:root {
  --bg-body: #F7F8FC;
  --bg-card: #FFFFFF;
  --bg-nav: rgba(255, 255, 255, 0.72);
  --bg-footer: #1A1D2B;
  --bg-hero: #F0EDF5;
  --text-primary: #17202A;
  --text-secondary: #334155;
  --text-muted: #475569;
  --text-heading: #0F172A;
  --text-nav: #1F2937;
  --text-footer: #D1D5DB;
  --text-footer-heading: #F1F5F9;
  --text-link: #6B3FA0;
  --text-link-hover: #4A2A72;
  --text-button: #FFFFFF;
  --bg-button: #7A4B8E;
  --bg-button-hover: #5E3670;
  --border-color: #E2E8F0;
  --accent: #7A4B8E;
  --accent-light: #EDE7F3;
  --accent-2: #E8547C;
  --accent-3: #5B8DEF;
  --shadow: 0 2px 12px rgba(0, 0, 0, 0.06);
  --shadow-hover: 0 12px 32px rgba(122, 75, 142, 0.16);
  --bg-input: #FFFFFF;
  --text-input: #17202A;
  --placeholder: #6B7280;
  --bg-tag: #EDE7F3;
  --text-tag: #4A2A72;
  --glass-bg: rgba(255, 255, 255, 0.6);
  --glass-border: rgba(255, 255, 255, 0.5);
  --glass-blur: 14px;
  --grad-banner: linear-gradient(135deg, #7A4B8E 0%, #A855A8 45%, #E8547C 100%);
  --grad-banner-soft: linear-gradient(135deg, #F0EDF5 0%, #FBE9F1 55%, #EDE7F3 100%);
  --grad-accent: linear-gradient(135deg, #7A4B8E, #E8547C);
  --radius-sm: 10px;
  --radius: 16px;
  --radius-lg: 24px;
  --radius-pill: 999px;
  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
}

[data-theme="dark"] {
  --bg-body: #0F1117;
  --bg-card: #1A1D2B;
  --bg-nav: rgba(21, 23, 34, 0.72);
  --bg-footer: #0B0D14;
  --bg-hero: #1A1226;
  --text-primary: #E5E7EB;
  --text-secondary: #CBD5E1;
  --text-muted: #94A3B8;
  --text-heading: #F8FAFC;
  --text-nav: #E2E8F0;
  --text-footer: #9CA3AF;
  --text-footer-heading: #F1F5F9;
  --text-link: #C4A5E0;
  --text-link-hover: #D8BFEC;
  --text-button: #FFFFFF;
  --bg-button: #8B5FA8;
  --bg-button-hover: #A070C0;
  --border-color: #2D3348;
  --accent: #A070C0;
  --accent-light: #2A1F3D;
  --accent-2: #F06A93;
  --accent-3: #7BA6F5;
  --shadow: 0 2px 12px rgba(0, 0, 0, 0.4);
  --shadow-hover: 0 12px 32px rgba(160, 112, 192, 0.24);
  --bg-input: #1E2235;
  --text-input: #E5E7EB;
  --placeholder: #9CA3AF;
  --bg-tag: #2A1F3D;
  --text-tag: #D8BFEC;
  --glass-bg: rgba(26, 29, 43, 0.55);
  --glass-border: rgba(255, 255, 255, 0.08);
  --grad-banner: linear-gradient(135deg, #4A2A72 0%, #7A3F8E 45%, #A83F6E 100%);
  --grad-banner-soft: linear-gradient(135deg, #1A1226 0%, #241630 55%, #1F1830 100%);
  --grad-accent: linear-gradient(135deg, #A070C0, #F06A93);
}

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

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
  background: var(--bg-body);
  color: var(--text-primary);
  line-height: 1.8;
  font-size: 16px;
  transition: background 0.35s var(--ease), color 0.35s var(--ease);
  overflow-x: hidden;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -1;
  background:
    radial-gradient(ellipse 60% 40% at 8% 0%, rgba(122, 75, 142, 0.10), transparent 60%),
    radial-gradient(ellipse 50% 35% at 95% 12%, rgba(232, 84, 124, 0.09), transparent 60%),
    radial-gradient(ellipse 55% 45% at 50% 100%, rgba(91, 141, 239, 0.07), transparent 65%);
  pointer-events: none;
}

[data-theme="dark"] body::before {
  background:
    radial-gradient(ellipse 60% 40% at 8% 0%, rgba(160, 112, 192, 0.14), transparent 60%),
    radial-gradient(ellipse 50% 35% at 95% 12%, rgba(240, 106, 147, 0.10), transparent 60%),
    radial-gradient(ellipse 55% 45% at 50% 100%, rgba(123, 166, 245, 0.08), transparent 65%);
}

a {
  color: var(--text-link);
  text-decoration: none;
  transition: color 0.2s var(--ease);
}

a:hover {
  color: var(--text-link-hover);
  text-decoration: underline;
}

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

strong {
  color: var(--text-heading);
  font-weight: 700;
}

.container {
  max-width: 1180px;
  margin: 0 auto;
  padding: 0 20px;
}

/* ===== 滚动动画 ===== */
.reveal {
  opacity: 0;
  transform: translateY(28px);
  transition: opacity 0.7s var(--ease), transform 0.7s var(--ease);
  will-change: opacity, transform;
}

.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

.reveal-delay-1 { transition-delay: 0.08s; }
.reveal-delay-2 { transition-delay: 0.16s; }
.reveal-delay-3 { transition-delay: 0.24s; }
.reveal-delay-4 { transition-delay: 0.32s; }

@media (prefers-reduced-motion: reduce) {
  .reveal {
    opacity: 1;
    transform: none;
    transition: none;
  }
  html { scroll-behavior: auto; }
}

/* ===== 导航 ===== */
.nav {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: var(--bg-nav);
  -webkit-backdrop-filter: saturate(180%) blur(var(--glass-blur));
  backdrop-filter: saturate(180%) blur(var(--glass-blur));
  border-bottom: 1px solid var(--glass-border);
  box-shadow: 0 1px 0 rgba(0, 0, 0, 0.02), var(--shadow);
  transition: background 0.35s var(--ease), border-color 0.35s var(--ease);
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
  gap: 16px;
}

.nav-logo {
  font-size: 1.35rem;
  font-weight: 800;
  letter-spacing: 0.5px;
  display: flex;
  align-items: center;
  gap: 8px;
  background: var(--grad-accent);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  color: var(--accent);
  white-space: nowrap;
}

.nav-logo span {
  color: var(--text-muted);
  -webkit-text-fill-color: var(--text-muted);
  font-weight: 600;
  font-size: 0.82rem;
  letter-spacing: 1px;
}

.nav-logo:hover {
  text-decoration: none;
  filter: brightness(1.08);
}

.nav-links {
  display: flex;
  gap: 26px;
  list-style: none;
}

.nav-links a {
  position: relative;
  color: var(--text-nav);
  font-weight: 500;
  font-size: 0.95rem;
  padding: 4px 0;
  border-bottom: 2px solid transparent;
  transition: color 0.25s var(--ease), border-color 0.25s var(--ease);
}

.nav-links a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -2px;
  width: 0;
  height: 2px;
  background: var(--grad-accent);
  border-radius: 2px;
  transition: width 0.3s var(--ease);
}

.nav-links a:hover {
  color: var(--accent);
  border-bottom-color: transparent;
  text-decoration: none;
}

.nav-links a:hover::after {
  width: 100%;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 14px;
}

.search-box {
  display: flex;
  align-items: center;
  background: var(--glass-bg);
  -webkit-backdrop-filter: blur(8px);
  backdrop-filter: blur(8px);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-pill);
  padding: 5px 14px;
  transition: border-color 0.25s var(--ease), box-shadow 0.25s var(--ease);
}

.search-box:focus-within {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-light);
}

.search-box input {
  border: none;
  background: transparent;
  outline: none;
  color: var(--text-input);
  font-size: 0.9rem;
  width: 130px;
  font-family: inherit;
}

.search-box input::placeholder {
  color: var(--placeholder);
}

.search-box button {
  border: none;
  background: transparent;
  cursor: pointer;
  color: var(--text-muted);
  font-size: 1rem;
  line-height: 1;
  transition: transform 0.2s var(--ease), color 0.2s var(--ease);
}

.search-box button:hover {
  color: var(--accent);
  transform: scale(1.15);
}

.theme-toggle {
  background: var(--accent-light);
  border: 1px solid transparent;
  cursor: pointer;
  border-radius: 50%;
  width: 38px;
  height: 38px;
  font-size: 1.05rem;
  color: var(--text-heading);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.3s var(--ease), color 0.3s var(--ease), transform 0.3s var(--ease), box-shadow 0.3s var(--ease);
}

.theme-toggle:hover {
  background: var(--grad-accent);
  color: #fff;
  transform: rotate(-18deg) scale(1.06);
  box-shadow: var(--shadow-hover);
}

.mobile-menu-btn {
  display: none;
  background: none;
  border: none;
  font-size: 1.6rem;
  cursor: pointer;
  color: var(--text-heading);
  line-height: 1;
  transition: transform 0.25s var(--ease);
}

.mobile-menu-btn:hover {
  transform: scale(1.1);
}

/* ===== 面包屑 ===== */
.breadcrumb {
  padding: 16px 0 0;
  font-size: 0.85rem;
  color: var(--text-muted);
}

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

/* ===== Hero ===== */
.hero {
  position: relative;
  overflow: hidden;
  background: var(--grad-banner-soft);
  padding: 72px 0 64px;
  border-bottom: 1px solid var(--border-color);
  transition: background 0.35s var(--ease);
}

.hero::before {
  content: "";
  position: absolute;
  top: -160px;
  right: -120px;
  width: 460px;
  height: 460px;
  border-radius: 50%;
  background: var(--grad-banner);
  opacity: 0.14;
  filter: blur(70px);
  pointer-events: none;
}

.hero::after {
  content: "";
  position: absolute;
  bottom: -180px;
  left: -100px;
  width: 380px;
  height: 380px;
  border-radius: 50%;
  background: var(--grad-accent);
  opacity: 0.10;
  filter: blur(80px);
  pointer-events: none;
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 800px;
  animation: heroIn 0.9s var(--ease) both;
}

@keyframes heroIn {
  from {
    opacity: 0;
    transform: translateY(26px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.hero h1 {
  font-size: 2.4rem;
  font-weight: 800;
  color: var(--text-heading);
  line-height: 1.35;
  margin-bottom: 20px;
  letter-spacing: -0.5px;
}

.hero h1 .highlight {
  background: var(--grad-accent);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  color: var(--accent);
}

.hero p {
  font-size: 1.08rem;
  color: var(--text-secondary);
  margin-bottom: 12px;
  line-height: 1.95;
}

.hero-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 26px;
}

.hero-tags span {
  background: var(--glass-bg);
  -webkit-backdrop-filter: blur(8px);
  backdrop-filter: blur(8px);
  color: var(--text-tag);
  padding: 7px 18px;
  border-radius: var(--radius-pill);
  font-size: 0.88rem;
  font-weight: 500;
  border: 1px solid var(--glass-border);
  transition: transform 0.25s var(--ease), box-shadow 0.25s var(--ease), background 0.25s var(--ease), color 0.25s var(--ease);
  cursor: default;
}

.hero-tags span:hover {
  transform: translateY(-3px);
  background: var(--grad-accent);
  color: #fff;
  box-shadow: var(--shadow-hover);
}

/* ===== 通用区块 ===== */
section {
  padding: 64px 0;
  position: relative;
}

.section-title {
  font-size: 1.9rem;
  font-weight: 800;
  color: var(--text-heading);
  margin-bottom: 12px;
  position: relative;
  padding-left: 18px;
  letter-spacing: -0.3px;
}

.section-title::before {
  content: "";
  position: absolute;
  left: 0;
  top: 8px;
  width: 5px;
  height: 26px;
  background: var(--grad-accent);
  border-radius: 3px;
}

.section-sub {
  color: var(--text-muted);
  font-size: 1rem;
  margin-bottom: 36px;
  padding-left: 18px;
}

/* ===== 卡片 ===== */
.card {
  position: relative;
  background: var(--bg-card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 28px;
  border: 1px solid var(--border-color);
  transition: transform 0.35s var(--ease), box-shadow 0.35s var(--ease), background 0.35s var(--ease), border-color 0.35s var(--ease);
  overflow: hidden;
}

.card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--grad-accent);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.4s var(--ease);
}

.card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-hover);
  border-color: transparent;
}

.card:hover::before {
  transform: scaleX(1);
}

.card h3 {
  font-size: 1.22rem;
  font-weight: 700;
  color: var(--text-heading);
  margin-bottom: 10px;
  line-height: 1.5;
}

.card p {
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.85;
}

/* ===== 网格 ===== */
.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.grid-4 {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}

/* ===== 品牌介绍 ===== */
.about-text {
  color: var(--text-secondary);
  font-size: 1rem;
  line-height: 2;
}

.about-text p {
  margin-bottom: 16px;
}

.about-text strong {
  color: var(--text-heading);
}

/* ===== 产品/服务 ===== */
.service-icon {
  width: 54px;
  height: 54px;
  border-radius: 14px;
  background: var(--accent-light);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  margin-bottom: 18px;
  transition: transform 0.35s var(--ease), background 0.35s var(--ease), box-shadow 0.35s var(--ease);
}

.card:hover .service-icon {
  transform: translateY(-4px) rotate(-6deg) scale(1.06);
  background: var(--grad-accent);
  box-shadow: var(--shadow-hover);
}

/* ===== 文章列表 ===== */
.article-item {
  position: relative;
  background: var(--bg-card);
  border-radius: var(--radius-sm);
  padding: 24px;
  border: 1px solid var(--border-color);
  transition: transform 0.35s var(--ease), box-shadow 0.35s var(--ease), border-color 0.35s var(--ease), background 0.35s var(--ease);
  overflow: hidden;
}

.article-item::after {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 3px;
  background: var(--grad-accent);
  transform: scaleY(0);
  transform-origin: top;
  transition: transform 0.4s var(--ease);
}

.article-item:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-hover);
  border-color: transparent;
}

.article-item:hover::after {
  transform: scaleY(1);
}

.article-item h3 {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-heading);
  margin-bottom: 8px;
  line-height: 1.55;
}

.article-item h3 a {
  color: var(--text-heading);
  transition: color 0.25s var(--ease);
}

.article-item h3 a:hover {
  color: var(--accent);
  text-decoration: none;
}

.article-meta {
  font-size: 0.82rem;
  color: var(--text-muted);
  margin-bottom: 10px;
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

.article-item p {
  color: var(--text-secondary);
  font-size: 0.92rem;
  margin-bottom: 12px;
  line-height: 1.85;
}

.read-more {
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--text-link);
  display: inline-flex;
  align-items: center;
  gap: 4px;
  transition: gap 0.25s var(--ease), color 0.25s var(--ease);
}

.read-more:hover {
  color: var(--text-link-hover);
  text-decoration: none;
  gap: 9px;
}

/* ===== FAQ ===== */
.faq-item {
  background: var(--bg-card);
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
  margin-bottom: 12px;
  overflow: hidden;
  transition: box-shadow 0.3s var(--ease), border-color 0.3s var(--ease);
}

.faq-item:hover {
  box-shadow: var(--shadow);
}

.faq-item.open {
  border-color: var(--accent);
  box-shadow: var(--shadow-hover);
}

.faq-question {
  padding: 18px 22px;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  font-weight: 600;
  color: var(--text-heading);
  font-size: 1rem;
  line-height: 1.6;
  transition: background 0.25s var(--ease), color 0.25s var(--ease);
}

.faq-question:hover {
  background: var(--accent-light);
}

.faq-question .arrow {
  flex-shrink: 0;
  transition: transform 0.35s var(--ease), color 0.35s var(--ease);
  color: var(--text-muted);
  font-size: 0.8rem;
}

.faq-item.open .faq-question {
  color: var(--accent);
}

.faq-item.open .faq-question .arrow {
  transform: rotate(180deg);
  color: var(--accent);
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s var(--ease), padding 0.35s var(--ease);
  padding: 0 22px;
}

.faq-item.open .faq-answer {
  max-height: 500px;
  padding: 0 22px 22px;
}

.faq-answer p {
  color: var(--text-secondary);
  font-size: 0.94rem;
  line-height: 1.95;
}

/* ===== HowTo ===== */
.howto-step {
  display: flex;
  gap: 18px;
  margin-bottom: 24px;
  align-items: flex-start;
  padding: 18px;
  border-radius: var(--radius-sm);
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  transition: transform 0.35s var(--ease), box-shadow 0.35s var(--ease), border-color 0.35s var(--ease);
}

.howto-step:hover {
  transform: translateX(6px);
  box-shadow: var(--shadow);
  border-color: var(--accent);
}

.step-num {
  flex-shrink: 0;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--grad-accent);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.95rem;
  box-shadow: 0 4px 12px rgba(122, 75, 142, 0.28);
  transition: transform 0.35s var(--ease);
}

.howto-step:hover .step-num {
  transform: scale(1.1) rotate(-8deg);
}

.step-content h4 {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--text-heading);
  margin-bottom: 4px;
}

.step-content p {
  color: var(--text-secondary);
  font-size: 0.93rem;
  line-height: 1.85;
}

/* ===== 案例 ===== */
.case-card {
  text-align: center;
}

.case-card .case-avatar {
  width: 68px;
  height: 68px;
  border-radius: 50%;
  background: var(--accent-light);
  margin: 0 auto 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.9rem;
  border: 2px solid transparent;
  transition: transform 0.4s var(--ease), border-color 0.4s var(--ease), box-shadow 0.4s var(--ease);
}

.case-card:hover .case-avatar {
  transform: scale(1.1) translateY(-4px);
  border-color: var(--accent);
  box-shadow: var(--shadow-hover);
}

.case-card h4 {
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-heading);
  margin-bottom: 8px;
}

.case-card p {
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.85;
}

/* ===== 联系 ===== */
.contact-info {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.contact-item {
  background: var(--glass-bg);
  -webkit-backdrop-filter: blur(var(--glass-blur));
  backdrop-filter: blur(var(--glass-blur));
  border-radius: var(--radius);
  padding: 26px;
  border: 1px solid var(--glass-border);
  box-shadow: var(--shadow);
  transition: transform 0.35s var(--ease), box-shadow 0.35s var(--ease), border-color 0.35s var(--ease);
}

.contact-item:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-hover);
  border-color: var(--accent);
}

.contact-item h4 {
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-heading);
  margin-bottom: 10px;
}

.contact-item p {
  font-size: 0.92rem;
  color: var(--text-secondary);
  line-height: 1.9;
}

/* ===== Footer ===== */
.footer {
  position: relative;
  background: var(--bg-footer);
  color: var(--text-footer);
  padding: 56px 0 28px;
  margin-top: 48px;
  transition: background 0.35s var(--ease), color 0.35s var(--ease);
  overflow: hidden;
}

.footer::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--grad-accent);
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 36px;
  margin-bottom: 36px;
}

.footer h4 {
  color: var(--text-footer-heading);
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 16px;
  position: relative;
  padding-bottom: 10px;
}

.footer h4::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 28px;
  height: 2px;
  background: var(--grad-accent);
  border-radius: 2px;
}

.footer p,
.footer li {
  font-size: 0.88rem;
  line-height: 2;
}

.footer ul {
  list-style: none;
}

.footer a {
  color: var(--text-footer);
  position: relative;
  transition: color 0.25s var(--ease), padding-left 0.25s var(--ease);
}

.footer a:hover {
  color: #fff;
  text-decoration: none;
  padding-left: 5px;
}

.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  padding-top: 22px;
  text-align: center;
  font-size: 0.82rem;
  color: var(--text-footer);
  line-height: 1.9;
}

.footer-bottom a {
  color: var(--text-footer);
}

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

/* ===== 返回顶部 ===== */
.back-top {
  position: fixed;
  right: 24px;
  bottom: 24px;
  width: 46px;
  height: 46px;
  border-radius: 50%;
  background: var(--grad-accent);
  color: #fff;
  border: none;
  font-size: 1.15rem;
  cursor: pointer;
  box-shadow: var(--shadow-hover);
  opacity: 0;
  visibility: hidden;
  transform: translateY(14px) scale(0.9);
  transition: opacity 0.35s var(--ease), visibility 0.35s var(--ease), transform 0.35s var(--ease), filter 0.25s var(--ease);
  z-index: 999;
}

.back-top.show {
  opacity: 1;
  visibility: visible;
  transform: translateY(0) scale(1);
}

.back-top:hover {
  filter: brightness(1.12);
  transform: translateY(-4px) scale(1.06);
}

/* ===== 响应式 ===== */
@media (max-width: 1024px) {
  .grid-4 {
    grid-template-columns: repeat(2, 1fr);
  }
  .nav-links {
    gap: 20px;
  }
  .search-box input {
    width: 100px;
  }
}

@media (max-width: 900px) {
  .grid-3 {
    grid-template-columns: repeat(2, 1fr);
  }
  .grid-4 {
    grid-template-columns: repeat(2, 1fr);
  }
  .footer-grid {
    grid-template-columns: 1fr 1fr;
    gap: 28px;
  }
  .contact-info {
    grid-template-columns: 1fr;
  }
  .hero {
    padding: 56px 0 48px;
  }
  .hero h1 {
    font-size: 1.95rem;
  }
  section {
    padding: 52px 0;
  }
}

@media (max-width: 768px) {
  .nav-links {
    display: none;
  }
  .mobile-menu-btn {
    display: block;
  }
  .grid-2,
  .grid-3,
  .grid-4 {
    grid-template-columns: 1fr;
  }
  .footer-grid {
    grid-template-columns: 1fr;
  }
  .hero h1 {
    font-size: 1.65rem;
  }
  .hero p {
    font-size: 1rem;
  }
  .section-title {
    font-size: 1.5rem;
  }
  .section-title::before {
    top: 5px;
    height: 22px;
  }
  .search-box {
    display: none;
  }
  .card {
    padding: 22px;
  }
  .article-item {
    padding: 20px;
  }
  .howto-step {
    padding: 16px;
  }
  .back-top {
    right: 16px;
    bottom: 16px;
    width: 42px;
    height: 42px;
  }
}

@media (max-width: 420px) {
  .hero h1 {
    font-size: 1.45rem;
  }
  .hero-tags span {
    font-size: 0.82rem;
    padding: 6px 14px;
  }
  .container {
    padding: 0 16px;
  }
  .nav-logo {
    font-size: 1.15rem;
  }
  .nav-logo span {
    display: none;
  }
}

/* ===== 移动菜单展开 ===== */
.nav-links.mobile-open {
  display: flex;
  flex-direction: column;
  position: absolute;
  top: 64px;
  left: 0;
  right: 0;
  background: var(--bg-nav);
  -webkit-backdrop-filter: saturate(180%) blur(var(--glass-blur));
  backdrop-filter: saturate(180%) blur(var(--glass-blur));
  padding: 20px;
  border-bottom: 1px solid var(--border-color);
  box-shadow: var(--shadow-hover);
  gap: 16px;
  animation: menuDrop 0.35s var(--ease) both;
}

@keyframes menuDrop {
  from {
    opacity: 0;
    transform: translateY(-10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.nav-links.mobile-open a {
  padding: 8px 4px;
  border-bottom: 1px solid var(--border-color);
}

.nav-links.mobile-open li:last-child a {
  border-bottom: none;
}

/* ===== 选择与滚动条 ===== */
::selection {
  background: var(--accent);
  color: #fff;
}

::-webkit-scrollbar {
  width: 10px;
  height: 10px;
}

::-webkit-scrollbar-track {
  background: var(--bg-body);
}

::-webkit-scrollbar-thumb {
  background: var(--accent-light);
  border-radius: var(--radius-pill);
  border: 2px solid var(--bg-body);
}

::-webkit-scrollbar-thumb:hover {
  background: var(--accent);
}

/* ===== 焦点可见性 ===== */
a:focus-visible,
button:focus-visible,
input:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-radius: 4px;
}