/* A quiet study desk: the code and its result carry the color. */
:root {
  --bg: #f7f7f4;
  --paper: #ffffff;
  --ink: #24352e;
  --muted: #65716a;
  --line: #dfe4de;
  --green: #1e5142;
  --mint: #edf2ed;
  --ease: cubic-bezier(.22, 1, .36, 1);
}
body { font-size: 15px; }
#main-content [tabindex="-1"]:focus { outline: none; }
button, a, input, select, textarea { transition: color .16s var(--ease), background-color .16s var(--ease), border-color .16s var(--ease); }
button:disabled { cursor: not-allowed; }
button:focus-visible, a:focus-visible, input:focus-visible, select:focus-visible, textarea:focus-visible, summary:focus-visible {
  outline: 3px solid var(--green); outline-offset: 3px;
}
button svg, .nav-button svg { width: 18px; height: 18px; flex: 0 0 18px; }
h1, h2, h3, p, button, span { letter-spacing: normal; }
.brand { font-size: 22px; font-weight: 600; gap: 12px; }
.brand-mark { width: 44px; height: 44px; border-radius: 12px; font-size: 20px; }
.brand small { font-size: 12px; margin-top: 8px; letter-spacing: 0; }
.sidebar { width: 248px; padding: 24px 16px 16px; }
.course-label { margin: 24px 12px 8px; font-size: 12px; }
.nav-button { min-height: 36px; padding: 8px 12px; margin: 2px 0; gap: 8px; font-size: 14px; line-height: 20px; }
.nav-button:not(.active) svg { color: var(--muted); }
.nav-button.active { background: var(--mint); box-shadow: inset -2px 0 var(--green); }
.nav-button .count { background: none; font-size: 12px; padding: 0; }
.side-divider { margin: 20px 0 12px; }
.side-plan { padding: 0 12px; font-size: 12px; }
.side-progress { background: #f1f3ef; padding: 16px; border-radius: 12px; }
.side-footer { font-size: 12px; padding: 16px 4px 0; }
.layout { margin-right: 248px; }
.topbar { height: 64px; padding: 0 32px; gap: 16px; }
.top-actions { gap: 16px; }
.day-pill { border: 0; padding: 0; border-radius: 0; background: none; color: var(--muted); }
.content { max-width: 1536px; padding: 32px; }
.page-title { font-size: 32px; margin: 0 0 8px; }
.lead { font-size: 15px; margin-bottom: 24px; }
.eyebrow { font-size: 12px; font-weight: 500; }
.btn { min-height: 40px; padding: 8px 16px; border-radius: 8px; font-size: 13px; }
.btn.small { min-height: 32px; padding: 4px 12px; font-size: 12px; }
.btn.orange { background: var(--green); border-color: var(--green); color: #fff; }
.btn.orange:hover { background: #153d31; }
.button-row { gap: 8px; }
.stat-row { border-radius: 12px; margin-bottom: 32px; }
.stat { padding: 16px 20px; gap: 12px; }
.stat b { color: var(--ink); font-size: 28px; }
.stat span { font-size: 12px; }
.stat b, .route-num, .timer, .count, .round-num, .attempt-meta { font-variant-numeric: tabular-nums; }
.section-head { margin: 32px 0 16px; gap: 16px; }
.section-head h2 { font-size: 22px; font-weight: 500; }
.toggle-group { padding: 4px; gap: 4px; border-radius: 8px; }
.toggle-group button { padding: 8px 12px; border-radius: 4px; }
.route-grid { gap: 16px; }
.route-card { padding: 24px; border-radius: 12px; }
.route-card:hover { border-color: #a7b7ab; box-shadow: none; }
.route-card h3 { margin: 16px 0 8px; font-size: 18px; font-weight: 500; }
.route-card p { font-size: 13px; line-height: 1.8; min-height: 48px; }
.route-bottom { font-size: 12px; margin-top: 16px; padding-top: 16px; }
.route-num { font-size: 12px; color: var(--muted); }
.icon-box { width: 32px; height: 32px; border-radius: 8px; background: #f1f3ef; color: var(--muted); }
.tag { font-size: 12px; background: #f1f3ef; color: var(--muted); padding: 0 8px; border-radius: 4px; }
.tag.amber { background: #f6f0e4; color: #775b2d; }
.panel, .exam-card { padding: 24px; border-radius: 12px; }
.panel h3 { font-weight: 500; font-size: 18px; }
.panel p { font-size: 14px; }
.note { padding: 16px 20px; margin: 24px 0; border-radius: 8px; font-size: 14px; }
.note.green { background: #f2f6f0; color: #355b3e; }
.dashboard-bottom { gap: 24px; margin-top: 32px; }
.inline-list { gap: 12px; margin: 16px 0; font-size: 14px; }
.round-num { width: 24px; min-width: 24px; height: 24px; line-height: 24px; }

/* A real, readable example is the only visual centerpiece. */
.hero { grid-template-columns: minmax(0,1.05fr) minmax(0,1fr); min-height: 280px; margin: 24px 0; border-color: var(--line); border-radius: 16px; background: var(--paper); }
.hero-copy { padding: 32px; align-self: center; }
.hero h1 { font-size: 36px; font-weight: 500; line-height: 1.5; margin: 8px 0 16px; }
.hero p { font-size: 15px; color: var(--muted); margin: 0 0 24px; }
.hero-art { display: flex; padding: 32px; background: #f0f3ee; }
.tiny-terminal { transform: none; width: 100%; max-width: 440px; padding: 0; box-shadow: 0 4px 16px #24352e08; background: #fff; color: #000; border: 1px solid #dbe2d8; border-radius: 12px; overflow: hidden; }
.tiny-terminal .dots { margin: 0; padding: 12px 16px; border-color: var(--line); font: 12px var(--mono); color: var(--muted); }
.tiny-terminal .dots i { display: none; }
.hero-code { width: 100%; max-width: 440px; background: white; border: 1px solid var(--line); border-radius: 12px; overflow: hidden; }
.hero-code pre.language-java { font-size: 13px; margin: 0; padding: 24px 16px; border: 0; border-radius: 0; box-shadow: none; }
.hero-example-label { padding: 12px 16px; color: var(--muted); font-size: 12px; border-bottom: 1px solid var(--line); }
.hero-signature { padding: 12px 16px; margin: 0 !important; font-size: 12px !important; text-align: center; }
.hero-result { display: flex; justify-content: space-between; align-items: center; }
.hero-result span { font: 12px var(--sans); }
.hero-result output { font-size: 18px; }
.hero-result { direction: ltr; text-align: left; padding: 12px 16px; border-top: 1px solid var(--line); background: #f7f9f6; color: var(--green); font: 14px/1.6 var(--mono); }
.hero-result small { color: var(--muted); display: block; font: 12px var(--sans); margin-bottom: 8px; }
.terminal-note { color: var(--muted); font-size: 12px; margin: 0; padding: 12px 16px; border-color: var(--line); }

/* Lessons and code get space before navigation does. */
.lesson-layout { grid-template-columns: 208px minmax(0,1fr); gap: 24px; }
.lesson-layout > *, .exam-workspace > *, .hero > * { min-width: 0; }
.lesson-menu { padding: 0; border-radius: 12px; top: 16px; max-height: calc(100vh - 32px); }
.lesson-menu > summary { padding: 16px; font-size: 13px; cursor: pointer; color: var(--ink); }
.lesson-menu > summary strong { display: block; margin-top: 8px; font-size: 12px; font-weight: 400; color: var(--muted); }
.lesson-index-content { padding: 0 12px 12px; }
.lesson-menu .search { font-size: 13px; padding: 8px 12px; margin-bottom: 8px; }
.phase-label { font-size: 12px; margin: 24px 8px 8px; }
.lesson-link { font-size: 13px; padding: 8px; gap: 8px; min-height: 36px; }
.lesson-link .idx { font-size: 12px; color: var(--muted); min-width: 20px; padding-top: 0; }
.lesson-heading { gap: 16px; margin-bottom: 16px; }
.lesson-heading h1 { font-size: 28px; margin: 4px 0; font-weight: 500; }
.lesson-heading p { font-size: 14px; }
.tabs { margin: 16px 0; gap: 4px; }
.tabs button { padding: 8px 12px; min-height: 40px; font-size: 13px; }
.lesson-article { padding: 24px; border-radius: 12px; }
.lesson-article h2 { font-size: 21px; font-weight: 500; margin: 24px 0 12px; }
.lesson-article p, .lesson-article li { font-size: 15px; line-height: 2; }
.objectives { margin: 12px 0 24px; gap: 8px; }
.objectives span { background: #f3f5f0; border-color: var(--line); padding: 4px 8px; font-size: 12px; }
.source-note { font-size: 12px; margin-top: 24px; padding-top: 16px; }
.lesson-bottom { margin: 24px 0; gap: 12px; }
.study-focus .sidebar { display: none; }
.study-focus .layout { margin-right: 0; }
.study-focus .content { max-width: 1440px; }
.study-focus .lesson-layout { grid-template-columns: 224px minmax(0,1fr); }
.editor-wrap { height: 320px; }
.editor-wrap.tall { height: 600px; }
.editor-toolbar { padding: 8px 12px; gap: 8px; }
.editor-toolbar .editor-tools { align-items: center; gap: 8px; flex-wrap: wrap; }
.editor-toolbar .btn { min-height: 36px; }
.editor-tools button { min-height: 32px; font-size: 12px; padding: 4px 8px; }
.runbar { padding: 12px 16px; gap: 12px; }
.runtime-status { font-size: 12px; }
.console-label { letter-spacing: 0; font-size: 12px; }
.console { font-size: 13px; }
.input-row { padding: 12px 16px; font-size: 13px; }
.code-editor, .line-numbers { font-size: 14px; }
.editor-wrap .CodeMirror-linenumber { color: #666; }
.editor-wrap .CodeMirror-focused { box-shadow: inset 0 0 0 2px #52769b; }
.saved-quiz-summary, .save-warning { padding: 16px 20px; border: 1px solid var(--line); border-radius: 8px; margin: 16px 0; background: #f3f6ef; font-size: 14px; }
.save-warning { background: #fff4e5; border-color: #c79d5d; color: #6b471a; }
.save-warning .btn { margin-right: 12px; }
.quiz-card { padding: 24px; }
.quiz-option { min-height: 44px; font-size: 14px; padding: 12px 16px; margin: 8px 0; }
.quiz-explanation { font-size: 14px; }
.attempt-history { margin: 24px 0; }
.attempt-row { display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: 16px; padding: 16px 0; border-bottom: 1px solid var(--line); }
.attempt-meta { font-size: 13px; color: var(--muted); display: grid; gap: 4px; }
.attempt-meta strong { color: var(--ink); font-weight: 500; }
.history-note { font-size: 13px; margin: 16px 0 0; }
.attempt-history .section-head { margin-top: 0; }
.timer-status { display: block; font-size: 12px; margin-top: 8px; }
.timer.expired { color: #9c422e; }
.quiz-saved-score { font-size: 28px !important; color: var(--green); }
.progress-heading { display: flex; justify-content: space-between; align-items: center; gap: 8px; margin-bottom: 12px; }
.progress-heading strong { font-size: 12px; font-weight: 500; }
.breadcrumb-divider { color: #a1aca4; margin: 0 8px; }
.sidebar-close { margin: 0 0 16px; padding: 8px 12px; min-height: 44px; border: 1px solid var(--line); background: white; border-radius: 8px; color: var(--ink); }
.save-failed { color: #915f21; }
.attempt-actions { display: flex; flex-wrap: wrap; gap: 8px; }
.exam-workspace { gap: 24px; }
.exam-spec { padding: 24px; }
.exam-spec p, .exam-spec li { font-size: 14px; }
.exam-cover span { background: #f1f3ef; color: var(--muted); }
.exam-number { color: var(--muted); }
.glossary-card { padding: 20px; }
.glossary-card code { font-size: 12px; }
.footer-note { font-size: 12px; margin-top: 32px; }
.kbd { font-size: 11px; }
#toast { transition: opacity .18s var(--ease), transform .18s var(--ease); }

@media (min-width: 1500px) {
  .content { padding: 32px 40px; }
  .lesson-layout { grid-template-columns: 232px minmax(0,1fr); }
}
@media (max-width: 1150px) {
  .sidebar { width: 224px; padding: 24px 16px 16px; }
  .layout { margin-right: 224px; }
  .content { padding: 24px; }
  .topbar { padding: 0 24px; }
  .lesson-layout { grid-template-columns: 184px minmax(0,1fr); gap: 16px; }
  .hero-copy, .hero-art { padding: 24px; }
  .hero h1 { font-size: 32px; }
}
@media (max-width: 850px) {
  .layout, .study-focus .layout { margin: 0; }
  .sidebar { width: 264px; }
  .study-focus .sidebar { display: flex; }
  .content { padding: 24px 20px; }
  .topbar { height: 64px; padding: 0 20px; }
  .top-actions { gap: 8px; }
  .top-actions .day-pill { display: none; }
  .lesson-layout, .study-focus .lesson-layout { grid-template-columns: minmax(0,1fr); gap: 16px; }
  .lesson-menu { position: static; max-height: none; }
  .lesson-menu > summary { min-height: 44px; padding: 12px 16px; }
  .lesson-index-content { max-height: 320px; overflow-y: auto; }
  .lesson-heading h1 { font-size: 26px; }
  .mobile-menu { width: 40px; height: 40px; }
  .sidebar { transition: transform .18s var(--ease); }
  .nav-button { min-height: 44px; }
  #focus-study { display: none; }
}
@media (max-width: 570px) {
  .content { padding: 20px 16px 32px; }
  .topbar { padding: 0 16px; }
  .hero { margin: 16px 0 24px; grid-template-columns: 1fr; }
  .hero-copy { padding: 24px; }
  .hero h1 { font-size: 30px; }
  .hero-art { display: flex; padding: 20px; }
  .hero-copy .tag { background: transparent; padding: 0; }
  .btn { min-height: 44px; }
  .btn.small { min-height: 40px; }
  .stat { padding: 16px; }
  .route-card, .panel, .exam-card { padding: 20px; }
  .lesson-heading { flex-wrap: wrap; }
  .lesson-heading h1 { font-size: 25px; }
  .lesson-article { padding: 20px; }
  .tabs button { min-height: 44px; font-size: 13px; padding: 8px 12px; }
  .source-note { font-size: 12px; }
  .editor-wrap { height: 320px; }
  .editor-wrap.tall { height: 520px; }
  .editor-toolbar { padding: 8px; }
  .editor-tools { width: 100%; }
  .editor-tools button { min-height: 40px; }
  .editor-toolbar #run { margin-left: auto; }
  .runbar { padding: 12px; }
  .runtime-status { order: 3; min-width: 100%; }
  .lesson-bottom .btn { font-size: 13px; padding: 8px 12px; }
  .section-head { gap: 12px; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition-duration: 0s !important; animation-duration: 0s !important; }
}
@media print {
  .save-warning, #focus-study, .attempt-actions { display: none; }
}

/* Class specifications stay readable at the width of the question panel. */
.brand { min-height: 44px; }
.uml-diagram {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 24rem), 1fr));
  gap: 16px;
  align-items: start;
  margin: 24px 0;
  direction: ltr;
  text-align: left;
}
.uml-diagram .uml-card {
  min-width: 0;
  margin: 0;
  padding: 0;
  border: 1px solid #a7b7ab;
  border-radius: 8px;
  background: #fff;
}
.uml-card h3 {
  margin: 0;
  padding: 12px 16px;
  border-bottom: 1px solid var(--line);
  font: 600 15px/1.6 var(--mono);
  overflow-wrap: anywhere;
}
.uml-card .uml-members {
  margin: 0;
  padding: 16px;
  border: 0;
  border-radius: 0 0 8px 8px;
  background: #fff;
  color: var(--ink);
  font: 14px/1.9 var(--mono);
  white-space: pre-wrap;
  overflow-wrap: anywhere;
  word-break: normal;
  overflow: visible;
}
.lesson-article { overflow-wrap: anywhere; }
.lesson-article :not(pre) > code { overflow-wrap: anywhere; }
.cheatsheet > *, .glossary-grid > *, .uml-builder > * { min-width: 0; }
.uml-class { overflow-wrap: anywhere; }
.virtual-file-row { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; margin-top: 8px; }
.virtual-file-row input { flex: 1 1 180px; min-width: 0; width: auto; }
.virtual-file-row button { flex: 0 0 auto; }
@media (max-width: 1150px) {
  .exam-spec { max-height: none; overflow: visible; }
}