/* MathViz shell — cream theme matching the junior / geomodels / zk look.
   Latin letters: Times New Roman italic; digits upright; Chinese falls back
   to system fonts (same trick as the original pages). */
@font-face{font-family:'JLat';src:local('Times New Roman Italic'),local('TimesNewRomanPS-ItalicMT'),local('Times New Roman-Italic');unicode-range:U+0041-005A,U+0061-007A}
@font-face{font-family:'JLat';src:local('Times New Roman');unicode-range:U+0030-0039}
:root{
  --bg:#fffaf0; --panel:#ffffff; --line:#d8e9f8; --text:#20344c; --muted:#6c8095;
  --cyan:#2fa8ff; --red:#ff5b5b; --yellow:#ffad0a; --purple:#8b5cf6;
  --green:#32d05f; --orange:#ff8133; --blue:#2878ff;
  --senior:#2563eb; --junior:#7c3aed; --geomodels:#059669; --zk:#ea580c;
  --radius:16px;
}
*{box-sizing:border-box}
html,body{margin:0}
body{
  background:var(--bg); color:var(--text);
  font-family:'JLat','Times New Roman',Georgia,-apple-system,"PingFang SC","Microsoft YaHei","Helvetica Neue",Arial,serif;
  font-synthesis:none; min-height:100vh; display:flex; flex-direction:column;
}
a{text-decoration:none;color:inherit}
a:hover{color:var(--blue)}

/* ---- header ---- */
.topbar{
  position:sticky; top:0; z-index:50;
  display:flex; align-items:center; gap:18px; flex-wrap:wrap;
  padding:10px 22px; background:rgba(255,250,240,.97);
  border-bottom:1px solid var(--line);
}
.brand{display:flex; align-items:center; gap:10px}
.brand-mark{
  width:42px; height:42px; border-radius:12px; flex:none;
  display:flex; align-items:center; justify-content:center;
  font-size:24px; color:#fff;
  background:linear-gradient(135deg,#2878ff,#8b5cf6);
}
.brand-text{display:flex; flex-direction:column; line-height:1.25}
.brand-text strong{font-size:19px}
.brand-text em{font-style:normal; font-size:12px; color:var(--muted)}
.mainnav{display:flex; gap:4px; flex-wrap:wrap}
.mainnav a{
  padding:7px 13px; border-radius:999px; font-size:15px; color:var(--text);
}
.mainnav a:hover{background:#eaf4ff; color:var(--blue)}
.mainnav a.active{background:var(--blue); color:#fff}
.search{margin-left:auto; display:flex; gap:0}
.search input{
  width:230px; max-width:52vw; padding:8px 12px; font-size:14px;
  border:1px solid var(--line); border-right:0; border-radius:999px 0 0 999px;
  background:#fff; color:var(--text); outline:none; font-family:inherit;
}
.search input:focus{border-color:var(--blue)}
.search button{
  padding:8px 14px; font-size:16px; cursor:pointer;
  border:1px solid var(--blue); border-radius:0 999px 999px 0;
  background:var(--blue); color:#fff;
}

/* ---- main ---- */
.view{flex:1; width:min(1180px,100%); margin:0 auto; padding:26px 22px 40px}
.view h1{font-size:26px; margin:4px 0 6px}
.lead{color:var(--muted); font-size:15px; margin:0 0 22px}
.section-tag{display:inline-block; font-size:12px; letter-spacing:2px; color:var(--muted); margin-bottom:2px}

/* stats */
.stats{display:flex; gap:12px; flex-wrap:wrap; margin:18px 0 26px}
.stat{
  flex:1 1 120px; background:var(--panel); border:1px solid var(--line);
  border-radius:var(--radius); padding:14px 16px; text-align:center;
}
.stat b{display:block; font-size:28px; line-height:1.1}
.stat span{font-size:13px; color:var(--muted)}

/* section cards on home */
.cards{display:grid; grid-template-columns:repeat(auto-fit,minmax(240px,1fr)); gap:16px}
.card{
  display:block; background:var(--panel); border:1px solid var(--line);
  border-radius:var(--radius); padding:20px; border-top:5px solid var(--blue);
  transition:transform .12s ease, box-shadow .12s ease;
}
.card:hover{transform:translateY(-2px); box-shadow:0 8px 22px rgba(32,52,76,.10)}
.card h2{margin:0 0 4px; font-size:20px}
.card h2 .count{float:right; font-size:15px; color:var(--muted); font-weight:400}
.card p{margin:0; color:var(--muted); font-size:14px; line-height:1.6}
.card .go{display:inline-block; margin-top:12px; font-size:14px; color:var(--blue)}
.card.c-senior{border-top-color:var(--senior)}
.card.c-junior{border-top-color:var(--junior)}
.card.c-geomodels{border-top-color:var(--geomodels)}
.card.c-zk{border-top-color:var(--zk)}

/* filter chips */
.chips{display:flex; gap:8px; flex-wrap:wrap; margin:14px 0 20px}
.chip{
  padding:6px 14px; border-radius:999px; border:1px solid var(--line);
  background:#fff; font-size:14px; cursor:pointer; font-family:inherit; color:var(--text);
}
.chip:hover{border-color:var(--blue); color:var(--blue)}
.chip.active{background:var(--blue); border-color:var(--blue); color:#fff}

/* item grid */
.grid{display:grid; grid-template-columns:repeat(auto-fill,minmax(250px,1fr)); gap:14px}
.item{
  display:block; background:var(--panel); border:1px solid var(--line);
  border-radius:var(--radius); padding:15px 16px;
  transition:transform .12s ease, box-shadow .12s ease;
}
.item:hover{transform:translateY(-2px); box-shadow:0 8px 22px rgba(32,52,76,.10)}
.item h3{margin:0 0 5px; font-size:16px; line-height:1.4}
.item p{margin:0; color:var(--muted); font-size:13.5px; line-height:1.55}
.tag{
  display:inline-block; font-size:12px; padding:2px 9px; border-radius:999px;
  background:#eaf4ff; color:var(--blue); margin-bottom:8px;
}
.tag.t-junior{background:#f1eafe; color:var(--junior)}
.tag.t-geomodels{background:#e6f7ee; color:var(--geomodels)}
.tag.t-zk{background:#fff1e6; color:var(--zk)}
.empty{color:var(--muted); padding:30px 0; text-align:center}

/* item view */
.crumb{font-size:13.5px; color:var(--muted); margin-bottom:10px}
.crumb a{color:var(--blue)}
.item-head{display:flex; align-items:flex-start; gap:14px; flex-wrap:wrap; margin-bottom:14px}
.item-head h1{flex:1 1 320px}
.item-head .desc{color:var(--muted); font-size:15px; margin:6px 0 0}
.open-new{
  flex:none; padding:8px 16px; border-radius:999px; font-size:14px;
  border:1px solid var(--blue); color:var(--blue); background:#fff;
}
.open-new:hover{background:var(--blue); color:#fff}
.frame-wrap{
  background:var(--panel); border:1px solid var(--line);
  border-radius:var(--radius); overflow:hidden;
}
.frame-wrap iframe{display:block; width:100%; height:78vh; min-height:520px; border:0; background:#fff}
.pager{display:flex; justify-content:space-between; gap:12px; margin-top:16px}
.pager a{
  flex:1; padding:11px 16px; border:1px solid var(--line); border-radius:12px;
  background:#fff; font-size:14.5px; overflow:hidden; text-overflow:ellipsis; white-space:nowrap;
}
.pager a:hover{border-color:var(--blue); color:var(--blue)}
.pager a.next{text-align:right}
.pager a.disabled{visibility:hidden}

.footer{
  border-top:1px solid var(--line); padding:16px 22px 22px;
  color:var(--muted); font-size:13px; text-align:center;
}
.footer p{margin:4px 0}

/* ---- phone ---- */
@media (max-width:720px){
  .topbar{padding:10px 14px; gap:10px}
  .search{margin-left:0; flex:1}
  .search input{flex:1; width:auto}
  .view{padding:20px 14px 32px}
  .frame-wrap iframe{height:72vh; min-height:440px}
}