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

body {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    font-family: 'Segoe UI', Arial, sans-serif;
    line-height: 1.6;
    background-color: #f9f9fb;
    color: #333;
}

/* 导航栏样式 */
header {
    background-color: #f8f9fa;
    padding: 1rem;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    position: fixed;
    width: 100%;
    top: 0;
    z-index: 1001;
}

.header-content {
    max-width: 1300px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.header-logo {
    width: 50px;
    height: 50px;
}

.header-logo img {
    width: 100%;
    height: 100%;
    transition: transform 0.3s cubic-bezier(0.68, -0.55, 0.265, 1.55);
}

.header-logo img:hover {
    transform: scale(1.15);
}

nav.top-nav {
    display: flex;
    gap: 0.5rem;
}

nav.top-nav a {
    text-decoration: none;
    color: #333;
    transition: color 0.3s ease;
}

nav.top-nav a:hover {
    color: #007bff;
}


/* 内容容器 */
.container {
    max-width: 900px;
    margin: 90px auto 40px;
    padding: 0 20px;
}

.page-title {
    text-align: center;
    margin-bottom: 40px;
    color: #2563eb;
    font-size: 32px;
    font-weight: 700;
    letter-spacing: -0.5px;
}

/* 更新列表样式 */
.update-list {
    position: relative;
    padding: 10px 0 30px;
}

/* 更新卡片样式 */
.update-card {
    background: #fff;
    border-radius: 12px;
    padding: 22px 25px;
    margin-bottom: 30px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
    position: relative;
    transition: all 0.3s;
    border: 1px solid rgba(0, 0, 0, 0.03);
}

.update-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.08);
    border-color: rgba(37, 99, 235, 0.15);
}

.grid {
    display: grid;
    gap: 16px;
}

.version {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid #f0f0f0;
    padding-bottom: 12px;
}

.version-number {
    font-size: 18px;
    font-weight: 600;
    color: #2563eb;
    display: flex;
    align-items: center;
}

.version-number::before {
    content: '📦';
    margin-right: 8px;
    font-size: 1.1em;
}

.date {
    font-size: 14px;
    color: #6b7280;
    font-weight: 500;
}

.changes {
    list-style-position: outside;
    color: #4b5563;
    padding-left: 18px;
}

.changes li {
    margin-bottom: 10px;
    position: relative;
    padding-left: 4px;
}

.changes li:last-child {
    margin-bottom: 0;
}

.changes li::marker {
    color: #7c3aed;
}

/* 自定义滚动条样式 */
* {
    /* Firefox */
    scrollbar-width: thin;
    scrollbar-color: #db91f3 #ffd6d6;
}

/* Webkit 浏览器的滚动条样式 */
::-webkit-scrollbar {
    width: 5px;
    height: 5px;
    background: #ffd6d6;
}

::-webkit-scrollbar-thumb {
    background: #db91f3;
    border-radius: 3px;
    transition: background 0.2s ease;
}

::-webkit-scrollbar-thumb:hover {
    background: #b63f9a;
}

/* iframe 样式 */
iframe {
    display: block;
    width: 100%;
    height: 365px;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
    border-radius: 10px;
    border: none;
}

/* 响应式设计 */
@media (max-width: 1300px) {
    iframe {
        height: 450px;
    }
}

@media (max-width: 1100px) {
    iframe {
        height: 750px;
    }
}

@media (max-width: 768px) {
    .header-logo {
        width: 35px;
        height: 35px;
    }

    nav.top-nav a {
        font-size: 0.9rem;
        padding: 0.25rem 0.5rem;
    }

    .page-title {
        font-size: 26px;
        margin-bottom: 30px;
    }

    .update-card {
        padding: 18px 20px;
    }

    .version-number {
        font-size: 16px;
    }

    iframe {
        height: 750px;
    }
}

@media (max-width: 480px) {
    .header-content {
        padding: 0 10px;
    }

    .container {
        padding: 0 15px;
        margin-top: 80px;
    }

    .page-title {
        font-size: 24px;
    }

    .update-card {
        padding: 15px;
    }

    iframe {
        height: 600px;
    }
}
/* ====== 返回顶部按钮样式 ====== */
#backToTop {
  position: fixed;
  bottom: 40px;
  right: 40px;
  width: 72px;
  height: 72px;
  border: none;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.25);
  backdrop-filter: blur(12px);
  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.25);
  cursor: pointer;
  display: none;
  justify-content: center;
  align-items: center;
  opacity: 0;
  transition: all 0.4s ease;
  z-index: 999;
  overflow: hidden;
  animation: breathing 3s ease-in-out infinite;
}

/* 呼吸闪动 */
@keyframes breathing {
  0%, 100% { box-shadow: 0 0 15px rgba(54 243 178 / 58%); }
  50% { box-shadow: 0 0 25px rgba(184 73 218 / 58%); }
}

/* 图片 */
#backToTop img {
  width: 60%;
  height: 60%;
  object-fit: contain;
  position: absolute;
  z-index: 2;
  transition: transform 0.4s ease;
}

/* 滚动进度环 */
.progress-ring {
  position: absolute;
  width: 100%;
  height: 100%;
  transform: rotate(-90deg);
  z-index: 1;
}
.progress-ring__background {
  fill: none;
  stroke: rgba(230 157 157 / 32%);
  stroke-width: 8;
}
.progress-ring__circle {
  fill: none;
  stroke: #d786dc;
  stroke-width: 8;
  stroke-dasharray: 283;
  stroke-dashoffset: 283;
  transition: stroke-dashoffset 0.2s ease;
}

/* 显示状态 */
#backToTop.show {
  display: flex;
  opacity: 1;
  animation: fadeInUp 0.4s ease, breathing 3s ease-in-out infinite;
}

/* 悬停动效 */
#backToTop:hover {
  transform: scale(1.08) translateY(-4px);
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.35);
}
#backToTop:hover img {
  transform: translateY(-2px) rotate(-8deg);
}

/* 点击反馈 */
#backToTop:active {
  transform: scale(0.9);
}

/* 出现动画 */
@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

/* 暗色模式 */
@media (prefers-color-scheme: dark) {
  #backToTop {
    background: rgba(40, 40, 40, 0.6);
  }
  .progress-ring__background {
    stroke: rgba(255, 255, 255, 0.1);
  }
}

/* 手机端优化 */
@media (max-width: 768px) {
  #backToTop {
    width: 60px;
    height: 60px;
    bottom: 25px;
    right: 25px;
  }
}

.back-link {
    display: inline-block;
    margin: 20px 0;
    color: #3498db;
    text-decoration: none;
    font-weight: 500
}

.back-link:hover {
    text-decoration: underline
}