/* Tesseract Lab / Mercury, additive v18 styles, preserve v17.1 */
.hg-lesson{--hg-ink:#1a4f73;--hg-accent:#2585b5;--hg-line:#d4e6f0;--hg-faint:#f2f9fd;--hg-muted:#68889c;color:#345c75;font-size:13.5px;line-height:1.72;min-width:0}
.hg-lesson h3{color:#194f72;margin:5px 0 11px;font-size:19px;line-height:1.45}.hg-lesson h4{color:#1d597e;margin:6px 0 10px;font-size:16px}.hg-lesson p{line-height:1.8}
.hg-lesson button{cursor:pointer}.hg-lesson img{max-width:100%}.hg-lesson .button{font-size:12px;white-space:normal;text-align:center}
.hg-lesson .source-lesson{font-size:13px;line-height:1.8}.hg-lesson .source-lesson table{display:block;max-width:100%;overflow:auto;border-collapse:collapse;margin:15px 0;font-size:12px}.hg-lesson .source-lesson th,.hg-lesson .source-lesson td{padding:9px 11px;border:1px solid #d4e6f0}.hg-lesson .source-lesson th{background:#eaf6fc}
.hg-source,.hg-step-source{border-radius:12px;background:#f8fcfe;border:1px solid var(--hg-line);margin:23px 0}.hg-source summary,.hg-step-source summary{padding:13px 17px;cursor:pointer;color:#216c95;font-weight:750;font-size:12.5px}.hg-source[open] summary,.hg-step-source[open] summary{border-bottom:1px solid var(--hg-line)}.hg-source-inner,.hg-step-source>div{padding:15px 18px}.hg-source-inner{padding:10px 4px}
.hg-source-inner .hg-formula{padding:12px 15px;border:1px solid #d4e7f2;border-radius:10px;background:#eff7fc;color:#125a80;font-weight:750;text-align:center;margin:11px 0;overflow-wrap:anywhere}
.hg-eyebrow{font-size:10.5px;font-weight:850;letter-spacing:1.5px;color:#3795c6;margin-bottom:6px}.hg-intro{background:#eff8fd;padding:16px 19px;border-left:3px solid #53a5ca;border-radius:8px;margin:7px 0 19px;line-height:1.8;color:#365e77;font-size:13px}
.hg-hero{background:linear-gradient(130deg,#eaf6fd,#ffffff 75%);border-radius:18px;border:1px solid var(--hg-line);padding:25px 27px;overflow:hidden;position:relative}.hg-hero h3{font-size:22px;max-width:580px}.hg-hero p{max-width:550px;font-size:14px}.hg-hero img{display:block;max-height:245px;max-width:500px;width:100%;object-fit:contain;margin:20px auto 0;mix-blend-mode:multiply}
.hg-hero-tags{display:flex;gap:7px;flex-wrap:wrap}.hg-hero-tags span{font-size:11px;color:#2d81af;background:#fff;border:1px solid #d8e7f0;padding:5px 10px;border-radius:20px;font-weight:750}
.hg-equipment-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:15px;margin:19px 0}.hg-equipment{border:1px solid var(--hg-line);border-radius:15px;background:#fff;overflow:hidden;min-width:0;box-shadow:0 5px 15px #9dcfe21c}.hg-equipment-image{height:210px;display:grid;place-items:center;background:#fff;border-bottom:1px solid #e4eef5;padding:13px}.hg-equipment-image img{width:100%;height:100%;object-fit:contain}.hg-equipment .hg-eq-content{padding:16px 19px}.hg-eq-content small{color:#3686b2;font-weight:850;letter-spacing:.85px;font-size:10px}.hg-eq-content h3{font-size:15px;margin:6px 0 10px}.hg-eq-content p{font-size:12px;line-height:1.7}.hg-eq-foot{font-size:11.4px;color:#7a643b;border-left:3px solid #ddb56c;background:#fffaf0;border-radius:6px;padding:8px 12px}
.hg-tip{background:#ecf6fc;border:1px solid #d5e8f1;border-radius:10px;padding:12px 14px;color:#4b7188;font-size:12px;line-height:1.75;margin:13px 0}.hg-small{color:#7891a4;font-size:11.5px!important;line-height:1.8}.hg-feedback{margin:12px 0;padding:12px 15px;border-radius:9px;font-size:12.5px;line-height:1.7}.hg-feedback.good{background:#eaf8f0;color:#276b50;border-left:3px solid #62ac8b}.hg-feedback.bad{background:#fff4ec;color:#985a35;border-left:3px solid #dc9465}
.hg-theory-top{background:linear-gradient(120deg,#edf7fd,#fff);border:1px solid var(--hg-line);border-radius:15px;padding:21px 24px;margin-bottom:13px}.hg-theory-top h3{font-size:23px}.hg-theory-top p{max-width:800px;margin:5px 0;color:#4a7189}
.hg-bl-card{border:1px solid #cee6f2;background:#fff;border-radius:19px;padding:22px;margin:16px 0 22px;box-shadow:0 9px 25px #bad9e929}.hg-bl-heading{display:flex;justify-content:space-between;flex-wrap:wrap;gap:8px;align-items:center}.hg-bl-heading strong{font-size:12.5px;letter-spacing:.6px;color:#1b658d}.hg-bl-heading span{font-size:11px;color:#7795a7}.hg-bl-visual{background:#f6fbfe;border-radius:13px;margin:17px 0 18px;overflow:hidden}.hg-bl-visual svg{width:100%;height:auto;display:block}.hg-photons{animation:hgLight 1.3s linear infinite}@keyframes hgLight{to{stroke-dashoffset:-56}}
.hg-bl-controls{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:13px}.hg-bl-controls label{border:1px solid #e1edf4;background:#f9fcfe;border-radius:10px;padding:12px 13px;font-size:12px;color:#537a91;min-width:0}.hg-bl-controls label span{display:flex;gap:6px;justify-content:space-between}.hg-bl-controls b{color:#267aa5}.hg-bl-controls input,.hg-form-label input[type=range]{display:block;width:100%;margin-top:12px;accent-color:#2c93bf;cursor:pointer}.hg-bl-readouts{display:grid;grid-template-columns:repeat(3,1fr);gap:9px;margin:15px 0}.hg-bl-readouts>div,.hg-mini-stats>div{padding:13px;background:#f1f8fd;border:1px solid #d9e9f2;border-radius:11px;min-width:0}.hg-bl-readouts small,.hg-mini-stats small{display:block;color:#7390a2;font-size:10.5px}.hg-bl-readouts b,.hg-mini-stats b{display:block;font-size:20px;color:#1c648b;font-variant-numeric:tabular-nums;overflow-wrap:anywhere}.hg-bl-card .hg-eq{font-size:16px}.hg-caution{color:#688196;font-size:11.8px!important;margin:16px 0 0}.hg-theory-recap{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:10px;margin:14px 0 20px}.hg-theory-recap>div{padding:15px;border:1px solid #dceaf2;border-radius:12px;background:#f8fcfe}.hg-theory-recap b{color:#276d91;font-size:13px}.hg-theory-recap p{font-size:12px;margin:7px 0 0}
.hg-procedure{display:grid;grid-template-columns:minmax(185px,28%) minmax(0,1fr);gap:14px;margin:13px 0}.hg-step-index{align-self:start;border-radius:15px;border:1px solid #d8e8f0;background:#f8fcfe;padding:8px;max-height:670px;overflow-y:auto;position:sticky;top:14px}.hg-step-index button{display:flex;align-items:flex-start;gap:9px;text-align:left;background:transparent;border:1px solid transparent;padding:11px 10px;border-radius:9px;width:100%;color:#55798f;line-height:1.42;font-size:11.5px}.hg-step-index button:hover{background:#ebf5fb}.hg-step-index button.sel{background:#e3f3fb;color:#135e88;border-color:#b5dced}.hg-step-index button b{font-weight:720}.hg-step-index button span{display:block;flex:none;font-size:10px;background:#e9f3f8;border-radius:7px;padding:4px 5px;color:#518cad;font-weight:900}.hg-step-index button.sel span{color:#fff;background:#2e85b4}.hg-step-detail{border-radius:16px;background:#fff;border:1px solid var(--hg-line);padding:17px 19px;min-width:0}.hg-step-top{border-bottom:1px solid #e3eef4;padding:4px 0 12px;margin-bottom:14px}.hg-step-top span{font-size:10px;color:#4a95b8;letter-spacing:1px;font-weight:800}.hg-step-top h3{font-size:17px;margin:5px 0}.hg-step-source{margin:18px 0}.hg-step-buttons,.hg-phase-navigation{display:flex;flex-wrap:wrap;gap:8px;justify-content:space-between;margin:15px 0 0}
.hg-sample-pair{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:12px}.hg-sample{border:1px solid #dceaf2;border-radius:13px;padding:18px 15px;background:#f9fcfe;min-width:0}.hg-sample.yes{border-top:3px solid #65ae91}.hg-sample.no{border-top:3px solid #e3a17a}.hg-sample strong{font-size:12px;display:block;margin:12px 0 4px}.hg-sample p{font-size:12px;margin:0}.hg-bottle{height:107px;border:3px solid #8db6c9;background:linear-gradient(#bdd8e6,#fafcfe);border-radius:20px 20px 15px 15px;display:grid;place-items:center;max-width:137px;margin:auto;box-shadow:inset 0 8px 0 #4d718e;color:#235273;font-weight:900;font-size:11px}.hg-grains{height:107px;position:relative;border:1px solid #dbe9f1;border-radius:10px;background:#e8f1f7;overflow:hidden}.hg-grains i{position:absolute;display:block;border-radius:40%;background:#263949}.hg-boat-card svg{width:100%;height:auto;display:block;background:#f6fbfe;border-radius:10px}.hg-boat-card p{font-size:12px;line-height:1.7}
.hg-image-strip{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px;margin:12px 0}.hg-image-strip img{width:100%;height:130px;object-fit:contain;border:1px solid #e0edf4;background:#fff;border-radius:11px}.hg-one-image{grid-template-columns:1fr}.hg-one-image img{height:155px}.hg-checklist{display:grid;gap:8px}.hg-checklist label,.hg-check-single{display:flex;gap:10px;align-items:flex-start;background:#f7fbfe;border:1px solid #dceaf1;border-radius:9px;padding:10px 12px;cursor:pointer;font-size:12px;line-height:1.7}.hg-checklist input,.hg-check-single input{flex:none;margin:5px 0 0;accent-color:#237dab}
.hg-sim{border:1px solid #d8e8f2;background:#fafdff;padding:17px 19px;border-radius:13px;line-height:1.8}.hg-sim h4{margin:3px 0 9px}.hg-sim p{font-size:12.5px;margin:8px 0 12px}.hg-sim-head{display:flex;flex-wrap:wrap;justify-content:space-between;align-items:center;gap:8px}.hg-sim-head span{font-size:11px;color:#7892a0}.hg-sim button{margin:3px 2px 3px 0}.hg-tabs,.hg-q-row{display:flex;gap:7px;align-items:center;flex-wrap:wrap;margin:13px 0}.hg-q-row>span{font-size:12px;color:#5b7a90}.hg-blank-bars{height:196px;display:flex;align-items:flex-end;justify-content:space-around;gap:5px;border-bottom:2px solid #b7cfdc;margin:14px 0 18px;padding:3px 5px 0}.hg-blank-bars>div{min-width:0;flex:1;display:flex;flex-direction:column;align-items:center;gap:3px}.hg-blank-bar{width:70%;max-width:38px;border-radius:7px 7px 0 0;min-height:8px}.hg-blank-bars b{font-size:10px;color:#41738c;font-variant-numeric:tabular-nums;white-space:nowrap}.hg-blank-bars small{font-size:10px;color:#7895a7}
.hg-mini-stats{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:8px;margin:14px 0}.hg-mini-stats>div{padding:10px}.hg-mini-stats b{font-size:15px;line-height:1.45}.hg-eq{border:1px dashed #a6d2e9;background:#f4faff;border-radius:10px;padding:13px 17px;text-align:center;color:#185d84;font-weight:750;margin:14px 0;line-height:1.75;overflow-wrap:anywhere}
.hg-balance-readout{padding:22px;text-align:center;background:linear-gradient(120deg,#eaf6fd,#f9fdff);border:1px solid #d0e9f4;border-radius:11px;margin:12px 0}.hg-balance-readout span{font-size:10px;color:#648da6;display:block;letter-spacing:1px}.hg-balance-readout strong{display:block;font-size:30px;color:#21688c;letter-spacing:1px;margin:4px 0}.hg-balance-readout small{font-size:12px;color:#5d8aa3}
.hg-form-label{display:block;margin:13px 0;color:#406d84;font-size:12px;font-weight:700}.hg-form-label b{color:#1b73a3;float:right}.hg-form-label>input[type=number],.hg-form-label>select{display:block;width:100%;margin:6px 0 0;padding:10px;border:1px solid #bfd8e7;border-radius:9px;color:#235672;font:inherit;background:#fff}.hg-soft-header{padding:14px 17px;background:#1b5b81;color:#fff;font-weight:800;border-radius:11px;display:flex;justify-content:space-between;gap:6px;flex-wrap:wrap}.hg-soft-header span{font-size:10px;color:#bee9fb}.hg-soft-grid,.hg-two-input{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:12px}.hg-soft-grid label,.hg-two-input label{font-size:12px;font-weight:700;color:#426a85}.hg-soft-grid input,.hg-two-input input,.hg-practice input{width:100%;display:block;padding:10px 11px;border:1px solid #bfd6e5;border-radius:8px;background:#fff;color:#1c5879;font:inherit;margin:4px 0}.hg-soft-grid small{font-weight:400;color:#8499a7;font-size:10px}
.hg-cinematic{border-radius:17px;overflow:hidden;border:1px solid #c8e1ef;background:linear-gradient(140deg,#f3faff,#fff);padding:17px 18px}.hg-cinema-head{display:flex;justify-content:space-between;align-items:center;gap:6px}.hg-cinema-head>span{border-radius:20px;padding:5px 11px;background:#e1f3fb;color:#337da6;font-weight:900;font-size:12px}.hg-cinema-head h4{margin:0 0 11px}.hg-phase-pills{display:flex;flex-wrap:wrap;gap:6px;margin:14px 0}.hg-phase-pills button{border:1px solid #cbe4f1;background:#fff;color:#34799c;border-radius:8px;font-size:11px;font-weight:750;padding:7px 9px}.hg-phase-pills button.active{background:#1e74a2;border-color:#1e74a2;color:#fff}.hg-gif-stage{background:#0d2742;overflow:hidden;border:1px solid #3a7090;border-radius:12px;box-shadow:0 8px 20px #1e638129}.hg-gif-stage img{display:block;width:100%;height:auto;aspect-ratio:800/410;object-fit:contain}.hg-phase-title small{display:block;color:#388db5;font-size:10px;letter-spacing:1px;font-weight:900;margin-top:18px}.hg-phase-title h4{font-size:17px;margin:5px 0}.hg-phase-copy{font-size:13px!important;line-height:1.8!important;margin:8px 0}.hg-atomic-detail{border:1px solid #cadeeb;border-radius:10px;background:#f7fcff;margin:15px 0}.hg-atomic-detail summary{cursor:pointer;padding:13px;color:#287aa4;font-weight:850}.hg-atomic-detail p{padding:0 14px 13px;margin:0;font-size:12px}.hg-cinematic .hg-small{margin:17px 0 4px}
.hg-order-list{display:grid;gap:7px;margin:17px 0}.hg-order-list>div{display:flex;gap:9px;align-items:center;border:1px solid #dbe9f2;border-radius:10px;background:#fff;padding:9px}.hg-order-num{display:grid;place-items:center;min-width:26px;height:26px;border-radius:7px;background:#e5f3fb;color:#287eab;font-size:12px;font-weight:850}.hg-order-list>div>span:nth-child(2){flex:1;font-size:12px}.hg-order-actions{display:flex;gap:3px}.hg-order-actions button{border:1px solid #d6e7ef;border-radius:7px;padding:5px 9px;font-size:15px;color:#247ba7;background:#f4fbfe}.hg-order-actions button:disabled{opacity:.35}
.hg-calc-section,.hg-qa-card{border:1px solid #d6e9f2;border-radius:16px;padding:20px 22px;background:#fff;margin:18px 0 22px}.hg-calc-section h3,.hg-qa-card h3{font-size:19px!important}.hg-calc-section>p,.hg-qa-card>p{color:#56768a;font-size:12.5px;line-height:1.8}.hg-calc-grid{display:grid;grid-template-columns:1.1fr .9fr;align-items:center;gap:16px;margin:20px 0 12px}.hg-calc-result{border:1px solid #cee5f2;border-radius:15px;background:linear-gradient(140deg,#e8f5fc,#f7fcff);padding:27px 13px;text-align:center}.hg-calc-result small{color:#538bb1;font-weight:750;display:block}.hg-calc-result strong{display:block;font-size:29px;color:#176590;letter-spacing:-.5px;line-height:1.7;font-variant-numeric:tabular-nums}.hg-calc-result>span{font-size:11px;color:#688ba5}.hg-practice{background:#f4faff;border:1px solid #dcebf4;border-radius:12px;padding:15px;margin-top:19px;font-size:12px}.hg-practice input{width:160px;display:inline-block;margin:5px}.hg-practice .button{display:inline-block;margin:4px}.hg-practice .hg-feedback{margin-bottom:0}
.hg-formulas-two{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:8px}.hg-two-input{margin:15px 0}.hg-qa-card .hg-eq{margin:0}.hg-three-input{grid-template-columns:repeat(3,minmax(0,1fr))}.hg-crm-chart{background:#fafdff;border:1px solid #dceaf3;border-radius:12px;overflow:hidden}.hg-crm-chart svg,.hg-lod-plot svg{display:block;width:100%;height:auto}.hg-lod-plot{border:1px solid #dcecf4;border-radius:13px;overflow:hidden;margin:15px 0}.hg-decision-tree{padding:14px;text-align:center;font-weight:800;font-size:12px;background:#eef7fc;color:#20658e;border:1px dashed #b5d9eb;border-radius:10px}.hg-qa-card select{margin:6px 0 10px;padding:10px;background:#fff;color:#245c7c;width:100%;border:1px solid #cbdfea;border-radius:9px}
.hg-safety-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:12px}.hg-safety-grid>div{border:1px solid #dce9f2;border-radius:13px;padding:18px;background:#f8fcfe}.hg-safety-grid strong{font-size:15px;color:#296888}.hg-safety-grid p{font-size:12px;margin-bottom:0}.hg-summary{border:1px solid #d7e9f3;border-radius:16px;padding:21px;background:#f7fcff}.hg-summary-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:11px}.hg-summary-grid>div{background:#fff;border:1px solid #dceaf1;border-radius:9px;padding:12px;display:flex;align-items:flex-start;gap:9px;font-size:12px;line-height:1.7}.hg-summary-grid span{background:#e7f4fc;color:#297da6;border-radius:7px;font-weight:900;font-size:11px;padding:4px 7px}.hg-exam-placeholder{border:1px dashed #bddbea;border-radius:16px;padding:50px 28px;text-align:center;background:#f6fbff}.hg-exam-placeholder h3{margin-top:9px}.hg-exam-placeholder p{font-size:13px;max-width:550px;margin:10px auto 25px}
@media(max-width:1190px){.hg-procedure{grid-template-columns:1fr}.hg-step-index{position:relative;top:0;max-height:195px;display:grid;grid-template-columns:repeat(3,1fr);gap:4px;overflow:auto}.hg-step-index button{padding:7px;font-size:10.5px}}
@media(max-width:760px){.hg-equipment-grid,.hg-theory-recap,.hg-bl-controls,.hg-three-input,.hg-safety-grid{grid-template-columns:1fr}.hg-step-index{grid-template-columns:repeat(2,1fr)}.hg-calc-grid{grid-template-columns:1fr}.hg-bl-readouts{grid-template-columns:repeat(3,minmax(0,1fr))}.hg-bl-readouts b{font-size:14px}.hg-summary-grid,.hg-formulas-two{grid-template-columns:1fr}.hg-calc-section,.hg-qa-card,.hg-bl-card{padding:15px}.hg-soft-grid{grid-template-columns:1fr}.hg-equipment-image{height:190px}}
@media(max-width:490px){.hg-sample-pair,.hg-two-input,.hg-image-strip,.hg-summary-grid{grid-template-columns:1fr}.hg-step-index{grid-template-columns:1fr 1fr}.hg-step-detail{padding:12px}.hg-mini-stats{grid-template-columns:1fr}.hg-blank-bars b{font-size:9px}.hg-phase-pills{gap:4px}.hg-phase-pills button{font-size:10px;padding:6px 7px}.hg-hero{padding:16px}.hg-equipment-image{height:160px}.hg-lesson .lesson-body{padding:15px}}
/* Keep the supplied tall analytical balance and wide O₂ photograph inside their cards. */
.hg-equipment-image{overflow:hidden;min-width:0;min-height:0;grid-template-rows:minmax(0,1fr)}
.hg-equipment-image img{display:block;width:100%;height:100%;max-height:100%;max-width:100%;min-height:0;object-fit:contain;object-position:center}

/* Stacked measurement formulae. */
.hg-fraction{display:inline-flex;flex-direction:column;vertical-align:middle;text-align:center;line-height:1.45;margin:0 .3em}.hg-fraction>span{padding:.1em .4em}.hg-fraction>span+span{border-top:1px solid currentColor}