:root {
  color-scheme: light;
  --ink: #16202a;
  --muted: #596675;
  --canvas: #f5f7f9;
  --paper: #ffffff;
  --line: #d9dee5;
  --line-strong: #b8c1cc;
  --blue: #0b6fc2;
  --blue-dark: #07558f;
  --blue-soft: #eaf4fc;
  --orange: #e8790c;
  --orange-soft: #fff3df;
  --green: #087f5b;
  --green-soft: #eaf8f2;
  --red: #b42318;
  --red-soft: #fff0ee;
  --violet: #6f42c1;
  --shadow: 0 8px 24px rgba(25, 39, 52, 0.08);
}

* {
  box-sizing: border-box;
}

html {
  background: var(--canvas);
  color: var(--ink);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont,
    "Segoe UI", sans-serif;
  line-height: 1.65;
  scroll-behavior: smooth;
}

body {
  margin: 0;
}

a {
  color: var(--blue-dark);
  text-underline-offset: 0.18em;
}

a:hover {
  color: var(--blue);
}

button,
input,
select {
  font: inherit;
}

button {
  cursor: pointer;
}

.topbar {
  background: #111820;
  border-bottom: 3px solid var(--orange);
  color: #fff;
}

.topbar-inner {
  align-items: center;
  display: flex;
  gap: 20px;
  justify-content: space-between;
  margin: 0 auto;
  max-width: 1180px;
  min-height: 58px;
  padding: 10px 24px;
}

.brand {
  color: #fff;
  font-size: 0.95rem;
  font-weight: 800;
  text-decoration: none;
}

.topnav {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
}

.topnav a {
  color: #dbe6ef;
  font-size: 0.86rem;
  text-decoration: none;
}

.topnav a:hover {
  color: #fff;
}

.page-shell {
  margin: 0 auto;
  max-width: 1180px;
  padding: 38px 24px 72px;
}

.course-header,
.lesson-header {
  border-bottom: 1px solid var(--line);
  margin-bottom: 30px;
  padding-bottom: 26px;
}

.eyebrow {
  color: var(--blue-dark);
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0;
  margin: 0 0 8px;
  text-transform: uppercase;
}

h1,
h2,
h3 {
  letter-spacing: 0;
  line-height: 1.25;
}

h1 {
  font-size: 2.5rem;
  margin: 0 0 14px;
  max-width: 880px;
}

h2 {
  font-size: 1.55rem;
  margin: 42px 0 16px;
}

h3 {
  font-size: 1.08rem;
  margin: 26px 0 9px;
}

p {
  margin: 0 0 14px;
}

ul,
ol {
  margin: 0 0 16px;
  padding-left: 1.35rem;
}

li + li {
  margin-top: 6px;
}

code {
  background: #edf0f3;
  border-radius: 4px;
  color: #25313d;
  font-family: "SFMono-Regular", Consolas, monospace;
  font-size: 0.9em;
  padding: 2px 5px;
}

.lead {
  color: var(--muted);
  font-size: 1.08rem;
  max-width: 820px;
}

.meta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 18px;
}

.chip {
  align-items: center;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--muted);
  display: inline-flex;
  font-size: 0.82rem;
  min-height: 30px;
  padding: 3px 10px;
}

.chip.high {
  background: var(--orange-soft);
  border-color: #efc17d;
  color: #8a4b08;
}

.chip.domain {
  background: var(--blue-soft);
  border-color: #afd3ee;
  color: var(--blue-dark);
}

.stats-grid {
  display: grid;
  gap: 12px;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  margin: 26px 0;
}

.stat {
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 6px;
  min-height: 118px;
  padding: 18px;
}

.stat strong {
  color: var(--blue-dark);
  display: block;
  font-size: 1.8rem;
  line-height: 1.1;
  margin-bottom: 8px;
}

.stat span {
  color: var(--muted);
  font-size: 0.88rem;
}

.progress-track {
  background: #dfe5ea;
  border-radius: 999px;
  height: 10px;
  margin-top: 14px;
  overflow: hidden;
}

.progress-fill {
  background: var(--green);
  height: 100%;
  transition: width 180ms ease;
  width: 0;
}

.chapter-list {
  display: grid;
  gap: 12px;
  margin-top: 18px;
}

.chapter-card {
  align-items: center;
  background: var(--paper);
  border: 1px solid var(--line);
  border-left: 5px solid var(--blue);
  border-radius: 6px;
  display: grid;
  gap: 18px;
  grid-template-columns: 58px minmax(0, 1fr) auto;
  min-height: 104px;
  padding: 16px 18px;
}

.chapter-card[data-status="complete"] {
  border-left-color: var(--green);
}

.chapter-number {
  color: var(--blue-dark);
  font-size: 1.35rem;
  font-weight: 900;
  text-align: center;
}

.chapter-copy h3 {
  font-size: 1.04rem;
  margin: 0 0 5px;
}

.chapter-copy p {
  color: var(--muted);
  font-size: 0.88rem;
  margin: 0;
}

.chapter-action {
  min-width: 110px;
  text-align: right;
}

.status-label {
  color: var(--muted);
  display: block;
  font-size: 0.78rem;
  margin-bottom: 6px;
}

.text-link {
  font-size: 0.88rem;
  font-weight: 800;
}

.button,
.check-answer,
.grade-chapter,
.secondary-button {
  align-items: center;
  border: 0;
  border-radius: 5px;
  display: inline-flex;
  font-weight: 800;
  justify-content: center;
  min-height: 40px;
  padding: 8px 14px;
  text-decoration: none;
}

.button,
.check-answer,
.grade-chapter {
  background: var(--blue-dark);
  color: #fff;
}

.button:hover,
.check-answer:hover,
.grade-chapter:hover {
  background: var(--blue);
  color: #fff;
}

.secondary-button {
  background: var(--paper);
  border: 1px solid var(--line-strong);
  color: var(--ink);
}

.secondary-button:hover {
  background: #eef1f4;
}

.toc,
.callout,
.decision,
.exam-note,
.memory-note {
  border-radius: 6px;
  margin: 20px 0;
  padding: 18px 20px;
}

.toc {
  background: var(--paper);
  border: 1px solid var(--line);
}

.toc strong {
  display: block;
  margin-bottom: 8px;
}

.toc ol {
  columns: 2;
  margin-bottom: 0;
}

.callout {
  background: var(--blue-soft);
  border-left: 5px solid var(--blue);
}

.decision {
  background: var(--orange-soft);
  border-left: 5px solid var(--orange);
}

.exam-note {
  background: var(--green-soft);
  border-left: 5px solid var(--green);
}

.memory-note {
  background: #f2eefb;
  border-left: 5px solid var(--violet);
}

.callout > :last-child,
.decision > :last-child,
.exam-note > :last-child,
.memory-note > :last-child {
  margin-bottom: 0;
}

.lesson-section {
  border-bottom: 1px solid var(--line);
  padding-bottom: 26px;
}

.lesson-section:last-of-type {
  border-bottom: 0;
}

.table-wrap {
  margin: 16px 0 22px;
  overflow-x: auto;
}

table {
  background: var(--paper);
  border: 1px solid var(--line);
  border-collapse: collapse;
  width: 100%;
}

th,
td {
  border-bottom: 1px solid var(--line);
  padding: 11px 13px;
  text-align: left;
  vertical-align: top;
}

th {
  background: #edf1f5;
  font-size: 0.84rem;
}

td {
  font-size: 0.92rem;
}

tr:last-child td {
  border-bottom: 0;
}

.flow {
  counter-reset: flow;
  display: grid;
  gap: 10px;
  margin: 18px 0;
}

.flow-step {
  background: var(--paper);
  border: 1px solid var(--line);
  border-left: 5px solid var(--orange);
  min-height: 58px;
  padding: 12px 14px 12px 52px;
  position: relative;
}

.flow-step::before {
  background: var(--orange);
  border-radius: 50%;
  color: #fff;
  content: counter(flow);
  counter-increment: flow;
  display: grid;
  font-size: 0.8rem;
  font-weight: 900;
  height: 26px;
  left: 14px;
  place-items: center;
  position: absolute;
  top: 15px;
  width: 26px;
}

.practice {
  border-top: 4px solid var(--orange);
  margin-top: 44px;
  padding-top: 4px;
}

.practice-intro {
  color: var(--muted);
  max-width: 780px;
}

.exam-toolbar {
  align-items: center;
  background: var(--paper);
  border: 1px solid var(--line);
  border-left: 5px solid var(--orange);
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  justify-content: space-between;
  margin: 18px 0;
  padding: 14px 16px;
}

.timer-display {
  font-family: "SFMono-Regular", Consolas, monospace;
  font-size: 1.45rem;
  font-weight: 900;
  min-width: 92px;
}

.timer-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.timer-actions button {
  min-height: 38px;
}

.exam-toolbar[data-expired="true"] {
  border-left-color: var(--red);
}

.exam-toolbar[data-expired="true"] .timer-display {
  color: var(--red);
}

.question {
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 6px;
  box-shadow: var(--shadow);
  margin: 18px 0;
  padding: 20px;
}

.question[data-result="correct"] {
  border-left: 5px solid var(--green);
}

.question[data-result="incorrect"] {
  border-left: 5px solid var(--red);
}

.question-kicker {
  color: var(--muted);
  font-size: 0.76rem;
  font-weight: 800;
  margin-bottom: 5px;
  text-transform: uppercase;
}

.question-text {
  font-weight: 750;
  margin-bottom: 14px;
}

.options {
  display: grid;
  gap: 8px;
  margin-bottom: 14px;
}

.option {
  align-items: flex-start;
  background: #f8fafb;
  border: 1px solid var(--line);
  border-radius: 5px;
  display: flex;
  gap: 10px;
  min-height: 46px;
  padding: 10px 12px;
}

.option:hover {
  border-color: #9eb5c8;
}

.option input {
  margin-top: 5px;
}

.matching-grid,
.ordering-grid {
  display: grid;
  gap: 10px;
  margin: 12px 0 16px;
}

.match-row,
.order-row {
  align-items: center;
  display: grid;
  gap: 12px;
  grid-template-columns: minmax(180px, 1fr) minmax(220px, 1.2fr);
}

.match-row select,
.order-row select {
  background: #fff;
  border: 1px solid var(--line-strong);
  border-radius: 5px;
  min-height: 42px;
  padding: 7px 9px;
  width: 100%;
}

.feedback {
  font-weight: 800;
  margin: 12px 0 0;
  min-height: 1.5em;
}

.feedback.correct {
  color: var(--green);
}

.feedback.incorrect {
  color: var(--red);
}

.explanation {
  background: #f4f7f9;
  border-left: 4px solid var(--line-strong);
  margin-top: 12px;
  padding: 12px 14px;
}

.score-panel {
  align-items: center;
  background: #111820;
  border-radius: 6px;
  color: #fff;
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  justify-content: space-between;
  margin-top: 22px;
  padding: 18px 20px;
}

.score-panel p {
  margin: 0;
}

.score-result {
  font-weight: 800;
}

.domain-results {
  border-top: 1px solid #45515d;
  margin-top: 12px;
  padding-top: 10px;
}

.domain-results p {
  color: #dbe6ef;
  font-size: 0.86rem;
  margin: 3px 0;
}

.domain-results p[data-status="pass"] {
  color: #a7e9cf;
}

.domain-results p[data-status="review"] {
  color: #ffd0ca;
}

.lesson-nav {
  border-top: 1px solid var(--line);
  display: flex;
  gap: 12px;
  justify-content: space-between;
  margin-top: 42px;
  padding-top: 20px;
}

.source-list {
  color: var(--muted);
  font-size: 0.9rem;
}

.footer {
  color: var(--muted);
  font-size: 0.82rem;
  margin-top: 50px;
  text-align: center;
}

[hidden] {
  display: none !important;
}

@media (max-width: 820px) {
  .stats-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .chapter-card {
    grid-template-columns: 46px minmax(0, 1fr);
  }

  .chapter-action {
    grid-column: 2;
    text-align: left;
  }

  .toc ol {
    columns: 1;
  }
}

@media (max-width: 620px) {
  .topbar-inner {
    align-items: flex-start;
    flex-direction: column;
    gap: 6px;
    padding: 12px 16px;
  }

  .page-shell {
    padding: 26px 16px 54px;
  }

  h1 {
    font-size: 2rem;
  }

  .stats-grid {
    grid-template-columns: 1fr;
  }

  .match-row,
  .order-row {
    grid-template-columns: 1fr;
  }

  .lesson-nav {
    align-items: stretch;
    flex-direction: column;
  }

  .exam-toolbar {
    align-items: stretch;
    flex-direction: column;
  }
}

@media print {
  html,
  body {
    background: #fff;
  }

  .topbar,
  .check-answer,
  .grade-chapter,
  .exam-toolbar,
  .lesson-nav,
  .footer,
  .progress-track {
    display: none !important;
  }

  .page-shell {
    max-width: none;
    padding: 0;
  }

  .question,
  .stat {
    break-inside: avoid;
    box-shadow: none;
  }

  a {
    color: var(--ink);
    text-decoration: none;
  }
}