/* ============================================================
   IDM下载器中文指南 · 编辑排版风格
   纸色底 / 衬线标题 / 朱砂点缀 —— 像一本印出来的手册
   ============================================================ */

:root {
  --paper: #F7F3EC;
  --paper-deep: #F1EBE0;
  --ink: #1C1B18;
  --ink-soft: #4A463F;
  --gray: #8A8377;
  --hairline: #D8CFC0;
  --cinnabar: #B23A26;
  --umber: #8A5B33;
  --serif: "Noto Serif SC", "Source Han Serif SC", "Songti SC", SimSun, Georgia, serif;
  --sans: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", sans-serif;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.9;
}

img { max-width: 100%; height: auto; display: block; }

a { color: inherit; text-decoration: none; }

.wrap {
  max-width: 1080px;
  margin: 0 auto;
  padding: 0 28px;
}

/* ---------- 顶栏 ---------- */

.site-head {
  border-bottom: 2px solid var(--ink);
}

.site-head .wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding-top: 18px;
  padding-bottom: 16px;
}

.site-head .logo img { height: 46px; width: auto; }

.site-nav { display: flex; gap: 6px; flex-wrap: wrap; }

.site-nav a {
  font-size: 14px;
  padding: 5px 13px;
  border-radius: 999px;
  color: var(--ink-soft);
  transition: background 0.2s, color 0.2s;
}

.site-nav a:hover {
  background: var(--ink);
  color: var(--paper);
}

/* ---------- 首屏 ---------- */

.hero {
  border-bottom: 1px solid var(--hairline);
  position: relative;
}

.hero .wrap {
  display: grid;
  grid-template-columns: 1.08fr 0.92fr;
  gap: 56px;
  align-items: center;
  padding-top: 72px;
  padding-bottom: 72px;
}

.eyebrow {
  display: inline-block;
  font-size: 13px;
  letter-spacing: 5px;
  color: var(--cinnabar);
  border: 1px solid var(--cinnabar);
  padding: 3px 14px 3px 19px;
  margin-bottom: 26px;
}

h1 {
  font-family: var(--serif);
  font-size: clamp(28px, 3.8vw, 42px);
  font-weight: 700;
  line-height: 1.42;
  letter-spacing: 1px;
}

h1 em {
  font-style: normal;
  color: var(--cinnabar);
  /* 着重号：中文排版里的老手法 */
  -webkit-text-emphasis: dot var(--cinnabar);
  text-emphasis: dot var(--cinnabar);
  -webkit-text-emphasis-position: under right;
  text-emphasis-position: under right;
}

.hero-intro {
  margin-top: 26px;
  color: var(--ink-soft);
  max-width: 34em;
}

.hero-cta {
  display: flex;
  gap: 16px;
  margin-top: 34px;
  flex-wrap: wrap;
}

.btn-main,
.btn-ghost {
  display: inline-block;
  font-size: 16px;
  font-weight: 700;
  letter-spacing: 2px;
  padding: 13px 34px;
  transition: transform 0.15s, box-shadow 0.15s, background 0.2s, color 0.2s;
}

.btn-main {
  background: var(--cinnabar);
  color: var(--paper);
  box-shadow: 5px 6px 0 rgba(28, 27, 24, 0.85);
}

.btn-main:hover {
  transform: translate(2px, 2px);
  box-shadow: 2px 3px 0 rgba(28, 27, 24, 0.85);
}

.btn-ghost {
  border: 1.5px solid var(--ink);
  color: var(--ink);
}

.btn-ghost:hover { background: var(--ink); color: var(--paper); }

.nav-cta {
  background: var(--cinnabar);
  color: var(--paper) !important;
  font-weight: 700;
}

.nav-cta:hover { background: var(--ink); }

.hero-stats {
  display: flex;
  margin-top: 42px;
  border-top: 1px solid var(--hairline);
}

.hero-stats > div {
  padding: 20px 34px 4px 0;
}

.hero-stats > div + div {
  border-left: 1px solid var(--hairline);
  padding-left: 34px;
}

.hero-stats b {
  display: block;
  font-family: var(--serif);
  font-size: 34px;
  font-weight: 700;
  line-height: 1.2;
  color: var(--cinnabar);
}

.hero-stats span { font-size: 13px; color: var(--gray); }

.hero-figure { position: relative; }

.hero-figure img {
  transform: rotate(0.8deg);
  box-shadow: 10px 12px 0 rgba(28, 27, 24, 0.08);
}

/* 竖排装饰 */
.vertical-note {
  position: absolute;
  right: -30px;
  top: 8px;
  writing-mode: vertical-rl;
  font-family: var(--serif);
  font-size: 13px;
  letter-spacing: 9px;
  color: var(--gray);
}

/* ---------- 章节通用 ---------- */

section { padding: 76px 0 20px; }

.sec-head {
  display: flex;
  align-items: baseline;
  gap: 20px;
  margin-bottom: 14px;
}

.sec-num {
  font-family: Georgia, var(--serif);
  font-style: italic;
  font-size: 46px;
  color: var(--cinnabar);
  line-height: 1;
  flex-shrink: 0;
}

h2 {
  font-family: var(--serif);
  font-size: clamp(24px, 3vw, 32px);
  font-weight: 700;
  letter-spacing: 1px;
}

.sec-head::after {
  content: "";
  flex: 1;
  border-bottom: 1px solid var(--hairline);
  transform: translateY(-8px);
}

h3 {
  font-family: var(--serif);
  font-size: 20px;
  font-weight: 700;
  margin: 34px 0 8px;
}

h4 {
  font-size: 15px;
  font-weight: 700;
  color: var(--umber);
  margin: 26px 0 6px;
}

h4::before { content: "◆ "; color: var(--cinnabar); font-size: 11px; }

section p { color: var(--ink-soft); max-width: 46em; }

/* ---------- 能力四栏 ---------- */

.feature-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0;
  margin-top: 38px;
  border: 1px solid var(--hairline);
  background: var(--paper-deep);
}

.feature-grid article {
  padding: 30px 34px 26px;
  position: relative;
}

.feature-grid article:nth-child(2),
.feature-grid article:nth-child(4) { border-left: 1px solid var(--hairline); }

.feature-grid article:nth-child(3),
.feature-grid article:nth-child(4) { border-top: 1px solid var(--hairline); }

.feature-grid h3 { margin-top: 0; }

.feature-grid h3::before {
  content: attr(data-no);
  font-family: Georgia, serif;
  font-style: italic;
  color: var(--cinnabar);
  margin-right: 10px;
  font-size: 17px;
}

.feature-grid p { font-size: 15px; }

/* ---------- 图文与图注 ---------- */

figure { margin: 40px 0 8px; }

figcaption {
  font-size: 13px;
  color: var(--gray);
  margin-top: 12px;
  padding-left: 14px;
  border-left: 3px solid var(--cinnabar);
  line-height: 1.7;
}

/* 正文内链 */
.text-link {
  color: var(--cinnabar);
  font-weight: 700;
  border-bottom: 1.5px solid var(--cinnabar);
  padding-bottom: 1px;
}

.text-link:hover { background: var(--cinnabar); color: var(--paper); }

/* ---------- 安装步骤 ---------- */

.steps-list { counter-reset: step; margin-top: 10px; }

.tip-box {
  margin-top: 30px;
  padding: 20px 26px;
  background: var(--paper-deep);
  border: 1px solid var(--hairline);
  border-left: 4px solid var(--cinnabar);
  max-width: 46em;
}

.tip-box h4 { margin: 0 0 4px; }
.tip-box p { font-size: 15px; }

/* ---------- 常见问题 ---------- */

.faq-item {
  border-bottom: 1px solid var(--hairline);
  padding-bottom: 26px;
}

.faq-item h3::before {
  content: "问";
  display: inline-block;
  font-family: var(--sans);
  font-size: 13px;
  color: var(--paper);
  background: var(--ink);
  width: 24px;
  height: 24px;
  line-height: 24px;
  text-align: center;
  border-radius: 50%;
  margin-right: 12px;
  transform: translateY(-2px);
}

.faq-item p { padding-left: 36px; }

/* ---------- 页脚 ---------- */

.site-foot {
  margin-top: 90px;
  border-top: 2px solid var(--ink);
  background: var(--paper-deep);
}

.site-foot .wrap {
  padding-top: 44px;
  padding-bottom: 44px;
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  gap: 30px;
  flex-wrap: wrap;
}

.site-foot .slogan {
  font-family: var(--serif);
  font-size: 19px;
  font-weight: 700;
}

.site-foot small {
  display: block;
  color: var(--gray);
  font-size: 12.5px;
  margin-top: 10px;
  line-height: 1.8;
}

/* ---------- 响应式 ---------- */

@media (max-width: 860px) {
  .hero .wrap { grid-template-columns: 1fr; gap: 44px; padding-top: 48px; padding-bottom: 52px; }
  .vertical-note { display: none; }
  .feature-grid { grid-template-columns: 1fr; }
  .feature-grid article:nth-child(n+2) { border-left: none; border-top: 1px solid var(--hairline); }
  .hero-stats { flex-wrap: wrap; }
  section { padding-top: 56px; }
  .sec-num { font-size: 36px; }
}