:root{--ink:#172d49;--blue:#165fce;--line:#d5dfe9;--muted:#65778d;--paper:#fff;--orange:#bd4b17}*{box-sizing:border-box}body{margin:0;background:#f2f5f9;color:var(--ink);font:16px/1.5 system-ui,-apple-system,"Segoe UI",sans-serif}button,input,select{font:inherit;color:inherit}button{cursor:pointer}button:focus-visible,a:focus-visible,select:focus-visible,input:focus-visible{outline:3px solid #80b4ff;outline-offset:2px}button{border:1px solid #bdcbdc;background:white;border-radius:7px;padding:8px 12px;min-height:42px;font-size:14px}button:hover{background:#f0f5fc}button:disabled{opacity:.45;cursor:default}.primary{background:var(--blue);color:white;border-color:var(--blue)}.primary:hover{background:#104ea9}.danger{color:#ad2e28}header{background:white;border-bottom:1px solid var(--line)}.header-inner{max-width:1540px;margin:auto;padding:16px 22px;display:flex;align-items:center;justify-content:space-between;gap:18px;flex-wrap:wrap}h1{margin:0;font-size:21px;font-weight:650;letter-spacing:-.025em}.brand{display:flex;align-items:center;gap:12px}.brand-mark{font:28px Georgia;color:var(--blue)}.subtitle{font-size:13px;color:var(--muted);margin:0}.actions{display:flex;gap:7px;flex-wrap:wrap}main{max-width:1540px;margin:auto;padding:20px 22px 36px}.workbench{display:grid;grid-template-columns:245px minmax(300px,1fr) 275px;gap:14px;align-items:start}.pane{background:white;border:1px solid var(--line);border-radius:11px;min-width:0;overflow:hidden}.pane-head{padding:15px 17px;border-bottom:1px solid var(--line);display:flex;align-items:center;justify-content:space-between;gap:8px}h2{font-size:17px;line-height:1.4;margin:0;font-weight:650}h3{font-size:16px;margin:0 0 10px}.pane-body{padding:16px}.muted,.hint{color:var(--muted);font-size:14px}.hint{margin:9px 0}.empty-state{padding:18px;color:var(--muted);font-size:14px}.field{margin-bottom:13px}.field label{display:block;font-size:14px;margin-bottom:5px}.input-wrap{display:flex;align-items:center;border:1px solid #b9c9dc;border-radius:7px;background:#fbfcfe}.input-wrap input{border:0;background:transparent;padding:9px 10px;width:100%;min-width:0;outline:none;font-variant-numeric:tabular-nums}.input-wrap:focus-within{border-color:var(--blue);box-shadow:0 0 0 2px #e0edff}.unit{padding-right:10px;font-size:14px;color:var(--muted);white-space:nowrap}select{width:100%;padding:9px;border:1px solid #b9c9dc;border-radius:7px;background:#fff;font-size:14px}.field input[aria-invalid=true]{background:#fff1f0}.mini-grid{display:grid;grid-template-columns:1fr 1fr;gap:7px}.choice{padding:5px;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:3px;min-height:76px}.choice svg{width:100%;height:49px;display:block}.choice span{font-size:12px;line-height:1.25;text-align:center}.choice[aria-pressed=true]{color:var(--blue);background:#eef5ff;border-color:var(--blue);box-shadow:inset 0 0 0 1px var(--blue)}.tool-grid{display:grid;grid-template-columns:1fr 1fr;gap:8px}.tool-grid>.choice{min-height:94px}.tool-grid>.choice:last-child:nth-child(odd){grid-column:1/-1}.palette-back{border:0;padding:3px 0;min-height:30px;color:var(--blue);background:none;margin-bottom:9px}.palette-stage{font-size:13px;color:var(--muted);margin:0 0 12px}.stamp{margin-top:14px;border:1px dashed var(--blue);border-radius:9px;padding:12px;background:#f5f9ff;touch-action:none;user-select:none;cursor:grab;text-align:center}.stamp svg{height:65px;width:100%}.stamp strong{font-size:14px;display:block}.stamp p{font-size:13px;color:var(--muted);margin:5px 0}.stamp button{margin-top:7px;width:100%}.canvas-pane{position:relative}.canvas-head{padding:12px 14px;display:flex;align-items:center;justify-content:space-between;border-bottom:1px solid var(--line);gap:8px;flex-wrap:wrap}.mode-buttons{display:flex;gap:5px}.mode-buttons button{min-height:34px;font-size:13px;padding:5px 8px}.mode-buttons button[aria-pressed=true]{background:#eaf2ff;color:var(--blue);border-color:var(--blue)}.scene-wrap{position:relative;background:white;min-height:420px}.scene-wrap.placing{box-shadow:inset 0 0 0 2px var(--blue)}#scene{display:block;width:100%;height:490px;touch-action:none;user-select:none}#scene text{font-family:system-ui,-apple-system,"Segoe UI",sans-serif;font-size:14px;fill:var(--ink);paint-order:stroke;stroke:#fff;stroke-width:4px;stroke-linejoin:round}#scene .dimension-label{font-size:13px;fill:var(--muted)}#scene .reaction-label{fill:var(--blue);font-weight:600}#scene [data-kind]{cursor:pointer}#scene [data-kind]:focus{outline:none}#scene [data-kind]:focus .hit{stroke:#80b4ff;stroke-opacity:.5}#scene .node-handle{cursor:pointer}.canvas-bottom{display:flex;justify-content:space-between;gap:10px;flex-wrap:wrap;padding:9px 14px;border-top:1px solid var(--line);font-size:13px;color:var(--muted)}.zoom-controls{display:flex;gap:5px}.zoom-controls button{min-height:32px;padding:3px 9px;font-size:13px}.error{padding:10px 14px;margin:12px 0 0;border-radius:7px;background:#fff0ed;color:#9b2b24;font-size:14px}.selection-note{font-size:13px;padding:9px 14px;color:var(--muted);border-top:1px solid var(--line)}.inspector-footer{padding:0 16px 16px}.inspector-footer button{width:100%}.section-title{display:flex;align-items:center;justify-content:space-between;gap:14px;margin:25px 0 12px;flex-wrap:wrap}.section-title h2{font-size:20px}.status-pill{font-size:14px;padding:5px 10px;background:#e9f3ee;color:#246247;border-radius:5px}.status-pill.warning{background:#fff2df;color:#88501b}.calculation-grid{display:grid;grid-template-columns:1fr 1fr;gap:14px}.calculation-grid .wide{grid-column:1/-1}.calc{padding:18px 20px}.calc-header{display:flex;gap:10px;align-items:baseline;margin-bottom:13px}.roman{color:var(--blue);font-weight:700}.calc p{margin:7px 0;font-size:14px}.formula{font:19px/1.7 Georgia,"Times New Roman",serif;overflow-wrap:anywhere}.numeric{font-variant-numeric:tabular-nums}.formula-line{margin:7px 0;padding-bottom:7px;border-bottom:1px solid #edf1f6}.formula-line:last-child{border:0}.force-results{display:grid;grid-template-columns:repeat(auto-fit,minmax(210px,1fr));gap:12px}.force-card{border:1px solid var(--line);border-radius:8px;padding:13px}.force-card h4{margin:0 0 8px;font-size:15px}.answer{font-size:19px;font-weight:650;margin:6px 0}.data-table{width:100%;border-collapse:collapse;font-size:14px}.data-table th,.data-table td{padding:9px 7px;border-bottom:1px solid #e7edf4;text-align:left;vertical-align:top}.data-table th{font-weight:500;color:var(--muted)}.table-scroll{overflow:auto}.solve-steps{margin:0;padding-left:22px;font-size:14px}.check-list{display:flex;gap:12px 24px;flex-wrap:wrap;font-size:14px}.check-list strong{color:#246247}.drag-ghost{position:fixed;pointer-events:none;width:95px;height:80px;background:#fff;border:2px solid var(--blue);border-radius:8px;box-shadow:0 8px 30px #172d4926;z-index:10}.drag-ghost svg{width:100%;height:100%}.sr-only{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0,0,0,0)}[hidden]{display:none!important}.reset-note{font-size:13px;color:var(--muted)}
@media(min-width:1180px){.inspector,.toolbox{position:sticky;top:14px;max-height:calc(100vh - 28px);overflow:auto}}@media(max-width:1100px){.workbench{grid-template-columns:215px minmax(280px,1fr) 225px}.pane-body{padding:12px}.choice span{font-size:12px}main{padding:14px}.header-inner{padding:13px 16px}}@media(max-width:820px){.workbench{grid-template-columns:1fr 1fr}.canvas-pane{grid-column:1/-1;grid-row:1}.inspector{grid-column:1;grid-row:2}.toolbox{grid-column:2;grid-row:2}#scene{height:430px}.scene-wrap{min-height:0}.calculation-grid{grid-template-columns:1fr}.calculation-grid .wide{grid-column:auto}}@media(max-width:480px){main{padding:10px}.workbench{gap:9px;grid-template-columns:minmax(0,1fr) minmax(0,1fr)}h1{font-size:18px}.subtitle{font-size:12px}.header-inner{padding:11px 12px;gap:10px}.actions{gap:5px}.actions button{font-size:12px;padding:6px 8px;min-height:36px}.pane-head{padding:12px 10px}h2{font-size:15px}.pane-body{padding:10px}.choice{min-height:69px}.choice svg{height:42px}.tool-grid{gap:5px}.tool-grid>.choice{min-height:77px}.canvas-head{padding:10px}.mode-buttons button{font-size:12px}.canvas-bottom{padding:8px 10px}.calc{padding:15px}.formula{font-size:17px}#scene{height:370px}.field label{font-size:13px}.input-wrap input{font-size:15px;padding:8px}.stamp{padding:8px}.stamp strong{font-size:13px}.zoom-controls{width:100%}.inspector-footer{padding:0 10px 10px}.inspector .mini-grid{gap:4px}}
@media print{body{background:white}header .actions,.inspector,.toolbox,.canvas-head,.canvas-bottom,.selection-note,.error,.zoom-controls{display:none!important}main{padding:0}.workbench{display:block}.pane{border:0;border-radius:0}.canvas-pane{max-width:700px;margin:auto}#scene{height:380px}.calculation-grid{display:block}.calc{break-inside:avoid;padding:12px 0}.section-title{margin:10px 0}.header-inner{padding:0;border-bottom:1px solid #aaa}.formula{font-size:16px}.calc p,.data-table{font-size:12px}.status-pill{background:none}.force-card{break-inside:avoid}.scene-wrap{min-height:0}}