/* ==========================================================================
   快连官网下载 - 全站样式
   命名规范：区块用 .block 形式，元素用 .block-name，状态类统一 is- 前缀
   ========================================================================== */

/* 1. 变量与基础
   ========================================================================== */
:root {
  --bg: #f5f7fa;
  --surface: #ffffff;
  --ink: #101a2c;
  --ink-soft: #3d4a60;
  --muted: #6b7a91;
  --line: #e3e8f0;
  --line-strong: #d3dae6;
  --primary: #1f5eff;
  --primary-dark: #1746c4;
  --primary-soft: #eef3ff;
  --accent: #ff6b35;
  --accent-soft: #fff1eb;
  --green: #17a673;
  --radius-sm: 8px;
  --radius: 14px;
  --radius-lg: 20px;
  --shadow-sm: 0 1px 2px rgba(16, 26, 44, 0.05);
  --shadow: 0 10px 30px rgba(16, 26, 44, 0.07);
  --container: 1120px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

h1,
h2,
h3,
h4,
p,
ul,
ol,
figure {
  margin: 0;
}

ul,
ol {
  padding: 0;
  list-style: none;
}

a {
  color: var(--primary);
  text-decoration: none;
}

a:hover {
  color: var(--primary-dark);
}

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

code {
  padding: 2px 6px;
  border-radius: 5px;
  background: #eef1f6;
  color: #29364c;
  font-family: Consolas, Menlo, monospace;
  font-size: 0.9em;
  word-break: break-all;
}

/* 2. 布局工具
   ========================================================================== */
.container {
  width: 100%;
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 80px 0;
}

.section--tight {
  padding: 56px 0;
}

.section--white {
  background: var(--surface);
}

.section-head {
  max-width: 720px;
  margin-bottom: 44px;
}

.section-head--center {
  margin-left: auto;
  margin-right: auto;
  text-align: center;
}

.eyebrow {
  display: inline-block;
  margin-bottom: 12px;
  color: var(--accent);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.section-title {
  font-size: 34px;
  line-height: 1.3;
  letter-spacing: -0.01em;
}

.section-desc {
  margin-top: 14px;
  color: var(--muted);
  font-size: 16px;
}

.grid {
  display: grid;
  gap: 20px;
}

.grid--2 {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.grid--3 {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.grid--4 {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

/* 3. 按钮
   ========================================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 13px 24px;
  border: 1px solid transparent;
  border-radius: 10px;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.2s ease, border-color 0.2s ease, color 0.2s ease,
    transform 0.2s ease;
}

.btn:hover {
  transform: translateY(-1px);
}

.btn-primary {
  background: var(--primary);
  color: #fff;
}

.btn-primary:hover {
  background: var(--primary-dark);
  color: #fff;
}

.btn-ghost {
  border-color: var(--line-strong);
  background: var(--surface);
  color: var(--ink);
}

.btn-ghost:hover {
  border-color: var(--primary);
  color: var(--primary);
}

.btn-accent {
  background: var(--accent);
  color: #fff;
}

.btn-accent:hover {
  background: #e85a26;
  color: #fff;
}

.btn-sm {
  padding: 9px 16px;
  font-size: 14px;
}

.btn-block {
  width: 100%;
}

/* 4. 顶部导航
   ========================================================================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255, 255, 255, 0.92);
  border-bottom: 1px solid var(--line);
  backdrop-filter: saturate(180%) blur(12px);
  transition: box-shadow 0.2s ease;
}

.site-header.is-scrolled {
  box-shadow: 0 6px 20px rgba(16, 26, 44, 0.06);
}

.header-inner {
  display: flex;
  align-items: center;
  gap: 28px;
  height: 68px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--ink);
  font-weight: 800;
  letter-spacing: -0.01em;
}

.brand:hover {
  color: var(--ink);
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 34px;
  height: 34px;
  border-radius: 9px;
  background: linear-gradient(135deg, #1f5eff, #5b8bff);
  color: #fff;
  font-size: 16px;
  font-weight: 800;
}

.brand-text small {
  display: block;
  color: var(--muted);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.14em;
  line-height: 1;
}

.nav {
  margin-left: auto;
}

.nav-list {
  display: flex;
  align-items: center;
  gap: 6px;
}

.nav-link {
  display: block;
  padding: 8px 12px;
  border-radius: 8px;
  color: var(--ink-soft);
  font-size: 15px;
  white-space: nowrap;
}

.nav-link:hover {
  background: #f1f4f9;
  color: var(--ink);
}

.nav-link.is-active {
  color: var(--primary);
  font-weight: 600;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 10px;
}

.nav-toggle {
  display: none;
  width: 40px;
  height: 40px;
  border: 1px solid var(--line-strong);
  border-radius: 9px;
  background: var(--surface);
  cursor: pointer;
}

.nav-toggle span {
  display: block;
  width: 18px;
  height: 2px;
  margin: 4px auto;
  border-radius: 2px;
  background: var(--ink);
}

/* 5. 首页 Hero
   ========================================================================== */
.hero {
  position: relative;
  padding: 72px 0 64px;
  background: linear-gradient(180deg, #ffffff 0%, #f5f7fa 100%);
  overflow: hidden;
}

.hero::before {
  content: "";
  position: absolute;
  top: -180px;
  right: -140px;
  width: 520px;
  height: 520px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(31, 94, 255, 0.14), transparent 66%);
}

.hero-inner {
  position: relative;
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  gap: 56px;
  align-items: center;
}

.hero-tag {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 12px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--surface);
  color: var(--ink-soft);
  font-size: 13px;
}

.hero-tag i {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--green);
}

.hero-title {
  margin-top: 20px;
  font-size: 44px;
  line-height: 1.22;
  letter-spacing: -0.02em;
}

.hero-title em {
  background: linear-gradient(100deg, #1f5eff, #4f86ff 60%, #ff6b35);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  font-style: normal;
}

.hero-desc {
  margin-top: 20px;
  max-width: 520px;
  color: var(--muted);
  font-size: 17px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 30px;
}

.hero-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 22px;
  margin-top: 26px;
  color: var(--muted);
  font-size: 13px;
}

.hero-meta span {
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.hero-meta b {
  color: var(--ink);
}

/* 下载面板 */
.download-panel {
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--surface);
  box-shadow: var(--shadow);
  overflow: hidden;
}

.panel-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 18px 22px;
  border-bottom: 1px solid var(--line);
  background: linear-gradient(180deg, #fbfcfe, #ffffff);
}

.panel-head h2 {
  font-size: 16px;
}

.panel-head .version-tag {
  padding: 3px 9px;
  border-radius: 6px;
  background: var(--primary-soft);
  color: var(--primary);
  font-size: 12px;
  font-weight: 600;
}

.panel-list {
  padding: 8px;
}

.panel-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 13px 14px;
  border-radius: 10px;
  color: var(--ink);
  transition: background 0.18s ease;
}

.panel-item:hover {
  background: #f7f9fc;
  color: var(--ink);
}

.panel-icon {
  display: grid;
  place-items: center;
  flex: none;
  width: 38px;
  height: 38px;
  border-radius: 9px;
  background: var(--primary-soft);
  color: var(--primary);
  font-size: 15px;
  font-weight: 700;
}

.panel-icon--accent {
  background: var(--accent-soft);
  color: var(--accent);
}

.panel-info {
  flex: 1;
  min-width: 0;
}

.panel-info strong {
  display: block;
  font-size: 15px;
  font-weight: 600;
}

.panel-info small {
  color: var(--muted);
  font-size: 12px;
}

.panel-dl {
  color: var(--primary);
  font-size: 13px;
  font-weight: 600;
  white-space: nowrap;
}

.panel-foot {
  padding: 12px 22px 18px;
  color: var(--muted);
  font-size: 12px;
  text-align: center;
}

/* 6. 版本卡片
   ========================================================================== */
.version-card {
  display: flex;
  flex-direction: column;
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.version-card:hover {
  border-color: #c9d6ef;
  box-shadow: var(--shadow-sm);
}

.version-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 14px;
}

.version-name {
  font-size: 17px;
  font-weight: 700;
}

.badge {
  display: inline-block;
  padding: 3px 9px;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 12px;
  font-weight: 600;
}

.badge--soft {
  background: #eef2f8;
  color: var(--ink-soft);
  font-weight: 500;
}

.version-spec {
  margin-bottom: 18px;
  color: var(--muted);
  font-size: 14px;
}

.version-spec li {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  padding: 7px 0;
  border-bottom: 1px dashed var(--line);
}

.version-spec li:last-child {
  border-bottom: 0;
}

.version-spec b {
  color: var(--ink-soft);
  font-weight: 600;
}

/* 7. 步骤
   ========================================================================== */
.step {
  position: relative;
  padding: 26px 24px 24px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
}

.step-num {
  display: inline-block;
  margin-bottom: 14px;
  color: var(--accent);
  font-size: 13px;
  font-weight: 800;
  letter-spacing: 0.1em;
}

.step h3 {
  margin-bottom: 8px;
  font-size: 18px;
}

.step p {
  color: var(--muted);
  font-size: 14.5px;
}

/* 8. 特性卡片
   ========================================================================== */
.feature {
  padding: 26px 24px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
}

.feature-icon {
  display: grid;
  place-items: center;
  width: 42px;
  height: 42px;
  margin-bottom: 16px;
  border-radius: 11px;
  background: var(--primary-soft);
  color: var(--primary);
  font-size: 18px;
  font-weight: 700;
}

.feature h3 {
  margin-bottom: 8px;
  font-size: 17px;
}

.feature p {
  color: var(--muted);
  font-size: 14.5px;
}

/* 9. 说明区块（左右图文）
   ========================================================================== */
.split {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 56px;
  align-items: center;
}

.split--reverse .split-media {
  order: -1;
}

.split-title {
  font-size: 30px;
  line-height: 1.32;
}

.split-text {
  margin-top: 14px;
  color: var(--muted);
}

.check-list {
  margin-top: 22px;
}

.check-list li {
  position: relative;
  padding-left: 26px;
  margin-bottom: 10px;
  color: var(--ink-soft);
  font-size: 15px;
}

.check-list li::before {
  content: "✓";
  position: absolute;
  left: 0;
  top: 1px;
  color: var(--green);
  font-weight: 700;
}

.panel-box {
  padding: 26px;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--surface);
  box-shadow: var(--shadow-sm);
}

.panel-box h4 {
  margin-bottom: 14px;
  font-size: 15px;
}

/* 10. 表格
   ========================================================================== */
.table-wrap {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  overflow-x: auto;
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 14.5px;
}

thead th {
  padding: 13px 18px;
  background: #f8fafd;
  color: var(--ink-soft);
  font-size: 13px;
  font-weight: 700;
  text-align: left;
  white-space: nowrap;
}

tbody td {
  padding: 14px 18px;
  border-top: 1px solid var(--line);
  color: var(--ink-soft);
}

tbody tr:hover {
  background: #fafcff;
}

td strong {
  color: var(--ink);
}

.table-note {
  margin-top: 12px;
  color: var(--muted);
  font-size: 13px;
}

/* 11. 提示框
   ========================================================================== */
.notice {
  display: flex;
  gap: 12px;
  padding: 16px 18px;
  border: 1px solid #ffe0d3;
  border-left: 3px solid var(--accent);
  border-radius: var(--radius-sm);
  background: #fff8f4;
  color: #8a4a26;
  font-size: 14px;
}

.notice strong {
  color: #7a3d1c;
}

.notice--info {
  border-color: #d8e3ff;
  border-left-color: var(--primary);
  background: #f4f8ff;
  color: #2b4a7d;
}

.notice--info strong {
  color: #1b3a6b;
}

/* 12. FAQ
   ========================================================================== */
.faq-group + .faq-group {
  margin-top: 40px;
}

.faq-group-title {
  margin-bottom: 14px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--line);
  font-size: 18px;
}

.faq-item {
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--surface);
  overflow: hidden;
}

.faq-item + .faq-item {
  margin-top: 10px;
}

.faq-question {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  width: 100%;
  padding: 17px 20px;
  border: 0;
  background: transparent;
  color: var(--ink);
  font-family: inherit;
  font-size: 15.5px;
  font-weight: 600;
  text-align: left;
  cursor: pointer;
}

.faq-icon {
  flex: none;
  color: var(--muted);
  font-size: 18px;
  line-height: 1;
  transition: transform 0.2s ease;
}

.faq-item.is-open .faq-icon {
  transform: rotate(45deg);
  color: var(--primary);
}

.faq-answer {
  display: none;
  padding: 0 20px 18px;
  color: var(--muted);
  font-size: 14.5px;
}

.faq-item.is-open .faq-answer {
  display: block;
}

/* 13. 页头（内页）
   ========================================================================== */
.page-head {
  padding: 56px 0 44px;
  background: var(--surface);
  border-bottom: 1px solid var(--line);
}

.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 16px;
  color: var(--muted);
  font-size: 13px;
}

.breadcrumb a {
  color: var(--muted);
}

.breadcrumb a:hover {
  color: var(--primary);
}

.breadcrumb span::before {
  content: "/";
  margin-right: 8px;
  color: #c3ccda;
}

.page-title {
  font-size: 40px;
  line-height: 1.25;
  letter-spacing: -0.02em;
}

.page-desc {
  max-width: 680px;
  margin-top: 14px;
  color: var(--muted);
  font-size: 16.5px;
}

/* 14. 下载页：系统切换
   ========================================================================== */
.tab-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  padding: 6px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--surface);
}

.tab-btn {
  flex: 1;
  min-width: 100px;
  padding: 11px 16px;
  border: 0;
  border-radius: 8px;
  background: transparent;
  color: var(--ink-soft);
  font-family: inherit;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.18s ease, color 0.18s ease;
}

.tab-btn:hover {
  background: #f3f6fb;
}

.tab-btn.is-active {
  background: var(--primary);
  color: #fff;
}

.tab-panel {
  display: none;
  margin-top: 24px;
}

.tab-panel.is-active {
  display: block;
}

.detail-card {
  display: grid;
  grid-template-columns: 1fr 320px;
  gap: 32px;
  padding: 30px;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--surface);
}

.detail-card h3 {
  margin-bottom: 6px;
  font-size: 22px;
}

.detail-card > div > p {
  color: var(--muted);
  font-size: 14.5px;
}

.detail-side {
  padding-left: 28px;
  border-left: 1px solid var(--line);
}

.detail-side li {
  display: flex;
  justify-content: space-between;
  gap: 10px;
  padding: 8px 0;
  border-bottom: 1px dashed var(--line);
  color: var(--muted);
  font-size: 13.5px;
}

.detail-side li:last-child {
  border-bottom: 0;
}

.detail-side b {
  color: var(--ink);
  font-weight: 600;
}

.detail-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 20px;
}

.hash-line {
  display: block;
  margin-top: 16px;
  padding: 10px 12px;
  border: 1px dashed var(--line-strong);
  border-radius: 8px;
  color: var(--muted);
  font-family: Consolas, Menlo, monospace;
  font-size: 12px;
  word-break: break-all;
}

/* 15. 教程页：步骤块
   ========================================================================== */
.guide-block {
  padding: 30px;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--surface);
}

.guide-block + .guide-block {
  margin-top: 22px;
}

.guide-head {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 22px;
}

.guide-index {
  display: grid;
  place-items: center;
  flex: none;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--ink);
  color: #fff;
  font-size: 15px;
  font-weight: 700;
}

.guide-head h2 {
  font-size: 21px;
}

.guide-head p {
  color: var(--muted);
  font-size: 13.5px;
}

.step-list {
  counter-reset: step;
}

.step-list li {
  position: relative;
  padding: 0 0 18px 40px;
  counter-increment: step;
}

.step-list li::before {
  content: counter(step);
  position: absolute;
  left: 0;
  top: 2px;
  display: grid;
  place-items: center;
  width: 24px;
  height: 24px;
  border: 1px solid var(--line-strong);
  border-radius: 50%;
  background: #fbfcfe;
  color: var(--ink-soft);
  font-size: 12px;
  font-weight: 700;
}

.step-list li::after {
  content: "";
  position: absolute;
  left: 12px;
  top: 30px;
  bottom: 6px;
  width: 1px;
  background: var(--line);
}

.step-list li:last-child {
  padding-bottom: 0;
}

.step-list li:last-child::after {
  display: none;
}

.step-list h4 {
  margin-bottom: 4px;
  font-size: 15.5px;
}

.step-list p {
  color: var(--muted);
  font-size: 14.5px;
}

/* 16. 联系页
   ========================================================================== */
.contact-card {
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
}

.contact-card h3 {
  margin-bottom: 6px;
  font-size: 16px;
}

.contact-card p {
  color: var(--muted);
  font-size: 14px;
}

.contact-card strong {
  display: block;
  margin-top: 10px;
  color: var(--primary);
  font-size: 15px;
  font-weight: 700;
  overflow-wrap: anywhere;
}

.form {
  padding: 30px;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--surface);
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.field {
  margin-bottom: 16px;
}

.field label {
  display: block;
  margin-bottom: 6px;
  color: var(--ink-soft);
  font-size: 14px;
  font-weight: 600;
}

.field input,
.field select,
.field textarea {
  width: 100%;
  padding: 11px 13px;
  border: 1px solid var(--line-strong);
  border-radius: 8px;
  background: #fbfcfe;
  color: var(--ink);
  font-family: inherit;
  font-size: 14.5px;
  transition: border-color 0.18s ease, box-shadow 0.18s ease;
}

.field textarea {
  min-height: 120px;
  resize: vertical;
}

.field input:focus,
.field select:focus,
.field textarea:focus {
  outline: 0;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(31, 94, 255, 0.12);
}

.field-error {
  display: none;
  margin-top: 5px;
  color: #d33b2c;
  font-size: 12.5px;
}

.field.has-error input,
.field.has-error textarea {
  border-color: #e07264;
}

.field.has-error .field-error {
  display: block;
}

.form-tip {
  margin-top: 14px;
  color: var(--muted);
  font-size: 12.5px;
}

.form-success {
  display: none;
  margin-top: 14px;
  padding: 12px 14px;
  border-radius: 8px;
  background: #effaf4;
  color: #17734f;
  font-size: 14px;
}

.form-success.is-visible {
  display: block;
}

/* 17. CTA
   ========================================================================== */
.cta {
  padding: 44px;
  border-radius: var(--radius-lg);
  background: linear-gradient(120deg, #14224a, #1f5eff);
  color: #fff;
}

.cta-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 32px;
}

.cta h2 {
  font-size: 28px;
  line-height: 1.3;
}

.cta p {
  margin-top: 8px;
  color: rgba(255, 255, 255, 0.78);
  font-size: 15px;
}

.cta-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.cta .btn-ghost {
  border-color: rgba(255, 255, 255, 0.5);
  background: transparent;
  color: #fff;
}

.cta .btn-ghost:hover {
  border-color: #fff;
  color: #fff;
}

.cta .btn-primary {
  background: #fff;
  color: #14224a;
}

.cta .btn-primary:hover {
  background: #eef2fa;
  color: #14224a;
}

/* 18. 页脚
   ========================================================================== */
.site-footer {
  padding: 56px 0 28px;
  background: #0e1728;
  color: #9aa8bd;
  font-size: 14px;
}

.footer-top {
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr 1fr;
  gap: 36px;
  padding-bottom: 36px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.09);
}

.footer-brand .brand {
  color: #fff;
}

.footer-brand .brand:hover {
  color: #fff;
}

.footer-brand p {
  margin-top: 14px;
  max-width: 300px;
  line-height: 1.7;
}

.footer-col h4 {
  margin-bottom: 14px;
  color: #fff;
  font-size: 14px;
}

.footer-col li {
  margin-bottom: 9px;
}

.footer-col a {
  color: #9aa8bd;
}

.footer-col a:hover {
  color: #fff;
}

.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding-top: 22px;
  font-size: 13px;
}

.footer-bottom p {
  color: #7d8ba1;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 18px;
}

/* 19. 返回顶部
   ========================================================================== */
.back-top {
  position: fixed;
  right: 24px;
  bottom: 24px;
  z-index: 40;
  display: grid;
  place-items: center;
  width: 44px;
  height: 44px;
  border: 1px solid var(--line-strong);
  border-radius: 50%;
  background: var(--surface);
  color: var(--ink-soft);
  font-size: 12px;
  font-weight: 700;
  cursor: pointer;
  box-shadow: var(--shadow-sm);
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.2s ease, visibility 0.2s ease;
}

.back-top.is-visible {
  opacity: 1;
  visibility: visible;
}

/* 20. 滚动入场
   默认可见，仅在脚本可用（html 带 js 类）时才启用隐藏与淡入
   ========================================================================== */
.js .reveal {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}

.js .reveal.is-visible {
  opacity: 1;
  transform: none;
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  .js .reveal {
    opacity: 1;
    transform: none;
    transition: none;
  }

  .btn:hover {
    transform: none;
  }
}

/* 21. 响应式
   ========================================================================== */
@media (max-width: 1024px) {
  .hero-inner {
    grid-template-columns: 1fr;
    gap: 40px;
  }

  .hero-title {
    font-size: 42px;
  }

  .grid--4 {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .split {
    gap: 36px;
  }

  .detail-card {
    grid-template-columns: 1fr;
    gap: 24px;
  }

  .detail-side {
    padding-left: 0;
    padding-top: 20px;
    border-left: 0;
    border-top: 1px solid var(--line);
  }

  .footer-top {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 860px) {
  .nav {
    position: absolute;
    left: 0;
    right: 0;
    top: 68px;
    margin: 0;
    padding: 10px 24px 18px;
    border-bottom: 1px solid var(--line);
    background: var(--surface);
    box-shadow: var(--shadow);
    display: none;
  }

  .nav.is-open {
    display: block;
  }

  .nav-list {
    flex-direction: column;
    align-items: stretch;
    gap: 2px;
  }

  .nav-link {
    padding: 11px 12px;
    font-size: 15.5px;
  }

  .nav-toggle {
    display: block;
  }

  .header-actions .btn {
    display: none;
  }

  .grid--3 {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .split {
    grid-template-columns: 1fr;
  }

  .split--reverse .split-media {
    order: 0;
  }

  .cta-inner {
    flex-direction: column;
    align-items: flex-start;
  }
}

@media (max-width: 640px) {
  .section {
    padding: 56px 0;
  }

  .hero {
    padding: 44px 0 48px;
  }

  .hero-title {
    font-size: 33px;
  }

  .hero-desc {
    font-size: 15.5px;
  }

  .section-title {
    font-size: 26px;
  }

  .page-title {
    font-size: 29px;
  }

  .grid--2,
  .grid--3,
  .grid--4 {
    grid-template-columns: 1fr;
  }

  .form-row {
    grid-template-columns: 1fr;
    gap: 0;
  }

  .cta {
    padding: 28px 22px;
  }

  .cta h2 {
    font-size: 22px;
  }

  .detail-card,
  .guide-block,
  .form {
    padding: 22px 20px;
  }

  .footer-top {
    grid-template-columns: 1fr;
    gap: 26px;
  }

  .footer-bottom {
    flex-direction: column;
    align-items: flex-start;
  }

  .panel-item {
    padding: 12px 10px;
  }
}