:root{
  --bg:#f4f6fa;
  --panel:#ffffff;
  --line:#e2e8f0;
  --ink:#1f2937;
  --ink2:#64748b;
  --brand:#2563eb;
  --brand-soft:#eff6ff;
  --danger:#dc2626;
  --ok:#16a34a;
  --shadow:0 1px 2px rgba(15,23,42,.06),0 4px 12px rgba(15,23,42,.06);
}
*{box-sizing:border-box}
html,body{height:100%}
body{
  margin:0;background:var(--bg);color:var(--ink);
  font-family:"Microsoft YaHei","PingFang SC","Hiragino Sans GB","Segoe UI",sans-serif;
  font-size:13px;overflow:hidden;
}
button{font-family:inherit;font-size:12px;cursor:pointer}

/* ---------- 顶栏 ---------- */
.topbar{
  height:54px;display:flex;align-items:center;gap:14px;padding:0 14px;
  background:var(--panel);border-bottom:1px solid var(--line);box-shadow:var(--shadow);
  position:relative;z-index:20;
}
.brand{display:flex;align-items:center;gap:9px;min-width:210px}
.logo{
  width:32px;height:32px;border-radius:9px;background:linear-gradient(135deg,#2563eb,#4f8ff7);
  color:#fff;display:grid;place-items:center;font-weight:700;font-size:17px;
  box-shadow:0 2px 8px rgba(37,99,235,.35);
}
.brand-txt{display:flex;flex-direction:column;line-height:1.25}
.brand-txt b{font-size:14px;letter-spacing:.3px}
.brand-txt small{color:var(--ink2);font-size:11px}

.sections{display:flex;gap:6px;background:#f1f5f9;padding:4px;border-radius:10px}
.sec-btn{
  border:none;background:transparent;padding:7px 16px;border-radius:7px;color:var(--ink2);
  font-size:13px;font-weight:600;display:flex;align-items:center;gap:6px;transition:.15s;
}
.sec-btn i{
  font-style:normal;width:17px;height:17px;border-radius:50%;background:#cbd5e1;color:#fff;
  display:grid;place-items:center;font-size:11px;
}
.sec-btn:hover{color:var(--ink)}
.sec-btn.active{background:#fff;color:var(--brand);box-shadow:0 1px 4px rgba(15,23,42,.12)}
.sec-btn.active i{background:var(--brand)}

.file-actions{display:flex;align-items:center;gap:5px;margin-left:auto;flex-wrap:wrap}
.tbtn{
  border:1px solid var(--line);background:#fff;color:var(--ink);padding:6px 10px;border-radius:7px;
  transition:.15s;white-space:nowrap;
}
.tbtn:hover{border-color:#b9c6da;background:#f8fafc}
.tbtn:active{transform:translateY(1px)}
.tbtn.sm{padding:5px 8px;font-size:11px}
.tbtn.danger{color:var(--danger);border-color:#fecaca}
.tbtn.danger:hover{background:#fef2f2}
.sep{width:1px;height:18px;background:var(--line);margin:0 3px}

/* 实验按钮 */
.tbtn.lab{color:#fff;background:var(--ok);border-color:var(--ok);font-weight:600}
.tbtn.lab:hover{background:#15803d;border-color:#15803d;color:#fff}
.tbtn.lab.running{background:var(--danger);border-color:var(--danger);animation:labpulse 1.6s ease-in-out infinite}
@keyframes labpulse{0%,100%{box-shadow:0 0 0 0 rgba(220,38,38,.45)}50%{box-shadow:0 0 0 5px rgba(220,38,38,0)}}

/* 电流流向图例（实验模式显示） */
.flow-legend{
  display:inline-flex;align-items:center;gap:4px;margin-left:6px;
  font-size:11px;color:var(--muted);white-space:nowrap;
}
.flow-legend .sw{
  display:inline-block;width:16px;height:4px;border-radius:2px;margin-left:4px;
}
.flow-legend .sw.red{background:#dc2626}
.flow-legend .sw.blue{background:#2563eb}

/* 下拉菜单 */
.menu{position:relative}
.menu-pop{
  display:none;position:absolute;right:0;top:calc(100% + 6px);min-width:210px;
  background:#fff;border:1px solid var(--line);border-radius:10px;padding:6px;
  box-shadow:0 10px 30px rgba(15,23,42,.15);z-index:60;
}
.menu.open .menu-pop{display:block}
.menu-pop button{
  display:block;width:100%;text-align:left;border:none;background:transparent;
  padding:8px 10px;border-radius:7px;color:var(--ink);font-size:12.5px;line-height:1.4;
}
.menu-pop button:hover{background:var(--brand-soft);color:var(--brand)}

/* ---------- 侧栏折叠 ---------- */
.fold{
  border:none;background:transparent;color:var(--ink2);font-size:14px;line-height:1;
  padding:2px 5px;border-radius:6px;cursor:pointer;
}
.fold:hover{background:#f1f5f9;color:var(--brand)}
.panel-head .fold{margin-left:auto}
.tabs .fold{margin-left:auto;margin-right:2px}
.layout.no-left{grid-template-columns:0 1fr 262px}
.layout.no-right{grid-template-columns:214px 1fr 0}
.layout.no-left.no-right{grid-template-columns:0 1fr 0}
.layout.no-left .panel.left,.layout.no-right .panel.right{display:none}
/* 显式钉住列位置：面板隐藏后画布不能前移（否则会被挤进 0 宽列而消失） */
.layout > .panel.left{grid-column:1;grid-row:1}
.layout > .stage{grid-column:2;grid-row:1}
.layout > .panel.right{grid-column:3;grid-row:1}
.layout > .stage{min-width:0}
.edge-tab{
  position:fixed;top:50%;transform:translateY(-50%);z-index:15;
  width:20px;height:64px;border:1px solid var(--line);background:#fff;color:var(--ink2);
  border-radius:0 8px 8px 0;cursor:pointer;font-size:13px;box-shadow:var(--shadow);
}
.edge-tab.left{left:0;border-radius:0 8px 8px 0}
.edge-tab.right{right:0;border-radius:8px 0 0 8px}
.edge-tab:hover{color:var(--brand);background:var(--brand-soft)}
.edge-tab.hidden{display:none}

/* ---------- 布局 ---------- */
.layout{
  height:calc(100vh - 54px);display:grid;grid-template-columns:214px 1fr 262px;
}
.panel{background:var(--panel);display:flex;flex-direction:column;min-height:0}
.panel.left{border-right:1px solid var(--line)}
.panel.right{border-left:1px solid var(--line)}
.panel-head{
  padding:9px 11px;border-bottom:1px solid var(--line);font-weight:700;font-size:12.5px;
  display:flex;flex-direction:column;gap:7px;
}
.panel-body{overflow:auto;padding:9px;flex:1;min-height:0}
.panel-foot{padding:7px 11px;border-top:1px solid var(--line);font-size:11px;line-height:1.5}
.hint{color:var(--ink2)}
.mini-search,.mini-sel{
  width:100%;border:1px solid var(--line);border-radius:6px;padding:5px 7px;font-size:12px;
  font-family:inherit;outline:none;color:var(--ink);
}
.mini-search:focus{border-color:var(--brand)}
.mini-sel{width:auto;padding:4px 5px}

/* ---------- 元件库 ---------- */
.lib-cat{margin-bottom:8px}
.lib-cat h5{
  margin:6px 2px;font-size:11px;color:var(--ink2);font-weight:700;letter-spacing:.5px;
  display:flex;align-items:center;gap:5px;
}
.lib-cat h5::after{content:"";flex:1;height:1px;background:var(--line)}
.lib-grid{display:grid;grid-template-columns:1fr 1fr;gap:6px}
.lib-item{
  border:1px solid var(--line);border-radius:8px;background:#fff;padding:4px 3px 3px;
  display:flex;flex-direction:column;align-items:center;gap:2px;transition:.15s;cursor:grab;
}
.lib-item:hover{border-color:var(--brand);background:var(--brand-soft);transform:translateY(-1px)}
.lib-item svg{width:100%;height:34px;pointer-events:none}
.lib-item span{font-size:10.5px;color:var(--ink2);text-align:center;line-height:1.2}
.lib-item:hover span{color:var(--brand)}

/* ---------- 舞台 ---------- */
.stage{display:flex;flex-direction:column;min-width:0;min-height:0}
.toolbar{
  display:flex;align-items:center;gap:8px;padding:7px 10px;background:var(--panel);
  border-bottom:1px solid var(--line);flex-wrap:wrap;
}
.tool-group{display:flex;align-items:center;gap:4px}
.tool-group.right{margin-left:auto}
.tool{
  border:1px solid var(--line);background:#fff;border-radius:7px;padding:6px 9px;color:var(--ink);
  transition:.15s;white-space:nowrap;
}
.tool:hover{background:#f8fafc;border-color:#b9c6da}
.tool.active{background:var(--brand);border-color:var(--brand);color:#fff;box-shadow:0 2px 6px rgba(37,99,235,.3)}
.chk{display:flex;align-items:center;gap:4px;color:var(--ink2);font-size:11.5px;cursor:pointer;user-select:none}
.chk input{margin:0;cursor:pointer}
.zoomtxt{font-size:11px;color:var(--ink2);min-width:36px;text-align:center}

.canvas-wrap{
  flex:1;min-height:0;overflow:hidden;position:relative;background:
    radial-gradient(circle at 1px 1px,#d7dee9 1px,transparent 0) 0 0/22px 22px, #fbfcfe;
}
#canvas{width:100%;height:100%;display:block;touch-action:none}
#canvas.drawing{cursor:crosshair}
#canvas text{font-family:"Microsoft YaHei","PingFang SC",sans-serif}

.statusbar{
  height:28px;display:flex;align-items:center;gap:10px;padding:0 12px;background:var(--panel);
  border-top:1px solid var(--line);color:var(--ink2);font-size:11.5px;
}
.grow{flex:1}

/* ---------- 右侧面板 ---------- */
.tabs{display:flex;border-bottom:1px solid var(--line)}
.tab{
  flex:1;border:none;background:transparent;padding:10px 4px;color:var(--ink2);font-size:12.5px;
  font-weight:600;border-bottom:2px solid transparent;
}
.tab.active{color:var(--brand);border-bottom-color:var(--brand);background:var(--brand-soft)}
.hidden{display:none !important}

.prop-body{padding:2px}
.prop-empty{color:var(--ink2);font-size:12px;line-height:1.7}
.field{margin-bottom:9px}
.field label{display:block;font-size:11px;color:var(--ink2);margin-bottom:3px;font-weight:600}
.field input[type=text],.field input[type=number],.field select{
  width:100%;border:1px solid var(--line);border-radius:6px;padding:6px 8px;font-size:12.5px;
  font-family:inherit;outline:none;color:var(--ink);background:#fff;
}
.field input:focus,.field select:focus{border-color:var(--brand)}
.field-row{display:flex;gap:6px}
.field-row>*{flex:1}
.field.inline{display:flex;align-items:center;gap:8px}
.field.inline label{margin:0;flex:1}
.field.inline input[type=checkbox]{width:auto}
.fbtns{display:flex;gap:5px;flex-wrap:wrap;margin:8px 0 4px}
.fbtns button{
  flex:1;min-width:64px;border:1px solid var(--line);background:#fff;border-radius:6px;padding:6px 4px;
  color:var(--ink);
}
.fbtns button:hover{background:var(--brand-soft);border-color:var(--brand);color:var(--brand)}
.sec-title{
  font-size:11px;font-weight:700;color:var(--ink2);margin:12px 0 6px;padding-bottom:4px;
  border-bottom:1px solid var(--line);letter-spacing:.5px;
}
.tag{
  display:inline-block;background:#eef2ff;color:#4338ca;border-radius:5px;padding:2px 7px;
  font-size:11px;margin:0 4px 4px 0;
}

/* 模板 */
.tpl-body{padding:2px}
.tpl-group{margin-bottom:12px}
.tpl-group h5{font-size:11px;color:var(--ink2);margin:0 0 6px;letter-spacing:.5px}
.tpl-item{
  border:1px solid var(--line);border-radius:8px;padding:6px;margin-bottom:6px;cursor:pointer;
  transition:.15s;background:#fff;
}
.tpl-item:hover{border-color:var(--brand);box-shadow:0 2px 8px rgba(37,99,235,.12)}
.tpl-item b{font-size:12px;display:block;margin-bottom:2px}
.tpl-item small{color:var(--ink2);font-size:10.5px;line-height:1.4;display:block}
.tpl-item svg{width:100%;height:52px;background:#fcfdff;border:1px solid #eef2f7;border-radius:5px;margin-top:4px}

.help-body{padding:2px 4px 20px;font-size:12px;line-height:1.75;color:#334155}
.help-body h4{margin:14px 0 5px;font-size:12.5px;color:var(--brand)}
.help-body h4:first-child{margin-top:2px}
.help-body ul{margin:0;padding-left:17px}
.help-body li{margin-bottom:3px}
.help-body b{color:var(--ink)}
kbd{
  background:#f1f5f9;border:1px solid #d8e0ea;border-bottom-width:2px;border-radius:4px;
  padding:0 4px;font-size:11px;font-family:inherit;
}

/* ---------- toast ---------- */
.toast{
  position:fixed;left:50%;bottom:52px;transform:translate(-50%,20px);
  background:rgba(17,24,39,.92);color:#fff;padding:9px 16px;border-radius:8px;font-size:12.5px;
  opacity:0;pointer-events:none;transition:.25s;z-index:99;box-shadow:0 6px 20px rgba(0,0,0,.2);
}
.toast.show{opacity:1;transform:translate(-50%,0)}

/* ---------- 画布中图元 ---------- */
.it{cursor:move}
.it.free{cursor:default}
.sel-outline{fill:none;stroke:var(--brand);stroke-width:1;stroke-dasharray:4 3;pointer-events:none}
.handle{fill:#fff;stroke:var(--brand);stroke-width:1.5;cursor:pointer}
.handle.rot{cursor:grab}
.port-dot{fill:var(--brand);opacity:0}
.it:hover .port-dot{opacity:.35}
.wire-hot{fill:none;stroke:transparent;stroke-width:14;cursor:move}
.temp-path{fill:none;stroke:var(--brand);stroke-width:2;stroke-dasharray:5 4;pointer-events:none}
.marquee{fill:rgba(37,99,235,.08);stroke:var(--brand);stroke-width:1;stroke-dasharray:3 3}

@media (max-width:1180px){
  .layout{grid-template-columns:180px 1fr 230px}
  .brand-txt small{display:none}
}
@media (max-width:960px){
  .layout{grid-template-columns:1fr}
  .panel.left,.panel.right{position:fixed;top:54px;bottom:0;width:250px;z-index:30;box-shadow:0 0 30px rgba(0,0,0,.15)}
  .panel.left{left:0}.panel.right{right:0}
}