/* tangxinvlog.xyz — timeline template, cool blue-teal */
:root {
  --bg: #eef6f8;
  --bg-deep: #d9eef2;
  --soft: #f7fcfd;
  --ink: #12333a;
  --muted: #4a6b73;
  --line: #b7d4db;
  --accent: #0d8a9a;
  --accent-2: #1a6fbf;
  --accent-soft: rgba(13, 138, 154, 0.12);
  --spine: #2aa8b8;
  --max: 980px;
  --radius: 12px;
  --shadow: 0 10px 28px rgba(18, 51, 58, 0.08);
  --font: "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
}

*,
*::before,
*::after { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font);
  color: var(--ink);
  background:
    radial-gradient(1200px 500px at 10% -10%, rgba(26, 111, 191, 0.12), transparent 55%),
    radial-gradient(900px 420px at 90% 0%, rgba(13, 138, 154, 0.14), transparent 50%),
    linear-gradient(180deg, var(--bg) 0%, #f4fafb 45%, var(--bg-deep) 100%);
  line-height: 1.75;
  min-height: 100vh;
}

a { color: var(--accent-2); text-decoration-thickness: 1px; text-underline-offset: 2px; }
a:hover { color: var(--accent); }

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

.skip {
  position: absolute;
  left: -999px;
  top: 0;
  background: #fff;
  padding: .5rem .8rem;
  z-index: 100;
}
.skip:focus { left: .5rem; top: .5rem; }

/* —— header / nav —— */
.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  backdrop-filter: blur(10px);
  background: rgba(247, 252, 253, 0.88);
  border-bottom: 1px solid var(--line);
}

.nav-row {
  max-width: var(--max);
  margin: 0 auto;
  padding: .65rem 1rem;
  display: flex;
  align-items: center;
  gap: .75rem;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: .55rem;
  color: var(--ink);
  text-decoration: none;
  font-weight: 700;
  letter-spacing: .02em;
}
.brand img {
  width: 40px;
  height: 40px;
  border-radius: 10px;
  border: 1px solid var(--line);
  background: #fff;
}

.menu-toggle {
  margin-left: auto;
  display: none;
  border: 1px solid var(--line);
  background: var(--soft);
  color: var(--ink);
  border-radius: 10px;
  padding: .45rem .8rem;
  font-size: .92rem;
  cursor: pointer;
}
.menu-toggle:hover { border-color: var(--accent); color: var(--accent); }

.nav-links {
  display: flex;
  flex-wrap: wrap;
  gap: .35rem .9rem;
  margin-left: auto;
}
.nav-links a {
  color: var(--muted);
  text-decoration: none;
  font-size: .95rem;
  padding: .2rem 0;
  border-bottom: 2px solid transparent;
}
.nav-links a:hover,
.nav-links a[aria-current="page"] {
  color: var(--accent);
  border-bottom-color: var(--accent);
}

/* —— ads slot —— */
.ads-slot { max-width: var(--max); margin: 0 auto; padding: 0 .75rem; }
.ads-slot .ads-head { padding-left: 0; padding-right: 0; }
.ads-slot .ads-wrap {
  border-color: var(--line);
  background: var(--soft);
  box-shadow: var(--shadow);
}

/* —— main / timeline —— */
main#main,
.page-main {
  max-width: var(--max);
  margin: 0 auto;
  padding: 1.25rem 1rem 3rem;
}

.tl-intro h1 {
  margin: .4rem 0 .75rem;
  font-size: clamp(1.45rem, 2.6vw, 2rem);
  line-height: 1.35;
  color: #0b3d48;
}

.tl-intro .lead {
  margin: 0 0 1.4rem;
  color: var(--muted);
  font-size: 1.05rem;
  background: var(--accent-soft);
  border-left: 4px solid var(--accent);
  padding: .9rem 1rem;
  border-radius: 0 10px 10px 0;
}

.tl-meta {
  display: flex;
  flex-wrap: wrap;
  gap: .5rem .75rem;
  margin: 0 0 1.6rem;
  padding: 0;
  list-style: none;
}
.tl-meta li {
  font-size: .85rem;
  color: var(--muted);
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: .25rem .7rem;
}

.tl-spine {
  position: relative;
  margin: 1.5rem 0 2.5rem;
  padding: .5rem 0;
}
.tl-spine::before {
  content: "";
  position: absolute;
  left: 50%;
  top: 0;
  bottom: 0;
  width: 3px;
  margin-left: -1.5px;
  background: linear-gradient(180deg, transparent, var(--spine) 8%, var(--accent-2) 92%, transparent);
  border-radius: 3px;
}

.tl-item {
  position: relative;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2.2rem;
  align-items: center;
  margin: 0 0 2.4rem;
  padding: 0 .5rem;
}
.tl-item::after {
  content: "";
  position: absolute;
  left: 50%;
  top: 1.4rem;
  width: 14px;
  height: 14px;
  margin-left: -7px;
  border-radius: 50%;
  background: #fff;
  border: 3px solid var(--spine);
  box-shadow: 0 0 0 4px var(--accent-soft);
  z-index: 2;
}

.tl-item .tl-media,
.tl-item .tl-copy { min-width: 0; }

.tl-item.flip .tl-media { order: 2; }
.tl-item.flip .tl-copy { order: 1; text-align: right; }
.tl-item.flip .tl-copy .tl-tag { margin-left: auto; }

.tl-media figure {
  margin: 0;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
}
.tl-media img {
  width: 100%;
  aspect-ratio: 16 / 10;
  object-fit: cover;
  background: #e6f2f5;
}
.tl-media figcaption {
  padding: .55rem .8rem .7rem;
  font-size: .86rem;
  color: var(--muted);
  border-top: 1px solid var(--line);
  background: var(--soft);
}

.tl-tag {
  display: inline-block;
  font-size: .78rem;
  font-weight: 700;
  letter-spacing: .04em;
  color: var(--accent);
  background: var(--accent-soft);
  padding: .18rem .55rem;
  border-radius: 6px;
  margin-bottom: .45rem;
}
.tl-copy h2 {
  margin: 0 0 .55rem;
  font-size: 1.2rem;
  line-height: 1.4;
  color: #0b3d48;
}
.tl-copy p {
  margin: 0 0 .65rem;
  color: var(--ink);
  font-size: .98rem;
}
.tl-copy p:last-child { margin-bottom: 0; }

.tl-prose {
  background: rgba(255, 255, 255, 0.72);
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 1.25rem 1.2rem 1.5rem;
  box-shadow: var(--shadow);
}
.tl-prose h2 {
  margin: 1.6rem 0 .7rem;
  font-size: 1.25rem;
  color: #0b3d48;
  padding-bottom: .35rem;
  border-bottom: 1px dashed var(--line);
}
.tl-prose h2:first-child { margin-top: 0; }
.tl-prose h3 {
  margin: 1.1rem 0 .45rem;
  font-size: 1.05rem;
  color: #165864;
}
.tl-prose p { margin: 0 0 .85rem; }
.tl-prose ul {
  margin: 0 0 1rem;
  padding-left: 1.2rem;
}
.tl-prose li { margin: .25rem 0; }

.ext-links {
  display: flex;
  flex-wrap: wrap;
  gap: .6rem;
  margin: 1rem 0 1.4rem;
}
.ext-links a {
  display: inline-flex;
  align-items: center;
  padding: .45rem .9rem;
  border-radius: 999px;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #fff;
  text-decoration: none;
  font-size: .92rem;
  font-weight: 600;
  box-shadow: 0 6px 16px rgba(26, 111, 191, 0.25);
}
.ext-links a:hover { filter: brightness(1.06); color: #fff; }

.faq details {
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--soft);
  padding: .7rem .9rem;
  margin: 0 0 .55rem;
}
.faq summary {
  cursor: pointer;
  font-weight: 600;
  color: #0b3d48;
}
.faq details p { margin: .55rem 0 0; color: var(--muted); }

.page-main h1 {
  margin: .3rem 0 1rem;
  font-size: 1.55rem;
  color: #0b3d48;
}
.page-main p { margin: 0 0 .9rem; }
.err-box {
  text-align: center;
  padding-top: 2.5rem;
  padding-bottom: 3rem;
}
.err-box h1 { font-size: 1.8rem; }
.err-code {
  display: inline-block;
  font-size: .85rem;
  letter-spacing: .12em;
  color: var(--accent);
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: .2rem .75rem;
  margin-bottom: .8rem;
  background: #fff;
}

.site-footer {
  border-top: 1px solid var(--line);
  background: rgba(247, 252, 253, 0.9);
  margin-top: auto;
}
.footer-inner {
  max-width: var(--max);
  margin: 0 auto;
  padding: 1.1rem 1rem 1.4rem;
  display: flex;
  flex-wrap: wrap;
  gap: .6rem 1.2rem;
  justify-content: space-between;
  color: var(--muted);
  font-size: .9rem;
}
.footer-inner a { color: var(--muted); text-decoration: none; }
.footer-inner a:hover { color: var(--accent); }

/* —— mobile —— */
@media (max-width: 820px) {
  .menu-toggle { display: inline-flex; }
  .nav-links {
    display: none;
    position: absolute;
    left: 0;
    right: 0;
    top: 100%;
    margin: 0;
    flex-direction: column;
    gap: 0;
    background: rgba(247, 252, 253, 0.98);
    border-bottom: 1px solid var(--line);
    padding: .4rem 1rem .8rem;
    box-shadow: var(--shadow);
  }
  .nav-links.open { display: flex; }
  .nav-links a {
    padding: .65rem 0;
    border-bottom: 1px solid var(--line);
  }

  .tl-spine::before {
    left: 18px;
    margin-left: 0;
  }
  .tl-item {
    grid-template-columns: 1fr;
    gap: .85rem;
    padding-left: 2.4rem;
    margin-bottom: 1.8rem;
  }
  .tl-item::after {
    left: 18px;
    margin-left: -6px;
    top: 1.1rem;
  }
  .tl-item.flip .tl-media,
  .tl-item.flip .tl-copy { order: unset; }
  .tl-item.flip .tl-copy { text-align: left; }
  .tl-item.flip .tl-copy .tl-tag { margin-left: 0; }
}