:root{
  --blue:#1a4f7a;
  --lblue:#2d7cc1;
  --bg:#f3f7fb;
  --accent:#e8f2fb;
  --ink:#1b2733;
  --muted:#5b6b7c;
  --orange:#EA7600;
  --card:#ffffff;
  --line:#dbe7f2;
}
*{box-sizing:border-box;margin:0;padding:0}
body{
  font-family:"PingFang SC","Microsoft YaHei","Helvetica Neue",Arial,sans-serif;
  color:var(--ink);background:var(--bg);line-height:1.75;
}
a{color:var(--lblue);text-decoration:none}
a:hover{color:var(--orange)}

/* ── 顶栏 ── */
.back-bar{
  position:sticky;top:0;z-index:50;
  display:flex;align-items:center;gap:1rem;
  padding:.7rem 1.6rem;background:#fff;
  border-bottom:1px solid var(--line);
}
.back-bar .logo{font-weight:700;color:var(--blue);font-size:1.05rem;letter-spacing:.5px}
.back-bar .tag{
  font-size:.78rem;color:#fff;background:var(--lblue);
  padding:.15rem .6rem;border-radius:999px;
}
.back-bar nav{margin-left:auto;display:flex;gap:1.1rem;font-size:.92rem}
.back-bar nav a{color:var(--muted)}
.back-bar nav a:hover{color:var(--orange)}

/* ── Hero ── */
.hero{
  background:linear-gradient(135deg,#0c2d50 0%,#1a6fab 55%,#2596d4 100%);
  color:#fff;padding:3.2rem 1.6rem 3.6rem;text-align:center;
}
.hero h1{font-size:2.2rem;letter-spacing:1px;margin-bottom:.6rem}
.hero p{opacity:.9;font-size:1.05rem;max-width:640px;margin:0 auto}
.hero .meta{margin-top:1.4rem;font-size:.86rem;opacity:.78}

/* ── 主体 ── */
main{max-width:1080px;margin:0 auto;padding:2.4rem 1.6rem 4rem}
.section-title{
  display:flex;align-items:center;gap:.7rem;
  font-size:1.3rem;color:var(--blue);margin:2.2rem 0 1.2rem;
}
.section-title::before{content:"";width:4px;height:22px;background:var(--lblue);border-radius:2px}
.section-title small{font-size:.82rem;color:var(--muted);font-weight:400}

.grid{display:grid;gap:1.1rem;grid-template-columns:repeat(auto-fill,minmax(280px,1fr))}
.card{
  background:var(--card);border:1px solid var(--line);border-radius:14px;
  padding:1.3rem 1.4rem;display:flex;flex-direction:column;gap:.5rem;
  transition:transform .18s ease,box-shadow .18s ease;
}
.card:hover{transform:translateY(-3px);box-shadow:0 10px 24px rgba(26,79,122,.12)}
.card .kind{
  align-self:flex-start;font-size:.72rem;letter-spacing:.5px;
  color:var(--lblue);background:var(--accent);
  padding:.15rem .55rem;border-radius:6px;
}
.card h3{font-size:1.06rem;color:var(--blue)}
.card p{font-size:.9rem;color:var(--muted);flex:1}
.card .meta{font-size:.8rem;color:#8b9bab}
.card .actions{display:flex;flex-wrap:wrap;gap:.5rem;margin-top:.4rem}
.btn{
  font-size:.82rem;padding:.35rem .8rem;border-radius:8px;
  border:1px solid var(--lblue);color:var(--lblue);background:#fff;
}
.btn:hover{background:var(--lblue);color:#fff}
.btn.primary{background:var(--orange);border-color:var(--orange);color:#fff}
.btn.primary:hover{opacity:.88;color:#fff}

/* ── 预览图 ── */
.preview{
  width:100%;border-radius:10px;border:1px solid var(--line);
  background:#fff;display:block;
}
.preview-wrap{
  border-radius:12px;overflow:hidden;border:1px solid var(--line);
  background:linear-gradient(135deg,#eaf3fb,#dcebf8);
  display:flex;align-items:center;justify-content:center;min-height:150px;margin-bottom:.2rem;
}
.preview-wrap img{max-width:100%;height:auto;display:block}

/* ── 说明块 ── */
.note{
  background:#fff;border:1px solid var(--line);border-left:4px solid var(--lblue);
  border-radius:0 12px 12px 0;padding:1rem 1.3rem;margin:1rem 0;font-size:.92rem;color:var(--muted);
}
.note b{color:var(--blue)}
pre{
  background:#0f2233;color:#d7e6f2;padding:1rem 1.2rem;border-radius:10px;
  overflow-x:auto;font-size:.85rem;line-height:1.6;
}
code{background:var(--accent);color:var(--blue);padding:.1rem .35rem;border-radius:4px;font-size:.86em}
pre code{background:none;color:inherit;padding:0}

footer{
  border-top:1px solid var(--line);background:#fff;
  padding:1.6rem;text-align:center;color:var(--muted);font-size:.86rem;
}
footer a{color:var(--lblue)}

@media(max-width:600px){
  .back-bar nav{display:none}
  .hero h1{font-size:1.6rem}
  main{padding:1.6rem 1rem 3rem}
}