/* 龙智光年科技 · 培训资料
   Paper, ink and fine rules. Keep colour secondary to the course content. */

/* 1. Foundations and shared controls ---------------------------------------- */
:root {
  color-scheme: light;
  --paper: #f7f6f3;
  --surface: #fff;
  --ink: #252525;
  --secondary: #62605b;
  --muted: #6d6a64;
  --line: #dedbd5;
  --subtle: #eeece7;
  --accent: #984336;
  --danger: #984336;
  --header-height: 68px;
  --sidebar-width: 244px;
  --radius: 3px;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  font-size: 15px;
  color: var(--ink);
  background: var(--paper);
  font-synthesis: none;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}
* { box-sizing: border-box; }
html { scroll-padding-top: 0; }
body { margin: 0; min-width: 320px; line-height: 1.6; }
body.drawer-open { overflow: hidden; }
[hidden] { display: none !important; }
button, input, textarea { font: inherit; }
button { color: inherit; cursor: pointer; }
button, input { -webkit-tap-highlight-color: transparent; }
button { touch-action: manipulation; }
button:disabled { cursor: default; opacity: .48; }
button, a, input { outline-offset: 4px; }
:focus-visible { outline: 2px solid var(--accent); }
a { color: inherit; }
button, input, h1, h2, h3, p { margin: 0; }
h1, h2, h3, h4 { line-height: 1.5; }
button { border: 0; background: none; }
::selection { color: var(--ink); background: #e6ddd2; }
.svg-sprite { position: absolute; width: 0; height: 0; overflow: hidden; }
.icon { width: 20px; height: 20px; flex: 0 0 auto; fill: none; stroke: currentColor; stroke-width: 1.6; stroke-linecap: round; stroke-linejoin: round; vertical-align: middle; }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0; }
.copy-helper { position: fixed; top: 0; left: -10000px; }
.skip-link { position: fixed; top: -100px; left: 16px; z-index: 100; padding: 9px 16px; background: var(--ink); color: var(--surface); }
.skip-link:focus { top: 12px; }
.icon-button { display: inline-flex; align-items: center; justify-content: center; width: 40px; height: 40px; padding: 0; border-radius: var(--radius); color: var(--secondary); }
.icon-button:hover { color: var(--ink); background: var(--subtle); }
.button { display: inline-flex; align-items: center; justify-content: center; gap: 10px; min-height: 42px; padding: 9px 18px; border: 1px solid var(--line); border-radius: var(--radius); line-height: 1.5; font-size: 14px; font-weight: 500; }
.button-primary { border-color: var(--ink); background: var(--ink); color: var(--surface); }
.button-primary:hover:not(:disabled) { border-color: #44413c; background: #44413c; }
.button-soft { background: transparent; }
.button-soft:hover:not(:disabled) { background: var(--subtle); border-color: #aaa69e; }
.quiet-button { display: inline-flex; align-items: center; justify-content: center; gap: 7px; min-height: 40px; padding: 6px 8px; color: var(--secondary); font-size: 13px; border-radius: var(--radius); }
.quiet-button:hover { color: var(--ink); background: var(--subtle); }
kbd { display: inline-block; padding: 1px 5px; border: 1px solid var(--line); border-radius: 2px; font: 11px/1.5 ui-monospace, SFMono-Regular, Consolas, monospace; color: var(--muted); }
.eyebrow { display: block; color: var(--secondary); font-size: 12px; line-height: 1.6; letter-spacing: .04em; }

/* 2. Masthead -------------------------------------------------------------- */
.brand { display: inline-flex; align-items: center; gap: 11px; min-width: 0; color: var(--ink); text-decoration: none; }
.brand-mark { display: inline-flex; align-items: center; justify-content: center; width: 32px; height: 34px; flex: 0 0 auto; border: 1px solid var(--ink); border-radius: 2px; }
.brand-mark .icon { width: 21px; height: 21px; }
.brand-name { font-size: 17px; font-weight: 650; letter-spacing: .02em; line-height: 1.4; white-space: nowrap; }
.brand-name-tail { display: inline-block; margin-left: 13px; padding-left: 13px; border-left: 1px solid var(--line); font-size: 14px; font-weight: 400; color: var(--secondary); letter-spacing: 0; }
.app-header, .login-header { display: flex; align-items: center; justify-content: space-between; min-height: var(--header-height); padding: 0 28px; border-bottom: 1px solid var(--line); background: var(--paper); }
.app-header { position: fixed; top: 0; left: 0; right: 0; z-index: 30; height: var(--header-height); }
.header-start, .header-actions { display: flex; align-items: center; min-width: 0; }
.header-start { gap: 12px; }
.header-actions { gap: 17px; }
.header-note { color: var(--secondary); font-size: 12px; }
.header-divider { width: 1px; height: 19px; background: var(--line); }
.search-trigger { display: inline-flex; align-items: center; gap: 9px; min-height: 38px; padding: 5px 0; color: var(--secondary); font-size: 13px; }
.search-trigger:hover { color: var(--ink); }
.search-trigger .icon { width: 17px; height: 17px; }
.search-trigger kbd { margin-left: 18px; }
.mobile-menu { display: none; }
.reading-progress-track { position: fixed; top: 0; left: 0; right: 0; z-index: 60; height: 2px; pointer-events: none; }
#reading-progress { width: 0; height: 100%; background: var(--accent); }

/* 3. Password entry -------------------------------------------------------- */
.login-view { display: flex; min-height: 100vh; min-height: 100svh; flex-direction: column; }
.login-main { width: min(100% - 48px, 400px); margin: auto; padding: 68px 0 80px; }
.login-intro { margin-bottom: 30px; }
.login-intro h1 { font-size: 26px; font-weight: 600; letter-spacing: -.02em; }
.login-intro .eyebrow { margin-bottom: 13px; }
.login-lead, .login-intro > p { margin-top: 14px; font-size: 14px; line-height: 1.9; color: var(--secondary); }
.login-card { padding: 0; }
.login-card h2 { margin-bottom: 8px; font-size: 18px; font-weight: 600; }
.login-card-description { color: var(--secondary); font-size: 14px; margin-bottom: 26px; }
.login-lock { display: inline-flex; margin-bottom: 18px; color: var(--secondary); }
.login-features { margin-top: 24px; color: var(--secondary); font-size: 13px; }
.login-features > div { display: flex; gap: 8px; align-items: center; margin-top: 10px; }
.feature-icon { display: inline-flex; }
.feature-icon .icon { width: 16px; height: 16px; }
#login-form > label { display: block; margin-bottom: 9px; font-size: 13px; font-weight: 500; }
.password-field { display: flex; align-items: center; width: 100%; border: 1px solid #bab6ae; border-radius: var(--radius); background: var(--surface); }
.password-field:focus-within { border-color: var(--ink); outline: 1px solid var(--ink); }
.password-field input { width: 100%; min-width: 0; height: 46px; padding: 10px 13px; color: var(--ink); background: transparent; border: 0; outline: 0; font-size: 16px; }
.password-field input::placeholder { color: var(--muted); font-size: 14px; }
.password-field .icon-button { flex: 0 0 42px; margin-right: 3px; }
.form-message { min-height: 28px; padding-top: 5px; font-size: 12px; color: var(--secondary); }
.form-message.is-error, .form-message.error { color: var(--danger); }
.login-submit { width: 100%; min-height: 46px; }
.setup-note { display: flex; align-items: flex-start; gap: 9px; margin-top: 22px; padding: 13px 0; border-top: 1px solid var(--line); color: var(--secondary); font-size: 13px; line-height: 1.8; }
.setup-note .icon { width: 16px; height: 16px; margin-top: 3px; }
.login-footnote { margin-top: 19px; color: var(--muted); font-size: 12px; }
.login-footer { display: flex; justify-content: space-between; gap: 16px; padding: 21px 28px; border-top: 1px solid var(--line); color: var(--muted); font-size: 12px; }

/* 4. Course navigation ----------------------------------------------------- */
.app-layout { padding-top: var(--header-height); }
.sidebar { position: fixed; top: var(--header-height); bottom: 0; left: 0; z-index: 20; width: var(--sidebar-width); padding: 27px 17px 22px; border-right: 1px solid var(--line); overflow-y: auto; overscroll-behavior: contain; background: var(--paper); scrollbar-width: thin; }
.sidebar-mobile-heading { display: none; }
.home-link { display: flex; align-items: center; gap: 11px; width: 100%; min-height: 40px; padding: 8px 13px; text-align: left; border-radius: 2px; font-size: 14px; color: var(--secondary); }
.home-link .icon { width: 17px; height: 17px; }
.home-link:hover, .home-link.is-active { color: var(--ink); background: var(--subtle); }
.home-link.is-active { font-weight: 600; }
.sidebar-label { display: flex; align-items: center; justify-content: space-between; margin: 28px 13px 13px; font-size: 12px; color: var(--secondary); }
.sidebar-count { font-variant-numeric: tabular-nums; }
.lesson-nav { display: grid; gap: 3px; }
.lesson-link { display: grid; grid-template-columns: 24px minmax(0, 1fr); align-items: start; gap: 9px; width: 100%; padding: 12px 11px; border-left: 2px solid transparent; text-align: left; border-radius: 0; }
.lesson-link:hover { background: var(--subtle); }
.lesson-link.is-active { border-left-color: var(--accent); background: var(--subtle); }
.lesson-number { display: block; white-space: nowrap; padding-top: 1px; color: var(--muted); font-size: 12px; line-height: 1.8; font-variant-numeric: tabular-nums; }
.lesson-link.is-active .lesson-number { color: var(--accent); }
.lesson-copy { display: block; min-width: 0; }
.lesson-name { display: block; color: var(--secondary); font-size: 13px; line-height: 1.7; overflow-wrap: anywhere; }
.lesson-link.is-active .lesson-name { font-weight: 600; color: var(--ink); }
.lesson-link.introduction-link { grid-template-columns: minmax(0, 1fr); margin-bottom: 8px; padding-bottom: 17px; border-bottom: 1px solid var(--line); }
.lesson-meta { display: block; margin-top: 4px; color: var(--muted); font-size: 11px; line-height: 1.7; }
.drawer-backdrop { position: fixed; inset: 0; z-index: 40; width: 100%; height: 100%; background: rgb(25 24 21 / 32%); }

/* 5. Course overview: a reading list, not a card dashboard ------------------- */
.workspace { margin-left: var(--sidebar-width); padding: 0 44px; min-width: 0; outline: none; }
.overview-view { max-width: 1020px; margin: 0 auto; padding: 48px 0 50px; }
.overview-intro h1 { font-size: 30px; font-weight: 600; letter-spacing: -.02em; }
.overview-intro > .eyebrow { margin-bottom: 10px; }
.overview-stats { display: flex; align-items: center; flex-wrap: wrap; gap: 9px 22px; margin-top: 24px; padding: 15px 0; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); color: var(--secondary); font-size: 13px; }
.stat-item { display: flex; align-items: baseline; gap: 6px; }
.stat-item strong { font-size: 14px; font-weight: 500; color: var(--ink); font-variant-numeric: tabular-nums; }
.stat-item strong > span { margin-left: 5px; font-size: 13px; font-weight: 400; }
.stat-note { display: flex; align-items: center; gap: 7px; color: var(--muted); font-size: 12px; }
.stat-note .icon { width: 15px; height: 15px; }
.introduction-entry { margin-top: 30px; padding-bottom: 25px; border-bottom: 1px solid var(--line); }
.introduction-entry h2 { font-size: 20px; font-weight: 600; }
.introduction-entry p { max-width: 730px; margin-top: 12px; font-size: 14px; line-height: 1.9; color: var(--secondary); overflow-wrap: anywhere; }
.introduction-actions { display: flex; align-items: center; flex-wrap: wrap; gap: 8px 24px; margin-top: 18px; }
.introduction-read { display: inline-flex; align-items: center; gap: 16px; min-height: 42px; padding: 8px 14px; border: 1px solid var(--ink); border-radius: 2px; font-size: 13px; }
.introduction-read:hover { background: var(--subtle); }
.introduction-actions a { display: inline-flex; align-items: center; min-height: 42px; font-size: 13px; text-decoration: underline; text-decoration-color: #aaa69e; text-underline-offset: 4px; }
.introduction-actions a:hover { text-decoration-color: var(--accent); }
.startup-resources { margin-top: 30px; padding-bottom: 25px; border-bottom: 1px solid var(--line); }
.setup-heading { margin-bottom: 23px; }
.setup-heading h2 { font-size: 18px; font-weight: 600; }
.setup-grid { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: 36px; align-items: start; }
.setup-section { min-width: 0; }
.setup-section + .setup-section { padding-left: 36px; border-left: 1px solid var(--line); }
.setup-section-heading { display: flex; align-items: baseline; gap: 12px; margin-bottom: 17px; }
.setup-number { color: var(--accent); font: 20px/1.5 Georgia, "Times New Roman", serif; font-variant-numeric: tabular-nums; }
.setup-section-heading h3 { font-size: 16px; font-weight: 600; overflow-wrap: anywhere; }
.resource-block + .resource-block { margin-top: 22px; }
.resource-block h4 { margin: 0 0 7px; font-size: 14px; font-weight: 550; }
.resource-block p { color: var(--secondary); font-size: 13px; line-height: 1.85; overflow-wrap: anywhere; }
.resource-links { display: flex; flex-wrap: wrap; align-items: center; gap: 2px 17px; margin-top: 8px; }
.resource-link { display: inline-flex; align-items: center; gap: 7px; max-width: 100%; min-height: 40px; padding: 6px 0; color: var(--ink); font-size: 13px; line-height: 1.65; text-decoration-line: underline; text-decoration-color: #aaa69e; text-underline-offset: 4px; overflow-wrap: anywhere; }
.resource-link:hover { text-decoration-color: var(--accent); color: var(--accent); }
.resource-link .icon { width: 15px; height: 15px; }
.contact-list { display: grid; gap: 8px; margin-top: 12px; }
.contact-row { display: flex; align-items: center; justify-content: space-between; gap: 14px; width: 100%; max-width: 340px; min-width: 0; }
.contact-value { color: var(--ink); font: 14px/1.7 ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; overflow-wrap: anywhere; user-select: all; }
.contact-copy { flex: 0 0 auto; min-height: 40px; padding: 7px 12px; border: 1px solid var(--line); border-radius: 2px; color: var(--secondary); font-size: 12px; line-height: 1.5; }
.contact-copy:hover { color: var(--ink); border-color: #aaa69e; background: var(--subtle); }
.setup-steps { margin: 12px 0 0; padding-left: 1.5em; color: var(--secondary); font-size: 13px; line-height: 1.85; }
.setup-steps li { padding-left: .15em; margin: 4px 0; overflow-wrap: anywhere; }
.section-heading { display: flex; align-items: baseline; justify-content: space-between; gap: 16px; margin: 34px 0 13px; }
.section-heading h2 { font-size: 16px; font-weight: 600; }
.section-heading p { font-size: 12px; color: var(--muted); }
.section-kicker { display: block; margin-bottom: 5px; font-size: 11px; color: var(--secondary); }
.chapter-grid { display: block; border-top: 1px solid var(--ink); }
.chapter-card { display: grid; grid-template-columns: 40px minmax(0, 1fr) 22px; gap: 18px; align-items: center; width: 100%; padding: 25px 4px; border-bottom: 1px solid var(--line); border-radius: 0; text-align: left; }
.chapter-card:hover { background: #eeece7; }
.chapter-card:focus-visible { position: relative; z-index: 1; outline-offset: -2px; }
.chapter-number { align-self: start; padding-top: 1px; color: var(--accent); font-family: Georgia, "Times New Roman", serif; font-size: 22px; line-height: 1.5; font-variant-numeric: tabular-nums; }
.chapter-card-body { display: grid; grid-template-columns: minmax(0, 1fr) 110px; grid-template-rows: auto auto; gap: 6px 26px; align-items: center; min-width: 0; }
.chapter-title { display: block; grid-column: 1; color: var(--ink); font-size: 16px; font-weight: 550; line-height: 1.65; overflow-wrap: anywhere; }
.chapter-description { display: block; grid-column: 1; color: var(--secondary); font-size: 13px; line-height: 1.8; overflow-wrap: anywhere; }
.chapter-meta { display: block; grid-column: 2; grid-row: 1 / 3; color: var(--muted); font-size: 11px; line-height: 1.9; }
.chapter-meta > span[aria-hidden] { padding: 0 3px; }
.chapter-arrow { color: var(--muted); font-size: 20px; text-align: right; }
.chapter-arrow .icon { width: 17px; height: 17px; }
.chapter-card:hover .chapter-arrow { color: var(--ink); }
.overview-note { display: flex; align-items: flex-start; gap: 8px; margin-top: 22px; color: var(--muted); font-size: 12px; line-height: 1.8; }
.overview-note .icon { width: 15px; height: 15px; margin-top: 3px; }
.workspace-footer { display: flex; justify-content: space-between; gap: 16px; max-width: 1040px; margin: 0 auto; padding: 23px 0 28px; border-top: 1px solid var(--line); color: var(--muted); font-size: 11px; }

/* Practical path, reference reading and the compact task index. */
.practice-index { margin-top: 28px; padding-bottom: 24px; border-bottom: 1px solid var(--line); }
.practice-index-heading { display: flex; flex-wrap: wrap; align-items: baseline; justify-content: space-between; gap: 8px 20px; margin-bottom: 12px; }
.practice-index-heading h2 { font-size: 18px; font-weight: 600; }
.practice-index-list { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 0 30px; margin: 0; padding: 0; list-style: none; }
.practice-index-list li { min-width: 0; border-bottom: 1px solid var(--line); }
.practice-index-list a { display: flex; justify-content: space-between; align-items: baseline; gap: 12px; padding: 12px 0; min-height: 44px; font-size: 13px; line-height: 1.75; text-decoration: none; overflow-wrap: anywhere; }
.practice-index-list a:hover { color: var(--accent); }
.starter-download { display: inline-flex; align-items: center; gap: 9px; min-height: 40px; color: var(--secondary); font-size: 12px; line-height: 1.8; text-decoration: underline; text-underline-offset: 4px; text-decoration-color: #aaa69e; }
.starter-download:hover { color: var(--accent); text-decoration-color: var(--accent); }
.reader-modes { display: flex; gap: 24px; margin: -8px 0 25px; border-bottom: 1px solid var(--line); }
.reader-modes button { min-height: 44px; padding: 9px 0 11px; border-bottom: 2px solid transparent; color: var(--secondary); font-size: 14px; }
.reader-modes button[aria-pressed="true"] { border-bottom-color: var(--accent); color: var(--ink); font-weight: 600; }
.reader-modes button:hover { color: var(--accent); }
.practice-quick-start { padding: 20px 22px 15px; margin-bottom: 32px; border: 1px solid var(--line); background: var(--subtle); }
.practice-quick-start h2 { margin: 0 0 10px; font-size: 14px; font-weight: 650; }
.quick-outcome { color: var(--ink); font-size: 14px; line-height: 1.85; overflow-wrap: anywhere; }
.quick-inputs { margin-top: 8px; color: var(--secondary); font-size: 12px; line-height: 1.9; overflow-wrap: anywhere; }
.quick-inputs > span { margin-right: 10px; color: var(--ink); }
.quick-steps { margin: 13px 0 8px; padding-left: 1.45em; color: var(--accent); font-size: 13px; line-height: 1.85; }
.quick-steps li { padding: 3px 0 3px 2px; }
.quick-steps a { color: var(--ink); text-decoration: underline; text-decoration-color: #b6b0a6; text-underline-offset: 3px; overflow-wrap: anywhere; }
.quick-steps a:hover { color: var(--accent); }
.reference-start { display: block; scroll-margin-top: calc(var(--header-height) + 22px); }

/* 6. Reader and article typography ---------------------------------------- */
.reader-view { max-width: 1040px; margin: 0 auto; }
.reader-toolbar { display: flex; align-items: center; justify-content: space-between; gap: 16px; min-height: 72px; border-bottom: 1px solid var(--line); }
.breadcrumb { color: var(--secondary); font-size: 12px; overflow-wrap: anywhere; }
.breadcrumb button { padding: 5px 0; color: var(--secondary); font-size: inherit; }
.breadcrumb button:hover { color: var(--ink); text-decoration: underline; }
.breadcrumb .separator { margin: 0 10px; color: var(--muted); }
.toc-toggle { display: none; white-space: nowrap; flex-shrink: 0; }
.reading-layout { display: grid; grid-template-columns: minmax(0, 740px) 220px; align-items: start; gap: 40px; padding: 33px 0 50px; }
.reader-main { min-width: 0; }
.lesson-header { padding-bottom: 28px; margin-bottom: 32px; border-bottom: 1px solid var(--line); }
.lesson-header .eyebrow { margin-bottom: 12px; color: var(--accent); }
.lesson-header h1 { font-size: clamp(24px, 2.1vw, 32px); font-weight: 600; line-height: 1.55; letter-spacing: -.015em; overflow-wrap: anywhere; }
.lesson-intro { margin-top: 16px; color: var(--secondary); font-size: 14px; line-height: 1.9; }
.article-body { min-width: 0; font-size: 16px; line-height: 1.95; color: var(--ink); overflow-wrap: anywhere; }
.article-body > :first-child { margin-top: 0; }
.article-body > h1:first-child, .article-body > .reference-start + h1 { display: none; }
.article-body h1, .article-body h2, .article-body h3, .article-body h4, .article-body h5, .article-body h6 { scroll-margin-top: calc(var(--header-height) + 22px); font-weight: 600; }
.article-body h1 { margin: 45px 0 21px; font-size: 27px; }
.article-body h2 { margin: 44px 0 20px; padding-top: 4px; font-size: 22px; line-height: 1.6; }
.article-body h3 { margin: 32px 0 14px; font-size: 18px; line-height: 1.7; }
.article-body h4 { margin: 26px 0 12px; font-size: 16px; }
.article-body h5, .article-body h6 { margin: 22px 0 10px; font-size: 15px; }
.article-body p { margin: 0 0 20px; }
.article-body ul, .article-body ol { margin: 16px 0 23px; padding-left: 1.5em; }
.article-body li { padding-left: .2em; margin: 6px 0; }
.article-body li > p { margin-bottom: 9px; }
.article-body li > ul, .article-body li > ol { margin: 8px 0; }
.article-body strong { font-weight: 650; }
.article-body a { color: var(--ink); text-decoration-line: underline; text-decoration-color: #aaa69e; text-underline-offset: 3px; overflow-wrap: anywhere; }
.article-body a:hover { text-decoration-color: var(--accent); }
.article-body blockquote { margin: 24px 0; padding: 2px 0 2px 20px; border-left: 2px solid #aaa69e; color: var(--secondary); }
.article-body blockquote > :last-child { margin-bottom: 0; }
.article-body hr { border: 0; border-top: 1px solid var(--line); margin: 34px 0; }
.article-body code { padding: 2px 5px; border-radius: 2px; color: #4d4338; background: var(--subtle); font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; font-size: .84em; overflow-wrap: anywhere; }
.article-body pre { position: relative; max-width: 100%; margin: 23px 0; padding: 42px 19px 18px; overflow-x: auto; overscroll-behavior-x: contain; border: 1px solid var(--line); border-radius: var(--radius); background: #f0eeea; font-size: 13px; line-height: 1.85; tab-size: 2; }
.article-body pre code { display: block; padding: 0; border: 0; background: transparent; color: var(--ink); font-size: inherit; white-space: pre; overflow-wrap: normal; word-break: normal; }
.article-body pre.copy-prompt code { white-space: pre-wrap; overflow-wrap: anywhere; }
.article-body .sourceCode { max-width: 100%; }
.article-body pre .copy-code { position: absolute; top: 8px; right: 9px; display: inline-flex; align-items: center; gap: 4px; padding: 3px 8px; border: 1px solid #c8c4bc; border-radius: 2px; color: var(--secondary); background: var(--paper); font-size: 11px; line-height: 1.5; }
.article-body pre .copy-code:hover { color: var(--ink); border-color: #aaa69e; }
.article-body pre .copy-code .icon { width: 12px; height: 12px; }
.article-body .table-scroll, .article-body .table-wrapper { max-width: 100%; margin: 24px 0; overflow-x: auto; overscroll-behavior-x: contain; border: 1px solid var(--line); border-radius: 2px; }
.article-body table { width: 100%; margin: 24px 0; border-collapse: collapse; text-align: left; font-size: 14px; line-height: 1.8; }
.article-body .table-scroll table, .article-body .table-wrapper table { min-width: 480px; margin: 0; }
.article-body th, .article-body td { padding: 12px 14px; border-bottom: 1px solid var(--line); vertical-align: top; text-align: left; }
.article-body th { font-weight: 600; background: var(--subtle); }
.article-body tr:last-child td { border-bottom: 0; }
.article-body td p { margin: 0; }
.article-body img, .article-body video { display: block; max-width: 100%; height: auto; margin: 23px auto; border: 1px solid var(--line); }
.article-body figure { max-width: 100%; margin: 24px 0; }
.article-body figcaption { color: var(--secondary); font-size: 12px; text-align: center; }
.article-body mark { padding: 0 3px; background: #e6ddd2; color: var(--ink); }
.article-body .math { font-family: Georgia, "Times New Roman", serif; }
.article-body .math.display { display: block; max-width: 100%; padding: 19px 16px; margin: 22px 0; overflow-x: auto; background: var(--subtle); border-radius: 2px; text-align: center; }
.article-body .math.inline { display: inline; }
.article-body input[type="checkbox"] { accent-color: var(--ink); }

/* 7. Chapter contents and navigation -------------------------------------- */
.toc-panel { position: sticky; top: calc(var(--header-height) + 27px); max-height: calc(100vh - var(--header-height) - 55px); max-height: calc(100svh - var(--header-height) - 55px); overflow-y: auto; padding-left: 21px; border-left: 1px solid var(--line); scrollbar-width: thin; }
.toc-heading { display: flex; align-items: center; justify-content: space-between; margin-bottom: 15px; color: var(--ink); font-size: 12px; font-weight: 600; }
.toc-list { display: grid; gap: 3px; }
.toc-link { display: block; padding: 6px 0; color: var(--secondary); font-size: 12px; line-height: 1.85; text-decoration: none; overflow-wrap: anywhere; }
.toc-link[data-level="3"] { padding-left: 12px; font-size: 11px; }
.toc-link:hover { color: var(--ink); text-decoration: underline; text-underline-offset: 3px; }
.toc-link.is-active { color: var(--accent); font-weight: 550; }
.toc-close { display: none; }
.toc-footnote { padding-top: 18px; margin-top: 14px; border-top: 1px solid var(--line); color: var(--muted); font-size: 11px; }
.empty-body { padding: 42px 0 55px; text-align: left; }
.empty-icon { display: block; margin-bottom: 16px; color: var(--secondary); }
.empty-body h2 { font-size: 19px; font-weight: 500; }
.empty-body p { margin-top: 13px; color: var(--secondary); font-size: 14px; line-height: 1.9; }
.reader-footer { margin-top: 48px; }
.chapter-pagination { display: flex; justify-content: space-between; gap: 16px; padding-top: 19px; }
.pagination-button { display: inline-flex; align-items: center; gap: 10px; min-height: 44px; padding: 6px 0; color: var(--secondary); font-size: 13px; }
.pagination-button:hover:not(:disabled) { color: var(--ink); text-decoration: underline; text-underline-offset: 4px; }
.arrow-back { transform: rotate(180deg); }

/* 8. Search and unobtrusive feedback --------------------------------------- */
.search-dialog { width: min(660px, calc(100vw - 40px)); max-height: min(740px, calc(100vh - 80px)); max-height: min(740px, calc(100svh - 80px)); margin: 8vh auto auto; padding: 0; border: 1px solid #aaa69e; border-radius: 4px; background: var(--paper); color: var(--ink); overflow-y: auto; overscroll-behavior: contain; }
.search-dialog::backdrop { background: rgb(25 24 21 / 35%); }
.search-dialog-header { display: flex; align-items: center; justify-content: space-between; padding: 16px 21px 7px; }
.search-dialog-header h2 { font-size: 16px; font-weight: 600; }
.search-form { display: flex; align-items: center; gap: 10px; margin: 6px 22px 0; padding: 0 12px; border: 1px solid #bab6ae; border-radius: var(--radius); background: var(--surface); }
.search-form:focus-within { border-color: var(--ink); }
.search-form .icon { color: var(--secondary); width: 18px; height: 18px; }
.search-form input { min-width: 0; width: 100%; height: 45px; padding: 9px 0; border: 0; outline: 0; color: var(--ink); background: transparent; font-size: 16px; }
.search-form input::placeholder { color: var(--muted); font-size: 14px; }
.search-hint { padding: 12px 23px; color: var(--secondary); font-size: 12px; }
.search-results { padding: 0 22px 10px; }
.search-result { display: block; width: 100%; padding: 17px 0; border-top: 1px solid var(--line); border-radius: 0; text-align: left; }
.search-result:hover { background: var(--subtle); }
.search-result-meta, .search-result-title, .search-result-excerpt { display: block; }
.search-result-meta { color: var(--muted); font-size: 11px; line-height: 1.8; }
.search-result-title { margin-top: 4px; color: var(--ink); font-size: 15px; font-weight: 500; line-height: 1.7; overflow-wrap: anywhere; }
.search-result-excerpt { margin-top: 6px; color: var(--secondary); font-size: 13px; line-height: 1.8; overflow-wrap: anywhere; }
.search-result mark { padding: 1px 2px; color: var(--ink); background: #e6ddd2; }
.search-empty { padding: 27px 0 35px; color: var(--secondary); font-size: 14px; text-align: center; }
.search-dialog-footer { display: flex; align-items: center; justify-content: space-between; gap: 12px; padding: 13px 22px; border-top: 1px solid var(--line); color: var(--muted); font-size: 11px; }
.toast { position: fixed; bottom: 26px; left: 50%; z-index: 90; transform: translateX(-50%); width: max-content; max-width: calc(100vw - 40px); padding: 11px 18px; border: 1px solid var(--ink); border-radius: var(--radius); color: var(--surface); background: var(--ink); font-size: 13px; text-align: center; }

/* 9. Responsive layout ---------------------------------------------------- */
@media (min-width: 1600px) {
  .workspace { padding-right: 64px; padding-left: 64px; }
  .article-body { font-size: 17px; }
}
@media (max-width: 1200px) {
  .workspace { padding-right: 30px; padding-left: 30px; }
  .reading-layout { gap: 27px; grid-template-columns: minmax(0, 1fr) 200px; }
  .chapter-card-body { grid-template-columns: minmax(0, 1fr) 125px; gap: 6px 18px; }
}
@media (max-width: 1080px) {
  .setup-grid { grid-template-columns: minmax(0, 1fr); gap: 23px; }
  .setup-section + .setup-section { padding-top: 23px; padding-left: 0; border-top: 1px solid var(--line); border-left: 0; }
  .reading-layout { grid-template-columns: minmax(0, 740px); justify-content: center; }
  .toc-toggle { display: inline-flex; }
  .toc-panel { display: none; position: fixed; top: 0; right: 0; bottom: 0; z-index: 45; width: min(340px, calc(100vw - 36px)); max-height: 100vh; max-height: 100svh; padding: 24px; border-left: 1px solid var(--line); background: var(--paper); }
  .toc-panel.is-open { display: block; }
  .toc-heading { min-height: 40px; margin-bottom: 17px; }
  .toc-link { padding-top: 9px; padding-bottom: 9px; font-size: 13px; }
  .toc-link[data-level="3"] { font-size: 12px; }
  .toc-close { display: inline-flex; }
  .brand-name-tail { margin-left: 10px; padding-left: 10px; }
  .search-trigger kbd { display: none; }
  .chapter-card-body { grid-template-columns: minmax(0, 1fr); }
  .chapter-meta { grid-column: 1; grid-row: auto; margin-top: 2px; }
  .chapter-card { gap: 12px; padding-top: 22px; padding-bottom: 22px; }
}
@media (max-width: 850px) {
  .app-header, .login-header { padding: 0 20px; }
  .header-actions { gap: 10px; }
  .brand-name { font-size: 16px; }
  .brand-name-tail { font-size: 12px; }
  .search-trigger { width: 38px; justify-content: center; }
  .search-trigger > span { display: none; }
  .workspace { padding-right: 26px; padding-left: 26px; }
  .overview-intro h1 { font-size: 27px; }
  .chapter-title { font-size: 15px; }
  .chapter-card { grid-template-columns: 30px minmax(0, 1fr) 17px; }
  .chapter-number { font-size: 20px; }
}
@media (max-width: 720px) {
  :root { --header-height: 64px; }
  .app-header, .login-header { padding-right: 16px; padding-left: 14px; }
  .app-header { gap: 8px; }
  .header-start { gap: 7px; }
  .header-actions { gap: 4px; }
  .header-divider { display: none; }
  .mobile-menu { display: inline-flex; width: 34px; flex-shrink: 0; }
  .brand { gap: 8px; }
  .brand-mark { width: 29px; height: 31px; }
  .brand-mark .icon { width: 18px; height: 18px; }
  .app-header .brand-mark { display: none; }
  .brand-name { font-size: 15px; }
  .brand-name-tail { display: block; margin: 2px 0 0; padding: 0; border: 0; font-size: 10px; line-height: 1.3; letter-spacing: .07em; }
  .search-trigger { width: 34px; height: 40px; }
  .logout-button { width: 34px; padding: 6px; }
  .logout-button span { display: none; }
  .logout-button .icon { width: 18px; height: 18px; }
  .header-note { font-size: 11px; }
  .sidebar { z-index: 45; top: 0; width: min(300px, calc(100vw - 44px)); padding: 18px 16px 28px; transform: translateX(-100%); visibility: hidden; }
  .sidebar.is-open { transform: translateX(0); visibility: visible; }
  .sidebar-mobile-heading { display: flex; justify-content: space-between; align-items: center; padding: 0 5px 15px 12px; font-size: 14px; font-weight: 500; }
  .sidebar-label { margin-top: 24px; }
  .lesson-link { padding-top: 13px; padding-bottom: 13px; }
  .lesson-name { font-size: 14px; }
  .lesson-meta { font-size: 12px; }
  .workspace { margin-left: 0; padding: 0 22px; }
  .overview-view { padding: 30px 0 35px; }
  .overview-intro h1 { font-size: 25px; }
  .overview-stats { margin-top: 21px; padding: 13px 0; gap: 6px 17px; font-size: 12px; }
  .stat-item { gap: 5px; }
  .stat-item strong { font-size: 13px; }
  .stat-item strong > span { font-size: 12px; }
  .startup-resources { margin-top: 25px; padding-bottom: 22px; }
  .introduction-entry { margin-top: 25px; padding-bottom: 22px; }
  .introduction-entry h2 { font-size: 19px; }
  .introduction-entry p { font-size: 13px; }
  .introduction-actions { gap: 8px 18px; margin-top: 15px; }
  .setup-heading { margin-bottom: 19px; }
  .setup-heading h2 { font-size: 17px; }
  .setup-section-heading { gap: 10px; margin-bottom: 14px; }
  .setup-section-heading h3 { font-size: 15px; }
  .setup-number { font-size: 19px; }
  .resource-block + .resource-block { margin-top: 19px; }
  .resource-links { column-gap: 15px; }
  .contact-row { max-width: none; }
  .practice-index-list { grid-template-columns: minmax(0, 1fr); }
  .practice-index { margin-top: 24px; }
  .practice-index-heading h2 { font-size: 17px; }
  .practice-quick-start { padding: 17px 16px 12px; margin-bottom: 26px; }
  .reader-modes { gap: 24px; margin-bottom: 22px; }
  .reader-modes button { font-size: 13px; }
  .section-heading { margin-top: 29px; gap: 12px; }
  .section-heading h2 { font-size: 15px; }
  .section-heading p { font-size: 11px; }
  .chapter-card { grid-template-columns: 26px minmax(0, 1fr) 15px; gap: 10px; padding: 20px 0; }
  .chapter-number { font-size: 19px; }
  .chapter-card-body { row-gap: 6px; }
  .chapter-title { font-size: 15px; line-height: 1.7; font-weight: 550; }
  .chapter-description { font-size: 12px; line-height: 1.85; }
  .chapter-meta { font-size: 11px; line-height: 1.8; }
  .chapter-arrow { font-size: 18px; }
  .overview-note { margin-top: 19px; font-size: 11px; }
  .workspace-footer { flex-direction: column; gap: 4px; padding-top: 18px; padding-bottom: 22px; font-size: 10px; }
  .reader-toolbar { min-height: 62px; gap: 8px; }
  .breadcrumb { font-size: 11px; }
  .breadcrumb .separator { margin: 0 6px; }
  .toc-toggle { font-size: 11px; padding: 5px 0 5px 7px; }
  .toc-toggle .icon { width: 16px; height: 16px; }
  .reading-layout { padding-top: 27px; padding-bottom: 34px; }
  .lesson-header { margin-bottom: 28px; padding-bottom: 22px; }
  .lesson-header .eyebrow { margin-bottom: 10px; font-size: 11px; }
  .lesson-header h1 { font-size: 25px; line-height: 1.6; }
  .lesson-intro { margin-top: 13px; font-size: 13px; }
  .article-body { font-size: 16px; line-height: 1.95; }
  .article-body h1 { font-size: 24px; }
  .article-body h2 { margin-top: 36px; margin-bottom: 16px; font-size: 20px; line-height: 1.65; }
  .article-body h3 { margin-top: 28px; font-size: 17px; }
  .article-body p { margin-bottom: 18px; }
  .article-body blockquote { padding-left: 15px; }
  .article-body pre { padding-right: 14px; padding-left: 14px; font-size: 12px; }
  .article-body table { font-size: 13px; }
  .article-body th, .article-body td { padding: 10px 12px; }
  .reader-footer { margin-top: 38px; }
  .pagination-button { font-size: 12px; }
  .login-main { width: min(100% - 44px, 400px); padding: 48px 0 60px; }
  .login-intro { margin-bottom: 26px; }
  .login-intro h1 { font-size: 25px; }
  .login-footer { padding: 18px 22px; flex-wrap: wrap; gap: 5px 15px; font-size: 11px; }
  .search-dialog { width: calc(100vw - 24px); max-height: calc(100svh - 38px); margin-top: 18px; }
  .search-dialog-header { padding: 12px 15px 6px; }
  .search-form { margin-right: 16px; margin-left: 16px; }
  .search-hint { padding-right: 17px; padding-left: 17px; }
  .search-results { padding-right: 16px; padding-left: 16px; }
  .search-dialog-footer { padding-right: 16px; padding-left: 16px; }
  .toast { bottom: calc(20px + env(safe-area-inset-bottom)); font-size: 12px; }
}
@media (max-width: 380px) {
  .workspace { padding-right: 17px; padding-left: 17px; }
  .brand-name { font-size: 14px; }
  .header-note { max-width: 80px; text-align: right; }
  .chapter-card { gap: 8px; }
  .chapter-title { font-size: 14px; }
  .lesson-header h1 { font-size: 23px; }
  .section-heading { flex-wrap: wrap; gap: 3px; }
}

/* 10. Motion preferences and print ---------------------------------------- */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: .01ms !important; animation-iteration-count: 1 !important; transition-duration: .01ms !important; scroll-behavior: auto !important; }
}
@media print {
  :root { color-scheme: light; }
  body { background: #fff; color: #000; }
  .app-header, .sidebar, .toc-panel, .reader-toolbar, .reader-footer, .workspace-footer, .reading-progress-track, .drawer-backdrop, .search-dialog, .toast, .skip-link, .copy-code, .contact-copy, .reader-modes, .starter-download { display: none !important; }
  .app-layout { padding-top: 0; }
  .workspace { padding: 0; margin: 0; }
  .reader-view, .overview-view { max-width: none; padding: 0; }
  .reading-layout { display: block; padding: 0; }
  .lesson-header { margin-bottom: 20px; padding-bottom: 16px; }
  .lesson-header h1 { font-size: 22pt; }
  .article-body { font-size: 11pt; line-height: 1.8; color: #000; }
  .article-body h2 { font-size: 16pt; }
  .article-body h3 { font-size: 13pt; }
  .article-body h1, .article-body h2, .article-body h3, .article-body h4 { break-after: avoid; }
  .article-body p { orphans: 3; widows: 3; }
  .article-body pre { padding: 12px; white-space: pre-wrap; overflow: visible; }
  .article-body pre code { white-space: pre-wrap; overflow-wrap: anywhere; }
  .article-body .table-scroll, .article-body .table-wrapper { overflow: visible; }
  .article-body .table-scroll table, .article-body .table-wrapper table { min-width: 0; }
  .chapter-card { break-inside: avoid; }
  .article-body .math.display { overflow: visible; }
  .login-header, .login-footer { padding-right: 0; padding-left: 0; }
}

/* Experience-first reading: details remain available without blocking the story. */
.nav-track-label {margin:18px 12px 5px;color:var(--muted);font-size:11px;letter-spacing:.03em;}
.track-heading {padding:26px 4px 16px;border-bottom:1px solid var(--line);}
.track-heading h2 {font-size:21px;font-weight:600;}
.track-heading p {margin-top:7px;color:var(--secondary);font-size:13px;line-height:1.8;}
.chapter-grid {border-top:0;}
.chapter-number {font-size:17px;white-space:nowrap;}
.practice-index {margin:18px 0;padding:0;border:0;}
.index-disclosure > summary,.setup-disclosure > summary {padding:15px 0;cursor:pointer;font-size:14px;color:var(--secondary);}
.index-disclosure[open] > summary,.setup-disclosure[open] > summary {margin-bottom:14px;}
.setup-heading {display:none;}
.practice-quick-start {padding:0;margin:0 0 22px;border:0;border-bottom:1px solid var(--line);background:transparent;}
.quick-disclosure > summary {display:list-item;cursor:pointer;padding:12px 0 16px;font-size:13px;font-weight:600;}
.quick-disclosure > summary span {margin-left:16px;color:var(--muted);font-size:12px;font-weight:400;}
.quick-disclosure[open] {padding-bottom:15px;}
.article-body > h2:first-child {margin-top:12px;}
.article-body .result-preview {margin:22px 0 30px;padding:20px 23px;border-left:3px solid var(--accent);background:#eeece6;}
.article-body .result-preview p {margin:10px 0;line-height:1.85;}
.article-body .result-preview .preview-label {margin-top:0;color:var(--secondary);font-size:12px;font-weight:500;}
.article-body .result-preview ul,.article-body .result-preview ol {margin:12px 0;padding-left:1.4em;}
.article-body .result-preview li {margin:6px 0;}
.article-body details:not(.prompt-disclosure) {margin:20px 0;padding:15px 18px;border:1px solid var(--line);}
.article-body details > summary {cursor:pointer;font-size:14px;line-height:1.8;}
.article-body details[open] > summary {margin-bottom:12px;}
.prompt-card {position:relative;margin:18px 0 24px;border:1px solid var(--line);background:var(--surface);border-radius:3px;}
.prompt-disclosure > summary {min-height:62px;padding:19px 115px 18px 17px;color:var(--secondary);font-size:13px;}
.article-body .prompt-disclosure[open] > summary {margin:0;border-bottom:1px solid var(--line);}
.article-body .prompt-disclosure pre {margin:0;border:0;border-radius:0;padding:18px;font-size:13px;background:#f2f0eb;}
.prompt-copy {position:absolute;right:12px;top:12px;min-height:36px;padding:6px 12px;border:1px solid #cbc5bc;background:var(--paper);border-radius:2px;color:var(--ink);font-size:12px;}
.prompt-copy:hover {border-color:var(--ink);}
@media(max-width:600px){
 .quick-disclosure > summary span {display:none;}
 .article-body .result-preview {padding:16px 17px;}
 .prompt-disclosure > summary {padding:16px 104px 16px 13px;min-height:60px;font-size:12px;}
 .prompt-copy {right:9px;top:10px;padding:6px 10px;}
 .track-heading h2 {font-size:20px;}
}
@media print {.prompt-copy,.quick-disclosure,.index-disclosure,.setup-disclosure {display:none!important;}.prompt-card{break-inside:auto;}.prompt-disclosure>summary{padding:8px 0;}.article-body .prompt-disclosure pre{padding:12px;}}