:root{
  --blue:#1d6fd1; --blue-dark:#164e96; --green:#12995c; --green-bg:#e6f7ee;
  --gray:#8a94a6; --gray-bg:#f1f3f7; --blue-soft:#e8f1fc;
  --red:#e0483d; --amber:#e8912a;
  --text:#1c2430; --text-2:#5b6577; --line:#e6e9ef; --bg:#f6f7f9; --card:#fff;
  --safe-top:env(safe-area-inset-top,0px);
  --safe-bottom:env(safe-area-inset-bottom,0px);
}
*{box-sizing:border-box;-webkit-tap-highlight-color:transparent}
/* 关键：hidden 属性必须优先于任何 display 声明，否则弹窗无法隐藏 */
[hidden]{display:none!important}
html,body{margin:0;padding:0}
body{
  font-family:-apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei","Helvetica Neue",Arial,sans-serif;
  background:var(--bg); color:var(--text); font-size:16px; line-height:1.5;
  padding-top:calc(var(--safe-top));
  padding-bottom:calc(60px + var(--safe-bottom));
  -webkit-text-size-adjust:100%;
}
button{font-family:inherit;cursor:pointer;border:none;background:none;font-size:inherit}
input,textarea{font-family:inherit;font-size:16px}

/* ---------- 顶部栏 ---------- */
.topbar{
  position:sticky; top:0; z-index:50;
  background:linear-gradient(135deg,var(--blue),var(--blue-dark));
  color:#fff; padding:12px 14px 0;
  box-shadow:0 2px 10px rgba(0,0,0,.12);
}
.topbar-row{display:flex;align-items:center;justify-content:space-between;gap:10px}
.brand{display:flex;align-items:center;gap:10px;min-width:0}
.brand-logo{
  width:36px;height:36px;border-radius:10px;background:rgba(255,255,255,.2);
  display:flex;align-items:center;justify-content:center;font-size:20px;font-weight:700;flex-shrink:0;
}
.brand-text{min-width:0}
.brand-name{font-size:17px;font-weight:600;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.brand-date{font-size:12px;opacity:.85;white-space:nowrap}
.topbar-actions{display:flex;align-items:center;gap:8px;flex-shrink:0}
.sync-badge{
  display:flex;align-items:center;gap:5px;font-size:12px;
  background:rgba(255,255,255,.18);padding:5px 10px;border-radius:20px;white-space:nowrap;
}
.sync-badge .dot{width:7px;height:7px;border-radius:50%;background:#9fe8b8;flex-shrink:0}
.sync-badge.offline .dot{background:#ffc9c4}
.sync-badge.syncing .dot{background:#ffe08a;animation:pulse .9s infinite}
.sync-badge.local .dot{background:#cfd8e3}
@keyframes pulse{0%,100%{opacity:1}50%{opacity:.25}}
.icon-btn{
  width:34px;height:34px;border-radius:9px;background:rgba(255,255,255,.18);
  color:#fff;font-size:17px;display:flex;align-items:center;justify-content:center;
}
.icon-btn:active{background:rgba(255,255,255,.32)}

/* ---------- 统计 ---------- */
.stats{display:grid;grid-template-columns:repeat(4,1fr);gap:6px;padding:12px 0 10px;position:relative}
.stat{text-align:center}
.stat .num{display:block;font-size:22px;font-weight:700;line-height:1.1}
.stat .lbl{display:block;font-size:11px;opacity:.85;margin-top:2px}
.stat-progress{
  grid-column:1/-1;height:5px;background:rgba(255,255,255,.25);border-radius:3px;overflow:hidden;margin-top:4px;
}
.stat-progress-bar{height:100%;width:0;background:#7ef0ac;border-radius:3px;transition:width .35s ease}

/* ---------- 分组标签 ---------- */
.group-tabs{
  display:flex;gap:6px;overflow-x:auto;padding:0 0 10px;
  -webkit-overflow-scrolling:touch;scrollbar-width:none;
}
.group-tabs::-webkit-scrollbar{display:none}
.gtab{
  flex-shrink:0;padding:6px 13px;border-radius:16px;font-size:13px;
  background:rgba(255,255,255,.18);color:#fff;white-space:nowrap;
}
.gtab.active{background:#fff;color:var(--blue-dark);font-weight:600}
.gtab .cnt{opacity:.7;font-size:12px;margin-left:3px}

/* ---------- 老师条 ---------- */
.teacher-strip{
  display:flex;align-items:center;gap:8px;padding:9px 14px;
  background:#fff;border-bottom:1px solid var(--line);font-size:13px;color:var(--text-2);
}
.teacher-name{
  color:var(--blue);font-weight:600;font-size:13px;padding:3px 10px;
  background:var(--blue-soft);border-radius:12px;
}
.teacher-tip{margin-left:auto;font-size:11px;color:var(--gray)}
.teacher-tip.demo{color:var(--amber);font-weight:600}

/* ---------- 学生列表 ---------- */
.list{padding:10px 12px 20px;display:flex;flex-direction:column;gap:9px}
.group-head{
  font-size:13px;font-weight:600;color:var(--text-2);
  padding:10px 4px 2px;display:flex;align-items:baseline;gap:8px;
}
.group-head .gh-count{font-weight:400;font-size:12px;color:var(--gray)}

.scard{
  background:var(--card);border-radius:13px;padding:12px 13px;
  border:1px solid var(--line);border-left:4px solid var(--gray);
  display:flex;align-items:center;gap:11px;
  transition:background .18s,border-color .18s,transform .1s;
  position:relative;overflow:hidden;
}
.scard:active{transform:scale(.995)}
.scard.s-picked{border-left-color:var(--green);background:var(--green-bg)}
.scard.s-parent{border-left-color:var(--blue);background:var(--blue-soft)}
.scard.s-pending{border-left-color:#d9dee7}
.scard.flash{animation:flash .7s ease}
@keyframes flash{0%{box-shadow:0 0 0 3px rgba(29,111,209,.45)}100%{box-shadow:0 0 0 0 rgba(29,111,209,0)}}

.sc-avatar{
  width:40px;height:40px;border-radius:50%;flex-shrink:0;
  display:flex;align-items:center;justify-content:center;
  font-size:16px;font-weight:600;color:#fff;background:var(--gray);
}
.scard.s-picked .sc-avatar{background:var(--green)}
.scard.s-parent .sc-avatar{background:var(--blue)}
.sc-avatar.has-photo{background:none}
.sc-avatar .sc-photo{width:100%;height:100%;border-radius:50%;object-fit:cover;display:block}
.sc-main{flex:1;min-width:0}
.sc-name{font-size:16px;font-weight:600;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.sc-meta{font-size:11px;color:var(--text-2);margin-top:2px;display:flex;gap:6px;flex-wrap:wrap}
.sc-meta .tag{background:var(--gray-bg);padding:1px 7px;border-radius:9px}
.sc-meta .who{color:var(--green);font-weight:600}
.sc-meta .time{color:var(--gray);font-variant-numeric:tabular-nums}

.sc-chips{display:flex;flex-direction:column;gap:5px;flex-shrink:0}
.chip{
  font-size:12px;padding:5px 11px;border-radius:14px;min-width:58px;text-align:center;
  background:var(--gray-bg);color:var(--text-2);border:1px solid transparent;white-space:nowrap;
}
.chip:active{transform:scale(.94)}
.chip.on-green{background:var(--green);color:#fff;font-weight:600}
.chip.on-blue{background:var(--blue);color:#fff;font-weight:600}
.chip.on-gray{background:var(--gray);color:#fff;font-weight:600}

/* ---------- 底部 ---------- */
.bottombar{
  position:fixed;left:0;right:0;bottom:0;z-index:45;
  display:flex;gap:1px;background:var(--line);
  padding-bottom:var(--safe-bottom);border-top:1px solid var(--line);
}
.bb-btn{flex:1;padding:15px 8px;background:#fff;font-size:14px;color:var(--text-2);font-weight:500}
.bb-btn:active{background:#f0f2f6}
.bb-btn:disabled{color:#c4cad4}
.bb-warn{color:var(--amber)}

/* ---------- 空状态 ---------- */
.empty-state{text-align:center;padding:70px 30px;color:var(--text-2)}
.empty-icon{font-size:46px;margin-bottom:12px}
.empty-title{font-size:17px;font-weight:600;color:var(--text);margin-bottom:6px}
.empty-desc{font-size:13px;line-height:1.7}

/* ---------- 弹窗 ---------- */
.modal-mask{
  position:fixed;inset:0;z-index:100;background:rgba(20,26,36,.5);
  display:flex;align-items:center;justify-content:center;padding:18px;
  animation:fadeIn .18s ease;
}
@keyframes fadeIn{from{opacity:0}to{opacity:1}}
.modal{
  background:#fff;border-radius:16px;width:100%;max-width:380px;
  max-height:88vh;display:flex;flex-direction:column;overflow:hidden;
  animation:slideUp .22s ease;
}
.modal-wide{max-width:520px}
@keyframes slideUp{from{transform:translateY(18px);opacity:.6}to{transform:none;opacity:1}}
.modal-head{display:flex;align-items:center;justify-content:space-between;padding:16px 18px 0}
.modal-head .icon-btn{background:var(--gray-bg);color:var(--text-2)}
.modal-title{font-size:17px;font-weight:600;padding:16px 18px 0}
.modal-head .modal-title{padding:0}
.modal-desc{font-size:13px;color:var(--text-2);padding:8px 18px 0;line-height:1.6}
.modal-body{padding:6px 18px 18px;overflow-y:auto;-webkit-overflow-scrolling:touch}
.modal-btns{display:flex;gap:9px;padding:16px 18px}
.modal-btns .btn{flex:1}
.modal-err{color:var(--red);font-size:13px;padding:8px 18px 0}

.section{padding:14px 0;border-bottom:1px solid var(--line)}
.section:last-child{border-bottom:none}
.section-title{font-size:14px;font-weight:600;margin-bottom:10px;display:flex;gap:8px;align-items:baseline}
.muted{color:var(--gray);font-weight:400;font-size:12px}
.hint{font-size:12px;color:var(--gray);margin-top:8px;line-height:1.6}

.input{
  width:100%;padding:11px 12px;border:1px solid var(--line);border-radius:10px;
  background:#fafbfc;font-size:15px;color:var(--text);outline:none;
}
.input:focus{border-color:var(--blue);background:#fff}
.textarea{min-height:110px;resize:vertical;line-height:1.7;font-size:14px}
.row-2{display:grid;grid-template-columns:1fr 1fr;gap:9px;margin-bottom:9px}
.row-bulk{margin-bottom:9px}

.btn{padding:11px 16px;border-radius:10px;font-size:15px;font-weight:500;transition:opacity .15s}
.btn:active{opacity:.75}
.btn-primary{background:var(--blue);color:#fff}
.btn-ghost{background:var(--gray-bg);color:var(--text-2)}
.btn-danger{background:#fdecea;color:var(--red)}
.btn-sm{padding:7px 12px;font-size:13px}
.btn-block{width:100%;display:block}

.admin-list,.log-list{display:flex;flex-direction:column;gap:7px;max-height:300px;overflow-y:auto}
.admin-item{
  display:flex;align-items:center;gap:9px;padding:9px 11px;
  background:#fafbfc;border:1px solid var(--line);border-radius:10px;font-size:14px;
}
.admin-item .ai-name{font-weight:600;flex-shrink:0}
.admin-item .ai-group{color:var(--gray);font-size:12px;flex:1;min-width:0;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.admin-item .ai-del{color:var(--red);font-size:18px;padding:2px 8px;flex-shrink:0}
.log-item{display:flex;gap:9px;font-size:13px;padding:7px 10px;background:#fafbfc;border-radius:8px;align-items:baseline}
.log-item .lg-time{color:var(--gray);font-variant-numeric:tabular-nums;flex-shrink:0;font-size:12px}
.log-item .lg-name{font-weight:600;flex-shrink:0}
.log-item .lg-st{flex:1}
.log-item .lg-who{color:var(--text-2);font-size:12px}
.st-picked{color:var(--green);font-weight:600}
.st-parent{color:var(--blue);font-weight:600}
.st-pending{color:var(--gray)}

/* ---------- Toast ---------- */
.toast{
  position:fixed;left:50%;bottom:calc(84px + var(--safe-bottom));transform:translateX(-50%);
  z-index:200;background:rgba(28,36,48,.94);color:#fff;padding:11px 18px;border-radius:22px;
  font-size:14px;max-width:86%;text-align:center;box-shadow:0 6px 20px rgba(0,0,0,.25);
  animation:toastIn .2s ease;
}
@keyframes toastIn{from{opacity:0;transform:translate(-50%,10px)}to{opacity:1;transform:translate(-50%,0)}}

/* ---------- 桌面端 ---------- */
@media(min-width:700px){
  body{padding-bottom:calc(64px + var(--safe-bottom))}
  .list{max-width:900px;margin:0 auto;padding:16px}
  .list.grid{display:grid;grid-template-columns:repeat(2,1fr);gap:11px;align-items:start}
  .list.grid .group-head{grid-column:1/-1}
  .modal{max-width:440px}
}
@media(min-width:1000px){
  .list.grid{grid-template-columns:repeat(3,1fr);max-width:1180px}
}