:root {
  --paper: #f4f1e9;
  --paper-2: #ebe7dd;
  --ink: #12243a;
  --muted: #586779;
  --blue: #1857ff;
  --blue-dark: #0d39a8;
  --green: #00a57b;
  --orange: #ff6b2c;
  --line: #cfd1cc;
  --white: #fffefa;
  --max: 1180px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", Arial, sans-serif;
  font-size: 16px;
  line-height: 1.75;
  text-rendering: optimizeLegibility;
}
a { color: inherit; text-decoration-thickness: 1px; text-underline-offset: 4px; }
a:hover { color: var(--blue); }
img { max-width: 100%; height: auto; }
.skip-link { position: absolute; left: -9999px; top: 0; z-index: 99; background: var(--white); padding: 12px; }
.skip-link:focus { left: 12px; }
.container { width: min(calc(100% - 40px), var(--max)); margin-inline: auto; }
.narrow { width: min(calc(100% - 40px), 840px); margin-inline: auto; }

.site-header {
  position: sticky; top: 0; z-index: 30;
  border-bottom: 1px solid rgba(18,36,58,.18);
  background: rgba(244,241,233,.95);
  backdrop-filter: blur(12px);
}
.nav-wrap { min-height: 74px; display: flex; align-items: center; justify-content: space-between; gap: 24px; }
.brand { display: flex; align-items: center; gap: 11px; text-decoration: none; font-weight: 900; letter-spacing: -.02em; font-size: 21px; }
.brand-mark { display: grid; place-items: center; width: 33px; height: 33px; color: white; background: var(--ink); border-radius: 50% 50% 50% 12%; font-size: 14px; }
.brand-logo { display: block; width: 33px; height: 33px; flex: 0 0 33px; }
.main-nav { display: flex; gap: 4px; align-items: center; }
.main-nav a { padding: 8px 10px; text-decoration: none; font-size: 14px; border-bottom: 2px solid transparent; }
.main-nav a[aria-current="page"] { color: var(--blue); border-color: var(--blue); font-weight: 700; }
.nav-cta { background: var(--ink); color: white !important; border-radius: 999px; padding-inline: 15px !important; }

.hero { padding: 92px 0 76px; border-bottom: 1px solid var(--line); overflow: hidden; }
.hero-grid { display: grid; grid-template-columns: minmax(0,1.3fr) minmax(300px,.7fr); gap: 72px; align-items: end; }
.eyebrow { margin: 0 0 18px; color: var(--blue); font-weight: 800; font-size: 13px; letter-spacing: .12em; text-transform: uppercase; }
h1,h2,h3 { margin-top: 0; line-height: 1.22; letter-spacing: -.035em; }
h1 { font-size: clamp(42px, 6.5vw, 82px); max-width: 950px; margin-bottom: 24px; }
h2 { font-size: clamp(30px, 4vw, 50px); margin-bottom: 22px; }
h3 { font-size: clamp(20px, 2.3vw, 28px); margin-bottom: 12px; }
p { margin: 0 0 1em; }
.lead { font-size: clamp(18px, 2vw, 22px); color: #34475b; max-width: 760px; }
.hero-note { border-top: 4px solid var(--blue); padding-top: 20px; }
.hero-note strong { display: block; font-size: 22px; line-height: 1.45; margin-bottom: 12px; }
.hero-media { width: min(100%, 460px); margin: 42px auto 0; position: relative; }
.hero-media img { width: 100%; height: auto; aspect-ratio: 3 / 2; object-fit: cover; display: block; }
.hero-media figcaption, .content-media figcaption { margin-top: 10px; color: var(--muted); font-size: 13px; }
.hero-media::before { content: "学习现场 / 01"; position: absolute; left: 18px; top: 18px; z-index: 2; padding: 6px 10px; background: var(--ink); color: white; font: 800 11px ui-monospace, Consolas, monospace; letter-spacing: .06em; }
.content-media { width: min(100%, 420px); margin: 30px 0 34px; }
.content-media img { display: block; width: 100%; height: auto; aspect-ratio: 3 / 2; object-fit: cover; background: var(--paper-2); }
.content-media.compact { max-width: 820px; }
.content-media.split-image img { aspect-ratio: 3 / 2; }
.image-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.image-grid figure { margin: 0; background: var(--white); }
.image-grid figure:first-child { grid-row: auto; }
.image-grid img, .image-grid figure:first-child img { width: 100%; height: auto; min-height: 0; aspect-ratio: 3 / 2; object-fit: cover; display: block; }
.image-grid figcaption { padding: 12px 14px 15px; color: var(--muted); font-size: 13px; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 30px; }
.button { display: inline-flex; align-items: center; justify-content: center; padding: 12px 19px; border: 1px solid var(--ink); background: var(--ink); color: #fff; text-decoration: none; font-weight: 700; }
.button.alt { color: var(--ink); background: transparent; }
.button.blue { background: var(--blue); border-color: var(--blue); }
.button.disabled { background: #d9d8d2; color: #6c7174; border-color: #b9bbb7; cursor: not-allowed; }

.section { padding: 88px 0; border-bottom: 1px solid var(--line); }
.section.blue-section { background: var(--ink); color: white; }
.section.blue-section .muted { color: #c7d0db; }
.section-title { display: grid; grid-template-columns: .48fr 1fr; gap: 42px; align-items: start; margin-bottom: 44px; }
.section-index { font-family: ui-monospace, Consolas, monospace; color: var(--blue); font-weight: 800; }
.muted { color: var(--muted); }
.kicker { color: var(--green); font-weight: 800; font-size: 13px; letter-spacing: .08em; }

.problem-list { list-style: none; padding: 0; margin: 0; border-top: 1px solid var(--line); }
.problem-list li { border-bottom: 1px solid var(--line); }
.problem-list a { display: grid; grid-template-columns: 50px 1fr 28px; gap: 16px; align-items: center; padding: 20px 0; text-decoration: none; font-size: clamp(17px,2vw,23px); font-weight: 700; }
.problem-list span:first-child { color: var(--blue); font: 700 13px ui-monospace, Consolas, monospace; }
.problem-list span:last-child { font-size: 24px; color: var(--blue); }

.workflow { display: grid; grid-template-columns: repeat(6,1fr); border: 1px solid #526274; }
.workflow-step { min-height: 230px; padding: 22px 18px; border-right: 1px solid #526274; position: relative; }
.workflow-step:last-child { border-right: 0; }
.workflow-step b { display: block; color: #58d7bc; font: 800 12px ui-monospace, Consolas, monospace; margin-bottom: 48px; }
.workflow-step h3 { font-size: 19px; }
.workflow-step p { color: #c7d0db; font-size: 14px; }
.workflow-step:not(:last-child)::after { content: "→"; position: absolute; right: -12px; top: 50%; z-index: 2; background: var(--ink); color: #58d7bc; padding: 2px; }

.feature-ledger { display: grid; grid-template-columns: repeat(2,1fr); border-top: 1px solid var(--line); border-left: 1px solid var(--line); }
.feature-item { padding: 30px; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); min-height: 185px; }
.feature-item:nth-child(3n) h3 { color: var(--green); }
.feature-item b { font: 800 12px ui-monospace, Consolas, monospace; color: var(--blue); }

.table-wrap { overflow-x: auto; border: 1px solid var(--line); background: rgba(255,255,255,.24); }
table { border-collapse: collapse; width: 100%; min-width: 680px; }
th, td { text-align: left; padding: 15px 18px; border-bottom: 1px solid var(--line); border-right: 1px solid var(--line); vertical-align: top; }
th { background: var(--ink); color: white; font-size: 14px; }
tr:last-child td { border-bottom: 0; }
td:first-child { font-weight: 800; }
.table-note { max-width: 820px; margin-top: 22px; color: var(--muted); }

.magazine { display: grid; grid-template-columns: 230px minmax(0, 1fr); gap: 55px; }
.magazine-index { position: sticky; top: 105px; align-self: start; }
.magazine-index ol { padding-left: 20px; margin: 20px 0 0; }
.magazine-index li { margin-bottom: 9px; font-size: 13px; line-height: 1.45; }
.magazine-index a { text-decoration: none; }
.article { padding: 0 0 74px; margin-bottom: 74px; border-bottom: 1px solid var(--line); }
.article:last-child { margin-bottom: 0; }
.article-num { color: var(--blue); font: 900 14px ui-monospace, Consolas, monospace; }
.article h2 { max-width: 900px; }
.article .dek { font-size: 19px; color: #43566a; border-left: 4px solid var(--orange); padding-left: 18px; }
.article p, .article li { max-width: 820px; }
.article ol, .article ul { padding-left: 24px; }
.article li { margin-bottom: 7px; }
.article-quote { margin: 28px 0; padding: 22px 26px; background: var(--white); border-top: 4px solid var(--green); font-size: 19px; font-weight: 700; }
.split { display: grid; grid-template-columns: repeat(2,1fr); gap: 42px; }
.checklist { list-style: none; padding: 0 !important; }
.checklist li { padding: 12px 0 12px 31px; border-bottom: 1px solid var(--line); position: relative; }
.checklist li::before { content: "✓"; position: absolute; left: 0; color: var(--green); font-weight: 900; }
.number-steps { counter-reset: item; list-style: none; padding: 0; border-top: 1px solid var(--line); }
.number-steps li { counter-increment: item; display: grid; grid-template-columns: 55px 1fr; gap: 18px; padding: 22px 0; border-bottom: 1px solid var(--line); }
.number-steps li::before { content: counter(item, decimal-leading-zero); color: var(--blue); font: 800 13px ui-monospace, Consolas, monospace; }

.page-hero { padding: 76px 0 58px; border-bottom: 1px solid var(--line); }
.page-hero h1 { font-size: clamp(40px,6vw,70px); }
.breadcrumbs { display: flex; flex-wrap: wrap; gap: 8px; color: var(--muted); font-size: 13px; margin-bottom: 28px; }
.page-grid { display: grid; grid-template-columns: 245px minmax(0, 1fr); gap: 60px; }
.toc { position: sticky; top: 105px; align-self: start; border-top: 4px solid var(--blue); padding-top: 16px; }
.toc a { display: block; padding: 8px 0; text-decoration: none; font-size: 14px; border-bottom: 1px solid var(--line); }
.content-section { padding: 0 0 62px; margin-bottom: 62px; border-bottom: 1px solid var(--line); }
.content-section p, .content-section li { max-width: 800px; }
.callout { padding: 26px 28px; background: var(--white); border-left: 5px solid var(--blue); margin: 26px 0; }
.callout.green { border-color: var(--green); }
.case-board { background: var(--ink); color: white; padding: 34px; margin: 26px 0; }
.case-board .muted { color: #c4ceda; }
.tag-row { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 24px; }
.tag { padding: 5px 10px; border: 1px solid currentColor; color: var(--blue); font-size: 12px; font-weight: 800; }
.status { display: inline-flex; align-items: center; gap: 7px; color: var(--green); font-weight: 800; font-size: 13px; }
.status::before { content: ""; width: 8px; height: 8px; border-radius: 50%; background: currentColor; }
.download-panel { display: grid; grid-template-columns: 1fr auto; gap: 30px; align-items: center; padding: 34px; border: 2px solid var(--ink); background: var(--white); }

.faq { max-width: 920px; }
.faq details { border-top: 1px solid var(--line); }
.faq details:last-child { border-bottom: 1px solid var(--line); }
.faq summary { cursor: pointer; list-style: none; padding: 22px 46px 22px 0; font-size: 19px; font-weight: 800; position: relative; }
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: "+"; position: absolute; right: 6px; font-size: 24px; color: var(--blue); }
.faq details[open] summary::after { content: "−"; }
.faq details p { padding: 0 40px 22px 0; color: var(--muted); }

.site-footer { background: #0c1c2d; color: white; padding: 60px 0 26px; }
.footer-grid { display: grid; grid-template-columns: 1.2fr 1fr 1fr; gap: 60px; padding-bottom: 45px; }
.footer-brand { font-size: 30px; font-weight: 900; margin-bottom: 8px; }
.footer-title { color: #7e91a5; font: 800 12px ui-monospace, Consolas, monospace; letter-spacing: .08em; }
.footer-links a { display: block; padding: 4px 0; color: #d9e0e7; text-decoration: none; font-size: 14px; }
.footer-bottom { border-top: 1px solid #354454; padding-top: 22px; display: flex; justify-content: space-between; gap: 20px; flex-wrap: wrap; color: #9caaba; font-size: 12px; }

@media (max-width: 900px) {
  .nav-wrap { align-items: flex-start; flex-direction: column; padding-block: 14px; gap: 10px; }
  .main-nav { display: flex; width: 100%; overflow-x: auto; padding-bottom: 5px; }
  .main-nav a { white-space: nowrap; }
  .hero-grid, .section-title, .page-grid, .magazine { grid-template-columns: 1fr; }
  .hero { padding-top: 60px; }
  .workflow { grid-template-columns: repeat(2,1fr); }
  .workflow-step { border-bottom: 1px solid #526274; }
  .workflow-step:nth-child(2n) { border-right: 0; }
  .workflow-step::after { display: none; }
  .magazine-index, .toc { position: static; }
  .magazine-index { display: none; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .image-grid { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 600px) {
  .container, .narrow { width: min(calc(100% - 28px), var(--max)); }
  .hero, .section { padding: 58px 0; }
  h1 { font-size: 40px; }
  h2 { font-size: 30px; }
  .workflow, .feature-ledger, .split, .footer-grid { grid-template-columns: 1fr; }
  .image-grid { grid-template-columns: 1fr; }
  .image-grid figure:first-child { grid-row: auto; }
  .image-grid figure:first-child img, .image-grid img { min-height: 0; aspect-ratio: 3 / 2; }
  .workflow-step { border-right: 0; min-height: 0; }
  .feature-item { padding: 23px 20px; }
  .download-panel { grid-template-columns: 1fr; }
  .problem-list a { grid-template-columns: 36px 1fr 18px; }
  .article { padding-bottom: 50px; margin-bottom: 50px; }
  .hero-media { margin-top: 34px; }
  .hero-media img { aspect-ratio: 3 / 2; }
}
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }