/* ================================================================
   张竞一个人主页样式 - v2.0
   参考: https://github.com/academicpages/academicpages.github.io
   设计: Masthead 顶栏 + 左侧作者栏 + 主内容区 + 页脚
   特性: 浅色/暗色双主题、响应式、可访问性优化
================================================================ */

/* ============== CSS 变量 - 浅色主题（默认） ============== */
:root {
  --global-base-color: #2f7f93;
  --global-bg-color: #ffffff;
  --global-bg-alt-color: #f2f3f3;
  --global-footer-bg-color: #f2f3f3;
  --global-border-color: #f2f3f3;
  --global-dark-border-color: #bdc1c4;
  --global-code-background-color: #fafafa;
  --global-code-text-color: #313436;
  --global-link-color: #52adc8;
  --global-link-color-hover: #1f5e6e;
  --global-link-color-visited: #7fc4d6;
  --global-masthead-link-color: #494e52;
  --global-masthead-link-color-hover: #2f7f93;
  --global-text-color: #494e52;
  --global-text-color-light: #bdc1c4;
  --global-thead-color: #f2f3f3;
  --global-sidebar-bg: #f7f8f8;

  /* Typography */
  --font-serif: "PT Serif", "Noto Serif SC", Georgia, "Times New Roman", serif;
  --font-sans: "Source Sans Pro", "Noto Sans SC", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --font-mono: "Source Code Pro", "SFMono-Regular", Menlo, Consolas, monospace;

  /* Layout sizes */
  --sidebar-width: 280px;
  --masthead-height: 60px;
  --content-max-width: 880px;
  --page-max-width: 1280px;
}

/* ============== 暗色主题 ============== */
html[data-theme="dark"] {
  --global-base-color: #0ea1c5;
  --global-bg-color: #1a1d1f;
  --global-bg-alt-color: #24272a;
  --global-footer-bg-color: #24272a;
  --global-border-color: #2d3134;
  --global-dark-border-color: #3d4248;
  --global-code-background-color: #2a2e31;
  --global-code-text-color: #e8eaed;
  --global-link-color: #4ab9d4;
  --global-link-color-hover: #6fd0e8;
  --global-link-color-visited: #3a9bb5;
  --global-masthead-link-color: #e8eaed;
  --global-masthead-link-color-hover: #4ab9d4;
  --global-text-color: #e8eaed;
  --global-text-color-light: #888c90;
  --global-thead-color: #24272a;
  --global-sidebar-bg: #1f2225;
}

/* ============== 全局重置 ============== */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  -ms-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--masthead-height) + 24px);
}

@media (min-width: 48em) {
  html { font-size: 18px; }
}

body {
  font-family: var(--font-serif);
  color: var(--global-text-color);
  background: var(--global-bg-color);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  transition: background-color 0.3s ease, color 0.3s ease;
}

::selection {
  color: #fff;
  background: var(--global-base-color);
}

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

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

a:visited {
  color: var(--global-link-color-visited);
}

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

/* ============== Masthead 顶部导航 ============== */
.masthead {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--masthead-height);
  background: var(--global-bg-color);
  border-bottom: 1px solid var(--global-border-color);
  z-index: 1000;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.04);
}

.masthead__inner-wrap {
  max-width: var(--page-max-width);
  margin: 0 auto;
  height: 100%;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.site-name {
  font-family: var(--font-sans);
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--global-masthead-link-color);
  text-decoration: none;
  letter-spacing: 0.3px;
  white-space: nowrap;
}

.site-name:hover {
  color: var(--global-masthead-link-color-hover);
  text-decoration: none;
}

.site-name .sep {
  color: var(--global-text-color-light);
  font-weight: 400;
  margin: 0 6px;
}

.site-name .en {
  font-weight: 400;
  color: var(--global-text-color-light);
  font-size: 0.92em;
}

/* 桌面导航 */
.masthead__menu {
  display: flex;
  align-items: center;
  gap: 4px;
}

.masthead__menu-item a,
.masthead__menu-item span {
  display: block;
  font-family: var(--font-sans);
  font-size: 0.92rem;
  font-weight: 500;
  color: var(--global-masthead-link-color);
  padding: 8px 14px;
  border-radius: 4px;
  text-decoration: none;
  transition: all 0.2s ease;
}

.masthead__menu-item a:hover {
  background: var(--global-bg-alt-color);
  color: var(--global-masthead-link-color-hover);
  text-decoration: none;
}

.masthead__menu-item.active a,
.masthead__menu-item.active span {
  color: var(--global-base-color);
  font-weight: 700;
}

/* 主题切换按钮 */
.theme-toggle {
  background: none;
  border: 1px solid var(--global-border-color);
  border-radius: 4px;
  cursor: pointer;
  padding: 6px 10px;
  font-size: 1rem;
  color: var(--global-masthead-link-color);
  transition: all 0.2s ease;
  margin-left: 8px;
  line-height: 1;
}

.theme-toggle:hover {
  background: var(--global-bg-alt-color);
  color: var(--global-base-color);
}

/* 移动端汉堡按钮 */
.menu-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  font-size: 1.4rem;
  color: var(--global-masthead-link-color);
  line-height: 1;
}

/* ============== 页面布局 ============== */
.page {
  max-width: var(--page-max-width);
  margin: 0 auto;
  padding-top: var(--masthead-height);
  display: flex;
  align-items: flex-start;
  gap: 0;
}

/* ============== 左侧作者栏 ============== */
.sidebar {
  width: var(--sidebar-width);
  flex-shrink: 0;
  background: var(--global-sidebar-bg);
  border-right: 1px solid var(--global-border-color);
  padding: 32px 24px 40px;
  position: sticky;
  top: var(--masthead-height);
  align-self: flex-start;
  max-height: calc(100vh - var(--masthead-height));
  overflow-y: auto;
}

.sidebar::-webkit-scrollbar { width: 6px; }
.sidebar::-webkit-scrollbar-thumb {
  background: var(--global-dark-border-color);
  border-radius: 3px;
}

.author__avatar {
  width: 140px;
  height: 140px;
  border-radius: 50%;
  margin: 0 auto 16px;
  background: linear-gradient(135deg, var(--global-base-color), var(--global-link-color));
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-family: var(--font-sans);
  font-size: 3.5rem;
  font-weight: 700;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.12);
  overflow: hidden;
}

.author__avatar img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.author__name {
  font-family: var(--font-sans);
  text-align: center;
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--global-text-color);
  margin-bottom: 4px;
  letter-spacing: 0.5px;
}

.author__name .en {
  display: block;
  font-size: 0.85rem;
  font-weight: 400;
  color: var(--global-text-color-light);
  margin-top: 2px;
  letter-spacing: 0.5px;
}

.author__bio {
  text-align: center;
  font-family: var(--font-sans);
  font-size: 0.86rem;
  color: var(--global-text-color);
  line-height: 1.6;
  margin-bottom: 20px;
  padding: 0 4px;
}

.author__bio strong {
  color: var(--global-base-color);
  font-weight: 600;
}

/* 作者联系方式 */
.author__urls-wrapper {
  border-top: 1px solid var(--global-border-color);
  padding-top: 16px;
  margin-bottom: 24px;
}

.author__urls {
  list-style: none;
  font-family: var(--font-sans);
  font-size: 0.86rem;
}

.author__urls li {
  margin-bottom: 8px;
  display: flex;
  align-items: flex-start;
  gap: 8px;
  line-height: 1.5;
  word-break: break-word;
}

.author__urls .icon {
  flex-shrink: 0;
  width: 16px;
  text-align: center;
  color: var(--global-base-color);
  font-weight: 700;
  line-height: 1.5;
}

.author__urls a {
  color: var(--global-text-color);
  text-decoration: none;
}

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

/* 侧栏目录 */
.sidebar__nav {
  border-top: 1px solid var(--global-border-color);
  padding-top: 18px;
  font-family: var(--font-sans);
}

.sidebar__nav-title {
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 1.2px;
  color: var(--global-text-color-light);
  margin-bottom: 10px;
  font-weight: 700;
}

.sidebar__nav ul {
  list-style: none;
}

.sidebar__nav li {
  margin-bottom: 2px;
}

.sidebar__nav a {
  display: block;
  padding: 5px 10px;
  color: var(--global-text-color);
  text-decoration: none;
  font-size: 0.88rem;
  border-radius: 3px;
  border-left: 2px solid transparent;
  transition: all 0.2s ease;
}

.sidebar__nav a:hover {
  background: var(--global-bg-alt-color);
  color: var(--global-base-color);
  border-left-color: var(--global-base-color);
  text-decoration: none;
}

.sidebar__nav-group {
  margin-bottom: 18px;
}

/* ============== 主内容区 ============== */
.main {
  flex: 1;
  min-width: 0;
  padding: 40px 48px 60px;
  background: var(--global-bg-color);
}

.page__inner-wrap {
  max-width: var(--content-max-width);
  margin: 0 auto;
}

.page__title {
  font-family: var(--font-sans);
  font-size: 1.85rem;
  font-weight: 700;
  color: var(--global-text-color);
  margin-bottom: 6px;
  letter-spacing: -0.3px;
}

.page__meta {
  font-family: var(--font-sans);
  font-size: 0.82rem;
  color: var(--global-text-color-light);
  margin-bottom: 32px;
  padding-bottom: 14px;
  border-bottom: 1px solid var(--global-border-color);
}

/* Headings */
.main h2 {
  font-family: var(--font-sans);
  font-size: 1.45rem;
  font-weight: 700;
  margin-top: 2.4rem;
  margin-bottom: 1rem;
  padding-bottom: 0.4rem;
  border-bottom: 1px solid var(--global-border-color);
  color: var(--global-text-color);
  letter-spacing: -0.2px;
}

.main h3 {
  font-family: var(--font-sans);
  font-size: 1.15rem;
  font-weight: 600;
  margin-top: 1.8rem;
  margin-bottom: 0.7rem;
  color: var(--global-text-color);
}

.main h4 {
  font-family: var(--font-sans);
  font-size: 1rem;
  font-weight: 600;
  margin-top: 1.4rem;
  margin-bottom: 0.5rem;
  color: var(--global-text-color);
}

/* Paragraphs */
.main p {
  margin-bottom: 1rem;
  line-height: 1.85;
  font-size: 1rem;
}

.main strong {
  font-weight: 700;
  color: var(--global-text-color);
}

/* Lists */
.main ul,
.main ol {
  margin-left: 1.5rem;
  margin-bottom: 1rem;
}

.main li {
  margin-bottom: 0.4rem;
  line-height: 1.75;
}

/* Resource link button style */
.resource-link {
  display: inline-block;
  font-family: var(--font-sans);
  font-size: 0.85rem;
  padding: 4px 12px;
  margin: 3px 4px 3px 0;
  background: var(--global-bg-alt-color);
  color: var(--global-base-color) !important;
  border: 1px solid var(--global-border-color);
  border-radius: 4px;
  text-decoration: none !important;
  transition: all 0.2s ease;
  white-space: nowrap;
}

.resource-link:hover {
  background: var(--global-base-color);
  color: #fff !important;
  border-color: var(--global-base-color);
  text-decoration: none !important;
}

.resource-link:visited {
  color: var(--global-base-color) !important;
}

/* Course card list */
.course-list {
  list-style: none;
  margin-left: 0;
}

.course-list > li {
  background: var(--global-bg-alt-color);
  border: 1px solid var(--global-border-color);
  border-left: 3px solid var(--global-base-color);
  border-radius: 4px;
  padding: 14px 18px;
  margin-bottom: 12px;
  transition: box-shadow 0.2s ease, border-left-color 0.2s ease;
}

.course-list > li:hover {
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.06);
  border-left-color: var(--global-link-color);
}

.course-list > li > h3,
.course-list > li > .course-title {
  font-family: var(--font-sans);
  font-size: 1.08rem;
  font-weight: 700;
  color: var(--global-text-color);
  margin-bottom: 6px;
  padding: 0;
  border: none;
}

.course-list .meta {
  font-family: var(--font-sans);
  font-size: 0.85rem;
  color: var(--global-text-color-light);
  margin-bottom: 8px;
  line-height: 1.6;
}

.course-list .resources {
  margin-top: 6px;
}

/* Section heading with anchor */
.section-anchor {
  scroll-margin-top: calc(var(--masthead-height) + 20px);
}

/* Horizontal rule */
.main hr {
  border: none;
  border-top: 1px solid var(--global-border-color);
  margin: 2.2rem 0;
}

/* Code */
.main code {
  font-family: var(--font-mono);
  font-size: 0.88em;
  background: var(--global-code-background-color);
  color: var(--global-code-text-color);
  padding: 2px 6px;
  border-radius: 3px;
  border: 1px solid var(--global-border-color);
}

.main pre {
  font-family: var(--font-mono);
  font-size: 0.88em;
  background: var(--global-code-background-color);
  color: var(--global-code-text-color);
  padding: 14px 18px;
  border-radius: 4px;
  border: 1px solid var(--global-border-color);
  overflow-x: auto;
  line-height: 1.55;
  margin-bottom: 1rem;
}

.main pre code {
  background: none;
  border: none;
  padding: 0;
}

/* Blockquote */
.main blockquote {
  border-left: 4px solid var(--global-base-color);
  padding: 4px 16px;
  margin: 1.2rem 0;
  color: var(--global-text-color);
  background: var(--global-bg-alt-color);
  font-style: italic;
}

.main blockquote p {
  margin-bottom: 0;
}

/* Tables */
.main table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.2rem 0;
  font-family: var(--font-sans);
  font-size: 0.92rem;
}

.main th,
.main td {
  padding: 8px 12px;
  border: 1px solid var(--global-border-color);
  text-align: left;
}

.main th {
  background: var(--global-thead-color);
  font-weight: 600;
  color: var(--global-text-color);
}

/* Update log / changelog */
.changelog {
  list-style: none;
  margin-left: 0;
  font-family: var(--font-sans);
}

.changelog li {
  padding: 8px 0;
  border-bottom: 1px dashed var(--global-border-color);
  font-size: 0.92rem;
}

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

.changelog .date {
  display: inline-block;
  min-width: 110px;
  font-weight: 600;
  color: var(--global-base-color);
  font-family: var(--font-mono);
  font-size: 0.85rem;
}

/* ============== 页脚 ============== */
.page__footer {
  background: var(--global-footer-bg-color);
  border-top: 1px solid var(--global-border-color);
  padding: 24px;
  margin-top: 0;
}

.page__footer-inner {
  max-width: var(--page-max-width);
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  font-family: var(--font-sans);
  font-size: 0.82rem;
  color: var(--global-text-color-light);
}

.page__footer a {
  color: var(--global-text-color);
  text-decoration: none;
}

.page__footer a:hover {
  color: var(--global-base-color);
  text-decoration: underline;
}

.page__footer-follow {
  display: flex;
  gap: 16px;
}

/* ============== 响应式 ============== */
@media (max-width: 1024px) {
  :root { --sidebar-width: 240px; }
  .main { padding: 36px 36px 50px; }
}

@media (max-width: 768px) {
  :root {
    --sidebar-width: 260px;
    --masthead-height: 56px;
  }

  .masthead__inner-wrap { padding: 0 16px; }

  .menu-toggle { display: block; }

  .masthead__menu {
    position: fixed;
    top: var(--masthead-height);
    right: 0;
    background: var(--global-bg-color);
    border-left: 1px solid var(--global-border-color);
    border-bottom: 1px solid var(--global-border-color);
    flex-direction: column;
    align-items: stretch;
    width: 220px;
    padding: 12px;
    transform: translateX(100%);
    transition: transform 0.3s ease;
    box-shadow: -2px 2px 12px rgba(0, 0, 0, 0.08);
    z-index: 999;
  }

  .masthead__menu.open {
    transform: translateX(0);
  }

  .masthead__menu-item a,
  .masthead__menu-item span {
    padding: 10px 14px;
    border-radius: 4px;
  }

  .page {
    flex-direction: column;
  }

  .sidebar {
    position: static;
    width: 100%;
    max-height: none;
    border-right: none;
    border-bottom: 1px solid var(--global-border-color);
    padding: 24px 20px;
    text-align: center;
  }

  .sidebar__nav {
    text-align: left;
  }

  .author__avatar {
    width: 110px;
    height: 110px;
    font-size: 2.8rem;
  }

  .main {
    padding: 28px 20px 40px;
  }

  .page__title { font-size: 1.55rem; }
  .main h2 { font-size: 1.25rem; }
  .main h3 { font-size: 1.05rem; }
  .main p, .main li { font-size: 0.95rem; }

  .page__footer-inner {
    flex-direction: column;
    text-align: center;
  }
}

@media (max-width: 480px) {
  .main { padding: 20px 16px 32px; }
  .author__avatar { width: 90px; height: 90px; font-size: 2.2rem; }
  .author__name { font-size: 1.15rem; }
  .resource-link {
    display: block;
    margin: 4px 0;
    text-align: center;
  }
}

/* ============== 打印 ============== */
@media print {
  .masthead,
  .sidebar,
  .menu-toggle,
  .theme-toggle,
  .page__footer-follow {
    display: none !important;
  }

  .main {
    padding: 0;
  }

  body {
    background: #fff;
    color: #000;
  }
}

/* ============== 工具类 ============== */
.text-center { text-align: center; }
.text-muted { color: var(--global-text-color-light); }
.mt-0 { margin-top: 0; }
.mb-0 { margin-bottom: 0; }