body.reaction-lab{--bg:#f3f7f8;--surface:#fff;--ink:#1b3038;--muted:#526b73;--line:#d6e2e4;--accent:#1768a8;--accent-dark:#105383;--soft:#e9f3f9;background:var(--bg);color:var(--ink);font-size:15px;line-height:1.8}
.reaction-lab [hidden]{display:none!important}
.reaction-lab .sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}
.lab-header{display:flex;align-items:center;justify-content:space-between;gap:20px;background:#fff;border-bottom:1px solid var(--line);padding:10px max(20px,calc((100vw - 1220px)/2));min-height:68px}
.lab-brand{display:flex;align-items:center;gap:10px;color:var(--ink);font-weight:750;font-size:17px;line-height:1.4;text-decoration:none}
.lab-brand:hover{text-decoration:none}.lab-brand small{display:block;color:var(--muted);font-size:11px;font-weight:400}
.lab-header nav{display:flex;align-items:center;gap:8px}.lab-header nav a{padding:7px 13px;border-radius:6px;color:var(--muted);font-weight:600;font-size:13px}.lab-header nav a[aria-current=page]{background:var(--soft);color:var(--accent)}
.lab-shell{max-width:1260px;margin:0 auto;padding:34px 20px 70px}
.lab-intro{display:flex;justify-content:space-between;align-items:center;gap:28px;padding:0 0 25px}.eyebrow{font-size:12px;font-weight:750;color:var(--accent);letter-spacing:.02em;margin:0 0 5px}.lab-intro h1{font-size:clamp(27px,3.3vw,42px);line-height:1.4;margin:0 0 7px;font-weight:800}.lab-intro p:last-child{margin:0;color:var(--muted);font-size:15px}.intro-mark{display:flex;align-items:center;gap:7px;direction:ltr;white-space:nowrap;color:var(--accent);font:700 20px/1.2 Arial,sans-serif;background:#e7f2f8;border:1px solid #cde2ee;padding:24px;border-radius:18px;transform:rotate(-2deg)}.intro-mark span{padding:6px 8px;background:#fff;border-radius:7px;box-shadow:0 2px 5px #164e6d15}.intro-mark b{font-size:17px;color:#698b9b}
.lab-steps{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:10px;margin:0 0 23px;padding:0;list-style:none}.lab-steps li{display:flex;align-items:center;gap:9px;padding:9px 13px;background:#fff;border:1px solid var(--line);border-radius:8px;color:var(--muted);font-size:13px;font-weight:650}.lab-steps span,.step-badge{display:grid;place-items:center;flex:none;background:var(--soft);color:var(--accent);border-radius:50%;width:26px;height:26px;font-weight:750;font-size:13px}
.lab-grid{display:grid;grid-template-columns:minmax(0,1fr) 278px;gap:22px;align-items:start}.lab-primary{display:grid;gap:18px;min-width:0}.lab-card,.coach-card,.concept-card{background:var(--surface);border:1px solid var(--line);border-radius:12px;box-shadow:0 3px 15px #223f4c0a}.lab-card{padding:24px 27px}.card-heading{display:flex;gap:10px;align-items:flex-start;margin-bottom:19px}.card-heading h2{font-size:21px;line-height:1.4;margin:0 0 2px}.card-heading p{color:var(--muted);font-size:13px;margin:0}.step-badge{width:30px;height:30px;margin-top:2px}.success-badge{background:#e6f5ed;color:#178054}
.reaction-picker{display:grid;gap:6px;max-width:440px;font-weight:700;font-size:13px}.reaction-picker select{height:44px;padding:8px 11px;background:#f9fcfd;border-color:#b9cbd2;border-radius:7px;font-size:15px}.scenario-description{color:var(--muted);margin:14px 0 0}.safety-note{background:#fff7e8;border-right:3px solid #c08b2f;color:#684e1f;padding:7px 11px;font-size:12px;margin:13px 0 0}
.catalog-controls{display:grid;grid-template-columns:minmax(0,1fr) 170px;gap:10px;margin-bottom:8px}.catalog-controls label{display:grid;gap:5px;font-weight:700;font-size:12px}.catalog-controls input,.catalog-controls select{width:100%;height:42px;padding:7px 10px;border:1px solid #b9cbd2;border-radius:7px;background:#f9fcfd;font:inherit;font-size:14px}.catalog-count{font-size:12px;color:var(--muted);margin:4px 0 9px}.reaction-catalog{display:grid;grid-template-columns:repeat(auto-fill,minmax(230px,1fr));gap:8px;max-height:325px;overflow:auto;padding:2px 2px 10px;margin-bottom:16px}.catalog-item{display:grid;gap:5px;min-width:0;padding:10px 12px;text-align:right;border:1px solid var(--line);border-radius:8px;background:#fbfdfe;color:var(--ink);cursor:pointer}.catalog-item:hover,.catalog-item:focus-visible{border-color:var(--accent);background:var(--soft)}.catalog-item.selected{border-color:var(--accent);box-shadow:inset 0 0 0 1px var(--accent)}.catalog-item-head{display:flex;justify-content:space-between;align-items:start;gap:5px}.catalog-item-head strong{font-size:13px;line-height:1.5}.catalog-item-head span{flex:none;color:var(--accent-dark);background:#e8f3f8;border-radius:4px;padding:1px 5px;font-size:10px}.catalog-equation{display:block;overflow-wrap:anywhere;text-align:left;font:13px/1.6 Arial,sans-serif;color:#355562}.catalog-equation sub{font-size:.7em}.catalog-item small,.scenario-source{color:var(--muted);font-size:11px}.catalog-empty{grid-column:1/-1;margin:8px 0;color:var(--muted)}.scenario-source{margin:12px 0 0}.scenario-source a{font-weight:700}
.equation{display:flex;align-items:center;justify-content:center;flex-wrap:wrap;gap:10px;min-height:95px;padding:16px;background:#f5fafc;border:1px solid #dae9ee;border-radius:10px}.eq-group{display:flex;align-items:center;justify-content:center;flex-wrap:wrap;gap:10px}.eq-species{display:flex;align-items:center;gap:8px;white-space:nowrap}.eq-species label{display:grid;gap:3px;text-align:center;font-size:10px;color:var(--muted);font-family:IRANSansX,Tahoma,sans-serif}.eq-species input{width:50px;height:43px;text-align:center;direction:ltr;font:700 20px Arial,sans-serif;border:1px solid #9eb9c6;border-radius:6px;background:#fff;color:var(--accent-dark)}.eq-species input:focus{border-color:var(--accent)}.eq-formula{font:700 clamp(19px,2.3vw,27px)/1.2 Arial,sans-serif;direction:ltr;color:#1f3e4e}.eq-formula sub{font-size:.65em}.eq-separator{font:600 21px Arial,sans-serif;color:#8da6b1}.eq-arrow{font:700 30px Arial,sans-serif;color:var(--accent);padding:0 7px}.balance-actions{display:flex;gap:9px;flex-wrap:wrap;margin-top:17px}.primary-button{background:var(--accent);border-color:var(--accent);color:#fff;font-weight:700;border-radius:7px;padding:9px 17px;min-height:42px}.primary-button:hover{background:var(--accent-dark)}.quiet-button{border-color:#b5cad3;color:var(--accent-dark);font-weight:650;border-radius:7px;padding:8px 13px;min-height:42px}.inline-status{margin:11px 0 0;font-size:13px;color:var(--ink)}.inline-status.muted{color:var(--muted)}.inline-status.good{color:#08744b}.inline-status.bad{color:#a53634}
.atom-ledger{margin-top:17px;border-top:1px solid var(--line);padding-top:13px}.atom-ledger h3{font-size:13px;margin:0 0 8px}.atom-row{display:grid;grid-template-columns:65px 1fr 1fr;gap:8px;align-items:center;padding:5px 0;border-bottom:1px solid #edf2f3;font-size:12px}.atom-row:first-child{color:var(--muted);font-size:11px}.atom-row b{font:700 14px Arial,sans-serif;direction:ltr}.atom-row span{font-variant-numeric:tabular-nums}.atom-row .mismatch{color:#aa3e3a;font-weight:700}.atom-row .match{color:#187c55}
.lab-card fieldset{border:0;padding:0;margin:0;min-width:0}.lab-card fieldset:disabled{opacity:.56}.amount-inputs{display:grid;grid-template-columns:repeat(auto-fit,minmax(210px,1fr));gap:12px}.amount-entry{display:grid;gap:7px;border:1px solid var(--line);background:#fafcfd;border-radius:8px;padding:12px}.amount-entry>span{font-size:14px;font-weight:700}.amount-entry .compound-symbol{font:700 18px Arial,sans-serif;direction:ltr;display:inline-block;margin-right:4px}.amount-entry .compound-symbol sub{font-size:.68em}.amount-controls{display:flex;gap:7px}.amount-controls input{min-width:0;width:100%;direction:ltr;text-align:center;border-radius:6px}.amount-controls select{width:68px;border-radius:6px}.amount-entry small{color:var(--muted);font-size:11px}
.prediction{margin-top:18px;border-top:1px solid var(--line);padding-top:16px}.prediction h3{font-size:16px;margin:0 0 2px}.prediction p{margin:0 0 10px;color:var(--muted);font-size:13px}.prediction-options{display:flex;gap:8px;flex-wrap:wrap}.prediction-options label{display:flex;align-items:center;gap:6px;border:1px solid #b9ccd5;border-radius:7px;padding:8px 12px;cursor:pointer}.prediction-options label:has(input:checked){border-color:var(--accent);background:var(--soft);color:var(--accent-dark)}.calculate-button{margin-top:18px}
.lab-aside{display:grid;gap:14px;position:sticky;top:18px}.coach-card,.concept-card{padding:22px}.coach-card h2{margin:0 0 8px;font-size:20px;line-height:1.45}.coach-card>p:not(.eyebrow),.concept-card p{margin:0 0 14px;color:var(--muted);font-size:13px}.hint-text{background:#f0f7fb;border-right:3px solid var(--accent);padding:9px 11px;margin:15px 0 0!important;color:var(--ink)!important}.concept-card h3{font-size:16px;margin:0 0 9px}.concept-formula{font:700 15px/1.5 Arial,sans-serif;color:var(--accent-dark);padding:12px 8px;background:#f4f8fa;text-align:center;border-radius:6px}.concept-card .concept-footnote{margin:12px 0 0;font-size:11px}.back-table{font-size:12px;font-weight:650;padding:4px 2px}
.prediction-feedback{border-radius:7px;background:#f0f7fb;padding:10px 13px;margin-bottom:16px;font-size:13px}.prediction-feedback.correct{background:#e9f7ee;color:#116d46}.prediction-feedback.incorrect{background:#fff5eb;color:#83531d}.outcome{background:#eaf5f0;border:1px solid #b9dec9;border-radius:9px;padding:16px}.outcome h3{margin:0 0 5px;font-size:18px;color:#126842}.outcome p{margin:0}.reaction-bars{display:grid;gap:12px;margin:19px 0}.bar-card{display:grid;grid-template-columns:115px 1fr 90px;gap:10px;align-items:center;font-size:12px}.bar-card strong{font:700 15px Arial,sans-serif;direction:ltr}.bar-track{height:20px;background:#e6edf0;border-radius:4px;overflow:hidden;display:flex;direction:ltr}.bar-used{height:100%;background:#2a82b6}.bar-left{height:100%;background:#b9cbd1}.bar-card .bar-numbers{direction:ltr;text-align:left;font:12px Arial,sans-serif}.bar-legend{display:flex;gap:15px;flex-wrap:wrap;font-size:11px;color:var(--muted)}.bar-legend i{display:inline-block;width:11px;height:11px;border-radius:2px;margin-left:4px}.bar-legend .used{background:#2a82b6}.bar-legend .left{background:#b9cbd1}
.worked-solution{border-top:1px solid var(--line);padding-top:16px}.worked-solution h3{font-size:16px;margin:0 0 9px}.worked-solution ol{margin:0 0 13px;padding-right:23px}.worked-solution li{margin:5px 0;font-size:13px}.worked-solution table{width:100%;border-collapse:collapse;margin-top:12px;font-size:12px}.worked-solution th,.worked-solution td{padding:8px 7px;border-bottom:1px solid var(--line);text-align:right}.worked-solution th{background:#f4f8fa}.worked-solution td.num{direction:ltr;text-align:right;font-family:Arial,sans-serif}.worked-solution .science-note{font-size:11px;color:var(--muted);margin:12px 0 0}
.example-note{margin-top:15px;padding:9px 12px;border:1px solid var(--line);border-radius:7px;background:#f9fcfd;font-size:12px}.example-note summary{cursor:pointer;font-weight:700}.example-note p{margin:8px 0 0;color:var(--muted)}
.lab-footer{display:flex;justify-content:space-between;gap:15px;padding:17px max(20px,calc((100vw - 1220px)/2));border-top:1px solid var(--line);color:var(--muted);font-size:11px;background:#fff}
@media(max-width:850px){.lab-grid{grid-template-columns:1fr}.lab-aside{position:static;grid-template-columns:repeat(2,minmax(0,1fr))}.back-table{grid-column:1/-1}}
@media(max-width:600px){.lab-header{padding:9px 14px;flex-wrap:wrap;gap:6px}.lab-brand{font-size:14px}.lab-brand .brand-icon{width:29px;height:32px;font-size:21px}.lab-header nav{width:100%}.lab-header nav a{padding:5px 10px;font-size:12px}.lab-shell{padding:20px 12px 45px}.lab-intro{padding-bottom:15px}.lab-intro h1{font-size:26px}.lab-intro p:last-child{font-size:13px}.intro-mark{display:none}.lab-steps{gap:5px;margin-bottom:13px}.lab-card{padding:17px 14px}.card-heading h2{font-size:18px}.card-heading p{font-size:12px}.catalog-controls{grid-template-columns:1fr}.reaction-catalog{grid-template-columns:1fr;max-height:290px}.equation{gap:5px;padding:12px 5px}.eq-group,.eq-species{gap:5px}.eq-species input{width:40px;height:39px;font-size:17px}.eq-formula{font-size:20px}.eq-arrow{padding:0;font-size:25px}.lab-aside{grid-template-columns:1fr}.lab-footer{display:grid;padding:15px 12px}.bar-card{grid-template-columns:70px 1fr 64px;gap:5px}.worked-solution{overflow-x:auto}}
@media(prefers-reduced-motion:reduce){.reaction-lab *{scroll-behavior:auto!important;transition:none!important}}