:root {
  --bg: #faf9f5;
  --bg-side: #f0eee6;
  --ink: #141413;
  --ink-soft: #3d3d3a;
  --line: #e4e1d6;
  --accent: #c96442;
  --callout: #f4efe4;
  --callout-line: #c96442;
  --code-bg: #1f1e1b;
  --code-ink: #f4f1ea;
  --chip: #e7e2d6;
  --max: 42rem;
  --side: 18.5rem;
  --header: 4.25rem;
  --serif: "Source Serif 4", "Iowan Old Style", Palatino, Georgia, serif;
  --sans: "Source Sans 3", "Helvetica Neue", Helvetica, Arial, sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, monospace;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

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

a { color: inherit; }

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.65rem 1.25rem;
  min-height: var(--header);
  padding: 0.7rem 1.5rem;
  background: var(--bg);
  border-bottom: 1px solid var(--line);
  font-family: var(--sans);
}

.wordmark {
  font-weight: 600;
  letter-spacing: 0.14em;
  font-size: 0.92rem;
  text-decoration: none;
}

.header-nav {
  display: flex;
  gap: 1.5rem;
  font-size: 0.95rem;
}

.header-nav a { text-decoration: none; }
.header-nav a:hover { text-decoration: underline; }
.header-nav a[aria-current="page"] {
  font-weight: 700;
  text-decoration: underline;
  text-underline-offset: 0.2em;
}

.layout {
  display: grid;
  grid-template-columns: var(--side) minmax(0, 1fr);
  min-height: calc(100vh - var(--header));
}

.sidebar {
  background: var(--bg-side);
  border-right: 1px solid var(--line);
  padding: 2rem 0 3rem;
  font-family: var(--sans);
}

.sidebar-inner {
  position: sticky;
  top: calc(var(--header) + 1.5rem);
  max-height: calc(100vh - var(--header) - 3rem);
  overflow-y: auto;
  overscroll-behavior: contain;
  scrollbar-width: thin;
  padding: 0 1.25rem 1rem;
}

.course-title {
  margin: 0 0 0.35rem;
  font-family: var(--serif);
  font-size: 1.55rem;
  font-weight: 560;
  line-height: 1.2;
  letter-spacing: -0.02em;
}

.course-kicker {
  display: inline-block;
  margin-bottom: 1.25rem;
  color: var(--ink-soft);
  font-size: 0.92rem;
  text-decoration: underline;
  text-underline-offset: 0.18em;
}

.nav-group {
  margin: 1.15rem 0 0.2rem;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.07em;
  text-transform: uppercase;
  color: var(--ink-soft);
}

.nav-group:first-of-type { margin-top: 0.15rem; }

.lesson-nav { list-style: none; margin: 0; padding: 0; }

.lesson-nav a {
  display: grid;
  grid-template-columns: 1.25rem 1fr;
  gap: 0.55rem;
  align-items: start;
  padding: 0.7rem 0.15rem;
  border-top: 1px solid var(--line);
  text-decoration: none;
  font-size: 0.95rem;
  line-height: 1.35;
}

.lesson-nav li:last-child a { border-bottom: 1px solid var(--line); }

.lesson-nav a[aria-current="page"] { font-weight: 650; }

.mark {
  width: 0.85rem;
  height: 0.85rem;
  margin-top: 0.15rem;
  border: 1.5px solid var(--ink);
  border-radius: 50%;
}

.lesson-nav a[aria-current="page"] .mark {
  background: var(--ink);
  box-shadow: inset 0 0 0 2px var(--bg-side);
}

.lesson {
  padding: 2.5rem 3rem 5rem;
  max-width: 52rem;
}

.lesson h1 {
  margin: 0 0 0.4rem;
  font-size: clamp(2.4rem, 4vw, 3.15rem);
  font-weight: 500;
  letter-spacing: -0.03em;
  line-height: 1.08;
}

.rule {
  height: 1px;
  margin: 1.1rem 0 1.6rem;
  background: var(--line);
}

.kicker {
  margin: 0 0 0.25rem;
  font-family: var(--sans);
  font-size: 1.15rem;
  font-weight: 600;
}

.estimate {
  margin: 0 0 0.8rem;
  font-style: italic;
  color: var(--ink-soft);
}

.objectives {
  margin: 0 0 2rem;
  padding: 0;
}

.objectives li {
  margin: 0.35rem 0;
  font-style: italic;
}

h2 {
  margin: 2.2rem 0 0.7rem;
  font-size: 1.85rem;
  font-weight: 520;
  letter-spacing: -0.02em;
  line-height: 1.2;
}

h3 {
  margin: 1.6rem 0 0.45rem;
  font-size: 1.25rem;
  font-weight: 600;
}

p { margin: 0.7rem 0; }

ul, ol { margin: 0.6rem 0 1rem; padding-left: 1.25rem; }
li { margin: 0.28rem 0; }

.video {
  margin: 1rem 0 1.4rem;
  aspect-ratio: 16 / 9;
  background: #111;
  border-radius: 8px;
  overflow: hidden;
}

.video iframe {
  width: 100%;
  height: 100%;
  border: 0;
}

.video-link {
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  gap: 0.2rem;
  min-height: 11rem;
  margin: 1rem 0 1.4rem;
  padding: 1.1rem 1.2rem;
  background:
    linear-gradient(160deg, rgba(20, 20, 19, 0.2), rgba(20, 20, 19, 0.72)),
    #1f1e1b;
  color: #faf9f5;
  border-radius: 8px;
  text-decoration: none;
  font-family: var(--sans);
}

.video-link strong {
  font-size: 1.15rem;
  font-weight: 650;
}

.video-link span { color: #e7e2d6; font-size: 0.95rem; }

.duration {
  margin: 0;
  font-family: var(--sans);
  font-size: 0.95rem;
  color: var(--ink-soft);
}

.callout {
  margin: 1.2rem 0 1.4rem;
  padding: 0.95rem 1.1rem 1rem;
  background: var(--callout);
  border-left: 3px solid var(--callout-line);
  border-radius: 0 8px 8px 0;
}

.callout-label {
  margin: 0 0 0.35rem;
  font-family: var(--sans);
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
}

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

pre {
  margin: 1rem 0 1.2rem;
  padding: 1rem 1.1rem;
  overflow-x: auto;
  background: var(--code-bg);
  color: var(--code-ink);
  border-radius: 8px;
  font-family: var(--mono);
  font-size: 0.86rem;
  line-height: 1.55;
}

code {
  font-family: var(--mono);
  font-size: 0.88em;
}

p code, li code, h2 code, h3 code {
  padding: 0.05em 0.28em;
  background: var(--chip);
  border-radius: 4px;
}

/* Длинный встроенный код и URL переносятся, а не растягивают страницу на телефоне. */
p code, li code, figcaption code, p a, li a {
  overflow-wrap: anywhere;
}

.terminal-label {
  margin: 1.1rem 0 0.35rem;
  font-family: var(--sans);
  font-size: 0.82rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--ink-soft);
}

.shot {
  margin: 1.15rem 0 1.35rem;
}

.shot img {
  display: block;
  width: 100%;
  height: auto;
  border: 1px solid var(--line);
  border-radius: 8px;
}

.shot figcaption {
  margin-top: 0.45rem;
  font-family: var(--sans);
  font-size: 0.9rem;
  line-height: 1.4;
  color: var(--ink-soft);
}

.reflection {
  margin-top: 0.4rem;
  padding-left: 1.1rem;
}

.pager {
  display: flex;
  justify-content: flex-end;
  gap: 0.75rem;
  margin-top: 2.5rem;
}

.pager a {
  display: inline-flex;
  align-items: center;
  min-height: 2.6rem;
  padding: 0.4rem 1.1rem;
  border-radius: 999px;
  font-family: var(--sans);
  font-size: 0.95rem;
  text-decoration: none;
}

.pager .next {
  background: #1c1c1a;
  color: #faf9f5;
}

.pager .ghost {
  border: 1px solid var(--ink);
}

.source {
  margin-top: 1.5rem;
  font-family: var(--sans);
  font-size: 0.92rem;
  color: var(--ink-soft);
}

.overview-lead {
  max-width: var(--max);
  font-size: 1.35rem;
  line-height: 1.45;
}

.card-list {
  list-style: none;
  margin: 1.5rem 0 0;
  padding: 0;
  max-width: 40rem;
}

.card-list a {
  display: block;
  padding: 0.95rem 0;
  border-top: 1px solid var(--line);
  text-decoration: none;
}

.card-list li:last-child a { border-bottom: 1px solid var(--line); }

.card-list strong {
  display: block;
  font-size: 1.2rem;
  font-weight: 560;
}

.card-list span {
  display: block;
  margin-top: 0.15rem;
  color: var(--ink-soft);
  font-family: var(--sans);
  font-size: 0.95rem;
}

.compare {
  width: 100%;
  border-collapse: collapse;
  margin: 1rem 0 1.3rem;
  font-family: var(--sans);
  font-size: 0.95rem;
}

.compare th,
.compare td {
  padding: 0.65rem 0.7rem;
  border-bottom: 1px solid var(--line);
  text-align: left;
  vertical-align: top;
}

.compare th { font-weight: 650; }

.q-list { margin: 0; padding: 0; list-style: none; }

.q-item {
  margin: 0 0 1.6rem;
  padding-top: 1.2rem;
  border-top: 1px solid var(--line);
}

.q-meta {
  margin: 0 0 0.35rem;
  font-family: var(--sans);
  font-size: 0.82rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--ink-soft);
}

.q-stem {
  margin: 0 0 0.35rem;
  font-size: 1.15rem;
  line-height: 1.45;
}

.q-pick {
  margin: 0 0 0.7rem;
  font-family: var(--sans);
  font-size: 0.92rem;
  color: var(--ink-soft);
}

.q-options { display: grid; gap: 0.45rem; }

.q-options label {
  display: grid;
  grid-template-columns: 1.15rem 1fr;
  gap: 0.6rem;
  align-items: start;
  padding: 0.65rem 0.75rem;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fffdf8;
  font-family: var(--sans);
  font-size: 0.98rem;
  line-height: 1.4;
  cursor: pointer;
}

.q-options input { margin-top: 0.2rem; }

.q-options label.is-correct { border-color: #2f6b45; background: #eef6f0; }
.q-options label.is-wrong { border-color: #8d3b32; background: #fbf1ef; }

.q-why {
  margin: 0.7rem 0 0;
  font-family: var(--sans);
  font-size: 0.95rem;
}

.score-banner {
  margin: 0 0 1.4rem;
  padding: 1rem 1.1rem;
  border-radius: 8px;
  font-family: var(--sans);
}

.score-banner.pass { background: #eef6f0; }
.score-banner.fail { background: #fbf1ef; }

.score-banner h2 {
  margin: 0 0 0.35rem;
  font-family: var(--sans);
  font-size: 1.35rem;
}

.domain-list {
  margin: 0.6rem 0 0;
  padding: 0;
  list-style: none;
}

.domain-list li {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.35rem 0;
  border-top: 1px solid var(--line);
  font-size: 0.95rem;
}

.exam-actions {
  display: flex;
  justify-content: flex-end;
  gap: 0.75rem;
  margin-top: 0.5rem;
}

.exam-actions button {
  min-height: 2.6rem;
  padding: 0.4rem 1.1rem;
  border-radius: 999px;
  border: 0;
  font-family: var(--sans);
  font-size: 0.95rem;
  cursor: pointer;
}

.exam-actions .submit {
  background: #1c1c1a;
  color: #faf9f5;
}

.exam-actions .retry {
  background: transparent;
  border: 1px solid var(--ink);
  color: var(--ink);
}

@media (max-width: 860px) {
  .layout { grid-template-columns: minmax(0, 1fr); }
  .sidebar { border-right: 0; border-bottom: 1px solid var(--line); }
  .sidebar-inner { position: static; max-height: none; overflow: visible; }
  .lesson { padding: 1.5rem 1.1rem 3rem; }
  .header-nav { gap: 0.9rem; }
}