/* Codex Learning — shared lesson styles */
:root {
  --font-body: -apple-system, BlinkMacSystemFont, "SF Pro Text", "Helvetica Neue", Helvetica, Arial, sans-serif;
  --font-heading: -apple-system, BlinkMacSystemFont, "SF Pro Display", "Helvetica Neue", Helvetica, Arial, sans-serif;
  --font-mono: "SF Mono", "Fira Code", Consolas, Menlo, monospace;
  --color-text: #1d1d1f;
  --color-muted: #6e6e73;
  --color-accent: #0071e3;
  --color-accent-light: #e8f0fe;
  --color-bg: #fff;
  --color-code-bg: #f5f5f7;
  --color-border: #d2d2d7;
  --color-card-bg: #fbfbfd;
  --color-success: #34c759;
  --color-warning: #ff9f0a;
  --color-danger: #ff3b30;
  --max-width: 740px;
  --radius: 12px;
  --shadow-card: 0 1px 3px rgb(0 0 0 / .04), 0 4px 12px rgb(0 0 0 / .06);
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html { font-size: 17px; -webkit-font-smoothing: antialiased; }
body {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 3rem 2rem 5rem;
  background: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-body);
  line-height: 1.58;
}

h1, h2, h3, h4 {
  margin: 2.5rem 0 .75rem;
  font-family: var(--font-heading);
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -.02em;
}
h1 { margin-top: 0; font-size: 2.4rem; letter-spacing: -.03em; }
h2 { margin-top: 3rem; font-size: 1.6rem; }
h3 { font-size: 1.2rem; }
p { margin-bottom: 1.2rem; }
a { color: var(--color-accent); text-decoration: none; transition: color .2s; }
a:hover { color: #0077ed; text-decoration: underline; }
strong { font-weight: 600; }
ul, ol { margin-bottom: 1.2rem; padding-left: 1.5rem; }
li { margin-bottom: .5rem; line-height: 1.5; }

code {
  padding: .2rem .45rem;
  border-radius: 6px;
  background: var(--color-code-bg);
  color: var(--color-text);
  font: .82rem var(--font-mono);
}
pre {
  position: relative;
  overflow-x: auto;
  margin-bottom: 1.75rem;
  padding: 1.25rem 1.5rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-code-bg);
  line-height: 1.55;
}
pre code { padding: 0; border-radius: 0; background: none; font-size: .8rem; }
.diagram {
  white-space: pre;
  font: .75rem/1.5 var(--font-mono);
}

.lesson-meta { margin-bottom: 2rem; color: var(--color-muted); font-size: .9rem; }
.callout, .primary-source, .ask-teacher, .quiz {
  margin-bottom: 1.75rem;
  padding: 1.25rem 1.5rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-card-bg);
  box-shadow: var(--shadow-card);
}
.callout-title, .primary-source-label {
  margin-bottom: .5rem;
  color: var(--color-accent);
  font-family: var(--font-heading);
  font-size: .8rem;
  font-weight: 600;
  letter-spacing: .04em;
  text-transform: uppercase;
}
.callout p:last-child, .primary-source p:last-child, .ask-teacher p:last-child { margin-bottom: 0; }
.callout.tip { border-color: var(--color-success); }
.callout.tip .callout-title { color: var(--color-success); }
.callout.warning { border-color: var(--color-warning); }
.callout.warning .callout-title { color: var(--color-warning); }
.callout.danger { border-color: var(--color-danger); }
.callout.danger .callout-title { color: var(--color-danger); }

table {
  width: 100%;
  margin-bottom: 1.75rem;
  overflow: hidden;
  border: 1px solid var(--color-border);
  border-collapse: separate;
  border-spacing: 0;
  border-radius: var(--radius);
  font-size: .9rem;
}
th, td { padding: .65rem 1rem; border-bottom: 1px solid var(--color-border); text-align: left; vertical-align: top; }
th {
  background: var(--color-code-bg);
  color: var(--color-muted);
  font-family: var(--font-heading);
  font-size: .82rem;
  font-weight: 600;
  letter-spacing: .03em;
  text-transform: uppercase;
}
tr:last-child td { border-bottom: none; }
.table-wrap { overflow-x: auto; margin-bottom: 1.75rem; }
.table-wrap table { margin-bottom: 0; }

.quiz-question { margin-bottom: 1rem; font-size: .95rem; font-weight: 600; }
.quiz-options { margin: 0; padding: 0; list-style: none; }
.quiz-options li {
  margin-bottom: .5rem;
  padding: .7rem 1rem;
  border: 1px solid var(--color-border);
  border-radius: 8px;
  cursor: pointer;
  font-size: .9rem;
  transition: all .2s;
}
.quiz-options li:hover {
  transform: translateY(-1px);
  border-color: var(--color-accent);
  background: var(--color-accent-light);
  box-shadow: 0 2px 8px rgb(0 113 227 / .1);
}
.quiz-options li.correct { border-color: var(--color-success); background: #e8f8ed; }
.quiz-options li.incorrect { border-color: var(--color-danger); background: #ffeaea; }
.quiz-feedback {
  display: none;
  margin-top: .75rem;
  padding: .85rem 1rem;
  border-radius: 8px;
  font-size: .88rem;
  line-height: 1.5;
}
.quiz-feedback.show { display: block; }
.quiz-feedback.correct { background: #e8f8ed; color: #1a7f37; }
.quiz-feedback.incorrect { background: #ffeaea; color: #c33; }

.lesson-top-nav, .lesson-nav {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  margin-bottom: 2.5rem;
}
.lesson-top-nav a, .lesson-nav a, .lesson-nav-disabled {
  color: var(--color-muted);
  font-size: .82rem;
}
.lesson-top-nav > :last-child, .lesson-nav > :last-child { text-align: right; }
.lesson-home-top, .lesson-nav-home {
  display: inline-flex;
  align-items: center;
  justify-content: center;
}
.lesson-back-top { display: inline-flex; align-items: center; gap: .45rem; }
.lesson-back-top:not(:has(svg))::before { content: "←"; }
.lesson-nav { margin: 3rem 0 0; padding-top: 1.5rem; border-top: 1px solid var(--color-border); }
.lesson-nav-disabled { opacity: .55; }
.ask-teacher { margin-top: 2rem; }

.course-header { margin-bottom: 3rem; }
.course-header h1 { margin-bottom: .75rem; font-size: 2.8rem; }
.course-header p { max-width: 600px; color: var(--color-muted); font-size: 1.05rem; line-height: 1.5; }
.section-label {
  margin: 2.5rem 0 .75rem;
  padding-left: 1rem;
  color: var(--color-muted);
  font-family: var(--font-heading);
  font-size: .72rem;
  font-weight: 600;
  letter-spacing: .06em;
  text-transform: uppercase;
}
.lesson-list { margin: 0; padding: 0; list-style: none; }
.lesson-list li { margin: 0; padding: 0; }
.lesson-card {
  display: grid;
  grid-template-columns: 2.5rem 1fr auto;
  gap: 1rem;
  align-items: baseline;
  padding: 1.1rem 1rem;
  border-radius: 10px;
  color: var(--color-text);
  text-decoration: none;
  transition: background .2s, transform .15s, box-shadow .2s;
}
.lesson-card:hover {
  transform: translateY(-1px);
  background: var(--color-card-bg);
  box-shadow: var(--shadow-card);
  text-decoration: none;
}
.lesson-num { color: var(--color-muted); font: 600 .78rem var(--font-mono); }
.lesson-info { display: flex; flex-direction: column; gap: .25rem; }
.lesson-title { color: var(--color-accent); font-family: var(--font-heading); font-size: 1rem; font-weight: 600; }
.lesson-desc { color: var(--color-muted); font-size: .85rem; line-height: 1.4; }
.lesson-time {
  padding: .2rem .5rem;
  border-radius: 4px;
  background: var(--color-code-bg);
  color: var(--color-muted);
  font: .72rem var(--font-mono);
  white-space: nowrap;
}
.resources-link { margin-top: 3rem; padding-top: 2rem; border-top: 1px solid var(--color-border); font-size: .9rem; }
.course-summary { margin-top: .5rem; color: var(--color-muted); font-size: .85rem; }
.all-courses-link { margin-top: 1rem; }

.reference-page > p:first-of-type { color: var(--color-muted); font-size: 1.05rem; }
.lesson-grid { display: grid; gap: 1rem; margin-bottom: 1.75rem; }
.lesson-grid .lesson-card {
  display: block;
  padding: 1.25rem 1.5rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-card-bg);
  box-shadow: var(--shadow-card);
}
.lesson-grid .lesson-card h2 { margin-top: .75rem; font-size: 1.15rem; }
.lesson-grid .lesson-card p:last-child, .lesson-grid .lesson-card ul:last-child { margin-bottom: 0; }
.tag {
  display: inline-block;
  padding: .15rem .5rem;
  border-radius: 999px;
  background: var(--color-accent-light);
  color: #0057a8;
  font-size: .72rem;
  font-weight: 700;
}
.compact-list { margin: .5rem 0 0; }

@media (max-width: 600px) {
  body { padding: 2rem 1.25rem 4rem; }
  .course-header h1 { font-size: 2rem; }
  .lesson-card { grid-template-columns: 2rem 1fr; }
  .lesson-time { display: none; }
  .table-wrap { margin-right: -1.25rem; }
}

@media print {
  body { max-width: none; padding: 0; }
  .lesson-top-nav, .lesson-nav, .quiz, .ask-teacher { display: none; }
  .callout, .primary-source, .lesson-grid .lesson-card { box-shadow: none; }
}