:root{color:#172033;--surface:#fff;--surface-strong:#f8fbff;--ink:#172033;--muted:#5b687c;--line:#c8d8ea;--blue:#2563eb;--green:#16a34a;--amber:#f59e0b;--red:#ef4444;--shadow:0 18px 45px #1b395d29;background:#eef7ff;font-family:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,sans-serif}*{box-sizing:border-box}body{background:var(--surface-strong);min-width:320px;min-height:100vh;color:var(--ink);background-image:radial-gradient(circle at 20px 20px,#2563eb1a 2px,#0000 2px);background-size:28px 28px;margin:0}button,input,textarea,select{font:inherit}.app-shell{width:min(1180px,100%);min-height:100vh;color:var(--ink);margin:0 auto;padding:24px}.lab-header,.lab-layout,.object-palette{width:min(1180px,100%);margin:0 auto}.lab-header{background:var(--surface);border:1px solid var(--line);box-shadow:var(--shadow);border-radius:8px;margin-bottom:14px;padding:16px 18px}.lab-header h1{margin:0;font-size:1.35rem;line-height:1.3}.lab-header p{color:var(--muted);margin:8px 0 0}.lab-layout{grid-template-columns:240px minmax(420px,1fr) 280px;align-items:stretch;gap:16px;display:grid}.challenge-panel,.feedback-panel{background:var(--surface);border:1px solid var(--line);box-shadow:var(--shadow);border-radius:8px;min-height:0;padding:14px}.challenge-panel{grid-column:1}.challenge-panel .challenge-list{gap:8px;display:grid}.challenge-panel button,.feedback-panel button{width:100%;color:var(--ink);cursor:pointer;text-align:left;background:#eef6ff;border:1px solid #d8e5f5;border-radius:8px;padding:10px 12px}.challenge-panel button[aria-pressed=true]{border-color:var(--blue);background:#dce8ff}.balance-stage{border:1px solid var(--line);min-height:430px;box-shadow:var(--shadow);background:linear-gradient(#fff,#e7f6ff);border-radius:8px;grid-column:2;padding:12px 12px 16px;position:relative}.balance-board{--seesaw-center-y:61%;--slot-layer-lift:-46px;--fulcrum-label-offset:52px;border:1px dashed #0000;border-radius:8px;align-content:center;justify-items:center;width:100%;height:100%;min-height:430px;display:grid;position:relative}.balance-board[data-status=balanced]{background:#16a34a08;border-color:#16a34a59}.balance-board[data-status=left-heavy]{background:#ef444408;border-color:#ef444459}.balance-board[data-status=right-heavy]{background:#2563eb08;border-color:#2563eb59}.balance-board h2{color:var(--muted);margin:0 0 16px;font-size:1rem}.seesaw-visual-layer{pointer-events:none;z-index:1;position:absolute;inset:0}.seesaw{left:8%;right:8%;top:var(--seesaw-center-y);transform-origin:50%;background:#9b6a32;border-radius:999px;height:18px;transition:transform .26s;position:absolute;box-shadow:0 8px 18px #59340e4d}.seesaw span{clip:rect(0 0 0 0);white-space:nowrap;width:1px;height:1px;position:absolute;overflow:hidden}.fulcrum{left:50%;top:var(--seesaw-center-y);background:#5d3e1e;border:3px solid #f6e5c5;border-radius:50%;width:28px;height:28px;position:absolute;transform:translate(-50%,-50%);box-shadow:0 0 0 6px #5a371629}.fulcrum-marker{left:50%;top:calc(var(--seesaw-center-y) + var(--fulcrum-label-offset));color:#5d3e1e;text-align:center;white-space:nowrap;font-size:.78rem;font-weight:800;line-height:1.15;position:absolute;transform:translate(-50%)}.board-row{width:min(760px,100%);min-height:320px;transform:translateY(var(--slot-layer-lift));z-index:2;grid-template-columns:minmax(0,1fr) 58px minmax(0,1fr);place-items:center;gap:10px;margin:0 auto;padding:0 0 10px;display:grid;position:relative}.slot-arm{grid-template-columns:repeat(3,minmax(0,1fr));align-items:start;gap:8px;width:100%;display:grid}.left-slot-group{grid-column:1}.right-slot-group{grid-column:3}.seesaw-slot{border:2px dashed var(--line);text-align:center;background:#ffffffe0;border-radius:8px;flex-direction:column;align-items:center;gap:6px;width:100%;min-width:0;min-height:96px;padding:6px;display:flex}.seesaw-slot>button{border:1px solid var(--blue);width:100%;min-height:44px;color:var(--ink);white-space:normal;text-overflow:clip;box-sizing:border-box;word-break:keep-all;text-align:center;background:#f0f6ff;border-radius:8px;padding:6px 8px;font-size:.9rem;line-height:1.25;overflow:visible}.placed-stack{place-items:center;gap:6px;width:100%;margin:0;padding:0;list-style:none;display:grid}.placed-stack li{justify-content:center;display:flex}.placed-object-card{width:46px;height:46px;min-height:46px;color:var(--ink);cursor:pointer;background:#fff;border:1px solid #c8d8ea;border-radius:8px;justify-content:center;align-items:center;padding:0;transition:transform .18s,border-color .18s,box-shadow .18s;display:inline-flex;box-shadow:0 6px 14px #1720331a}.placed-object-card:hover{border-color:var(--blue);transform:translateY(-1px);box-shadow:0 10px 18px #17203324}.placed-object-icon{flex:none;justify-content:center;align-items:center;width:34px;height:34px;display:inline-flex}.placed-object-icon svg{width:32px;height:32px}.object-palette{background:var(--surface);border:1px solid var(--line);box-shadow:var(--shadow);border-radius:8px;margin-top:16px;padding:14px}.object-palette h2{margin:0 0 8px;font-size:1rem}.palette-list{grid-template-columns:repeat(3,minmax(0,1fr));gap:8px;display:grid}.object-card{border:1px solid var(--line);background:var(--surface);text-align:left;cursor:pointer;border-radius:8px;align-items:center;gap:10px;padding:10px 12px;transition:transform .18s,border-color .18s,box-shadow .18s;display:flex}.object-card:hover{transform:translateY(-1px);box-shadow:0 10px 20px #17203314}.object-card[aria-pressed=true]{border-color:var(--blue);box-shadow:0 0 0 3px #2563eb29}.object-card .object-icon{flex:none;justify-content:center;align-items:center;width:28px;height:28px;display:inline-flex}.object-card .object-icon svg{width:26px;height:26px}.object-label{text-overflow:ellipsis;white-space:nowrap;flex:auto;min-width:0;overflow:hidden}.object-weight-badge{color:#1f4f93;white-space:nowrap;background:#eef6ff;border:1px solid #c8d8ea;border-radius:999px;justify-content:center;align-items:center;min-width:46px;min-height:28px;font-size:.82rem;font-weight:800;line-height:1;display:inline-flex}.feedback-panel{grid-column:3;align-content:start;gap:8px;display:grid}.feedback-panel [role=status]{color:var(--ink);background:#ecf7ee;border:1px solid #cde9d2;border-radius:8px;padding:10px 12px;font-weight:600}.success-dialog{color:#14532d;background:#ecfdf5;border:1px solid #bbf7d0;border-radius:8px;margin-top:16px;padding:12px}.success-dialog h2{margin:0 0 4px;font-size:1.1rem}button:focus-visible,.object-card:focus-visible,.seesaw-slot>button:focus-visible{outline:2px solid var(--blue);outline-offset:2px}.balance-board[data-status=left-heavy] .seesaw{box-shadow:0 -8px 12px #ef44442e}.balance-board[data-status=right-heavy] .seesaw{box-shadow:0 12px 12px #2563eb2e}.balance-board[data-status=balanced] .seesaw{box-shadow:0 0 0 2px #16a34a40}@media (width<=1040px){.lab-layout{grid-template-columns:1fr;grid-template-areas:"challenge""balance""feedback"}.challenge-panel{order:1;grid-area:challenge}.balance-stage{order:2;grid-area:balance;min-height:360px}.balance-board{--seesaw-center-y:62%;--slot-layer-lift:-44px;--fulcrum-label-offset:50px}.feedback-panel{order:3;grid-area:feedback}.board-row{grid-template-columns:minmax(0,1fr) 54px minmax(0,1fr);align-content:center;gap:8px;width:min(820px,100%)}.palette-list{grid-template-columns:repeat(2,minmax(0,1fr))}.app-shell,.lab-header,.lab-layout,.object-palette{width:100%}.lab-header,.object-palette,.challenge-panel,.balance-stage,.feedback-panel{padding:12px}.balance-stage h2,.feedback-panel p,.challenge-panel p{white-space:normal;word-break:keep-all}}@media (width<=560px){.balance-stage{min-height:420px}.balance-board{--seesaw-center-y:63%;--slot-layer-lift:-56px;--fulcrum-label-offset:54px}.board-row{grid-template-columns:minmax(0,1fr) 42px minmax(0,1fr);gap:6px;min-height:340px}.slot-arm{gap:4px}.seesaw-slot{min-height:106px;padding:4px}.seesaw-slot>button{min-height:54px;padding:5px 3px;font-size:.76rem;line-height:1.2}.placed-object-card{width:34px;height:34px;min-height:34px}.placed-object-icon{width:26px;height:26px}.placed-object-icon svg{width:24px;height:24px}.palette-list{grid-template-columns:1fr}.fulcrum-marker{font-size:.7rem}}@media (prefers-reduced-motion:reduce){.seesaw{transition:none}*{transition-duration:0s!important;animation-duration:0s!important;animation-iteration-count:1!important}}