:root{
  --bg:#f7f8fa; --card:#ffffff; --text:#1a1d21; --muted:#6b7280; --line:#e5e7eb;
  --accent:#2563eb; --accent-soft:#e8effe; --ok:#166534; --ok-bg:#e9f7ef;
  --warn-bg:#fdf6e3; --err:#b91c1c; --radius:14px;
}
@media (prefers-color-scheme: dark){
  :root:not([data-theme="light"]){--bg:#121417;--card:#1c1f24;--text:#e6e8eb;--muted:#9aa1ab;--line:#2c313a;
    --accent:#5b8cff;--accent-soft:#1d2a4a;--ok:#4ade80;--ok-bg:#14301f;--warn-bg:#33290f;--err:#f87171;}
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--text);
  font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;
  font-size:16px;line-height:1.75;}
.page{max-width:720px;margin:0 auto;padding:16px 16px 96px;}
.page-head h1{font-size:22px;margin:8px 0 4px}
.muted{color:var(--muted)} .small{font-size:13px} .right{float:right}
.ok{color:var(--ok)} .err{color:var(--err)}
h2{font-size:17px;margin:0 0 8px}
.card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);
  padding:16px;margin:14px 0;box-shadow:0 1px 2px rgba(0,0,0,.03)}
.card.empty{text-align:center;padding:28px 16px}
.body-text{white-space:pre-wrap;word-break:break-word}
.items{list-style:none;margin:0;padding:0}
.item{display:flex;flex-wrap:wrap;align-items:center;gap:8px;padding:10px 0;border-top:1px solid var(--line)}
.item:first-child{border-top:none}
.item-title{flex:1;min-width:50%}
.item-ops{display:flex;flex-wrap:wrap;gap:6px;max-width:100%}
.st-done{opacity:.65}
.badge{display:inline-block;font-size:12px;padding:1px 8px;border-radius:99px;
  border:1px solid var(--line);background:var(--bg);color:var(--muted);white-space:nowrap}
.badge-main{background:var(--accent-soft);color:var(--accent);border-color:transparent}
.badge-planned{background:var(--warn-bg);color:#92600a;border-color:transparent}
.badge-review,.badge-lesson,.badge-practice{background:var(--accent-soft);color:var(--accent);border-color:transparent}
.btn{display:inline-block;border:1px solid var(--line);background:var(--card);color:var(--text);
  border-radius:10px;padding:8px 14px;font-size:15px;cursor:pointer;text-decoration:none;
  min-height:44px;line-height:1.4;-webkit-tap-highlight-color:transparent}
.btn.primary{background:var(--accent);border-color:var(--accent);color:#fff}
.btn.ghost{background:transparent}
.btn.small{padding:9px 10px;min-height:44px;font-size:13px}
.btn.big{display:block;text-align:center;padding:14px;font-size:17px;margin-top:12px}
.btn[disabled]{opacity:.5;pointer-events:none}
a{color:var(--accent);text-decoration:none}
a:hover{text-decoration:underline}
.path{list-style:none;margin:0;padding:0}
.path-node{position:relative;padding:0 0 14px 26px;border-left:2px solid var(--line);margin-left:8px}
.path-node::before{content:"";position:absolute;left:-7px;top:6px;width:12px;height:12px;
  border-radius:50%;background:var(--accent);border:2px solid var(--card)}
.path-node.planned::before{background:var(--muted)}
.path-head{display:flex;flex-wrap:wrap;gap:6px;align-items:baseline}
details{margin-top:6px}
summary{cursor:pointer;color:var(--muted);font-size:14px;padding:9px 0;min-height:44px}
.flow{list-style:none;margin:8px 0;padding:0}
.flow li{background:var(--accent-soft);border-radius:10px;padding:10px 12px;margin:8px 0;position:relative}
.flow li+li::before{content:"↓";position:absolute;top:-16px;left:16px;color:var(--muted);font-size:12px}
.choices{display:flex;flex-direction:column;gap:8px;margin:12px 0}
.choice{display:block;padding:12px;border:1px solid var(--line);border-radius:10px;min-height:44px;cursor:pointer}
.choice input{margin-right:8px;transform:scale(1.2)}
#access-code{min-height:44px}
textarea{width:100%;border:1px solid var(--line);border-radius:10px;padding:10px;font-size:15px;
  font-family:inherit;background:var(--bg);color:var(--text)}
.ops{display:flex;flex-wrap:wrap;gap:8px;margin-top:12px}
.hidden{display:none}
.result{margin-top:14px;padding:12px;border-radius:10px;background:var(--ok-bg)}
.result.bad{background:var(--warn-bg)}
.answer{margin-top:12px;padding:12px;border:1px dashed var(--line);border-radius:10px}
.answer h3{font-size:15px;margin:8px 0 4px}
.answer ul{margin:4px 0;padding-left:20px}
.tbl{width:100%;border-collapse:collapse;font-size:14px;table-layout:fixed}
.tbl .muted.small{display:block;word-break:break-all}
.tbl th,.tbl td{border-top:1px solid var(--line);padding:8px 6px;text-align:left;vertical-align:top;overflow-wrap:anywhere;word-break:break-word}
.item a{overflow-wrap:anywhere}
.form label{display:block;margin:10px 0;font-size:14px}
.form input,.form select{width:100%;margin-top:4px;padding:10px;border:1px solid var(--line);
  border-radius:8px;font-size:15px;background:var(--bg);color:var(--text)}
.bottom-nav{position:fixed;left:0;right:0;bottom:0;display:flex;background:var(--card);
  border-top:1px solid var(--line);padding-bottom:env(safe-area-inset-bottom);z-index:10}
.bottom-nav a{flex:1;text-align:center;padding:10px 0 8px;font-size:12px;color:var(--muted);
  display:flex;flex-direction:column;gap:2px;min-height:52px;justify-content:center}
.bottom-nav a.on{color:var(--accent);font-weight:600}
.ni{font-size:18px;line-height:1}
:root[data-theme="dark"]{--bg:#121417;--card:#1c1f24;--text:#e6e8eb;--muted:#9aa1ab;--line:#2c313a;
  --accent:#5b8cff;--accent-soft:#1d2a4a;--ok:#4ade80;--ok-bg:#14301f;--warn-bg:#33290f;--err:#f87171;}
:focus-visible{outline:3px solid var(--accent);outline-offset:3px}
.skip-link{position:absolute;left:12px;top:-100px;background:var(--card);padding:10px;z-index:20}
.skip-link:focus{top:8px}
.page,.card,.item-title{min-width:0;overflow-wrap:anywhere}
pre{max-width:100%;overflow-x:auto;white-space:pre-wrap}
textarea,.form input,.form select{font-size:16px}
@media (min-width:768px){
  .page{max-width:760px}
  body{font-size:16.5px}
  .card{padding:20px}
}