/* =========================================================
   site.css — 买球APP官网 共享核心样式
   数据叙事型布局 / 深空蓝+橙黄状态系统 / 左右分置导航
   ========================================================= */

/* ---------- 1. Reset ---------- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-primary);
  font-size: 16px;
  line-height: 1.75;
  color: var(--color-text);
  background: var(--color-bg-light);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-wrap: break-word;
}

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

ul, ol {
  list-style: none;
}

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

button {
  font-family: inherit;
  font-size: inherit;
  background: none;
  border: none;
  cursor: pointer;
  color: inherit;
}

table {
  border-collapse: collapse;
  width: 100%;
}

input, textarea, select {
  font: inherit;
  color: inherit;
}

/* ---------- 2. CSS Variables ---------- */
:root {
  --color-space-blue: #0A1D3C;
  --color-deep: #0D264F;
  --color-orange: #FF6B35;
  --color-yellow: #FFC107;
  --color-mist: #D9E1EC;
  --color-bg-light: #F4F6FA;
  --color-white: #FFFFFF;
  --color-text: #1A1D24;
  --color-text-muted: #6C757D;
  --color-cyan: #00C2A8;
  --color-purple: #8A63D2;

  --font-primary: "Inter", -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif;
  --font-display: "Archivo Black", "Arial Black", "PingFang SC", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif;
  --font-editorial: "Noto Serif SC", "Source Han Serif CN", "Songti SC", SimSun, serif;
  --font-mono: "IBM Plex Mono", "SF Mono", "Cascadia Code", Consolas, "Liberation Mono", monospace;

  --container-width: 1280px;
  --header-height: 76px;
  --space-xs: 8px;
  --space-sm: 16px;
  --space-md: 32px;
  --space-lg: 64px;
  --space-xl: 96px;
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --shadow-card: 0 2px 16px rgba(10, 29, 60, 0.06);
  --shadow-lift: 0 6px 20px rgba(10, 29, 60, 0.1);
}

/* ---------- 3. 基础排版 ---------- */
h1, h2, h3 {
  font-family: var(--font-display);
  font-weight: 700;
  line-height: 1.3;
  letter-spacing: -0.01em;
  color: var(--color-text);
}

h4, h5, h6 {
  font-family: var(--font-primary);
  font-weight: 600;
  line-height: 1.4;
  color: var(--color-text);
}

p {
  margin-bottom: 1em;
}

em, cite {
  font-family: var(--font-editorial);
}

code, kbd {
  font-family: var(--font-mono);
  font-size: 0.92em;
  background: rgba(10, 29, 60, 0.06);
  border-radius: 4px;
  padding: 2px 6px;
}

::selection {
  background: rgba(255, 107, 53, 0.25);
}

:focus-visible {
  outline: 3px solid rgba(255, 107, 53, 0.65);
  outline-offset: 3px;
  border-radius: 2px;
}

/* ---------- 4. 工具类 ---------- */
.container {
  width: 100%;
  max-width: var(--container-width);
  margin-right: auto;
  margin-left: auto;
  padding-right: 24px;
  padding-left: 24px;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  border: 0;
  clip: rect(0 0 0 0);
  clip-path: inset(50%);
  overflow: hidden;
  white-space: nowrap;
}

.text-muted {
  color: var(--color-text-muted);
}

.font-mono {
  font-family: var(--font-mono);
}

.font-editorial {
  font-family: var(--font-editorial);
}

.display-title {
  font-family: var(--font-display);
  font-weight: 700;
}

.text-link {
  color: var(--color-orange);
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-color: rgba(255, 107, 53, 0.35);
  transition: color 0.2s ease, text-decoration-color 0.2s ease;
}

.text-link:hover,
.text-link:focus-visible {
  color: #e45320;
  text-decoration-color: currentColor;
}

.bg-space {
  background: var(--color-space-blue);
  color: var(--color-white);
}

.bg-deep {
  background: var(--color-deep);
  color: var(--color-white);
}

.bg-light {
  background: var(--color-bg-light);
}

.bg-white {
  background: var(--color-white);
}

.text-orange { color: var(--color-orange); }
.text-yellow { color: var(--color-yellow); }
.text-cyan { color: var(--color-cyan); }
.text-purple { color: var(--color-purple); }

/* ---------- 5. 头部 ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background:
    radial-gradient(circle at 88% 0%, rgba(0, 194, 168, 0.06) 0%, transparent 42%),
    var(--color-space-blue);
  color: var(--color-white);
  border-bottom: 1px solid rgba(255, 255, 255, 0.06);
}

.site-header::before {
  content: "";
  position: absolute;
  top: 0;
  right: 0;
  width: 22%;
  height: 100%;
  background: linear-gradient(225deg, rgba(255, 107, 53, 0.06) 0%, transparent 100%);
  clip-path: polygon(100% 0, 100% 100%, 0 100%);
  pointer-events: none;
}

.header-topbar {
  height: 3px;
  background: linear-gradient(90deg,
    var(--color-orange) 0%, var(--color-orange) 18%,
    var(--color-yellow) 18%, var(--color-yellow) 30%,
    transparent 30%, transparent 100%);
}

.header-inner {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  min-height: var(--header-height);
}

/* 品牌 */
.site-brand {
  flex-shrink: 0;
}

.site-brand-link {
  display: flex;
  align-items: center;
  gap: 12px;
}

.site-brand-mark {
  position: relative;
  width: 44px;
  height: 44px;
  border-radius: 14px 4px 14px 4px;
  background: linear-gradient(140deg, var(--color-orange) 0%, #ff9f1c 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-display);
  font-size: 20px;
  font-weight: 700;
  color: var(--color-white);
  box-shadow: 0 4px 14px rgba(255, 107, 53, 0.3);
  flex-shrink: 0;
  overflow: hidden;
  transition: box-shadow 0.25s ease;
}

.site-brand-mark::after {
  content: "";
  position: absolute;
  left: -20%;
  top: 50%;
  width: 140%;
  height: 2px;
  background: rgba(255, 255, 255, 0.35);
  transform: rotate(32deg);
}

.site-brand-link:hover .site-brand-mark,
.site-brand-link:focus-visible .site-brand-mark {
  box-shadow: 0 0 0 7px rgba(255, 107, 53, 0.14);
}

.site-brand-text {
  display: flex;
  flex-direction: column;
  line-height: 1.3;
}

.site-brand-name {
  font-family: var(--font-display);
  font-size: 19px;
  font-weight: 700;
  letter-spacing: 0.02em;
  color: var(--color-white);
  white-space: nowrap;
}

.site-brand-tagline {
  font-size: 12px;
  letter-spacing: 0.08em;
  color: rgba(255, 255, 255, 0.42);
  white-space: nowrap;
}

/* 导航 */
.site-nav-toggle {
  display: none;
  width: 44px;
  height: 44px;
  border-radius: 10px;
  border: 1px solid rgba(255, 255, 255, 0.12);
  background: rgba(255, 255, 255, 0.05);
  align-items: center;
  justify-content: center;
  flex-direction: column;
  gap: 5px;
  flex-shrink: 0;
  transition: background 0.25s ease, border-color 0.25s ease;
}

.site-nav-toggle:hover,
.site-nav-toggle:focus-visible {
  background: rgba(255, 255, 255, 0.1);
  border-color: rgba(255, 193, 107, 0.4);
}

.site-nav-toggle-line {
  width: 18px;
  height: 2px;
  background: var(--color-white);
  border-radius: 2px;
  transition: transform 0.3s ease, opacity 0.3s ease;
}

.site-nav-toggle[aria-expanded="true"] .site-nav-toggle-line:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.site-nav-toggle[aria-expanded="true"] .site-nav-toggle-line:nth-child(2) {
  opacity: 0;
}

.site-nav-toggle[aria-expanded="true"] .site-nav-toggle-line:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

.site-nav-list {
  display: flex;
  align-items: center;
  gap: 2px;
}

.site-nav-link {
  position: relative;
  display: inline-block;
  padding: 12px 16px;
  font-size: 15px;
  font-weight: 500;
  line-height: 1.4;
  color: rgba(255, 255, 255, 0.72);
  white-space: nowrap;
  transition: color 0.25s ease;
}

.site-nav-link::after {
  content: "";
  position: absolute;
  left: 16px;
  right: 16px;
  bottom: 5px;
  height: 2px;
  background: var(--color-orange);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform 0.3s ease, background 0.3s ease;
}

.site-nav-link:hover,
.site-nav-link:focus-visible {
  color: var(--color-white);
}

.site-nav-link:hover::after,
.site-nav-link:focus-visible::after {
  transform: scaleX(1);
}

.site-nav-link[aria-current="page"] {
  color: var(--color-orange);
}

.site-nav-link[aria-current="page"]::after {
  transform: scaleX(1);
  background: var(--color-yellow);
}

/* 滚动进度条 */
.scroll-progress {
  position: absolute;
  bottom: 0;
  left: 0;
  height: 2px;
  width: 0%;
  background: linear-gradient(90deg, var(--color-orange) 0%, var(--color-yellow) 100%);
  z-index: 2;
  pointer-events: none;
}

/* 跳转链接 */
.skip-link {
  position: fixed;
  top: -48px;
  left: 16px;
  z-index: 9999;
  padding: 10px 18px;
  background: var(--color-orange);
  color: var(--color-white);
  font-size: 14px;
  font-weight: 600;
  line-height: 1.4;
  border-radius: 0 0 10px 10px;
  transition: top 0.25s ease;
}

.skip-link:focus-visible {
  top: 0;
}

/* ---------- 6. 页脚 ---------- */
.site-footer {
  background:
    radial-gradient(ellipse at 85% 20%, rgba(255, 107, 53, 0.05) 0%, transparent 50%),
    linear-gradient(180deg, var(--color-deep) 0%, var(--color-space-blue) 100%);
  color: rgba(255, 255, 255, 0.7);
  position: relative;
}

.footer-ribbon {
  height: 5px;
  background: linear-gradient(90deg,
    var(--color-orange) 0%, var(--color-orange) 22%,
    var(--color-yellow) 22%, var(--color-yellow) 35%,
    var(--color-cyan) 35%, var(--color-cyan) 47%,
    rgba(255, 255, 255, 0.1) 47%, rgba(255, 255, 255, 0.1) 62%,
    var(--color-purple) 62%, var(--color-purple) 76%,
    transparent 76%, transparent 100%);
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1.5fr;
  gap: 48px;
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 56px 24px 48px;
}

.footer-brand-link {
  display: inline-flex;
  align-items: center;
  gap: 12px;
}

.footer-brand-mark {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  border-radius: 13px 4px 13px 4px;
  background: linear-gradient(140deg, var(--color-orange) 0%, var(--color-yellow) 100%);
  font-family: var(--font-display);
  font-size: 20px;
  font-weight: 700;
  color: var(--color-white);
  flex-shrink: 0;
  overflow: hidden;
  position: relative;
  box-shadow: 0 4px 12px rgba(255, 107, 53, 0.2);
  transition: box-shadow 0.25s ease;
}

.footer-brand-mark::after {
  content: "";
  position: absolute;
  left: -20%;
  top: 50%;
  width: 140%;
  height: 2px;
  background: rgba(255, 255, 255, 0.3);
  transform: rotate(32deg);
}

.footer-brand-link:hover .footer-brand-mark,
.footer-brand-link:focus-visible .footer-brand-mark {
  box-shadow: 0 0 0 7px rgba(255, 107, 53, 0.12);
}

.footer-brand-name {
  font-family: var(--font-display);
  font-size: 22px;
  font-weight: 700;
  letter-spacing: 0.02em;
  color: var(--color-white);
}

.footer-tagline {
  margin-top: 14px;
  font-family: var(--font-editorial);
  font-size: 18px;
  color: rgba(255, 255, 255, 0.55);
}

.footer-trust {
  margin-top: 12px;
  font-size: 14px;
  line-height: 1.7;
  color: rgba(255, 255, 255, 0.4);
  max-width: 300px;
}

.footer-col {
  min-width: 0;
}

.footer-heading {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-yellow);
  margin-bottom: 14px;
}

.footer-heading::before {
  content: "";
  display: block;
  width: 16px;
  height: 2px;
  background: var(--color-orange);
}

.footer-list li {
  border-bottom: 1px solid rgba(255, 255, 255, 0.05);
}

.footer-list li:last-child {
  border-bottom: none;
}

.footer-link {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 0;
  font-size: 15px;
  color: rgba(255, 255, 255, 0.7);
  transition: color 0.2s ease, padding-left 0.2s ease;
}

.footer-link::before {
  content: "\2192";
  font-size: 13px;
  color: var(--color-orange);
  opacity: 0;
  transition: opacity 0.2s ease;
  flex-shrink: 0;
}

.footer-link:hover,
.footer-link:focus-visible {
  color: var(--color-white);
  padding-left: 4px;
}

.footer-link:hover::before,
.footer-link:focus-visible::before {
  opacity: 1;
}

.footer-contact-item {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding: 9px 0;
  border-bottom: 1px solid rgba(255, 255, 255, 0.06);
}

.footer-contact-item:last-child {
  border-bottom: none;
}

.footer-meta-label {
  flex-shrink: 0;
  min-width: 42px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: rgba(255, 255, 255, 0.35);
  padding-top: 2px;
}

.footer-meta-value {
  font-size: 14px;
  line-height: 1.6;
  color: rgba(255, 255, 255, 0.75);
  word-break: break-word;
}

.footer-bottom {
  background: rgba(0, 0, 0, 0.22);
  border-top: 1px solid rgba(255, 255, 255, 0.05);
}

.footer-bottom-inner {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 14px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
}

.footer-copyright {
  font-size: 13px;
  color: rgba(255, 255, 255, 0.4);
}

.footer-icp {
  font-family: var(--font-mono);
  font-size: 13px;
  color: rgba(255, 255, 255, 0.35);
}

.back-to-top {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.08);
  color: rgba(255, 255, 255, 0.7);
  font-size: 16px;
  line-height: 1;
  transition: background 0.25s ease, color 0.25s ease;
}

.back-to-top:hover,
.back-to-top:focus-visible {
  background: var(--color-orange);
  color: var(--color-white);
}

/* ---------- 7. 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 24px;
  font-family: var(--font-primary);
  font-size: 15px;
  font-weight: 600;
  line-height: 1.5;
  border-radius: 8px;
  cursor: pointer;
  white-space: nowrap;
  border: 2px solid transparent;
  transition: background 0.25s ease, color 0.25s ease, border-color 0.25s ease, box-shadow 0.25s ease;
}

.btn-primary {
  background: var(--color-orange);
  color: var(--color-white);
  border-color: var(--color-orange);
  box-shadow: 0 4px 12px rgba(255, 107, 53, 0.22);
}

.btn-primary:hover,
.btn-primary:focus-visible {
  background: #f55c26;
  border-color: #f55c26;
  box-shadow: 0 6px 18px rgba(255, 107, 53, 0.3);
}

.btn-ghost {
  background: transparent;
  color: var(--color-space-blue);
  border-color: var(--color-mist);
}

.btn-ghost:hover,
.btn-ghost:focus-visible {
  border-color: var(--color-space-blue);
  color: var(--color-space-blue);
}

.btn-ghost-light {
  background: transparent;
  color: var(--color-white);
  border-color: rgba(255, 255, 255, 0.3);
}

.btn-ghost-light:hover,
.btn-ghost-light:focus-visible {
  border-color: var(--color-yellow);
  color: var(--color-yellow);
}

.btn-sm {
  padding: 8px 16px;
  font-size: 14px;
  border-radius: 6px;
}

/* ---------- 8. 面包屑 ---------- */
.breadcrumb {
  padding: 20px 0 4px;
}

.breadcrumb-list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px;
  font-size: 14px;
}

.breadcrumb-item {
  display: flex;
  align-items: center;
  gap: 6px;
  color: var(--color-text-muted);
}

.breadcrumb-item + .breadcrumb-item::before {
  content: "/";
  color: var(--color-mist);
}

.breadcrumb-link {
  color: var(--color-text-muted);
  transition: color 0.2s ease;
}

.breadcrumb-link:hover,
.breadcrumb-link:focus-visible {
  color: var(--color-orange);
}

.breadcrumb-item[aria-current="page"] {
  color: var(--color-text);
  font-weight: 500;
}

/* ---------- 9. 章节组件 ---------- */
.section {
  padding: var(--space-lg) 0;
}

.section-dark {
  background: var(--color-space-blue);
  color: var(--color-white);
}

.section-dark .section-title {
  color: var(--color-white);
}

.section-dark .section-desc {
  color: rgba(255, 255, 255, 0.6);
}

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

.section-header {
  margin-bottom: 32px;
}

.section-kicker {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-orange);
  margin-bottom: 10px;
}

.section-kicker::before {
  content: "";
  display: block;
  width: 24px;
  height: 2px;
  background: var(--color-orange);
}

.section-dark .section-kicker {
  color: var(--color-yellow);
}

.section-dark .section-kicker::before {
  background: var(--color-yellow);
}

.section-title {
  font-size: clamp(28px, 4vw, 40px);
  line-height: 1.2;
  margin-bottom: 12px;
}

.section-desc {
  font-size: 16px;
  color: var(--color-text-muted);
  max-width: 640px;
}

/* 章节预览 */
.chapter-index {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 20px;
}

.chapter-link {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  padding: 18px 20px;
  background: var(--color-white);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-card);
  border-left: 4px solid transparent;
  transition: border-color 0.25s ease, transform 0.2s ease, box-shadow 0.25s ease;
}

.chapter-link:hover,
.chapter-link:focus-visible {
  border-left-color: var(--color-orange);
  transform: translateY(-2px);
  box-shadow: var(--shadow-lift);
}

.chapter-index-num {
  font-family: var(--font-mono);
  font-size: 14px;
  font-weight: 600;
  color: var(--color-orange);
  padding-top: 2px;
  flex-shrink: 0;
}

.chapter-index-title {
  font-family: var(--font-display);
  font-size: 17px;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 4px;
}

.chapter-index-desc {
  font-size: 14px;
  color: var(--color-text-muted);
  line-height: 1.6;
}

/* ---------- 10. 网格 ---------- */
.grid {
  display: grid;
  gap: 24px;
}

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

/* ---------- 11. 面板 ---------- */
.panel {
  background: var(--color-white);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-card);
  border: 1px solid rgba(217, 225, 236, 0.5);
  overflow: hidden;
}

.panel-head {
  padding: 20px 24px 0;
}

.panel-body {
  padding: 20px 24px 24px;
}

.panel-dark {
  background: var(--color-space-blue);
  color: var(--color-white);
}

.panel-dark .panel-title {
  color: var(--color-white);
}

/* ---------- 12. 标签与状态 ---------- */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 10px;
  font-size: 13px;
  font-weight: 500;
  line-height: 1.6;
  border-radius: 999px;
  background: rgba(255, 193, 7, 0.14);
  color: #8a6d00;
}

.tag-orange {
  background: rgba(255, 107, 53, 0.12);
  color: var(--color-orange);
}

.tag-purple {
  background: rgba(138, 99, 210, 0.12);
  color: var(--color-purple);
}

.tag-cyan {
  background: rgba(0, 194, 168, 0.12);
  color: #00a08b;
}

.status-dot {
  display: inline-block;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--color-cyan);
  margin-right: 6px;
  vertical-align: middle;
}

.status-dot-warn {
  background: var(--color-yellow);
}

.status-dot-alert {
  background: var(--color-purple);
}

/* ---------- 13. 数据行与代码块 ---------- */
.data-row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 16px;
  padding: 10px 0;
  border-bottom: 1px solid var(--color-mist);
}

.data-row:last-child {
  border-bottom: none;
}

.data-label {
  font-size: 15px;
  color: var(--color-text-muted);
}

.data-value {
  font-family: var(--font-mono);
  font-size: 16px;
  font-weight: 500;
  color: var(--color-text);
  text-align: right;
}

.data-value strong {
  color: var(--color-orange);
}

.code-block {
  background: var(--color-space-blue);
  color: var(--color-mist);
  border-radius: var(--radius-md);
  padding: 20px 24px;
  font-family: var(--font-mono);
  font-size: 14px;
  line-height: 1.8;
  overflow-x: auto;
  border-left: 3px solid var(--color-orange);
}

/* ---------- 14. 步骤树（技能树式服务路径） ---------- */
.step-tree {
  position: relative;
  padding: 0;
}

.step-tree::before {
  content: "";
  position: absolute;
  left: 14px;
  top: 8px;
  bottom: 8px;
  width: 2px;
  background: linear-gradient(180deg, var(--color-orange) 0%, var(--color-yellow) 100%);
  opacity: 0.3;
  border-radius: 2px;
}

.step-item {
  position: relative;
  padding: 0 0 28px 52px;
}

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

.step-item::before {
  content: "";
  position: absolute;
  left: 7px;
  top: 4px;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--color-space-blue);
  border: 4px solid var(--color-orange);
  transition: background 0.25s ease, box-shadow 0.25s ease;
}

.step-item:hover::before {
  background: var(--color-orange);
  box-shadow: 0 0 0 6px rgba(255, 107, 53, 0.12);
}

.step-title {
  font-family: var(--font-display);
  font-size: 18px;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 6px;
}

.step-desc {
  font-size: 15px;
  color: var(--color-text-muted);
  line-height: 1.7;
}

/* ---------- 15. 图片占位容器 ---------- */
.img-frame {
  position: relative;
  display: block;
  overflow: hidden;
  border-radius: var(--radius-md);
  background:
    radial-gradient(ellipse at 20% 0%, rgba(255, 107, 53, 0.12) 0%, transparent 55%),
    radial-gradient(ellipse at 90% 90%, rgba(0, 194, 168, 0.08) 0%, transparent 45%),
    linear-gradient(135deg, var(--color-bg-light) 0%, var(--color-mist) 100%);
}

.img-frame::after {
  content: "";
  position: absolute;
  right: 0;
  bottom: 0;
  width: 45%;
  height: 100%;
  background: repeating-linear-gradient(-45deg,
    transparent 0 6px,
    rgba(255, 255, 255, 0.1) 6px 7px,
    transparent 7px 20px);
  z-index: 0;
  pointer-events: none;
}

.img-frame > img {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  z-index: 1;
}

.img-frame-16x9 { aspect-ratio: 16 / 9; }
.img-frame-4x3 { aspect-ratio: 4 / 3; }
.img-frame-1x1 { aspect-ratio: 1 / 1; }

/* ---------- 16. 响应式 ---------- */
@media (max-width: 1024px) {
  .footer-grid {
    grid-template-columns: 1fr 1fr;
    gap: 40px;
  }

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

@media (max-width: 860px) {
  .header-inner {
    min-height: 68px;
  }

  .site-nav-toggle {
    display: flex;
  }

  .site-nav {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--color-space-blue);
    padding: 12px 24px 20px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.08);
    box-shadow: 0 16px 32px rgba(0, 0, 0, 0.25);
    display: none;
    max-height: calc(100vh - var(--header-height));
    overflow-y: auto;
  }

  .site-nav[data-open] {
    display: block;
  }

  .site-nav-list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
  }

  .site-nav-item + .site-nav-item {
    border-top: 1px solid rgba(255, 255, 255, 0.05);
  }

  .site-nav-link {
    display: block;
    padding: 14px 8px;
    font-size: 16px;
    color: rgba(255, 255, 255, 0.8);
  }

  .site-nav-link::after {
    display: none;
  }

  .site-nav-link[aria-current="page"] {
    color: var(--color-orange);
    border-left: 3px solid var(--color-orange);
    padding-left: 13px;
  }

  .site-nav-link:hover,
  .site-nav-link:focus-visible {
    color: var(--color-white);
  }

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

@media (max-width: 640px) {
  .header-inner {
    padding: 0 16px;
  }

  .site-brand-name {
    font-size: 17px;
  }

  .site-brand-tagline {
    display: none;
  }

  .site-brand-mark {
    width: 38px;
    height: 38px;
    font-size: 17px;
    border-radius: 12px 3px 12px 3px;
  }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 32px;
    padding: 40px 16px 36px;
  }

  .footer-bottom-inner {
    flex-direction: column;
    align-items: flex-start;
    padding: 16px;
  }

  .back-to-top {
    align-self: flex-end;
  }

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

  .section {
    padding: 48px 0;
  }
}

/* ---------- 17. 减弱动效 ---------- */
@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    transition-delay: 0s !important;
  }
}