/* ============================================================
   学术宣纸风 · Academic Paper Theme
   ============================================================ */
:root {
  --paper: hsl(40, 33%, 97%);
  --card: #ffffff;
  --ink: hsl(158, 32%, 22%);
  --ink-deep: hsl(158, 36%, 15%);
  --brown: hsl(28, 38%, 42%);
  --brown-soft: hsl(28, 30%, 50%);
  --text: hsl(158, 18%, 16%);
  --muted: hsl(30, 10%, 46%);
  --border: hsl(40, 20%, 88%);
  --code-bg: hsl(40, 20%, 93%);
  --quote-bg: hsl(40, 25%, 94%);
  --shadow: 0 1px 3px hsl(40 20% 60% / 0.18);
  --shadow-hover: 0 8px 24px hsl(158 30% 20% / 0.14);
  --serif: "Noto Serif SC", "Songti SC", "SimSun", serif;
}

[data-theme="dark"] {
  --paper: hsl(158, 30%, 10%);
  --card: hsl(158, 24%, 15%);
  --ink: hsl(80, 18%, 82%);
  --ink-deep: hsl(158, 36%, 8%);
  --brown: hsl(28, 45%, 62%);
  --brown-soft: hsl(28, 35%, 55%);
  --text: hsl(40, 25%, 88%);
  --muted: hsl(40, 8%, 62%);
  --border: hsl(158, 16%, 24%);
  --code-bg: hsl(158, 20%, 19%);
  --quote-bg: hsl(158, 22%, 18%);
  --shadow: 0 1px 3px hsl(158 40% 5% / 0.5);
  --shadow-hover: 0 8px 24px hsl(158 40% 4% / 0.6);
}

/* ============ 基础 ============ */
* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: var(--serif);
  font-size: 16.5px;
  line-height: 1.9;
  background-color: var(--paper);
  color: var(--text);
  transition: background-color 0.3s ease, color 0.3s ease;
}

h1, h2, h3, h4 {
  font-family: var(--serif);
  color: var(--ink);
  line-height: 1.35;
  font-weight: 700;
}

a { color: var(--ink); text-decoration: none; transition: color 0.3s ease; }
a:hover { color: var(--brown); }

.container { max-width: 860px; margin: 0 auto; padding: 0 1.5rem; }

.muted { color: var(--muted); }
.mono { font-family: Consolas, "Courier New", monospace; font-size: 0.9em; }
.center { text-align: center; }

/* ============ kicker / 节标题 ============ */
.kicker {
  font-family: var(--serif);
  font-size: 0.75rem;
  letter-spacing: 0.3em;
  color: var(--brown);
  margin: 0 0 0.6rem;
}

.kicker-light { color: hsl(40, 30%, 85%); }

.section-head { text-align: center; margin: 0 0 2.2rem; }
.section-head h1, .section-head h2 { margin: 0.2rem 0 0.4rem; font-size: 2rem; }
.section-head .meta { margin-top: 0.6rem; }
.section-head-left { text-align: left; margin-bottom: 1.2rem; }

.rule {
  display: block;
  width: 48px;
  height: 3px;
  background: var(--brown);
  margin: 0.8rem auto 0;
  border-radius: 2px;
}

.section-head-left .rule, .rule-center { margin-left: 0; }
.rule-center { margin-left: auto; }

/* ============ 导航（吸顶） ============ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--card);
  border-bottom: 1px solid var(--border);
  transition: background-color 0.3s ease, border-color 0.3s ease;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.8rem;
  padding-top: 0.85rem;
  padding-bottom: 0.85rem;
}

.site-title {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--serif);
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--ink);
}

.site-mark { color: var(--ink); flex-shrink: 0; }

.site-nav { display: flex; align-items: center; gap: 1.4rem; }

.site-nav a {
  font-size: 0.95rem;
  color: var(--text);
  padding-bottom: 2px;
  border-bottom: 2px solid transparent;
  transition: color 0.3s ease, border-color 0.3s ease;
}

.site-nav a:hover { color: var(--brown); }
.site-nav a.active { color: var(--brown); border-bottom-color: var(--brown); }

.theme-toggle {
  background: none;
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 0.25rem 0.6rem;
  cursor: pointer;
  font-size: 0.95rem;
  color: var(--text);
  transition: transform 0.3s ease, border-color 0.3s ease;
}

.theme-toggle:hover { transform: scale(1.1); border-color: var(--brown); }

/* ============ Hero（横幅） ============ */
.hero {
  position: relative;
  min-height: 360px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: url("../images/hero.png") center / cover no-repeat;
}

.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(hsl(158 36% 12% / 0.55), hsl(158 36% 12% / 0.65));
}

.hero-overlay {
  position: relative;
  text-align: center;
  color: hsl(40, 33%, 97%);
  padding: 3rem 1.5rem;
  animation: fadeIn 0.6s ease both;
}

.hero-title {
  font-size: 2.6rem;
  color: #fff;
  margin: 0.4rem 0 0.8rem;
  letter-spacing: 0.06em;
}

.hero-sub {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.9rem;
  font-size: 1.05rem;
  color: hsl(40, 30%, 90%);
  margin: 0;
}

.hero-sub .dash { width: 44px; height: 1px; background: hsl(28, 45%, 62%); }

/* ============ 个人介绍 ============ */
.intro-card { margin-bottom: 2.8rem; }
.intro-owner { margin: 0.2rem 0 0.4rem; font-size: 1.4rem; }
.intro-card .rule { margin-left: 0; margin-bottom: 1.2rem; }
.intro-body > :first-child { margin-top: 0; }
.intro-body > :last-child { margin-bottom: 0; }

/* 后台设置页背景图预览 */
.hero-preview-row { display: flex; align-items: center; gap: 1rem; flex-wrap: wrap; }
.hero-preview {
  width: 180px;
  height: 90px;
  object-fit: cover;
  border-radius: 8px;
  border: 1px solid var(--border);
}

input[type="color"] {
  width: 64px;
  height: 40px;
  padding: 2px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--paper);
  cursor: pointer;
}

/* ============ 主体 ============ */
.main-content { padding-top: 3.2rem; padding-bottom: 4rem; min-height: 55vh; }

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 1.6rem 1.8rem;
  box-shadow: var(--shadow);
  transition: background-color 0.3s ease, border-color 0.3s ease,
              box-shadow 0.3s ease, transform 0.3s ease;
}

.article-list { display: flex; flex-direction: column; gap: 1.4rem; }

.article-card:hover { box-shadow: var(--shadow-hover); transform: translateY(-4px); }

.article-card .meta { margin: 0 0 0.35rem; }
.article-card h3 { margin: 0 0 0.5rem; font-size: 1.35rem; }
.article-card h3 a { color: var(--ink); }
.article-card h3 a:hover { color: var(--brown); }

.meta { font-size: 0.85rem; color: var(--muted); }
.summary { margin: 0.2rem 0 0.8rem; color: var(--text); }

.read-more { font-size: 0.9rem; color: var(--brown); font-weight: 600; }
.read-more .arrow { display: inline-block; transition: transform 0.3s ease; }
.read-more:hover .arrow { transform: translateX(4px); }

.tag {
  display: inline-block;
  border: 1px solid var(--brown-soft);
  color: var(--brown);
  border-radius: 999px;
  padding: 0 0.65rem;
  margin-right: 0.35rem;
  font-size: 0.78rem;
  line-height: 1.7;
  transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease;
}

.tag:hover { background: var(--brown); border-color: var(--brown); color: #fff; }

.pagination {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 1.4rem;
  margin-top: 2.4rem;
  font-size: 0.92rem;
}

.pagination a { color: var(--brown); }

/* ============ 文章详情 ============ */
.article-detail .section-head h1 { font-size: 2.1rem; }

.article-body-card { padding: 2rem 2.2rem; }

.article-body { color: var(--text); }
.article-body img { max-width: 100%; border-radius: 8px; }
.article-body h2 { margin-top: 2rem; color: var(--ink); }
.article-body h3 { margin-top: 1.6rem; color: var(--ink); }

.article-body pre {
  background: var(--code-bg);
  border-radius: 10px;
  padding: 1rem 1.2rem;
  overflow-x: auto;
}

.article-body code { font-family: Consolas, "Courier New", monospace; font-size: 0.9em; }

.article-body p code, .article-body li code {
  background: var(--code-bg);
  border-radius: 4px;
  padding: 0.1em 0.35em;
}

.article-body blockquote {
  margin: 1.2rem 0;
  padding: 0.6rem 1.2rem;
  border-left: 3px solid var(--ink);
  background: var(--quote-bg);
  border-radius: 0 8px 8px 0;
  color: var(--muted);
  transition: background-color 0.3s ease;
}

.article-body table { border-collapse: collapse; width: 100%; margin: 1.2rem 0; }
.article-body th, .article-body td {
  border: 1px solid var(--border);
  padding: 0.5rem 0.9rem;
  text-align: left;
}
.article-body th { background: var(--quote-bg); color: var(--ink); }

.bibtex-block { margin-top: 1.6rem; }
.bibtex-block .kicker { margin-bottom: 0.8rem; }
.bibtex-block pre {
  background: var(--code-bg);
  border-radius: 10px;
  padding: 1rem 1.2rem;
  overflow-x: auto;
  font-size: 0.85rem;
  white-space: pre-wrap;
  margin: 0 0 0.8rem;
}

/* ============ 评论区 ============ */
.comments { margin-top: 3rem; }
.comment { margin-bottom: 1rem; padding: 1.2rem 1.6rem; }
.comment-meta { margin: 0 0 0.3rem; font-size: 0.9rem; }
.comment-meta strong { color: var(--ink); }
.comment-content { margin: 0; white-space: pre-wrap; }
.comment-form { margin-top: 1.6rem; }
.form-title { margin-top: 0; }

.hp-field {
  position: absolute !important;
  left: -9999px !important;
  height: 0; width: 0;
  opacity: 0;
}

/* 验证码 */
.captcha-row { display: flex; align-items: center; gap: 0.7rem; }

.captcha-img {
  height: 52px;
  border: 1px solid var(--border);
  border-radius: 8px;
  cursor: pointer;
  background: #f5f4f0; /* 浅色底，深浅主题下均可读 */
  transition: border-color 0.3s ease, transform 0.3s ease;
}

.captcha-img:hover { border-color: var(--brown); transform: scale(1.02); }
.captcha-row input { width: 8rem; letter-spacing: 0.2em; text-transform: uppercase; }

/* ============ 表单 ============ */
.form-row { margin-bottom: 1.1rem; display: flex; flex-direction: column; gap: 0.35rem; }
.form-row label { font-size: 0.88rem; color: var(--muted); }

input[type="text"], input[type="password"], textarea, select {
  padding: 0.55rem 0.85rem;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--paper);
  color: var(--text);
  font-size: 1rem;
  font-family: var(--serif);
  transition: border-color 0.3s ease, background-color 0.3s ease;
}

input:focus, textarea:focus, select:focus { outline: none; border-color: var(--brown); }

.edit-form textarea#content, .edit-form textarea#bibtex, textarea.mono {
  font-family: Consolas, "Courier New", monospace;
  font-size: 0.92rem;
}

.search-form {
  display: flex;
  gap: 0.7rem;
  padding: 0.9rem 1rem;
  margin-bottom: 1.8rem;
}

.search-form input { flex: 1; }

.btn {
  display: inline-block;
  background: var(--ink);
  color: hsl(40, 33%, 97%);
  border: none;
  border-radius: 8px;
  padding: 0.5rem 1.3rem;
  font-size: 0.95rem;
  font-family: var(--serif);
  cursor: pointer;
  transition: background-color 0.3s ease, transform 0.3s ease, color 0.3s ease;
}

.btn:hover { background: var(--ink-deep); color: #fff; transform: translateY(-1px); }
[data-theme="dark"] .btn:hover { background: var(--brown); }

.btn-secondary {
  background: transparent;
  color: var(--ink);
  border: 1px solid var(--ink);
}

.btn-secondary:hover { background: var(--ink); color: hsl(40, 33%, 97%); }
.btn-small { padding: 0.25rem 0.8rem; font-size: 0.85rem; }
.btn-danger { background: hsl(5, 45%, 42%); }
.btn-danger:hover { background: hsl(5, 45%, 34%); }

.form-actions { display: flex; gap: 0.8rem; }

.login-card { max-width: 400px; margin: 3rem auto; }
.login-card h1 { margin-top: 0; }

/* ============ 后台 ============ */
.admin-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.8rem;
  margin-bottom: 1.4rem;
}

.admin-head h1 { margin: 0; }
.admin-actions { display: flex; gap: 0.6rem; flex-wrap: wrap; }

.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 1rem;
  margin-bottom: 1.6rem;
}

.stat { text-align: center; padding: 1.2rem 1rem; }
.stat-num { display: block; font-size: 1.9rem; font-weight: 700; color: var(--brown); }

.admin-table { width: 100%; border-collapse: collapse; padding: 0; overflow: hidden; }
.admin-table th, .admin-table td {
  padding: 0.75rem 1rem;
  text-align: left;
  border-bottom: 1px solid var(--border);
}
.admin-table th { background: var(--quote-bg); font-size: 0.9rem; color: var(--ink); }
.admin-table tr:last-child td { border-bottom: none; }
.admin-table .ops { display: flex; gap: 0.4rem; align-items: center; }
.admin-table .ops form { margin: 0; }

.badge { border-radius: 999px; padding: 0.1rem 0.65rem; font-size: 0.78rem; }
.badge-published { background: var(--ink); color: hsl(40, 33%, 97%); }
.badge-draft { background: var(--code-bg); color: var(--muted); }

/* ============ 提示 ============ */
.flash-wrap { padding-top: 1.2rem; }
.flash { border-radius: 8px; padding: 0.7rem 1.1rem; margin-bottom: 1rem; font-size: 0.95rem; }
.flash-ok { background: hsl(158, 30%, 22%, 0.1); border: 1px solid var(--ink); color: var(--text); }
.flash-error { background: hsl(5, 45%, 42%, 0.1); border: 1px solid hsl(5, 45%, 42%); color: var(--text); }

/* ============ 归档时间线 ============ */
.timeline { max-width: 640px; margin: 0 auto; }
.timeline-group { margin-bottom: 2rem; }

.timeline-ym {
  color: var(--brown);
  font-size: 1.1rem;
  letter-spacing: 0.1em;
  margin: 0 0 0.8rem;
  padding-left: 1.6rem;
  position: relative;
}

.timeline-ym::before {
  content: "";
  position: absolute;
  left: 0; top: 0.55em;
  width: 10px; height: 10px;
  border-radius: 50%;
  background: var(--brown);
}

.timeline-list { list-style: none; margin: 0; padding: 0 0 0 1.6rem; border-left: 1px solid var(--border); margin-left: 4px; }

.timeline-item {
  position: relative;
  padding: 0.35rem 0 0.35rem 1rem;
  display: flex;
  gap: 0.9rem;
  align-items: baseline;
}

.timeline-dot {
  position: absolute;
  left: -1.6rem;
  top: 0.95em;
  width: 7px; height: 7px;
  margin-left: 1px;
  border-radius: 50%;
  background: var(--paper);
  border: 2px solid var(--brown);
}

.timeline-date { font-size: 0.85rem; flex-shrink: 0; }
.timeline-item a { color: var(--ink); }
.timeline-item a:hover { color: var(--brown); }

/* ============ 页脚 ============ */
.site-footer {
  background: var(--ink-deep);
  color: hsl(40, 25%, 82%);
  padding: 2.2rem 0;
  text-align: center;
  margin-top: 2rem;
}

.footer-title {
  font-size: 1.05rem;
  font-weight: 700;
  color: hsl(40, 33%, 95%);
  letter-spacing: 0.1em;
  margin: 0 0 0.3rem;
}

.site-footer .muted { color: hsl(40, 10%, 62%); margin: 0; font-size: 0.85rem; }

/* ============ 动效 ============ */
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(10px); }
  to   { opacity: 1; transform: translateY(0); }
}

.js .reveal {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 0.3s ease, transform 0.3s ease;
}

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

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation: none !important; transition: none !important; }
  .js .reveal { opacity: 1; transform: none; }
}

/* ============ 响应式 ============ */
@media (max-width: 600px) {
  body { font-size: 15.5px; }
  .hero { min-height: 260px; }
  .hero-title { font-size: 1.8rem; }
  .hero-sub { font-size: 0.95rem; }
  .section-head h1, .section-head h2 { font-size: 1.5rem; }
  .article-detail .section-head h1 { font-size: 1.55rem; }
  .header-inner { flex-wrap: wrap; }
  .site-nav { gap: 1rem; width: 100%; overflow-x: auto; }
  .card { padding: 1.2rem 1.2rem; }
  .article-body-card { padding: 1.4rem 1.3rem; }
  .admin-table { font-size: 0.85rem; }
  .admin-table th, .admin-table td { padding: 0.5rem; }
  .timeline-item { flex-direction: column; gap: 0; }
  .search-form { flex-direction: column; }
}