:root{
  --ink:#1f2a44;
  --muted:#64708a;
  --paper:#ffffff;
  --bg:#edf3ff;
  --navy:#17233d;
  --blue:#4d78d0;
  --cyan:#48b6d9;
  --green:#3ca66b;
  --orange:#ef8b43;
  --red:#e75a67;
  --yellow:#ffd36a;
  --line:#d7dfef;
  --shadow:0 12px 30px rgba(34,48,80,.12);
  --radius:22px;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;font-family:Inter,Arial,Helvetica,sans-serif;color:var(--ink);background:
  radial-gradient(circle at 10% 0%,rgba(72,182,217,.16),transparent 28%),
  radial-gradient(circle at 90% 3%,rgba(239,139,67,.14),transparent 24%),var(--bg);min-height:100vh}
button,input,select{font:inherit}
button{cursor:pointer}
button:focus-visible,input:focus-visible,select:focus-visible{outline:4px solid rgba(72,182,217,.35);outline-offset:2px}
.hidden{display:none!important}

.site-shell{min-height:100vh}
.hero{background:linear-gradient(135deg,#17233d,#263f70);color:white;padding:38px 20px 48px;position:relative;overflow:hidden}
.hero:after{content:"";position:absolute;width:310px;height:310px;border:55px solid rgba(255,255,255,.06);border-radius:50%;right:-100px;top:-100px}
.hero-inner{max-width:1180px;margin:auto;position:relative;z-index:1}
.eyebrow{display:inline-flex;gap:8px;align-items:center;background:rgba(255,255,255,.13);padding:8px 12px;border-radius:999px;font-size:.88rem;font-weight:800;letter-spacing:.04em;text-transform:uppercase}
.hero h1{font-size:clamp(2.2rem,5vw,4.5rem);line-height:.98;margin:18px 0 12px;max-width:850px}
.hero p{font-size:1.12rem;max-width:760px;color:#e8efff;line-height:1.6;margin:0}
.mission-grid{max-width:1180px;margin:-26px auto 50px;padding:0 20px;display:grid;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));gap:18px;position:relative;z-index:2}
.mission-card{background:white;border:1px solid rgba(215,223,239,.9);border-radius:24px;box-shadow:var(--shadow);padding:22px;display:flex;flex-direction:column;min-height:300px;transition:.22s transform,.22s box-shadow}
.mission-card:hover{transform:translateY(-5px);box-shadow:0 18px 40px rgba(34,48,80,.18)}
.mission-icon{width:54px;height:54px;border-radius:16px;display:grid;place-items:center;font-size:1.7rem;background:#edf3ff;margin-bottom:14px}
.mission-card h2{margin:0 0 8px;font-size:1.3rem}
.mission-card p{color:var(--muted);line-height:1.5;margin:0 0 18px;flex:1}
.progress-mini{height:9px;background:#edf1f7;border-radius:999px;overflow:hidden;margin:10px 0 8px}.progress-mini span{display:block;height:100%;background:linear-gradient(90deg,var(--cyan),var(--green));border-radius:999px}
.card-meta{display:flex;justify-content:space-between;color:var(--muted);font-size:.86rem;margin-bottom:14px}
.primary-btn,.secondary-btn,.help-btn,.check-btn,.choice-btn,.order-btn,.tiny-btn{border:0;border-radius:14px;font-weight:800}
.primary-btn{background:linear-gradient(135deg,#4d78d0,#365faf);color:white;padding:12px 16px;box-shadow:0 8px 18px rgba(77,120,208,.23)}
.secondary-btn{background:#eef2fa;color:var(--ink);padding:11px 15px}
.help-btn{background:#fff4d6;color:#6e4a00;padding:10px 14px;border:1px solid #f6d98b}
.check-btn{background:#203b70;color:white;padding:11px 15px}
.tiny-btn{background:#eef2fa;color:var(--ink);padding:7px 10px}

.mission-topbar{position:sticky;top:0;z-index:20;background:rgba(255,255,255,.95);backdrop-filter:blur(12px);border-bottom:1px solid var(--line)}
.topbar-inner{max-width:1180px;margin:auto;padding:12px 20px;display:grid;grid-template-columns:auto 1fr auto;gap:16px;align-items:center}
.back-btn{border:0;background:#eef2fa;color:var(--ink);border-radius:12px;padding:9px 12px;font-weight:800}
.mission-title-small strong{display:block;font-size:1rem}.mission-title-small span{font-size:.82rem;color:var(--muted)}
.progress-wrap{display:flex;align-items:center;gap:10px}.progress-track{width:min(30vw,280px);height:10px;background:#e9eef8;border-radius:999px;overflow:hidden}.progress-fill{height:100%;background:linear-gradient(90deg,var(--cyan),var(--green));transition:.3s width}.progress-label{font-weight:800;font-size:.82rem;color:var(--muted)}

.mission-hero{max-width:1180px;margin:26px auto 16px;padding:0 20px}.mission-hero-card{background:linear-gradient(135deg,#20345f,#2f5a9a);color:white;border-radius:28px;padding:26px;box-shadow:var(--shadow);display:grid;grid-template-columns:1fr auto;gap:22px;align-items:center}.mission-hero h1{margin:0 0 8px;font-size:clamp(1.8rem,4vw,3rem)}.mission-hero p{margin:0;color:#e7efff;max-width:760px;line-height:1.55}.mission-badge{background:rgba(255,255,255,.14);border:1px solid rgba(255,255,255,.18);padding:14px 18px;border-radius:18px;font-weight:900;text-align:center}.mission-badge span{display:block;font-size:2rem}

.checkpoint-list{max-width:1180px;margin:0 auto 60px;padding:0 20px;display:grid;gap:18px}
.checkpoint{background:white;border:1px solid var(--line);border-radius:24px;box-shadow:var(--shadow);overflow:hidden}
.checkpoint.locked{filter:saturate(.55);opacity:.78}.checkpoint.locked .checkpoint-body{display:none}
.checkpoint-head{padding:18px 20px;display:grid;grid-template-columns:auto 1fr auto;gap:14px;align-items:center;background:linear-gradient(180deg,#fff,#f9fbff)}
.cp-num{width:46px;height:46px;border-radius:15px;display:grid;place-items:center;font-size:1.15rem;font-weight:900;background:#edf3ff;color:#315b9f}.checkpoint.complete .cp-num{background:#e1f5ea;color:#237947}.checkpoint.locked .cp-num{background:#eef0f4;color:#8a94a8}
.checkpoint-head h2{margin:0;font-size:1.18rem}.checkpoint-head p{margin:3px 0 0;color:var(--muted);font-size:.9rem}.lock-pill{font-size:.8rem;font-weight:900;padding:7px 11px;border-radius:999px;background:#eef2f8;color:#6d7890}.checkpoint.complete .lock-pill{background:#dcf4e7;color:#247646}.checkpoint.active .lock-pill{background:#e0efff;color:#315b9f}
.checkpoint-body{padding:0 20px 22px}
.story-strip{background:#f4f7ff;border-left:5px solid var(--blue);border-radius:12px;padding:13px 15px;line-height:1.5;margin:0 0 16px}
.content-grid{display:grid;grid-template-columns:minmax(0,1fr) minmax(280px,.85fr);gap:20px;align-items:start}
.theory-card,.activity-card,.diagram-card,.help-panel{border:1px solid var(--line);border-radius:18px;background:#fff;padding:17px}
.theory-card{background:#fbfcff}.theory-card h3,.activity-card h3,.diagram-card h3{margin:0 0 10px;font-size:1.05rem}.theory-card p{line-height:1.55;margin:8px 0;color:#3f4c64}.key-idea{display:flex;gap:10px;align-items:flex-start;background:#eef9f3;border-radius:13px;padding:11px 12px;margin-top:12px}.key-idea b{color:#237947}
.diagram-card{position:relative}.diagram-wrap{position:relative;border-radius:14px;overflow:hidden;background:#f4f7fb}.diagram-wrap img{width:100%;display:block}.info-hotspot{position:absolute;width:31px;height:31px;border-radius:50%;border:3px solid white;background:#17233d;color:#fff;font-weight:900;box-shadow:0 3px 12px rgba(0,0,0,.25);display:grid;place-items:center}.info-hotspot:hover{transform:scale(1.08)}
.help-row{margin:12px 0}.help-panel{display:none;background:#fff9e9;border-color:#f3d98f;margin-top:10px}.help-panel.open{display:block}.help-panel h4{margin:0 0 8px}.help-panel p,.help-panel li{line-height:1.5;color:#5c4d25}.help-panel ol,.help-panel ul{margin:8px 0 0;padding-left:20px}
.steps{margin:0;padding-left:22px}.steps li{padding:3px 0;line-height:1.45}
.activity-zone{margin-top:18px;display:grid;gap:16px}.activity-card{background:#fbfcff}.activity-card.complete{border-color:#8bd0aa;background:#f5fcf8}.activity-status{font-size:.82rem;font-weight:800;color:var(--muted);margin-left:8px}.activity-card.complete .activity-status{color:#237947}
.feedback{min-height:24px;margin-top:9px;font-weight:800;font-size:.9rem}.feedback.ok{color:#247646}.feedback.bad{color:#b63b49}

.sim-panel{display:grid;gap:12px}.control-row{display:flex;gap:12px;align-items:center;flex-wrap:wrap}.control-row label{font-weight:800;font-size:.9rem}.control-row select,.control-row input[type=number]{border:1px solid #cbd5e7;border-radius:10px;padding:8px 10px;background:white}.slider-row{display:grid;grid-template-columns:130px 1fr 60px;gap:10px;align-items:center}.slider-row label{font-weight:800}.slider-row output{text-align:center;background:#eef2fa;padding:5px 7px;border-radius:9px;font-weight:900}.sim-stage{min-height:150px;border:1px dashed #c8d1e2;background:white;border-radius:15px;padding:14px;position:relative;overflow:hidden}
.magnet-stage{height:190px;display:flex;align-items:center;justify-content:center;gap:var(--mag-gap,70px)}.mini-magnet{display:flex;width:140px;height:64px;border-radius:10px;overflow:hidden;box-shadow:0 5px 14px rgba(0,0,0,.12)}.mini-magnet span{width:50%;display:grid;place-items:center;color:white;font-weight:900;font-size:1.4rem}.north{background:#ef5c62}.south{background:#4d78d0}.force-meter{height:12px;background:#edf1f7;border-radius:999px;overflow:hidden}.force-meter span{height:100%;display:block;background:linear-gradient(90deg,#58c4e7,#ef8b43);width:40%;transition:.3s width}.force-readout{font-weight:900;text-align:center}
.electro-stage{display:grid;grid-template-columns:1fr 180px;gap:15px;align-items:center}.coil-vis{height:90px;position:relative}.core-vis{position:absolute;left:5%;right:5%;top:31px;height:28px;background:#929cae;border-radius:14px}.turns-vis{position:absolute;left:12%;right:12%;top:7px;height:75px;background:repeating-linear-gradient(90deg,transparent 0 12px,#d46a2c 12px 17px,transparent 17px 26px);border-radius:10px;opacity:.95}.clips{font-size:2rem;letter-spacing:4px;filter:grayscale(1)}.clips.active{filter:none}.strength-number{text-align:center;font-size:2rem;font-weight:900;color:#315b9f}
.motor-stage{height:180px;display:grid;place-items:center}.motor-visual{width:220px;height:125px;position:relative}.motor-magnet{position:absolute;top:24px;width:55px;height:78px;border-radius:8px;color:white;display:grid;place-items:center;font-weight:900;font-size:1.5rem}.motor-magnet.left{left:0;background:#ef5c62}.motor-magnet.right{right:0;background:#4d78d0}.motor-coil{position:absolute;left:71px;top:25px;width:78px;height:76px;border:8px solid #d46a2c;border-radius:10px;transform-origin:center;transition:.3s}.motor-visual.running .motor-coil{animation:spin 1.1s linear infinite}@keyframes spin{to{transform:rotate(360deg)}}
.bulb{width:84px;height:84px;border-radius:50%;border:4px solid #8d98aa;background:#f4f5f7;box-shadow:none;display:grid;place-items:center;font-weight:900;transition:.25s}.bulb.on{background:#ffe997;box-shadow:0 0 var(--glow,24px) rgba(255,199,68,.85)}
.sankey-stage{height:190px;position:relative}.sankey-input{position:absolute;left:3%;top:64px;height:68px;background:#4d78d0;border-radius:8px 0 0 8px;color:white;display:flex;align-items:center;padding:0 14px;font-weight:900}.sankey-useful{position:absolute;left:45%;top:64px;height:var(--useful-h,46px);width:48%;background:#4d78d0;border-radius:0 8px 8px 0;color:white;display:flex;align-items:center;justify-content:center;font-weight:900}.sankey-waste{position:absolute;left:45%;top:calc(64px + var(--useful-h,46px));width:70px;height:var(--waste-h,22px);background:#ef8b43;border-radius:0 0 9px 9px;color:#5d370e;font-weight:900;font-size:.8rem;display:flex;align-items:center;justify-content:center}

.choices{display:grid;gap:8px;margin-top:10px}.choice-btn{background:#fff;border:1px solid #cfd8e7;padding:11px 12px;text-align:left;color:var(--ink)}.choice-btn:hover{background:#f1f5fc}.choice-btn.selected{border-color:#4d78d0;background:#edf3ff}.choice-btn.correct{border-color:#54ae78;background:#eefaf3}.choice-btn.wrong{border-color:#e75a67;background:#fff0f2}
.order-list{display:grid;gap:8px;margin:10px 0}.order-item{display:grid;grid-template-columns:auto 1fr auto;gap:9px;align-items:center;border:1px solid #ced8e8;background:white;padding:9px 10px;border-radius:12px}.drag-handle{font-size:1.2rem;color:#8894a6;cursor:grab}.order-controls{display:flex;gap:5px}.order-btn{padding:5px 8px;background:#edf2fa;color:#46536a}.order-item.dragging{opacity:.45}
.sort-grid{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin-top:10px}.sort-bin{min-height:90px;border:2px dashed #c9d4e7;border-radius:14px;padding:10px}.sort-bin h4{margin:0 0 8px}.sort-chip{display:inline-block;background:#eef2fa;padding:7px 9px;border-radius:999px;margin:3px;font-size:.86rem;font-weight:800;cursor:pointer;border:1px solid transparent}.sort-chip.selected{border-color:#4d78d0;background:#dfeaff}.sort-source{padding:8px;border-radius:12px;background:#fff;margin-top:8px}
.calc-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(160px,1fr));gap:10px}.calc-box{background:white;border:1px solid #d4deed;border-radius:13px;padding:11px}.calc-box b{display:block;font-size:.82rem;color:var(--muted);margin-bottom:4px}.calc-box input{width:100%;border:1px solid #cbd5e7;border-radius:9px;padding:8px}.unlock-banner{margin-top:18px;border-radius:18px;padding:18px;background:linear-gradient(135deg,#e6f7ee,#f5fff9);border:1px solid #8bd0aa;display:flex;justify-content:space-between;gap:12px;align-items:center}.unlock-banner strong{font-size:1.05rem}.unlock-banner p{margin:3px 0 0;color:#47705a}.unlock-code{background:#1f7046;color:white;border-radius:12px;padding:10px 14px;font-size:1.15rem;font-weight:900;letter-spacing:.08em}
.final-complete{text-align:center;padding:30px 20px}.final-complete .big{font-size:4rem}.final-complete h2{font-size:2rem;margin:8px 0}.final-complete p{color:var(--muted);max-width:600px;margin:0 auto 18px;line-height:1.55}

.info-dialog{max-width:520px;border:0;border-radius:20px;padding:24px;box-shadow:0 30px 80px rgba(0,0,0,.3);color:var(--ink)}.info-dialog::backdrop{background:rgba(18,29,52,.58)}.dialog-close{float:right;border:0;background:#eef2fa;width:36px;height:36px;border-radius:50%;font-size:1.4rem}.info-dialog h2{margin:0 50px 10px 0}.info-dialog p{line-height:1.55;color:#4c5870}
.toast{position:fixed;left:50%;bottom:24px;transform:translateX(-50%) translateY(100px);background:#17233d;color:white;padding:12px 18px;border-radius:999px;font-weight:800;z-index:50;opacity:0;transition:.25s}.toast.show{transform:translateX(-50%) translateY(0);opacity:1}
.test-report{position:fixed;right:10px;bottom:10px;background:#111;color:#fff;padding:8px 10px;font:12px monospace;z-index:1000;border-radius:8px}

@media(max-width:820px){.content-grid{grid-template-columns:1fr}.topbar-inner{grid-template-columns:auto 1fr}.progress-wrap{grid-column:1/-1}.progress-track{width:100%}.mission-hero-card{grid-template-columns:1fr}.mission-badge{justify-self:start}.slider-row{grid-template-columns:100px 1fr 52px}.electro-stage{grid-template-columns:1fr}.sort-grid{grid-template-columns:1fr}.checkpoint-head{grid-template-columns:auto 1fr}.lock-pill{grid-column:2}.hero{padding-top:28px}}
@media(max-width:520px){.mission-grid,.mission-hero,.checkpoint-list{padding-left:12px;padding-right:12px}.checkpoint-body{padding-left:14px;padding-right:14px}.checkpoint-head{padding:15px}.hero{padding-left:14px;padding-right:14px}.control-row{align-items:stretch}.control-row>*{max-width:100%}.mission-card{min-height:270px}.slider-row{grid-template-columns:1fr 55px}.slider-row label{grid-column:1/-1}.topbar-inner{padding:10px 12px}.mission-title-small span{display:none}}
.mini-diagram-row{display:grid;grid-template-columns:1fr 1fr;gap:10px}.mini-diagram-row>div{border:1px solid var(--line);border-radius:12px;overflow:hidden;background:#f8fbff}.mini-diagram-row img{width:100%;display:block}.mini-info-row{display:flex;gap:6px;flex-wrap:wrap;padding:8px}.mini-info-row .tiny-btn{font-size:.78rem}
@media(max-width:620px){.mini-diagram-row{grid-template-columns:1fr}}

/* v1.1 checkpoint tabs, review, reset and robust drag/drop */
.topbar-actions{display:flex;align-items:center;gap:12px;justify-content:flex-end;min-width:0}.review-btn{background:#eef4ff;color:#284d88;border:1px solid #c5d5f0;padding:9px 12px;border-radius:11px;font-weight:850;white-space:nowrap}.review-btn:hover{background:#e1ebff}
.checkpoint-tabs{max-width:1180px;margin:0 auto 12px;padding:0 22px;display:grid;grid-template-columns:repeat(5,minmax(0,1fr));gap:8px;position:sticky;top:72px;z-index:12}.checkpoint-tab{min-width:0;background:#fff;border:1px solid var(--line);border-radius:15px;padding:10px;display:grid;grid-template-columns:34px 1fr;gap:8px;align-items:center;text-align:left;color:var(--ink);box-shadow:0 5px 16px rgba(37,53,86,.08)}.checkpoint-tab .tab-number{width:34px;height:34px;border-radius:50%;display:grid;place-items:center;background:#e9eef7;font-weight:900}.checkpoint-tab small{display:block;color:var(--muted);font-size:.72rem;line-height:1.15;margin-top:2px}.checkpoint-tab.active{border-color:#4d78d0;box-shadow:0 0 0 3px rgba(77,120,208,.14),0 8px 22px rgba(37,53,86,.12);background:#f8fbff}.checkpoint-tab.active .tab-number{background:#4d78d0;color:#fff}.checkpoint-tab.complete{border-color:#8bc9a8;background:#f6fff9}.checkpoint-tab.complete .tab-number{background:#4eaa76;color:#fff}.checkpoint-tab:disabled{opacity:.55;cursor:not-allowed;background:#f5f6f8}.checkpoint-panel[hidden]{display:none!important}.checkpoint-tab-panels{padding-top:0}.checkpoint-panel.tab-active{animation:tabIn .2s ease-out}@keyframes tabIn{from{opacity:.2;transform:translateY(5px)}to{opacity:1;transform:none}}
.diagram-tip{color:var(--muted);font-size:.86rem;margin-bottom:0}.power-compare{margin-top:16px;border-top:1px solid var(--line);padding-top:14px}.strength-label{text-align:center;color:var(--muted);font-weight:800}.bulb-stage{display:grid;place-items:center}.action-row{display:flex;gap:9px;align-items:center;flex-wrap:wrap;margin-top:10px}.reset-btn{background:#f3f5f8;color:#45516a;border:1px solid #cfd7e4;padding:9px 11px;border-radius:10px;font-weight:800}.reset-btn:hover{background:#e9edf3}.danger-btn{background:#fff1f2;color:#9e3040;border:1px solid #efb6be;padding:10px 14px;border-radius:11px;font-weight:850}.final-actions{display:flex;gap:10px;justify-content:center;flex-wrap:wrap}
.sort-source{min-height:58px;border:1px dashed #c4cfdf}.source-label{display:block;font-size:.78rem;font-weight:850;color:var(--muted);margin:0 4px 6px}.sort-chip{touch-action:none;user-select:none}.sort-chip.dragging{opacity:.35}.drop-zone.drag-over{outline:3px solid rgba(77,120,208,.24);background:#eef4ff}.sort-ghost,.drag-ghost{position:fixed!important;z-index:1000;pointer-events:none;max-width:360px;box-shadow:0 12px 30px rgba(0,0,0,.22);margin:0}.sort-ghost{background:#fff}.drag-handle{touch-action:none;user-select:none}.order-item.pointer-dragging{opacity:.28}.order-list{min-height:44px}
.saved-review{margin-top:18px;border-top:1px solid var(--line);padding-top:16px}.saved-review-empty{display:flex;gap:10px;align-items:flex-start;background:#f7f9fc;border:1px solid #dae2ee;padding:12px 14px;border-radius:13px;color:var(--muted)}.saved-review-empty span{font-size:1.4rem}.saved-review-empty p{margin:3px 0 0}.saved-review details{background:#eef8f2;border:1px solid #add7bd;border-radius:14px;padding:11px 13px}.saved-review summary{font-weight:900;color:#326a49;cursor:pointer}.saved-answer-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(230px,1fr));gap:10px;margin-top:10px}.saved-answer-grid article{background:white;border:1px solid #d5e6db;border-radius:12px;padding:10px}.saved-answer-grid h4{margin:0 0 7px}.saved-answer-grid ul{margin:0;padding-left:18px;color:#47566c;line-height:1.45;font-size:.9rem}.dialog-review{display:grid;gap:15px}.dialog-review-section{border-bottom:1px solid #e1e6ee;padding-bottom:12px}.dialog-review-section:last-child{border-bottom:0}.dialog-review-section h3{margin:0 0 8px}.dialog-answer{background:#f7f9fc;border-radius:11px;padding:9px 11px;margin:7px 0}.dialog-answer ul{margin:6px 0 0;padding-left:18px;line-height:1.45}.info-dialog{width:min(720px,calc(100vw - 28px));max-height:85vh;overflow:auto}
@media(max-width:980px){.checkpoint-tabs{grid-template-columns:repeat(5,170px);overflow-x:auto;padding-bottom:6px;scrollbar-width:thin;top:88px}.topbar-actions{gap:7px}.review-btn{font-size:.8rem}.topbar-inner{grid-template-columns:auto minmax(0,1fr) auto}}
@media(max-width:720px){.topbar-actions{grid-column:1/-1;justify-content:space-between;width:100%}.checkpoint-tabs{top:132px;padding-left:12px;padding-right:12px}.checkpoint-tab{grid-template-columns:30px 1fr}.checkpoint-tab .tab-number{width:30px;height:30px}.review-btn{white-space:normal}.checkpoint-panel{margin-top:4px}}

/* v1.2 draggable magnetic field simulator, Chemisode link and teacher skip code */
.sim-link-card{margin-top:14px;padding:13px 14px;border:1px solid #c8d8f1;border-radius:14px;background:#f3f7ff;display:flex;gap:14px;align-items:center;justify-content:space-between}.sim-link-card p{margin:4px 0 0;color:var(--muted);font-size:.88rem}.external-sim-btn{display:inline-flex;align-items:center;justify-content:center;text-decoration:none;background:#315fbd;color:white;padding:10px 13px;border-radius:11px;font-weight:850;white-space:nowrap;box-shadow:0 5px 14px rgba(49,95,189,.2)}.external-sim-btn:hover{background:#274f9e}
.mag-drag-toolbar{display:flex;gap:9px;align-items:center;flex-wrap:wrap;margin-bottom:10px}.mag-drag-toolbar .secondary-btn{padding:9px 12px}.drag-hint{margin-left:auto;color:var(--muted);font-weight:800;font-size:.86rem}.magnetic-drag-wrap{border-radius:16px;overflow:hidden;border:1px solid #cfd9e8;background:#f8fbff}.magnetic-drag-stage{display:block;width:100%;height:auto;min-height:250px;touch-action:none;user-select:none;cursor:default}.mag-stage-bg{fill:#f8fbff;stroke:#dbe4f0;stroke-width:2}.dynamic-field-lines{pointer-events:none}.field-line{fill:none;stroke:#687995;stroke-width:2;opacity:.56}.field-line.interaction{stroke:#4d6f9e;stroke-width:2.5;opacity:.8}.field-line.repel-line{stroke:#8190aa;stroke-dasharray:3 3}.drag-magnet{cursor:grab;touch-action:none;filter:drop-shadow(0 5px 7px rgba(30,45,70,.18))}.drag-magnet.dragging{cursor:grabbing;filter:drop-shadow(0 9px 12px rgba(30,45,70,.28))}.mag-outline{fill:#fff;stroke:#263855;stroke-width:3}.pole-n{fill:#ec5962}.pole-s{fill:#4774c7}.mag-divider{stroke:rgba(255,255,255,.75);stroke-width:2}.pole-label{fill:#fff;font-weight:900;font-size:27px;text-anchor:middle;font-family:Arial,sans-serif;pointer-events:none}.drag-mark{fill:none;stroke:rgba(255,255,255,.8);stroke-width:2;stroke-linecap:round;stroke-linejoin:round;pointer-events:none}
.skip-box{margin-top:20px;padding:16px;border:1px dashed #b8c5d8;border-radius:16px;background:#f8fafc}.skip-box.skip-used{border-style:solid;border-color:#95c7a8;background:#f5fcf7}.skip-head>div{display:flex;gap:11px;align-items:flex-start}.skip-icon{font-size:1.5rem}.skip-head b{font-size:1rem}.skip-head p{margin:3px 0 0;color:var(--muted);font-size:.86rem;line-height:1.4}.skip-controls{display:flex;gap:8px;align-items:center;margin-top:12px}.skip-controls input{width:150px;max-width:100%;padding:10px 11px;border:1px solid #c8d2e2;border-radius:10px;font:inherit;letter-spacing:.18em}.skip-btn{border:0;border-radius:10px;padding:10px 13px;background:#5e6b82;color:white;font-weight:850}.skip-btn:hover{background:#4e5b70}.skip-answer-panel[hidden]{display:none}.skip-reveal{margin-top:12px;padding:14px;border-radius:13px;background:#ecf8f0;border:1px solid #add5bb}.skip-reveal h4{margin:0 0 5px;color:#2f6b47}.skip-reveal p{margin:0 0 8px;color:#496354}.skip-reveal ul{margin:0 0 13px;padding-left:20px;line-height:1.5}.skip-reveal .primary-btn{padding:10px 13px}
@media(max-width:700px){.sim-link-card{align-items:stretch;flex-direction:column}.external-sim-btn{white-space:normal;text-align:center}.drag-hint{margin-left:0;width:100%}.magnetic-drag-stage{min-height:220px}.skip-controls{align-items:stretch;flex-direction:column}.skip-controls input{width:100%}.skip-btn{width:100%}}