/* --- 优化的颜色变量 --- */
:root {
  --accent-rgb: 200, 126, 106; /* 对应 --accent: #C87E6A; */
  /* 明亮主题：暖色调中性和谐配色，参考优秀设计 */
  --bg: #FDFBF8;              /* 温暖的米白色背景，柔和不刺眼 */
  --fg: #4A4A4A;              /* 深灰主文字，正式且易读 */
  --accent: #C87E6A;          /* 温暖的棕红色，活力且专业 */
  --accent-secondary: #D6BFAA;/* 温和的米色，和谐点缀 */
  --highlight: #B76E5A;       /* 深棕红色，悬停状态 */
  --card-bg: #ffffff;         /* 卡片纯白，干净清爽 */
  --border-color: #EAEAEA;    /* 浅灰边框，低调有层次 */
  --shadow: 0 4px 16px rgba(0, 0, 0, 0.05); /* 微阴影，现代感 */
  --text-color-light: #6B7280;/* 次要文字，灰蓝色 */
  --text-color-dark: #9CA3AF; /* 辅助文字，淡灰色 */
  --hover-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.05), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}

:root.dark-mode {
  --accent-rgb: 79, 156, 255; /* 对应 --accent: #4f9cff; */
  /* 深色主题：深蓝灰为主，蓝绿点缀，橙色高亮，科技感强 */
  --bg: #181f2a;              /* 深蓝灰背景，沉稳不死黑 */
  --fg: #f1f3f8;              /* 亮灰白主文字，清晰对比 */
  --accent: #4f9cff;          /* 明亮蓝色，深色下依然活力 */
  --accent-secondary: #3b7da8;/* 绿色点缀，深色下更显活力 */
  --highlight: #ffb300;       /* 橙色高亮，深色下依然醒目 */
  --card-bg: #232b3a;         /* 深蓝卡片，层次分明 */
  --border-color: #2c3442;    /* 深灰蓝边框 */
  --shadow: 0 4px 16px rgba(20, 30, 50, 0.32); /* 深色阴影 */
  --text-color-light: #b6c2d1;/* 次要文字，浅蓝灰 */
  --text-color-dark: #7a869a; /* 辅助文字，灰蓝 */
}

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

html {
  background-color: var(--bg);
  scroll-behavior: smooth;
}

body {
  font-family: 'Inter', 'Segoe UI', 'Roboto', 'Helvetica Neue', Arial, sans-serif;
  background: var(--bg);
  color: var(--fg);
  line-height: 1.7;
  font-size: 1.1rem;
  transition: background-color 0.3s ease, color 0.3s ease;
}

/* ===页头=== */
header {
  text-align: center;
  margin-bottom: 4rem;
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  padding: 5rem 2rem 3rem;
  color: #fff;
  position: relative;
  min-height: 350px;
  display: flex; 
  flex-direction: column;
  align-items: center;
  justify-content: center;
  overflow: hidden; /* 防止视差位移时露出边缘 */
}
header::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: linear-gradient(to top, rgba(0, 0, 0, 0.7) 0%, rgba(0, 0, 0, 0.3) 60%, rgba(0, 0, 0, 0.5) 100%);
  z-index: 1;
  pointer-events: none;
}
header > * {
  position: relative;
  z-index: 2;
}
.avatar {
  width: 140px;
  height: 140px;
  border-radius: 50%;
  margin-bottom: 1.5rem;
  border: 4px solid rgba(255, 255, 255, 0.8);
  box-shadow: 0 0 25px rgba(200, 126, 106, 0.5), 0 4px 16px rgba(0, 0, 0, 0.08);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  cursor: pointer;
}
.avatar:hover {
  transform: scale(1.05);
  box-shadow: 0 0 30px rgba(200, 126, 106, 0.7), 0 8px 25px rgba(0, 0, 0, 0.12);
}
.header-bg-slider {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0;
    overflow: hidden; /* 额外保险：裁剪内部位移 */
}
.header-bg-slider img {
    position: absolute;
    top: 50%;
    left: 50%;
    width: 110%; /* 超采样，避免鼠标位移出现空白边 */
    height: 110%;
    transform: translate(-50%, -50%); /* 仅提供初始基准，运行时由 JS 用 xPercent/yPercent 锁定 */
    object-fit: cover;
    opacity: 0;
    will-change: transform; /* 提升动画性能 */
}
h1 { font-size: 3rem; margin-bottom: .5rem; font-weight: 700; text-shadow: 1px 1px 3px rgba(0,0,0,0.4); }
header p { font-size: 1.2rem; color: #e0e0e0; text-shadow: 1px 1px 3px rgba(0,0,0,0.4);} 
.tagline{margin-top:.5rem;color:#e6edf5;opacity:.95}
.hero-tags{margin-top:1rem;display:flex;gap:.6rem;flex-wrap:wrap;justify-content:center}
.pill{
  display:inline-flex;
  gap:.35rem;
  align-items:center;
  padding:.4rem .7rem;
  border-radius:999px;
  background:rgba(255,255,255,.12);
  backdrop-filter: blur(6px);
  border:1px solid rgba(255,255,255,.25);
  font-size:.9rem;
  animation:breath 3s ease-in-out infinite;
  transition: all 0.3s ease;
  cursor: pointer;
}
.pill:hover {
  transform: translateY(-2px);
  background: rgba(255,255,255,.2);
  border-color: rgba(255,255,255,.4);
  box-shadow: 0 4px 12px rgba(0,0,0,0.2);
}
@keyframes breath{0%{box-shadow:0 0 0 rgba(255,255,255,0.0)}50%{box-shadow:0 0 18px rgba(255,255,255,0.35)}100%{box-shadow:0 0 0 rgba(255,255,255,0.0)}}
.hero-ctas{margin-top:1.2rem;display:flex;gap:.8rem;justify-content:center;flex-wrap:wrap}
.btn.secondary{background:transparent;color:#fff;border:1px solid rgba(255,255,255,.6)}
.btn.secondary:hover{
  background:var(--accent);
  border-color:var(--accent);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0,0,0,0.2);
} 
/* ghost 与 secondary 在 hover 时一致 */
.btn.ghost{background:transparent;color:#fff;border:1.6px solid rgba(255,255,255,.75)}
.btn.ghost:hover{
  background:var(--accent);
  border-color:var(--accent);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0,0,0,0.2);
}
.social a {
  margin: 0 .8rem;
  color: #fff;
  transition: all 0.3s ease;
  padding: 0.5rem;
  border-radius: 50%;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}
.social a:hover {
  color: var(--accent);
  transform: translateY(-2px);
  background: rgba(255, 255, 255, 0.1);
  box-shadow: 0 4px 12px rgba(0,0,0,0.2);
}

main {
  max-width: 1100px;
  margin: 0 auto;
  padding: 2rem;
  padding-left: 220px;
}

h2 {
  margin: 3rem 0 1.5rem; 
  font-size: 2rem; 
  font-weight: 600;
  padding-bottom: .5rem;
  display: inline-block;
  color: var(--fg);
  position: relative;
}
h2::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 2px;
  background-color: var(--accent);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.6s ease-out;
}
h2.is-visible::after {
  transform: scaleX(1);
}

h3 {
  margin-top: 0;
  margin-bottom: 1rem;
  font-size: 1.4rem;
  font-weight: 600;
  color: var(--fg);
}
section { margin-bottom: 2rem; }
ul { list-style: none; padding-left: 0; }

/* ===卡片辉光效果与文字布局最终修复=== */
li {
  background: transparent;
  border: none;
  padding: 2px; /* 辉光边框的宽度 */
  margin-bottom: 1rem;
  border-radius: 12px;
  box-shadow: var(--shadow);
  transition: transform 0.3s ease-in-out;
  position: relative;
  overflow: hidden;
}
li:hover {
  transform: translateY(-5px);
}
li strong { color: var(--accent); }

.card-content-wrapper {
  background-color: var(--card-bg);
  padding: 1.5rem;
  border-radius: 10px;
  width: 100%;
  height: 100%;
  color: var(--text-color-light);
  font-size: 1rem;
  border: 1px solid var(--border-color);
  position: relative; /* 添加此行以确保z-index生效 */
  z-index: 1; /* 内容在辉光之上 */
}

li::before {
  content: "";
  position: absolute;
  top: 50%;
  left: 50%;
  width: 150%;
  height: 150%;
  background: radial-gradient(circle, 
    rgba(var(--accent-rgb), 0.8) 0%, 
    rgba(var(--accent-rgb), 0.2) 40%,
    transparent 70%
  );
  transform: translate(-50%, -50%);
  transition: opacity 0.5s, transform 0.5s;
  animation: pulseGlow 2s ease-in-out infinite;
  z-index: 0; /* 确保辉光在最底层 */
}
@keyframes pulseGlow {
  0% {
    opacity: 0.4;
    transform: translate(-50%, -50%) scale(0.9);
  }
  50% {
    opacity: 0.8;
    transform: translate(-50%, -50%) scale(1);
  }
  100% {
    opacity: 0.4;
    transform: translate(-50%, -50%) scale(0.9);
  }
}

/* ===技能区美化=== */
.skills-container {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 1.5rem;
  background: transparent;
  border: none;
  padding: 0;
  box-shadow: none;
}
.skill-category {
  min-width: 0;
  background: var(--card-bg);
  padding: 1.5rem;
  border-radius: 12px;
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}
.skill-category:hover {
  transform: translateY(-5px);
  box-shadow: var(--hover-shadow);
}
.skill-category h3 {
  font-size: 1.3rem;
  color: var(--accent);
  margin-bottom: 1rem;
  display: inline-block;
  border-bottom: 2px solid var(--accent-secondary);
  padding-bottom: 0.3rem;
}
.tags span {
  display: inline-block;
  background: var(--bg);
  color: var(--text-color-light);
  padding: .4rem .8rem;
  margin: .3rem .2rem;
  border-radius: 6px;
  font-size: .9rem;
  border: 1px solid var(--border-color);
  transition: all 0.2s ease;
}
.tags span:hover {
  background-color: var(--accent);
  color: #fff;
  border-color: var(--accent);
  transform: translateY(-2px);
  box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

/* ===项目技术标签=== */
.project-tags {
    margin-top: 1.5rem;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
}
.project-tags .tag {
    display: inline-block;
    font-size: 0.85rem;
    font-weight: 500;
    padding: 0.3rem 0.8rem;
    background-color: var(--accent-secondary);
    color: #fff;
    border-radius: 16px;
    margin-right: 0.5rem;
    margin-bottom: 0.5rem;
}

/* ===图片居中和大小最终修复=== */
.image-container {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    margin-top: 1rem;
    justify-content: center;
    align-items: center;
}
.image-container img {
    flex: 1 1 auto;
    max-width: 100%;
    height: auto;
    border-radius: 8px;
    object-fit: contain;
}
.image-container.raicom-images {
    display: flex;
    align-items: center;
    gap: 1rem;
}
.image-container.raicom-images img {
    flex: 1;
    max-width: 50%;
    object-fit: contain;
}
.image-container .img-size-s { flex: 0 0 auto; width: 300px; max-width: 90%; }
.image-container .img-size-m { flex: 0 0 auto; width: 400px; max-width: 90%; }
.image-container .img-size-l { flex: 0 0 auto; width: 550px; max-width: 90%; }

/* --- 语言切换支持 --- */
.lang-zh {
    display: none; /* 默认隐藏中文 */
}
.lang-en, .lang-zh {
    vertical-align: middle; /* 确保切换时对齐一致 */
}

/* --- 其他组件样式 --- */
.award-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
}
.award-item, .award-item span {
   color: var(--text-color-light);
}
.btn {
  display: inline-block;
  margin-top: 1.5rem;
  padding: .9rem 1.8rem;
  background-color: var(--accent);
  color: #fff;
  text-decoration: none;
  border-radius: 8px;
  border: none;
  font-weight: 600;
  box-shadow: var(--shadow);
  transition: background-color 0.2s, transform 0.2s;
  font-size: 1.1rem;
}
.btn:hover {
  background-color: var(--highlight);
  transform: translateY(-2px);
  box-shadow: var(--hover-shadow);
}
footer { 
  max-width: 1100px;
  margin: 4rem auto 0;
  padding: 2rem;
  padding-left: 220px;
  font-size: 1rem; 
  text-align: center; 
  opacity: .8; 
  color: var(--text-color-dark); 
}

.theme-switcher {
  position: fixed;
  top: 1.5rem;
  right: 1.5rem;
  z-index: 1000;
  cursor: pointer;
  background: var(--card-bg);
  padding: 0.5rem;
  border-radius: 50%;
  box-shadow: var(--shadow);
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  transition: background-color 0.3s, color 0.3s;
}
.theme-switcher:hover { opacity: 0.9; }

/* 新增：语言切换器样式 */
.language-switcher {
  position: fixed;
  top: 1.5rem;
  right: 5rem; /* 放在主题切换器左边 */
  z-index: 1000;
  cursor: pointer;
  background: var(--card-bg);
  padding: 0.5rem;
  border-radius: 50%;
  box-shadow: var(--shadow);
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  transition: background-color 0.3s, color 0.3s;
  color: var(--fg); /* 文字颜色跟随主题 */
  font-weight: bold;
  font-size: 1rem;
}
.language-switcher:hover { 
  opacity: 0.9; 
}


.preloader {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: var(--bg);
  display: flex;
  justify-content: center;
  align-items: center;
  z-index: 9999;
  transition: opacity 0.5s ease-out, visibility 0.5s ease-out;
}
.preloader.loaded {
  opacity: 0;
  visibility: hidden;
}
.loader {
  width: 50px;
  height: 50px;
  border: 5px solid var(--border-color);
  border-top: 5px solid var(--accent);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}
@keyframes spin {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}
.cursor {
  position: fixed;
  width: 20px;
  height: 20px;
  border: 2px solid var(--fg);
  border-radius: 50%;
  left: 0;
  top: 0;
  pointer-events: none;
  transform: translate(-50%, -50%);
  z-index: 1001;
  mix-blend-mode: difference;
  transition: width 0.2s, height 0.2s;
}
.cursor.grow {
  width: 40px;
  height: 40px;
}
.collapsible-header {
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.collapse-icon {
  transition: transform 0.3s ease;
  margin-left: auto; /* 确保图标在最右边 */
}
.collapsible-header.collapsed .collapse-icon {
  transform: rotate(-90deg);
}
.collapsible-content {
  max-height: 0;
  opacity: 0;
  overflow: hidden;
  transition: max-height 0.5s ease-out, opacity 0.5s ease-out;
}
.collapsible-content ul {
  padding-bottom: 1rem;
}
.collapsible-content.is-expanded {
  max-height: 5000px;
  opacity: 1;
}
.quick-nav {
  position: fixed !important;
  left: 0;
  top: 50%;
  transform: translateY(-50%);
  width: 180px;
  padding: 1.5rem 1rem;
  background-color: var(--card-bg);
  border-right: 1px solid var(--border-color);
  box-shadow: var(--shadow);
  border-radius: 0 8px 8px 0;
  z-index: 999;
  transition: background-color 0.3s ease, border-color 0.3s ease;
}
.quick-nav h3 {
  font-size: 1.2rem;
  margin-bottom: 1rem;
  color: var(--fg);
}
.quick-nav ul { list-style: none; padding: 0; }
.quick-nav li {
  margin-bottom: .7rem;
  padding: 0;
  background: none;
  border: none;
  box-shadow: none;
  transform: none;
  overflow: visible;
  position: static;
}
.quick-nav li::before, .quick-nav li::after { display: none; }
.quick-nav li a {
  text-decoration: none;
  color: var(--text-color-light);
  font-size: 1rem;
  padding: .3rem .5rem;
  display: block;
  border-radius: 4px;
  transition: all 0.3s ease;
  border-bottom: 2px solid transparent;
}
.quick-nav li a:hover,
.quick-nav li a.active {
  color: var(--accent);
  border-bottom-color: var(--accent);
  font-weight: 700;
}

@media (max-width: 992px) {
  .quick-nav { display: none; }
  main, footer {
    padding: 2rem;
  }
}
@media (max-width: 600px) {
  body { font-size: 1rem; }
  main, footer { padding: 1.5rem; }
  h1 { font-size: 2.2rem; }
  h2 { font-size: 1.7rem; }
  h3 { font-size: 1.2rem; }
  .collapsible-header { font-size: 1.7rem; }
}
.project-header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  flex-wrap: wrap;
  gap: 1rem;
}
.project-subheader {
  margin-top: 0.5rem;
  font-style: italic;
  display: block;
}
.details-list {
  list-style-type: disc;
  padding-left: 20px;
  margin-top: 0.5rem;
}
.details-list li, .details-list li:hover {
  background: transparent !important;
  border: none !important;
  padding: 0.2rem 0 !important;
  margin: 0 !important;
  box-shadow: none !important;
  transform: none !important;
  position: static !important;
  overflow: visible !important;
}
.details-list li::before, .details-list li::after {
    display: none !important;
}

/* ===超链接样式优化=== */
a {
  color: inherit; /* 继承父元素的颜色 */
  text-decoration: none; /* 移除下划线 */
  transition: color 0.2s ease-in-out; /* 平滑过渡效果 */
}

a:hover {
  color: var(--accent); /* 鼠标悬停时使用主题强调色 */
  text-decoration: none; /* 确保悬停时也没有下划线 */
}

/* 确保在 card-content-wrapper 内部的链接颜色与普通文本接近 */
.card-content-wrapper a {
  color: var(--fg); /* 主文字颜色 */
}

.card-content-wrapper a:hover {
  color: var(--accent); /* 鼠标悬停时使用主题强调色 */
}

/* About / Services */
.service-grid{display:grid;gap:1rem;margin-top:1rem;align-items:stretch}
@media (min-width:1200px){.service-grid{grid-template-columns:repeat(4,1fr)}}
@media (min-width:768px) and (max-width:1199px){.service-grid{grid-template-columns:repeat(2,1fr)}}
@media (max-width:767px){.service-grid{grid-template-columns:1fr}}
.service-card{
  min-height:180px;
  display:flex;
  flex-direction:column;
  background: var(--card-bg);
  padding: 1.5rem;
  border-radius: 12px;
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  cursor: pointer;
}
.service-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--hover-shadow);
}
.service-card p{margin-top:.25rem}

/* Mini Terminal */
.terminal{
  margin-top:1.2rem;
  border:1px solid var(--border-color);
  border-radius:12px;
  overflow:hidden;
  background:var(--card-bg);
  box-shadow:var(--shadow);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  cursor: pointer;
}
.terminal:hover {
  transform: translateY(-2px);
  box-shadow: var(--hover-shadow);
}
.terminal-header{display:flex;align-items:center;gap:.4rem;padding:.5rem .8rem;background:linear-gradient(180deg, rgba(0,0,0,.08), rgba(0,0,0,.02));border-bottom:1px solid var(--border-color)}
.terminal-header .dot{width:10px;height:10px;border-radius:50%;display:inline-block}
.terminal-header .dot.red{background:#ff5f56}.terminal-header .dot.yellow{background:#ffbd2e}.terminal-header .dot.green{background:#27c93f}
.terminal-header .title{margin-left:.6rem;color:var(--text-color-light);font-weight:600}
.terminal-body{padding:1rem;font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', monospace;font-size:.95rem}
.terminal .prompt{color:var(--accent)}
.terminal .result{margin-top:.4rem;color:var(--text-color-light)}

/* --- Social icons as pill buttons --- */
.social{display:flex;gap:.6rem;justify-content:center;align-items:center;margin-top:1rem}
.social a{display:inline-flex;align-items:center;justify-content:center;width:40px;height:40px;border-radius:999px;background:rgba(255,255,255,.12);border:1px solid rgba(255,255,255,.25);backdrop-filter:blur(6px);color:#fff !important}
.social a:hover{background:var(--accent);border-color:var(--accent);color:#fff}
.social a{transition:transform .2s ease, background-color .2s ease, border-color .2s ease}
.social a:hover{transform:translateY(-2px)}
.service-card:hover{transform:translateY(-6px);}

/* --- Terminal polish & caret --- */
.terminal{background:linear-gradient(180deg, rgba(0,0,0,.06), rgba(0,0,0,.02));}
.caret{display:inline-block;width:10px;height:1.1em;margin-left:2px;background:var(--fg);opacity:.75;animation:blink 1s step-end infinite}
:root.dark-mode .caret{background:#e6edf5}
@keyframes blink{50%{opacity:0}}

/* tighten header spacing so icons don’t stick to text */
.hero-ctas{margin-top:1.2rem}
header .social{margin-top:1rem}

@media (max-width: 600px){
  .pill{font-size:.85rem}
}
.tagline, .hero-tags, .hero-ctas, header p{max-width:1100px;margin-left:auto;margin-right:auto}
@media (min-width:992px){header{padding-bottom:3.5rem}}

/* Service card lighting highlight (works with JS tilt) */
.service-card{position:relative;overflow:hidden}
.service-card::after{content:'';position:absolute;inset:-30%;background:radial-gradient(600px 300px at var(--mx,50%) var(--my,50%), rgba(var(--accent-rgb),.18), transparent 60%);opacity:.0;transition:opacity .2s ease;pointer-events:none}
.service-card:hover::after{opacity:.9}

@media (prefers-reduced-motion: reduce){
  .service-card:hover{transform:none}
  .service-card::after{display:none}
}

/* Avatar container */
.avatar-box{position:relative;display:inline-block}
/* stronger header overlay to avoid edges showing on scroll */
header::before{background:linear-gradient(to top, rgba(0,0,0,0.78) 0%, rgba(0,0,0,0.42) 60%, rgba(0,0,0,0.58) 100%);}

/* transparent ghost button for hero */
.btn.ghost{background:transparent;color:#fff;border:1.6px solid rgba(255,255,255,.75)}
.btn.ghost:hover{background:var(--accent);border-color:var(--accent);}

/* Skills grid compress to one column */
.skills-container{grid-template-columns:1fr}

/* --- 顶部滚动进度条 --- */
.scroll-progress{position:fixed;top:0;left:0;width:100%;height:4px;z-index:1100;background:transparent;pointer-events:none}
.scroll-progress .bar{height:100%;width:0;background:linear-gradient(90deg, var(--accent), var(--highlight));box-shadow:0 0 6px rgba(var(--accent-rgb),.7)}

/* --- 磁性按钮轻微跟随 --- */
.btn, .pill{transition: transform .15s ease, background-color .2s ease, border-color .2s ease}

/* --- 点击彩色纸屑画布，固定覆盖并不占据文档流 --- */
.effects-canvas{position:fixed;inset:0;z-index:2000;pointer-events:none;display:block}

/* --- 回到顶部按钮 --- */
.back-to-top{position:fixed;right:1.5rem;bottom:1.5rem;width:44px;height:44px;border-radius:50%;display:flex;align-items:center;justify-content:center;background:var(--accent);color:#fff;box-shadow:var(--shadow);z-index:1500;opacity:0;transform:translateY(20px);pointer-events:none;transition:opacity .25s ease, transform .25s ease, background-color .2s ease}
.back-to-top.visible{opacity:1;transform:translateY(0);pointer-events:auto}
.back-to-top:hover{background:var(--highlight)}