12px 20px; overscroll-behavior: contain; }

.track { margin-bottom: 4px; }
.track-btn {
  width: 100%; display: flex; align-items: center; gap: 10px; text-align: left;
  font: inherit; background: none; border: 0; cursor: pointer;
  padding: 9px 10px; border-radius: 9px; color: var(--ink);
}
.track-btn:hover { background: var(--canvas); }
.track-ico {
  width: 26px; height: 26px; flex: none; border-radius: 7px; display: grid; place-items: center;
  background: var(--blue-soft); color: var(--blue-dark);
}
.track-ico svg { width: 15px; height: 15px; }
.track.complete .track-ico { background: var(--ok-soft); color: var(--ok); }
.track-name { font-family: var(--font-display); font-size: 13.5px; font-weight: 500; flex: 1; min-width: 0; line-height: 1.3; }
.track-count { font-size: 11.5px; color: var(--ink-4); font-feature-settings: 'tnum'; }
.track-chev { width: 15px; height: 15px; color: var(--ink-4); transition: transform .18s; }
.track.open .track-chev { transform: rotate(90deg); }

.lesson-list { display: none; padding: 2px 0 8px 18px; margin-left: 12px; border-left: 1px solid var(--line-2); }
.track.open .lesson-list { display: block; }

.lesson-btn {
  width: 100%; display: flex; align-items: flex-start; gap: 9px; text-align: left;
  font: inherit; font-size: 13px; line-height: 1.4; background: none; border: 0; cursor: pointer;
  padding: 7px 10px; border-radius: 8px; color: var(--ink-2);
}
.lesson-btn:hover { background: var(--canvas); color: var(--ink); }
.lesson-btn.active { background: var(--blue-soft); color: var(--blue-dark); font-weight: 500; }
.lesson-tick {
  width: 15px; height: 15px; flex: none; margin-top: 3px; border-radius: 50%;
  border: 1.5px solid var(--line); display: grid; place-items: center; color: transparent;
}
.lesson-tick svg { width: 9px; height: 9px; stroke-width: 3; }
.lesson-btn.done .lesson-tick { background: var(--ok); border-color: var(--ok); color: #fff; }

.sidebar-foot { padding: 12px 16px 16px; border-top: 1px solid var(--line-2); }
.ghost-btn {
  font: inherit; font-size: 12.5px; color: var(--ink-3); background: none;
  border: 1px solid var(--line); border-radius: 8px; padding: 6px 11px; cursor: pointer;
}
.ghost-btn:hover { color: var(--bad); border-color: #f0c8c4; background: var(--bad-soft); }
.sidebar-note { font-size: 11.5px; color: var(--ink-4); margin: 9px 0 0; line-height: 1.45; }

.scrim { position: fixed; inset: var(--topbar-h) 0 0; background: rgba(10,8,59,.32); z-index: 29; }

.main { flex: 1; min-width: 0; margin-left: var(--side-w); }
.main:focus { outline: none; }
.page { max-width: 780px; margin: 0 auto; padding: 40px 32px 96px; }

/* ---------------------------------------------------------------- home */

.hero { margin-bottom: 34px; }
.hero .eyebrow { font-size: 12.5px; font-weight: 600; color: var(--accent); margin-bottom: 10px; letter-spacing: .01em; }
.hero h1 { font-size: 34px; font-weight: 600; letter-spacing: -.022em; margin-bottom: 12px; }
.hero .lede { font-size: 17.5px; line-height: 1.6; color: var(--ink-2); margin: 0; }

.hero-stats { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 24px; }
.hero-stat {
  background: var(--paper); border: 1px solid var(--line); border-radius: 10px;
  padding: 11px 15px; min-width: 108px;
}
.hero-stat b { display: block; font-family: var(--font-display); font-size: 21px; font-weight: 600; line-height: 1.15; }
.hero-stat span { font-size: 12px; color: var(--ink-3); }

.resume-card {
  display: flex; align-items: center; gap: 15px;
  background: var(--paper); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 16px 18px; margin: 26px 0 34px; box-shadow: var(--shadow);
}
.resume-card .rc-ico { width: 38px; height: 38px; flex: none; border-radius: 10px; background: var(--accent-soft); color: var(--accent); display: grid; place-items: center; }
.resume-card .rc-ico svg { width: 19px; height: 19px; }
.resume-card .rc-txt { flex: 1; min-width: 0; }
.resume-card .rc-txt small { display: block; font-size: 11.5px; color: var(--ink-3); }
.resume-card .rc-txt b { font-family: var(--font-display); font-size: 15px; font-weight: 500; }

.track-cards { display: grid; gap: 12px; }
.track-card {
  display: flex; align-items: flex-start; gap: 15px; width: 100%; text-align: left;
  font: inherit; cursor: pointer;
  background: var(--paper); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 17px 19px; box-shadow: var(--shadow); transition: box-shadow .16s, border-color .16s, transform .16s;
}
.track-card:hover { box-shadow: var(--shadow-2); border-color: #d3d8e0; transform: translateY(-1px); }
.tc-ico { width: 40px; height: 40px; flex: none; border-radius: 11px; background: var(--blue-soft); color: var(--blue-dark); display: grid; place-items: center; }
.tc-ico svg { width: 21px; height: 21px; }
.track-card.complete .tc-ico { background: var(--ok-soft); color: var(--ok); }
.tc-body { flex: 1; min-width: 0; }
.tc-body h3 { font-size: 16px; font-weight: 600; margin-bottom: 4px; }
.tc-body p { font-size: 14px; color: var(--ink-2); margin: 0 0 10px; line-height: 1.55; }
.tc-meter { display: flex; align-items: center; gap: 9px; }
.meter { flex: 1; height: 5px; background: var(--line-2); border-radius: 99px; overflow: hidden; max-width: 190px; }
.meter i { display: block; height: 100%; background: var(--blue); border-radius: 99px; transition: width .45s cubic-bezier(.4,0,.2,1); }
.track-card.complete .meter i { background: var(--ok); }
.tc-meter span { font-size: 11.5px; color: var(--ink-3); font-feature-settings: 'tnum'; }

/* ---------------------------------------------------------------- lesson */

.lesson-head { margin-bottom: 30px; padding-bottom: 22px; border-bottom: 1px solid var(--line); }
.crumb { display: flex; align-items: center; gap: 7px; font-size: 12.5px; color: var(--ink-3); margin-bottom: 11px; }
.crumb svg { width: 13px; height: 13px; }
.crumb b { font-weight: 500; color: var(--ink-2); }
.lesson-head h1 { font-size: 29px; font-weight: 600; letter-spacing: -.02em; margin-bottom: 10px; }
.lesson-head .sub { font-size: 16.5px; color: var(--ink-2); line-height: 1.58; margin: 0; }
.lesson-meta { display: flex; align-items: center; gap: 14px; font-size: 12.5px; color: var(--ink-3); margin-top: 13px; }
.lesson-meta span { display: inline-flex; align-items: center; gap: 5px; }
.lesson-meta svg { width: 13.5px; height: 13.5px; }

.body h2 { font-size: 21px; font-weight: 600; margin: 40px 0 13px; letter-spacing: -.015em; }
.body h3 { font-size: 16.5px; font-weight: 600; margin: 28px 0 9px; }
.body > *:first-child { margin-top: 0; }
.body p { font-size: 16px; line-height: 1.68; color: var(--ink-2); }
.body p strong, .body li strong { color: var(--ink); }
.body ul, .body ol { padding-left: 22px; margin: 0 0 1.1em; }
.body li { margin-bottom: .5em; line-height: 1.66; color: var(--ink-2); }
.body li::marker { color: var(--ink-4); }
.body ul.plain { list-style: none; padding-left: 0; }
.body ul.plain li { display: flex; gap: 10px; align-items: flex-start; }
.body ul.plain li::before {
  content: ''; width: 5px; height: 5px; border-radius: 50%; background: var(--accent);
  flex: none; margin-top: 10px;
}

/* callouts: a left rule, never a filled colour band */
.callout {
  border: 1px solid var(--line); border-left: 3px solid var(--blue);
  background: var(--paper); border-radius: 10px; padding: 15px 18px; margin: 22px 0;
}
.callout .co-title {
  font-family: var(--font-display); font-size: 13px; font-weight: 600; color: var(--blue-dark);
  display: flex; align-items: center; gap: 7px; margin-bottom: 6px;
}
.callout .co-title svg { width: 15px; height: 15px; }
.callout p:last-child, .callout ul:last-child { margin-bottom: 0; }
.callout p { font-size: 15px; }
.callout.key   { border-left-color: var(--accent); }
.callout.key   .co-title { color: #c2410c; }
.callout.warn  { border-left-color: #d97706; }
.callout.warn  .co-title { color: #b45309; }
.callout.quote { border-left-color: var(--ink-4); background: var(--canvas); }
.callout.quote .co-title { color: var(--ink-3); }
.callout.quote p { font-style: italic; color: var(--ink-2); }
.callout.quote cite { display: block; font-style: normal; font-size: 12.5px; color: var(--ink-3); margin-top: 8px; }

/* comparison pair */
.split { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin: 22px 0; }
.split-card { background: var(--paper); border: 1px solid var(--line); border-radius: 10px; padding: 16px 18px; }
.split-card h4 { font-size: 14.5px; font-weight: 600; margin-bottom: 8px; display: flex; align-items: center; gap: 7px; }
.split-card h4 svg { width: 15px; height: 15px; color: var(--blue); }
.split-card p, .split-card li { font-size: 14.5px; line-height: 1.6; color: var(--ink-2); }
.split-card p:last-child, .split-card ul:last-child { margin-bottom: 0; }
.split-card ul { padding-left: 19px; margin: 0; }

/* table */
.table-wrap { overflow-x: auto; margin: 22px 0; border: 1px solid var(--line); border-radius: 10px; background: var(--paper); }
table { border-collapse: collapse; width: 100%; font-size: 14.5px; min-width: 460px; }
th, td { text-align: left; padding: 11px 15px; border-bottom: 1px solid var(--line-2); vertical-align: top; line-height: 1.5; }
th { font-family: var(--font-display); font-weight: 600; font-size: 13px; color: var(--ink-2); background: var(--canvas); }
tr:last-child td { border-bottom: 0; }
td { color: var(--ink-2); }

/* sequence */
.flow { margin: 24px 0; display: grid; gap: 2px; }
.flow-step { display: flex; gap: 15px; }
.flow-rail { display: flex; flex-direction: column; align-items: center; flex: none; width: 26px; }
.flow-dot {
  width: 26px; height: 26px; border-radius: 50%; background: var(--paper); border: 1.5px solid var(--line);
  display: grid; place-items: center; font-family: var(--font-display); font-size: 12px; font-weight: 600; color: var(--ink-2);
}
.flow-line { flex: 1; width: 1.5px; background: var(--line); min-height: 12px; }
.flow-step:last-child .flow-line { display: none; }
.flow-body { padding-bottom: 18px; flex: 1; min-width: 0; }
.flow-step:last-child .flow-body { padding-bottom: 0; }
.flow-body b { display: block; font-family: var(--font-display); font-size: 14.5px; font-weight: 600; margin-bottom: 3px; }
.flow-body p { font-size: 14.5px; margin: 0; line-height: 1.6; }

/* glossary terms */
.terms { display: grid; gap: 9px; margin: 22px 0; }
.term { background: var(--paper); border: 1px solid var(--line); border-radius: 10px; padding: 13px 16px; }
.term-head { display: flex; align-items: baseline; gap: 9px; flex-wrap: wrap; margin-bottom: 4px; }
.term-en { font-family: var(--font-display); font-size: 14.5px; font-weight: 600; }
.term-es { font-size: 13px; color: var(--accent); font-weight: 500; }
.term p { font-size: 14.5px; margin: 0; line-height: 1.6; }

/* signal reading: what they say / what it means */
.signals { display: grid; gap: 10px; margin: 22px 0; }
.signal { background: var(--paper); border: 1px solid var(--line); border-radius: 10px; overflow: hidden; }
.signal-say { padding: 13px 16px 11px; border-bottom: 1px dashed var(--line); }
.signal-say q { font-size: 15px; color: var(--ink); font-style: italic; quotes: '"' '"'; }
.signal-read { padding: 12px 16px; display: grid; gap: 9px; }
.signal-row { display: flex; gap: 10px; align-items: flex-start; font-size: 14px; line-height: 1.55; color: var(--ink-2); }
.signal-row .sr-ico { width: 17px; height: 17px; flex: none; margin-top: 2px; color: var(--ink-4); }
.signal-row .sr-ico svg { width: 17px; height: 17px; }
.signal-row b { font-weight: 600; color: var(--ink); }
.signal-row.ask { color: var(--blue-dark); }
.signal-row.ask .sr-ico { color: var(--blue); }

/* ---------------------------------------------------------------- quiz */

.quiz {
  background: var(--paper); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 22px 24px; margin: 34px 0; box-shadow: var(--shadow);
  scroll-margin-top: calc(var(--topbar-h) + 20px);
}
.quiz-head { display: flex; align-items: center; gap: 10px; margin-bottom: 4px; }
.quiz-head .qh-ico { width: 30px; height: 30px; border-radius: 8px; background: var(--accent-soft); color: var(--accent); display: grid; place-items: center; flex: none; }
.quiz-head .qh-ico svg { width: 16px; height: 16px; }
.quiz-head h3 { font-size: 16px; font-weight: 600; }
.quiz-intro { font-size: 14px; color: var(--ink-3); margin: 0 0 20px; padding-left: 40px; }

.q { padding: 18px 0; border-top: 1px solid var(--line-2); }
.q:first-of-type { border-top: 0; padding-top: 4px; }
.q-stem { font-size: 15.5px; font-weight: 500; color: var(--ink); margin-bottom: 4px; line-height: 1.55; }
.q-hint { font-size: 12.5px; color: var(--ink-3); margin: 0 0 12px; }

.opts { display: grid; gap: 7px; }
.opt {
  display: flex; align-items: flex-start; gap: 11px; width: 100%; text-align: left;
  font: inherit; font-size: 14.8px; line-height: 1.55; cursor: pointer; color: var(--ink-2);
  background: var(--paper); border: 1px solid var(--line); border-radius: 9px; padding: 11px 14px;
  transition: border-color .14s, background .14s;
}
.opt:hover:not(:disabled) { border-color: #c9d2e2; background: #fafbfd; }
.opt:disabled { cursor: default; }
.opt-box {
  width: 19px; height: 19px; flex: none; margin-top: 1px; border-radius: 5px;
  border: 1.5px solid var(--line); display: grid; place-items: center; color: transparent; background: var(--paper);
}
.opt.radio .opt-box { border-radius: 50%; }
.opt-box svg { width: 11px; height: 11px; stroke-width: 3; }
.opt.picked .opt-box { border-color: var(--blue); background: var(--blue); color: #fff; }
.opt.picked { border-color: var(--blue); background: var(--blue-soft); color: var(--ink); }
.opt.right { border-color: var(--ok); background: var(--ok-soft); color: var(--ink); }
.opt.right .opt-box { border-color: var(--ok); background: var(--ok); color: #fff; }
.opt.wrong { border-color: #e8b4af; background: var(--bad-soft); color: var(--ink); }
.opt.wrong .opt-box { border-color: var(--bad); background: var(--bad); color: #fff; }
.opt.missed { border-color: var(--ok); border-style: dashed; }

/* match pairs */
.match { display: grid; gap: 8px; }
.match-row { display: grid; grid-template-columns: 1fr 200px; gap: 10px; align-items: center; }
.match-left {
  font-size: 14.5px; line-height: 1.5; color: var(--ink-2);
  background: var(--paper); border: 1px solid var(--line); border-radius: 9px; padding: 11px 14px;
}
.match-row select {
  font: inherit; font-size: 14px; color: var(--ink); width: 100%;
  border: 1px solid var(--line); border-radius: 9px; padding: 10px 12px; background: var(--paper); cursor: pointer;
}
.match-row.right select { border-color: var(--ok); background: var(--ok-soft); }
.match-row.wrong select { border-color: #e8b4af; background: var(--bad-soft); }

/* order the steps */
.order { display: grid; gap: 7px; }
.order-item {
  display: flex; align-items: center; gap: 11px;
  background: var(--paper); border: 1px solid var(--line); border-radius: 9px; padding: 10px 12px;
  font-size: 14.5px; line-height: 1.5; color: var(--ink-2);
}
.order-item .oi-num {
  width: 24px; height: 24px; flex: none; border-radius: 6px; background: var(--canvas);
  display: grid; place-items: center; font-family: var(--font-display); font-size: 12px; font-weight: 600; color: var(--ink-2);
}
.order-item .oi-txt { flex: 1; min-width: 0; }
.order-item .oi-moves { display: flex; gap: 3px; flex: none; }
.order-item button {
  width: 27px; height: 27px; display: grid; place-items: center; cursor: pointer;
  background: none; border: 1px solid var(--line); border-radius: 7px; color: var(--ink-3);
}
.order-item button:hover:not(:disabled) { background: var(--canvas); color: var(--ink); }
.order-item button:disabled { opacity: .3; cursor: default; }
.order-item button svg { width: 13px; height: 13px; }
.order-item.right { border-color: var(--ok); background: var(--ok-soft); }
.order-item.right .oi-num { background: var(--ok); color: #fff; }
.order-item.wrong { border-color: #e8b4af; background: var(--bad-soft); }
.order-item.wrong .oi-num { background: var(--bad); color: #fff; }

.why {
  margin-top: 11px; font-size: 14px; line-height: 1.6; color: var(--ink-2);
  border-left: 2px solid var(--line); padding: 2px 0 2px 13px;
}
.why b { color: var(--ink); }

.quiz-foot { display: flex; align-items: center; gap: 14px; flex-wrap: wrap; margin-top: 22px; padding-top: 18px; border-top: 1px solid var(--line-2); }
.quiz-score { font-size: 14.5px; color: var(--ink-2); }
.quiz-score b { font-family: var(--font-display); font-weight: 600; color: var(--ink); }
.quiz-score.pass b { color: var(--ok); }

/* ---------------------------------------------------------------- buttons */

.btn {
  font: inherit; font-family: var(--font-display); font-size: 14.5px; font-weight: 500;
  display: inline-flex; align-items: center; gap: 8px; cursor: pointer;
  border: 1px solid transparent; border-radius: 9px; padding: 10px 18px;
  background: var(--blue); color: #fff; transition: background .15s, box-shadow .15s;
}
.btn:hover { background: var(--blue-dark); }
.btn:disabled { opacity: .45; cursor: default; }
.btn svg { width: 16px; height: 16px; }
.btn.secondary { background: var(--paper); color: var(--ink-2); border-color: var(--line); }
.btn.secondary:hover { background: var(--canvas); color: var(--ink); }
.btn.accent { background: var(--accent); }
.btn.accent:hover { background: #e2540d; }
.btn.done-state { background: var(--ok-soft); color: var(--ok); border-color: #bfe3d6; }
.btn.done-state:hover { background: #d9f0e7; }

.lesson-nav { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; margin-top: 44px; padding-top: 26px; border-top: 1px solid var(--line); }
.lesson-nav .spacer { flex: 1; }

/* ---------------------------------------------------------------- exam */

.exam-intro { background: var(--paper); border: 1px solid var(--line); border-radius: var(--radius); padding: 24px 26px; box-shadow: var(--shadow); margin-bottom: 28px; }
.exam-intro h2 { margin-top: 0; }
.exam-rules { display: grid; gap: 9px; margin: 18px 0 22px; }
.exam-rule { display: flex; gap: 11px; align-items: flex-start; font-size: 14.5px; color: var(--ink-2); line-height: 1.55; }
.exam-rule svg { width: 17px; height: 17px; flex: none; margin-top: 3px; color: var(--blue); }

.result-card { background: var(--paper); border: 1px solid var(--line); border-radius: var(--radius); padding: 30px 28px; text-align: center; box-shadow: var(--shadow); margin-bottom: 26px; }
.result-ring { width: 116px; height: 116px; margin: 0 auto 16px; position: relative; display: grid; place-items: center; }
.result-ring svg { position: absolute; inset: 0; width: 116px; height: 116px; transform: rotate(-90deg); }
.result-ring circle { fill: none; stroke-width: 7; }
.result-ring .rr-bg { stroke: var(--line-2); }
.result-ring .rr-fg { stroke: var(--blue); stroke-linecap: round; stroke-dasharray: 320; transition: stroke-dashoffset .8s cubic-bezier(.4,0,.2,1); }
.result-card.pass .rr-fg { stroke: var(--ok); }
.result-ring b { font-family: var(--font-display); font-size: 29px; font-weight: 600; }
.result-card h2 { font-size: 22px; margin-bottom: 8px; }
.result-card p { font-size: 15.5px; color: var(--ink-2); max-width: 460px; margin: 0 auto 20px; }
.result-actions { display: flex; gap: 10px; justify-content: center; flex-wrap: wrap; }

.cert {
  background: var(--paper); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 38px 34px; text-align: center; box-shadow: var(--shadow-2); margin-bottom: 26px;
}
.cert .cert-mark { width: 46px; height: 46px; border-radius: 12px; background: var(--navy); color: #fff; display: grid; place-items: center; margin: 0 auto 18px; }
.cert .cert-mark svg { width: 25px; height: 25px; }
.cert small { display: block; font-size: 12.5px; color: var(--ink-3); margin-bottom: 8px; }
.cert h2 { font-size: 25px; margin-bottom: 6px; }
.cert .cert-name { font-family: var(--font-display); font-size: 19px; font-weight: 500; color: var(--accent); margin: 14px 0 6px; }
.cert .cert-meta { font-size: 13px; color: var(--ink-3); }

.empty { text-align: center; padding: 60px 20px; color: var(--ink-3); }

/* ---------------------------------------------------------------- responsive */

@media (max-width: 1000px) {
  .icon-btn { display: grid; }
  .sidebar { transform: translateX(-100%); transition: transform .22s cubic-bezier(.4,0,.2,1); box-shadow: var(--shadow-2); }
  .sidebar.open { transform: none; }
  .main { margin-left: 0; }
  .page { padding: 30px 22px 88px; }
}

@media (max-width: 700px) {
  body { font-size: 15.5px; }
  .topbar { padding: 0 12px 0 10px; gap: 10px; }
  .brand-text i { display: none; }
  .topbar-right { gap: 10px; }
  .lang-switch button { padding: 5px 9px; font-size: 12.5px; }
  .hero h1 { font-size: 27px; }
  .hero .lede { font-size: 16px; }
  .lesson-head h1 { font-size: 24px; }
  .body h2 { font-size: 19px; }
  .split { grid-template-columns: 1fr; }
  .match-row { grid-template-columns: 1fr; gap: 6px; }
  .quiz { padding: 18px 16px; margin-left: -4px; margin-right: -4px; }
  .quiz-intro { padding-left: 0; }
  .page { padding: 24px 16px 80px; }
  .result-card, .cert { padding: 26px 18px; }
}

@media print {
  .topbar, .sidebar, .scrim, .lesson-nav, .quiz { display: none; }
  .main { margin-left: 0; }
  .shell { padding-top: 0; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: .01ms !important; transition-duration: .01ms !important; }
}