:root{
  --bg:#f4f5f7;--panel:#fff;--line:#e3e6eb;--text:#1f2329;--muted:#8a919c;--accent:#2f6fde;--accent-soft:#e8f0fd;--danger:#d64545;
  --radius:8px;--shadow:0 6px 24px rgba(20,30,50,.12);
}
*{box-sizing:border-box}
html,body{margin:0;height:100%}
body{background:var(--bg);color:var(--text);font:14px/1.5 system-ui,-apple-system,"PingFang SC","Microsoft YaHei",sans-serif}
[hidden]{display:none!important}
button,input,select,textarea{font:inherit;color:inherit}
.muted{color:var(--muted)}
.sm{font-size:12px}
.row{display:flex;align-items:center}
.gap{gap:10px;flex-wrap:wrap}
.spacer{flex:1}

/* 按钮 */
.btn{border:1px solid var(--line);background:#fff;border-radius:6px;padding:5px 11px;cursor:pointer;white-space:nowrap;line-height:1.4}
.btn:hover{background:#f2f4f7}
.btn:disabled{opacity:.4;cursor:default;background:#fff}
.btn.primary{background:var(--accent);border-color:var(--accent);color:#fff}
.btn.primary:hover{filter:brightness(1.07)}
.btn.danger{color:var(--danger)}
.btn.link{border:none;background:none;color:var(--accent)}
.btn.block{display:block;width:100%;margin-top:8px}
.btn.sm{padding:2px 8px;font-size:12px}
.btn.icon{padding:5px 9px}

/* 登录 */
#auth{min-height:100%;display:flex;align-items:center;justify-content:center;padding:16px}
.auth-card{background:#fff;padding:32px 28px;border-radius:12px;box-shadow:var(--shadow);width:min(360px,100%)}
.auth-card h1{margin:0;font-size:24px}
.auth-card label{display:block;margin-top:14px;font-size:13px;color:#555}
.auth-card input{display:block;width:100%;margin-top:4px;padding:8px 10px;border:1px solid var(--line);border-radius:6px}
.auth-error{color:var(--danger);min-height:20px;margin:10px 0 0;font-size:13px}

/* 主界面 */
#app{height:100%;display:flex;flex-direction:column}
.topbar{display:flex;align-items:center;gap:10px;padding:8px 14px;background:#fff;border-bottom:1px solid var(--line);flex-wrap:wrap}
.brand{font-size:20px}
.class-picker{display:flex;gap:4px}
.class-picker select{max-width:220px;padding:5px 8px;border:1px solid var(--line);border-radius:6px;background:#fff;font-weight:600}
.tb-group{display:flex;gap:4px}
.seg{border:1px solid var(--line);border-radius:6px;overflow:hidden;gap:0}
.seg button{border:none;background:#fff;padding:5px 10px;cursor:pointer}
.seg button.on{background:var(--accent-soft);color:var(--accent);font-weight:600}
.toggle{display:flex;align-items:center;gap:4px;cursor:pointer;user-select:none}

.main{flex:1;min-height:0;display:flex}
.board-area{flex:1;min-width:0;display:flex;flex-direction:column;padding:12px 20px 10px;position:relative}
.board-title{margin:0 0 6px;text-align:center;font-weight:normal;font-size:clamp(18px,2.4vw,30px);font-family:"字酷堂清楷 简繁","Kaiti SC","STKaiti","KaiTi",serif}
.board-wrap{flex:1;min-height:0;background:#fff;border-radius:12px;border:1px solid var(--line);padding:2.2% 2.5%}
.edit-banner{position:absolute;top:10px;left:50%;transform:translateX(-50%);z-index:5;background:#fff7e0;border:1px solid #f0d58a;padding:6px 12px;border-radius:8px;display:flex;gap:10px;align-items:center;box-shadow:var(--shadow)}
.empty-state{position:absolute;inset:0;display:flex;flex-direction:column;align-items:center;justify-content:center;text-align:center;padding:16px}

.sidebar{width:260px;flex:none;border-left:1px solid var(--line);background:#fff;display:flex;flex-direction:column;min-height:0}
.panel{display:flex;flex-direction:column;min-height:0}
.pool-panel{max-height:42%;border-bottom:1px solid var(--line)}
.history-panel{flex:1}
.panel-head{display:flex;justify-content:space-between;align-items:center;padding:10px 12px 6px;font-weight:600}
.pool{overflow:auto;padding:4px 12px 12px;display:flex;flex-wrap:wrap;gap:6px;align-content:flex-start;min-height:56px;transition:background .15s}
.pool:empty::after{content:"把学生拖到这里可移出座位";color:var(--muted);font-size:12px;padding:8px 0}
.chip{display:inline-flex;align-items:center;gap:4px;padding:3px 9px;border-radius:14px;border:1px solid rgba(0,0,0,.1);cursor:grab;user-select:none;touch-action:none;font-size:13px}
.chip small{font-family:ui-monospace,Menlo,monospace;font-size:10px;color:#555}
.chip.selected{outline:2px solid var(--accent);outline-offset:1px}

.history{list-style:none;margin:0;padding:0 6px 12px;overflow:auto;flex:1}
.history li{display:flex;gap:6px;align-items:baseline;padding:5px 8px;border-radius:6px;cursor:pointer;font-size:13px}
.history li:hover{background:#f2f4f7}
.history li.cur{background:var(--accent-soft);color:var(--accent);font-weight:600}
.history li.future{opacity:.42}
.history li .t{margin-left:auto;font-size:11px;color:var(--muted);flex:none}
.history li .n{color:var(--muted);font-size:11px;width:18px;flex:none;text-align:right}

.statusbar{display:flex;gap:16px;align-items:center;padding:4px 14px;background:#fff;border-top:1px solid var(--line);font-size:12px}

/* 座位（应用内交互样式） */
.board-wrap .sc-seat{cursor:grab;touch-action:none;transition:transform .08s, box-shadow .12s}
.board-wrap .sc-seat.off{visibility:visible;background:transparent;border-color:transparent}
.board-wrap .sc-seat.selected{outline:.12em solid var(--accent);outline-offset:.06em;transform:scale(1.03)}
.board-wrap .sc-seat.drop{outline:.14em dashed var(--accent);outline-offset:.04em;background-color:var(--accent-soft)}
.board-wrap .sc-seat.dragging{opacity:.35}
.board-wrap .sc-seat.disabled-edit{background:repeating-linear-gradient(45deg,#f1f2f4 0 .3em,#fff .3em .6em);border:.05em dashed #c9ced6}
.board-wrap .sc-seat.flash{animation:flash .6s ease}
@keyframes flash{0%{box-shadow:0 0 0 .2em rgba(47,111,222,.6)}100%{box-shadow:0 0 0 0 rgba(47,111,222,0)}}
.pool.drop{background:var(--accent-soft)}
.ghost{position:fixed;z-index:1000;pointer-events:none;padding:6px 14px;border-radius:8px;box-shadow:var(--shadow);font-size:18px;transform:translate(-50%,-60%);font-family:"字酷堂清楷 简繁","Kaiti SC","STKaiti","KaiTi",serif;border:1px solid rgba(0,0,0,.12)}

/* 展示模式 */
body.present .topbar,body.present .sidebar,body.present .statusbar{display:none}
body.present .board-area{padding:3vh 3vw}
body.present .board-wrap{border:none}
body.present .board-title{font-size:min(5vh,3vw);margin-bottom:1.5vh}

/* 菜单 */
.menu{position:fixed;z-index:900;background:#fff;border:1px solid var(--line);border-radius:8px;box-shadow:var(--shadow);padding:4px;min-width:160px}
.menu button{display:block;width:100%;text-align:left;border:none;background:none;padding:7px 12px;border-radius:5px;cursor:pointer}
.menu button:hover{background:#f2f4f7}
.menu hr{border:none;border-top:1px solid var(--line);margin:4px 0}
.menu .danger{color:var(--danger)}

/* 弹窗 */
dialog.modal{border:none;border-radius:12px;padding:0;box-shadow:var(--shadow);width:min(560px,calc(100vw - 32px));max-height:calc(100vh - 40px);color:var(--text)}
dialog.modal.wide{width:min(820px,calc(100vw - 32px))}
dialog.modal::backdrop{background:rgba(20,25,35,.35)}
.modal-inner{display:flex;flex-direction:column;max-height:calc(100vh - 40px)}
.modal-head{padding:16px 20px 8px;font-size:17px;font-weight:600}
.modal-body{padding:4px 20px 12px;overflow:auto}
.modal-foot{padding:12px 20px 16px;display:flex;gap:8px;justify-content:flex-end;flex-wrap:wrap;border-top:1px solid var(--line)}
.form-grid{display:grid;grid-template-columns:auto 1fr;gap:10px 12px;align-items:center}
.form-grid label{color:#555;font-size:13px}
.modal input[type=text],.modal input[type=number],.modal input:not([type]),.modal select,.modal textarea{padding:6px 9px;border:1px solid var(--line);border-radius:6px;width:100%;background:#fff}
.modal textarea{min-height:70px;resize:vertical}
.modal h4{margin:16px 0 6px;font-size:14px}
.help{font-size:12px;color:var(--muted);margin:4px 0}
.radio-row{display:flex;gap:14px;flex-wrap:wrap}
.radio-row label{display:flex;gap:4px;align-items:center;cursor:pointer}
.lm-row{display:grid;grid-template-columns:1fr 1.2fr 1fr auto;gap:6px;margin-bottom:6px}
.preview-box{background:#f4f5f7;border-radius:8px;padding:8px;display:flex;justify-content:center}
.preview-box canvas,.preview-box img{max-width:100%;height:auto;border-radius:4px;box-shadow:0 1px 4px rgba(0,0,0,.1);background:#fff}
.list{list-style:none;margin:0;padding:0}
.list li{display:flex;align-items:center;gap:8px;padding:8px 4px;border-bottom:1px solid var(--line)}
.list li .grow{flex:1;min-width:0}
.list li .grow b{display:block;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.swatch{display:inline-block;width:28px;height:18px;border-radius:4px;border:1px solid rgba(0,0,0,.15);vertical-align:middle}
.color-map{display:grid;grid-template-columns:auto auto 1fr;gap:6px 10px;align-items:center}
.stats-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:8px;margin:8px 0}
.stat{background:#f4f5f7;border-radius:8px;padding:8px 10px}
.stat b{display:block;font-size:18px}
table.preview{border-collapse:collapse;font-size:12px;width:100%}
table.preview td,table.preview th{border:1px solid var(--line);padding:3px 6px;text-align:left}
.legend{display:flex;gap:10px;flex-wrap:wrap;font-size:12px;margin-top:6px}
.legend i{display:inline-block;width:10px;height:10px;border-radius:3px;margin-right:3px;vertical-align:-1px}

/* 提示 */
.toasts{position:fixed;bottom:40px;left:50%;transform:translateX(-50%);z-index:2000;display:flex;flex-direction:column;gap:6px;align-items:center}
.toast{background:#2a2f38;color:#fff;padding:8px 16px;border-radius:8px;box-shadow:var(--shadow);font-size:13px;animation:tin .2s ease}
.toast.err{background:var(--danger)}
@keyframes tin{from{opacity:0;transform:translateY(6px)}}

@media (max-width:900px){
  .main{flex-direction:column}
  .sidebar{width:auto;height:34%;border-left:none;border-top:1px solid var(--line);flex-direction:row}
  .sidebar .panel{flex:1;max-height:none;border-bottom:none}
  .pool-panel{border-right:1px solid var(--line)}
  .hint{display:none}
  .board-area{min-height:360px}
}