.ep-hero-grid{display:grid;grid-template-columns:minmax(0,1.15fr) minmax(320px,.85fr);gap:46px;align-items:center}.ep-series-mini{border:1px solid #c9d8d4;border-radius:18px;background:#fff;box-shadow:0 8px 28px rgba(16,43,63,.06);overflow:hidden}.ep-series-mini>div:not(.ep-series-cap){display:flex;justify-content:space-between;gap:18px;align-items:center;padding:11px 16px;border-bottom:1px solid #e0e7e5}.ep-series-mini strong{color:var(--navy);font-size:.91rem}.ep-series-mini span{font-variant-numeric:tabular-nums;color:var(--teal2);font-weight:800}.ep-series-cap{padding:8px 16px;background:#e7f2ee;color:#45616a;font-size:.72rem;font-weight:800;text-transform:uppercase;letter-spacing:.06em}.ep-series-cap.bottom{text-align:right;background:#f4f7f6}.ep-route-list{display:grid;gap:12px}.ep-route-row{display:grid;grid-template-columns:auto 1fr auto;gap:18px;align-items:center;padding:19px 20px;border:1px solid #ccd9d6;border-radius:15px;background:#fff;text-decoration:none;color:var(--ink);transition:.18s transform,.18s box-shadow,.18s border-color}.ep-route-row:hover{transform:translateY(-2px);box-shadow:var(--shadow);border-color:#9cbab2;color:var(--ink)}.ep-route-row.is-primary{border-color:#a9c8bf;background:linear-gradient(90deg,#f7fbf9,#fff)}.ep-route-number{display:grid;place-items:center;width:39px;height:39px;border-radius:50%;background:#e9f3ef;color:var(--teal2);font-weight:900}.ep-route-row>span:nth-child(2){display:grid;gap:4px}.ep-route-row strong{font-family:Georgia,"Times New Roman",serif;color:var(--navy);font-size:1.16rem}.ep-route-row small{color:var(--muted);line-height:1.42}.ep-route-row b{color:var(--teal2);font-size:.88rem}.ep-convention-grid{display:grid;grid-template-columns:1fr 1fr;gap:46px;align-items:center}.ep-two-directions{display:grid;gap:12px}.ep-two-directions>div{display:grid;gap:7px;padding:18px 20px;border:1px solid #c9d8d4;border-radius:14px;background:#fff}.ep-two-directions small,.ep-exam-safe span,.ep-language-compare span{font-size:.7rem;font-weight:900;text-transform:uppercase;letter-spacing:.06em;color:#5a7179}.ep-two-directions strong{font-family:Georgia,"Times New Roman",serif;color:var(--navy);font-size:1.1rem}.ep-two-directions span{color:var(--muted);font-size:.84rem;line-height:1.4}.ep-language-compare{display:grid;grid-template-columns:1fr 1fr;gap:14px}.ep-language-compare>div{padding:19px 20px;border-radius:14px;border:1px solid #d0d9d7}.ep-language-compare .is-weak{background:#fbf7f4;border-color:#e4d7ce}.ep-language-compare .is-strong{background:#f1f8f5;border-color:#bcd7ce}.ep-language-compare p{margin:.5rem 0 0;line-height:1.5}.ep-trap-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:0;border-top:1px solid #d6dfdc}.ep-trap-grid span{padding:14px 16px 14px 32px;border-bottom:1px solid #d6dfdc;position:relative}.ep-trap-grid span:before{content:'×';position:absolute;left:8px;top:12px;color:#a95c46;font-weight:900}.ep-breadcrumb{display:flex;gap:8px;align-items:center;margin-bottom:17px;font-size:.86rem}.ep-breadcrumb a{color:var(--teal2)}.ep-breadcrumb span{color:#87949a}.ep-breadcrumb strong{color:var(--muted)}.ep-hero-skills{display:flex;gap:7px;flex-wrap:wrap;margin-top:18px}.ep-hero-skills span{font-style:normal;border:1px solid #cedbd7;background:#f1f6f4;border-radius:999px;padding:4px 8px;color:#36535c;font-size:.73rem;font-weight:700}
.ep-explorer-shell,.ep-practice-shell{padding-top:52px}.ep-explorer{max-width:1000px;margin:auto;overflow:hidden}.ep-explorer-controls{display:grid;grid-template-columns:1fr 1fr auto;gap:14px;align-items:end;padding:22px 24px;background:#f3f7f5;border-bottom:1px solid var(--line)}.ep-explorer-controls label{display:grid;gap:5px;color:var(--navy);font-size:.82rem;font-weight:800}.ep-explorer-controls select{width:100%;padding:10px;border:1px solid #a8b9b5;border-radius:9px;background:#fff}.ep-explorer-output{padding:24px}.ep-explorer-result-head{display:flex;justify-content:space-between;align-items:center;gap:20px;padding:0 0 16px}.ep-explorer-result-head span{font-size:.75rem;font-weight:800;color:var(--muted)}.ep-explorer-result-head strong{font-size:1.4rem;color:var(--navy)}.ep-explorer-half-grid{display:grid;grid-template-columns:1fr 1fr;gap:14px}.ep-explorer-half-grid article{padding:18px;border-radius:14px;border:1px solid #cbd9d5}.ep-explorer-half-grid .is-reduction{background:#f0f8f5}.ep-explorer-half-grid .is-oxidation{background:#f8f6f2}.ep-explorer-half-grid small{font-size:.7rem;font-weight:900;text-transform:uppercase;letter-spacing:.055em;color:#5b7178}.ep-explorer-half-grid h3{margin:.4rem 0 .7rem;color:var(--navy);font-family:Georgia,"Times New Roman",serif}.ep-explorer-half-grid p{margin:.5rem 0;color:var(--muted)}.ep-chem-line,.ep-overall-equation{overflow-x:auto;padding:13px 15px;border:1px solid #d4ddda;border-radius:10px;background:#fff;color:var(--navy);font-family:Georgia,"Times New Roman",serif;text-align:center}.ep-explorer-working{margin-top:18px;padding:18px 20px;border:1px solid #d5dedb;border-radius:14px;background:#fafcfb}.ep-explorer-working h3{margin-top:0;color:var(--navy);font-family:Georgia,"Times New Roman",serif}.ep-exam-safe{margin-top:15px;padding:15px 17px;border-left:4px solid var(--teal);background:#edf7f3}.ep-exam-safe p{margin:.45rem 0;line-height:1.5}.ep-exam-safe small{color:var(--muted)}.ep-explorer-note,.ep-practice-principle{display:flex;justify-content:space-between;gap:28px;align-items:center}.ep-explorer-note h2,.ep-practice-principle h2{margin-top:0}
.ep-app{max-width:1000px;margin:auto;padding:0;overflow:hidden}.ep-app-header{display:flex;justify-content:space-between;gap:24px;align-items:end;padding:26px 30px 20px;border-bottom:1px solid var(--line);background:#fbfcfa}.ep-app-header h2{font-family:Georgia,"Times New Roman",serif;color:var(--navy);margin:.1em 0 0}.ep-session-summary{display:flex;gap:9px}.ep-session-summary span{min-width:104px;display:grid;text-align:center;border:1px solid #d2dfdc;background:#fff;border-radius:12px;padding:8px 10px}.ep-session-summary strong{font-size:1.3rem;color:var(--navy)}.ep-session-summary small{font-size:.68rem;color:var(--muted)}.ep-toolbar{display:flex;gap:14px;align-items:end;flex-wrap:wrap;padding:18px 30px;background:#f3f7f5;border-bottom:1px solid var(--line)}.ep-toolbar label{display:grid;gap:5px;font-size:.82rem;font-weight:750;color:var(--navy)}.ep-toolbar label small{max-width:22rem;color:var(--muted);font-weight:500;line-height:1.3}.ep-toolbar select{min-width:180px;background:#fff;border:1px solid #a9b8b5;border-radius:9px;padding:8px 10px}.ep-toolbar .button{margin-left:auto}.ep-question-stage{padding:28px 30px 32px}.ep-question-meta{display:flex;gap:7px;flex-wrap:wrap;margin-bottom:15px}.ep-question-meta span{background:#edf3f1;border:1px solid #d2ddda;border-radius:999px;padding:4px 9px;font-size:.74rem;font-weight:750;color:#415862}.ep-question{background:#f7f8f5;border:1px solid #e0e4df;border-radius:15px;padding:22px 24px}.ep-data-table{width:100%;border-collapse:collapse;margin:14px 0;background:#fff}.ep-data-table th,.ep-data-table td{padding:10px 12px;border:1px solid #d6dfdc;text-align:left}.ep-data-table th{background:#edf3f1;color:var(--navy)}.ep-data-table th:last-child,.ep-data-table td:last-child{text-align:right;white-space:nowrap}.ep-question-note{font-size:.84rem;color:var(--muted)}.ep-answer{display:flex;gap:15px;align-items:end;flex-wrap:wrap;margin:22px 0 8px}.ep-answer>#ep-answer-control{flex:1;min-width:260px}.ep-number-answer{display:grid;gap:7px;color:var(--navy);font-weight:750}.ep-number-entry{display:flex;align-items:center;border:1px solid #9eaeaa;border-radius:10px;background:#fff;overflow:hidden;max-width:390px}.ep-number-entry input{width:100%;border:0;padding:11px 12px;outline:0}.ep-number-entry b{padding:0 12px;color:var(--muted);white-space:nowrap}.ep-options{border:0;padding:0;display:grid;gap:9px}.ep-options legend{position:absolute;clip:rect(0 0 0 0);width:1px;height:1px;overflow:hidden}.ep-options label{display:grid;grid-template-columns:auto 1fr;gap:10px;padding:11px 13px;border:1px solid #c8d3d0;border-radius:10px;background:#fff;line-height:1.4}.ep-options input{margin-top:.2rem}.ep-help-row{display:flex;gap:18px;margin-top:8px}.ep-solution h3{font-family:Georgia,"Times New Roman",serif;color:var(--navy)}.ep-working{margin:.6rem 0 1rem;padding-left:1.35rem}.ep-working li{margin:.5rem 0;line-height:1.48}.ep-app-footer{display:flex;justify-content:space-between;gap:18px;border-top:1px solid var(--line);padding:17px 30px;background:#fbfcfa;font-size:.88rem}.ep-app-footer>span{color:var(--muted);margin-left:auto}.ep-app-footer a{color:var(--teal2)}
@media(max-width:900px){.ep-hero-grid,.ep-convention-grid{grid-template-columns:1fr}.ep-explorer-controls{grid-template-columns:1fr 1fr}.ep-explorer-controls .button{grid-column:1/3}.ep-explorer-note,.ep-practice-principle{align-items:flex-start;flex-direction:column}.ep-trap-grid{grid-template-columns:1fr}}
@media(max-width:650px){.ep-route-row{grid-template-columns:auto 1fr}.ep-route-row b{grid-column:2}.ep-language-compare,.ep-explorer-half-grid{grid-template-columns:1fr}.ep-explorer-controls{grid-template-columns:1fr}.ep-explorer-controls .button{grid-column:auto}.ep-app-header{align-items:start;flex-direction:column}.ep-session-summary{width:100%}.ep-session-summary span{flex:1}.ep-toolbar{align-items:stretch;flex-direction:column}.ep-toolbar label,.ep-toolbar select,.ep-toolbar .button{width:100%}.ep-toolbar .button{margin-left:0}.ep-answer{flex-direction:column;align-items:stretch}.ep-answer .button{width:100%}.ep-app-header,.ep-toolbar,.ep-question-stage,.ep-app-footer{padding-left:20px;padding-right:20px}.ep-app-footer{flex-direction:column}.ep-app-footer>span{margin-left:0}.ep-data-table th,.ep-data-table td{padding:8px;font-size:.86rem}}
/* Pass B: physical Cell Lab, standard hydrogen electrode and AQA notation builder. */
.ep-cell-lab-shell,.ep-notation-shell{padding-top:48px}.ep-cell-lab{max-width:1080px;margin:auto;overflow:hidden}.ep-lab-tabs{display:flex;gap:0;border-bottom:1px solid var(--line);background:#f8faf9}.ep-lab-tabs button{flex:1;border:0;border-right:1px solid var(--line);background:transparent;padding:15px 16px;color:#45606a;font-weight:800;cursor:pointer}.ep-lab-tabs button:last-child{border-right:0}.ep-lab-tabs button span{display:block;font-size:.64rem;letter-spacing:.08em;color:#82949a;margin-bottom:3px}.ep-lab-tabs button.is-active{background:#e7f2ee;color:var(--navy);box-shadow:inset 0 -3px 0 var(--teal)}.ep-lab-session{display:flex;align-items:end;gap:12px;padding:15px 22px;background:#f2f6f4;border-bottom:1px solid var(--line)}.ep-lab-session label{display:grid;gap:4px;font-size:.76rem;font-weight:800;color:var(--navy)}.ep-lab-session select{min-width:170px;padding:8px 9px;border:1px solid #abbcb8;border-radius:8px;background:#fff}.ep-lab-session>div{min-width:105px;display:grid;text-align:center;border-left:1px solid #ccd8d5;padding:2px 12px}.ep-lab-session small{color:var(--muted);font-size:.67rem}.ep-lab-session strong{font-size:1.2rem;color:var(--navy)}.ep-lab-session .button{margin-left:auto}.ep-lab-workspace{padding:28px 30px}.ep-lab-heading{display:grid;grid-template-columns:1fr auto;gap:24px;align-items:start;margin-bottom:22px}.ep-lab-heading h2{font-family:Georgia,"Times New Roman",serif;color:var(--navy);margin:.15rem 0 .45rem}.ep-lab-heading p{margin:.25rem 0;color:var(--muted);max-width:48rem}.ep-mini-data{border-collapse:collapse;background:#fff;min-width:255px}.ep-mini-data th,.ep-mini-data td{border:1px solid #d5dfdc;padding:7px 9px;font-size:.8rem;text-align:left}.ep-mini-data th{background:#edf3f1;color:var(--navy)}.ep-mini-data td:last-child{white-space:nowrap;font-variant-numeric:tabular-nums}.ep-cell-visual{position:relative;display:grid;grid-template-columns:1fr 130px 1fr;align-items:end;gap:10px;min-height:260px;margin:16px 0 25px;padding:54px 18px 18px;border:1px solid #cad9d5;border-radius:18px;background:linear-gradient(#fbfdfc,#f2f7f5)}.ep-wire{position:absolute;left:23%;right:23%;top:20px;height:48px;display:grid;grid-template-columns:1fr 52px 1fr;align-items:center}.ep-wire:before,.ep-wire:after{content:'';position:absolute;top:24px;width:3px;height:30px;background:#315565}.ep-wire:before{left:0}.ep-wire:after{right:0}.ep-wire-line{height:3px;background:#315565}.ep-meter{width:52px;height:52px;border:3px solid #315565;border-radius:50%;background:#fff;display:grid;place-items:center;color:var(--navy);font-weight:900;font-family:Georgia,"Times New Roman",serif}.ep-half-cell{position:relative;height:155px;border:3px solid #9eb4af;border-top:0;border-radius:0 0 18px 18px;padding:42px 12px 12px;background:linear-gradient(to top,rgba(197,226,221,.72) 0 72%,transparent 72%)}.ep-half-cell>span{position:absolute;bottom:-25px;left:0;right:0;text-align:center;color:#6f8288;font-size:.7rem}.ep-electrode{position:absolute;top:-17px;left:50%;transform:translateX(-50%);width:46px;height:96px;border:2px solid #687c82;border-radius:4px 4px 0 0;background:#e4e8e7;display:flex;align-items:center;justify-content:center;writing-mode:vertical-rl;font-size:.72rem;font-weight:900;color:#314a54}.ep-electrode.is-pt{background:#d8d9da}.ep-solution{position:absolute;left:8px;right:8px;bottom:16px;display:grid;text-align:center;gap:4px}.ep-solution strong{color:var(--navy);font-family:Georgia,"Times New Roman",serif}.ep-solution small{color:#536b73;font-size:.72rem}.ep-bridge{align-self:center;height:94px;position:relative;margin-bottom:34px}.ep-bridge i{position:absolute;left:5px;right:5px;top:30px;height:62px;border:10px solid #bed1cc;border-bottom:0;border-radius:48px 48px 0 0}.ep-bridge b{position:absolute;left:0;right:0;top:0;text-align:center;color:#60777e;font-size:.69rem}.ep-lab-fields{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:12px 15px;border-top:1px solid #d6e0dd;padding-top:20px}.ep-lab-field{display:grid;gap:5px;color:var(--navy);font-size:.78rem;font-weight:800}.ep-lab-field select{width:100%;padding:9px 10px;border:1px solid #a9b9b5;border-radius:9px;background:#fff;color:var(--ink)}.ep-lab-check-row{display:flex;justify-content:flex-end;margin-top:18px}.ep-lab-help{padding:0 30px 20px}.ep-lab-feedback,.ep-lab-solution{margin:0 30px 22px}.ep-field-feedback{list-style:none;padding:0;margin:.8rem 0 0;display:grid;gap:7px}.ep-field-feedback li{padding-left:20px;position:relative;line-height:1.42}.ep-field-feedback li:before{position:absolute;left:0;font-weight:900}.ep-field-feedback li.is-correct:before{content:'✓';color:#247158}.ep-field-feedback li.is-wrong:before{content:'×';color:#9d503b}.ep-worked-grid{display:grid;grid-template-columns:1fr 1fr;gap:10px 18px}.ep-worked-grid p{margin:0;padding:11px 12px;background:#fff;border:1px solid #d8e1de;border-radius:9px}.ep-lab-footer{display:flex;justify-content:space-between;gap:18px;padding:14px 22px;border-top:1px solid var(--line);background:#fafcfb;color:var(--muted);font-size:.76rem}.ep-lab-footer nav{display:flex;gap:17px}.ep-lab-footer a{color:var(--teal2)}.ep-cell-principles{display:grid;grid-template-columns:1fr 1fr;gap:48px;align-items:start}.ep-principle-list{display:grid;border-top:1px solid #cedbd7}.ep-principle-list p{margin:0;padding:12px 4px;border-bottom:1px solid #cedbd7;line-height:1.45}.ep-she-equation{padding:13px 16px;border:1px solid #c8d9d4;border-radius:11px;background:#fff;font-family:Georgia,"Times New Roman",serif;color:var(--navy);white-space:nowrap}.ep-she-visual{position:relative;width:min(480px,92%);height:225px;margin:18px auto 28px;border:3px solid #9eb4af;border-top:0;border-radius:0 0 24px 24px;background:linear-gradient(to top,rgba(197,226,221,.75) 0 60%,transparent 60%)}.ep-she-electrode{position:absolute;width:52px;height:150px;left:50%;top:-30px;transform:translateX(-50%);border:2px solid #687c82;background:#dedfe0;display:grid;place-items:center;color:#314a54;font-weight:900;writing-mode:vertical-rl}.ep-she-solution{position:absolute;left:0;right:0;bottom:38px;text-align:center;color:var(--navy);font-weight:800}.ep-she-gas{position:absolute;left:24px;top:18px;width:100px;height:112px;border-left:9px solid #c4d1ce}.ep-she-gas span{font-size:.72rem;color:#60777e}.ep-she-gas i{position:absolute;border:2px solid #8eaba5;border-radius:50%;width:10px;height:10px;left:-10px}.ep-she-gas i:nth-of-type(1){top:42px}.ep-she-gas i:nth-of-type(2){top:67px;left:-2px}.ep-she-gas i:nth-of-type(3){top:88px}.ep-she-wire{position:absolute;left:calc(50% + 26px);top:-18px;width:130px;border-top:3px solid #315565;padding-top:5px;color:#60777e;font-size:.7rem}.ep-she-answer{padding:15px 18px;border:1px solid #cbd9d5;border-radius:12px;background:#fff;text-align:center}.ep-she-answer strong{font-family:Georgia,"Times New Roman",serif;color:var(--navy);font-size:1.15rem}.ep-diagnose{max-width:780px;margin:auto}.ep-diagnose h2{font-family:Georgia,"Times New Roman",serif;color:var(--navy)}.ep-diagnose>.button{margin-top:15px}.ep-scope-note{max-width:800px;margin-top:15px;padding:10px 13px;border-left:3px solid var(--teal);background:#edf6f3;font-size:.84rem}.ep-notation-app{max-width:980px;margin:auto;overflow:hidden}.ep-notation-stage{padding:26px 30px 30px}.ep-notation-answer-wrap{margin:20px 0}.ep-notation-label{font-weight:800;color:var(--navy);font-size:.82rem}.ep-notation-answer{min-height:70px;display:flex;align-items:center;justify-content:center;gap:5px;flex-wrap:wrap;padding:13px;border:2px dashed #aebfbb;border-radius:12px;background:#f8fbfa}.ep-notation-placeholder{color:#82949a;font-size:.82rem}.ep-answer-token,.ep-bank-token{border:1px solid #b8c9c4;border-radius:8px;background:#fff;padding:8px 10px;color:var(--navy);font-family:Georgia,"Times New Roman",serif;font-size:.93rem;cursor:pointer}.ep-answer-token{background:#e8f3ef;border-color:#9ebdb5}.ep-token-bank{display:flex;gap:7px;flex-wrap:wrap;padding:13px 0}.ep-bank-token:hover,.ep-answer-token:hover{border-color:var(--teal)}.ep-notation-actions{display:flex;gap:10px;flex-wrap:wrap}.ep-notation-worked{display:flex;gap:5px;flex-wrap:wrap;align-items:center;padding:14px;border:1px solid #ccd9d6;background:#fff;border-radius:10px}.ep-notation-worked span{font-family:Georgia,"Times New Roman",serif;color:var(--navy);font-weight:700}.ep-notation-rules h2{margin-top:0}
@media(max-width:780px){.ep-lab-tabs{display:grid;grid-template-columns:1fr}.ep-lab-tabs button{border-right:0;border-bottom:1px solid var(--line);text-align:left}.ep-lab-session{align-items:stretch;flex-wrap:wrap}.ep-lab-session label{width:100%}.ep-lab-session select{width:100%}.ep-lab-session .button{margin-left:0;width:100%}.ep-lab-heading{grid-template-columns:1fr}.ep-mini-data{width:100%}.ep-cell-visual{grid-template-columns:1fr 72px 1fr;min-height:245px;padding-left:8px;padding-right:8px}.ep-bridge i{border-width:7px}.ep-lab-fields,.ep-cell-principles,.ep-worked-grid{grid-template-columns:1fr}.ep-lab-footer{flex-direction:column}.ep-lab-footer nav{flex-wrap:wrap}.ep-lab-workspace,.ep-notation-stage{padding-left:20px;padding-right:20px}.ep-lab-help{padding-left:20px;padding-right:20px}.ep-lab-feedback,.ep-lab-solution{margin-left:20px;margin-right:20px}}
@media(max-width:520px){.ep-cell-visual{grid-template-columns:minmax(0,1fr) 48px minmax(0,1fr);min-height:225px}.ep-wire{left:20%;right:20%}.ep-half-cell{height:140px;padding-left:5px;padding-right:5px}.ep-solution strong{font-size:.83rem}.ep-solution small{font-size:.62rem}.ep-electrode{width:37px;height:84px;font-size:.64rem}.ep-wire{left:13%;right:13%}.ep-meter{width:44px;height:44px}.ep-wire{grid-template-columns:1fr 44px 1fr}.ep-bridge b{font-size:.58rem}.ep-notation-actions .button{width:100%}.ep-answer-token,.ep-bank-token{font-size:.82rem;padding:7px 8px}}
/* Pass C: non-standard conditions, E versus E°, advanced feasibility and redox reasoning. */
.ep-concentration-shell{padding-top:48px}.ep-concentration-lab{max-width:980px;margin:auto;overflow:hidden}.ep-concentration-lab>header{padding:22px 26px 16px;border-bottom:1px solid var(--line);background:#f8faf9}.ep-concentration-lab>header h2{margin:.2rem 0;font-family:Georgia,"Times New Roman",serif;color:var(--navy)}.ep-concentration-controls{display:flex;gap:14px;align-items:end;padding:17px 26px;background:#eef4f2;border-bottom:1px solid var(--line)}.ep-concentration-controls label{display:grid;gap:5px;flex:1;color:var(--navy);font-size:.78rem;font-weight:800}.ep-concentration-controls select{width:100%;padding:10px 11px;border:1px solid #a9b9b5;border-radius:9px;background:#fff;color:var(--ink)}.ep-concentration-stage{padding:28px 30px}.ep-concentration-equilibrium{display:grid;gap:7px;padding:17px 19px;border:1px solid #c8d8d4;border-radius:13px;background:#fff}.ep-concentration-equilibrium small{color:var(--muted);text-transform:uppercase;letter-spacing:.06em;font-size:.68rem;font-weight:800}.ep-concentration-equilibrium strong{font-family:Georgia,"Times New Roman",serif;color:var(--navy);font-size:1.05rem}.ep-concentration-equilibrium span{color:var(--teal2);font-weight:800}.ep-concentration-change{margin:17px 0;padding:14px 17px;border-left:4px solid var(--warm);background:#fbf6f0}.ep-concentration-change span{display:block;color:#9b593f;font-size:.68rem;font-weight:900;text-transform:uppercase;letter-spacing:.07em}.ep-concentration-change p{margin:.35rem 0 0}.ep-concentration-question h3,.ep-cell-followup h3{color:var(--navy);margin:1.3rem 0 .65rem}.ep-predict-buttons{display:flex;gap:9px;flex-wrap:wrap}.ep-predict-buttons button{border:1px solid #9eb7b1;background:#fff;border-radius:9px;padding:9px 13px;color:var(--navy);font-weight:800;cursor:pointer}.ep-predict-buttons button:hover{border-color:var(--teal);background:#edf6f3}.ep-concentration-stage>.feedback-panel,.ep-cell-followup .feedback-panel{margin-top:13px}.ep-cell-followup{margin-top:22px;padding-top:18px;border-top:1px solid #d3dfdc}.ep-cell-followup p{color:var(--muted)}.ep-concentration-worked{margin-top:18px}.ep-e-vs-e0-note{display:grid;grid-template-columns:1fr auto;gap:34px;align-items:center}.ep-e-vs-e0-note h2{margin:.2rem 0 .55rem;color:var(--navy)}.ep-e-vs-e0-card{display:grid;grid-template-columns:1fr 1fr;gap:10px}.ep-e-vs-e0-card>div{display:grid;gap:5px;padding:20px;border:1px solid #c7d8d4;border-radius:13px;background:#fff}.ep-e-vs-e0-card small{text-transform:uppercase;letter-spacing:.07em;color:var(--muted);font-weight:800}.ep-e-vs-e0-card strong{font-family:Georgia,"Times New Roman",serif;color:var(--teal2);font-size:2rem}.ep-e-vs-e0-card span{color:var(--muted);font-size:.82rem}.ep-window{display:grid;grid-template-columns:1fr 1fr;gap:12px;margin:15px 0}.ep-window>div{display:grid;gap:5px;padding:14px 16px;border:1px solid #ccd9d6;border-radius:11px;background:#fff}.ep-window small{color:var(--muted);font-size:.69rem;text-transform:uppercase;letter-spacing:.06em;font-weight:800}.ep-window strong{color:var(--teal2);font-size:1.25rem}.ep-window span{color:var(--muted);font-size:.77rem}.ep-nonstandard-intro .text-link{display:inline-block;margin-top:.5rem;font-weight:800;color:var(--teal2)}
@media(max-width:780px){.ep-concentration-controls{align-items:stretch;flex-direction:column}.ep-concentration-controls .button{width:100%}.ep-concentration-stage{padding:22px 20px}.ep-e-vs-e0-note{grid-template-columns:1fr}.ep-e-vs-e0-card,.ep-window{grid-template-columns:1fr}.ep-predict-buttons{display:grid;grid-template-columns:1fr}.ep-predict-buttons button{width:100%;text-align:left}}
/* Pass D: commercial/storage/rechargeable/fuel-cell applications. */
.ep-commercial-hero-grid{display:grid;grid-template-columns:minmax(0,1.12fr) minmax(330px,.88fr);gap:42px;align-items:center}.ep-commercial-summary{display:grid;gap:9px}.ep-commercial-summary>div{display:grid;grid-template-columns:120px 1fr;gap:4px 14px;align-items:center;padding:14px 16px;border:1px solid #c8d8d4;border-radius:13px;background:#fff}.ep-commercial-summary strong{grid-row:1/3;color:var(--navy);font-family:Georgia,"Times New Roman",serif}.ep-commercial-summary span{font-weight:800;color:#36535c}.ep-commercial-summary small{color:var(--muted)}.ep-commercial-shell{padding-top:48px}.ep-commercial-app{max-width:1040px;margin:auto;overflow:hidden}.ep-commercial-board label{display:grid;gap:5px;color:var(--navy);font-size:.78rem;font-weight:800}.ep-commercial-board select{min-width:170px;padding:9px 10px;border:1px solid #a8b9b5;border-radius:9px;background:#fff}.ep-commercial-tabs{display:grid;grid-template-columns:repeat(3,1fr);border-bottom:1px solid var(--line);background:#eef4f2}.ep-commercial-tabs button{border:0;border-right:1px solid var(--line);background:transparent;padding:14px 16px;color:#526971;font-weight:800;cursor:pointer}.ep-commercial-tabs button:last-child{border-right:0}.ep-commercial-tabs button.is-active{background:#fff;color:var(--navy);box-shadow:inset 0 -3px 0 var(--teal)}.ep-commercial-stage{padding:28px 30px 32px}.ep-cell-type-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:13px}.ep-cell-type-grid article{padding:19px;border:1px solid #cbd9d5;border-radius:14px;background:#fff}.ep-cell-type-grid article>span{font-size:.68rem;text-transform:uppercase;letter-spacing:.06em;font-weight:900;color:#6a7f85}.ep-cell-type-grid h3{margin:.45rem 0;color:var(--navy);font-family:Georgia,"Times New Roman",serif;font-size:1.05rem}.ep-cell-type-grid p{color:var(--muted);line-height:1.46}.ep-cell-type-grid b{font-size:.78rem;color:var(--teal2)}.ep-commercial-controls{display:flex;align-items:end;gap:15px;padding-bottom:20px;border-bottom:1px solid #d8e1de}.ep-commercial-controls label{display:grid;gap:5px;flex:1;color:var(--navy);font-size:.78rem;font-weight:800}.ep-commercial-controls select{width:100%;padding:10px 11px;border:1px solid #a8b9b5;border-radius:9px;background:#fff}.ep-toggle-pair{display:flex;border:1px solid #a9bbb6;border-radius:10px;overflow:hidden;background:#fff}.ep-toggle-pair button{border:0;border-right:1px solid #c9d6d2;background:#fff;padding:10px 13px;color:#526971;font-weight:800;cursor:pointer}.ep-toggle-pair button:last-child{border-right:0}.ep-toggle-pair button.is-active{background:#e6f2ee;color:var(--navy)}.ep-toggle-pair button:disabled{opacity:.42;cursor:not-allowed}.ep-commercial-cell-head{display:flex;justify-content:space-between;gap:20px;align-items:start;margin:22px 0 16px}.ep-commercial-cell-head h3{font-family:Georgia,"Times New Roman",serif;color:var(--navy);margin:.35rem 0}.ep-commercial-cell-head p{max-width:690px;margin:.35rem 0;color:var(--muted)}.ep-scope-chip{display:inline-block;padding:4px 8px;border:1px solid #c9d8d4;border-radius:999px;background:#f2f6f4;color:#4f666e;font-size:.68rem;font-weight:900;text-transform:uppercase;letter-spacing:.05em}.ep-scope-chip.is-recall{border-color:#d5c09a;background:#fbf3e7;color:#8a5937}.ep-emf-badge{min-width:120px;display:grid;gap:2px;text-align:center;padding:10px 12px;border:1px solid #b9d0c9;border-radius:12px;background:#eef7f4}.ep-emf-badge small{color:var(--muted);font-weight:800}.ep-emf-badge strong{color:var(--teal2);font-size:1.25rem}.ep-commercial-equations{display:grid;grid-template-columns:1fr 1fr;gap:12px}.ep-commercial-equations>div{display:grid;gap:7px;padding:16px;border:1px solid #cbd9d5;border-radius:12px;background:#fff}.ep-commercial-equations small,.ep-overall-commercial small{color:var(--muted);font-size:.68rem;font-weight:900;text-transform:uppercase;letter-spacing:.055em}.ep-commercial-equations strong,.ep-overall-commercial strong{font-family:Georgia,"Times New Roman",serif;color:var(--navy);line-height:1.45}.ep-commercial-equations.compact{margin:13px 0}.ep-overall-commercial{display:grid;gap:7px;margin-top:13px;padding:16px 18px;border:1px solid #b9d0c9;border-radius:12px;background:#edf6f3;text-align:center}.ep-commercial-note{color:var(--muted);margin:15px 0 0}.ep-fuel-flow{display:grid;grid-template-columns:1fr minmax(130px,.45fr) 1fr;align-items:stretch;margin:20px 0 14px}.ep-fuel-flow>div:not(.ep-fuel-wire){display:grid;gap:5px;padding:18px;border:1px solid #c8d8d4;border-radius:13px;background:#fff}.ep-fuel-flow small{color:var(--muted);font-size:.68rem;font-weight:900;text-transform:uppercase;letter-spacing:.055em}.ep-fuel-flow strong{color:var(--navy);font-family:Georgia,"Times New Roman",serif}.ep-fuel-flow span{color:var(--muted);font-size:.78rem}.ep-fuel-wire{display:grid;place-items:center;align-content:center;gap:5px;position:relative}.ep-fuel-wire:before{content:'';position:absolute;left:0;right:0;top:50%;border-top:3px solid #315565;z-index:0}.ep-fuel-wire span,.ep-fuel-wire b{position:relative;z-index:1;background:#fff;padding:2px 7px}.ep-fuel-wire span{color:var(--teal2);font-weight:900}.ep-fuel-wire b{font-size:.68rem;color:#60777e}.ep-fuel-flow.is-stopped{opacity:.68}.ep-fuel-flow.is-stopped .ep-fuel-wire:before{border-top-style:dashed}.ep-commercial-scope{display:grid;grid-template-columns:1.15fr .85fr;gap:42px;align-items:start}.ep-commercial-scope h2{margin:.2rem 0;color:var(--navy)}.ep-commercial-rule{padding:20px;border:1px solid #c6d7d2;border-radius:13px;background:#fff}.ep-commercial-rule strong{font-family:Georgia,"Times New Roman",serif;color:var(--navy);font-size:1.1rem}.ep-commercial-rule p{margin:.55rem 0 0;line-height:1.5}.ep-commercial-examiner{display:grid;gap:20px}.ep-commercial-examiner h2{margin:.2rem 0;color:var(--navy)}.ep-commercial-practice .ep-question .ep-overall-commercial{margin:12px 0;background:#fff}.ep-commercial-practice .ep-question .ep-commercial-equations{margin:12px 0}.ep-commercial-practice .ep-question .ep-commercial-equations>div{background:#fff}.ep-commercial-practice .ep-options label span sub,.ep-commercial-practice .ep-options label span sup{line-height:0}.ep-commercial-practice .ep-data-table td:first-child{font-family:Georgia,"Times New Roman",serif}.ep-commercial-practice .ep-data-table th:last-child,.ep-commercial-practice .ep-data-table td:last-child{text-align:center}.ep-commercial-practice .ep-toolbar label:first-child{min-width:300px}
@media(max-width:900px){.ep-commercial-hero-grid,.ep-commercial-scope{grid-template-columns:1fr}.ep-cell-type-grid{grid-template-columns:1fr}.ep-commercial-equations{grid-template-columns:1fr}.ep-fuel-flow{grid-template-columns:1fr}.ep-fuel-wire{min-height:72px}.ep-fuel-wire:before{left:50%;right:auto;top:0;bottom:0;border-top:0;border-left:3px solid #315565}.ep-fuel-wire span{transform:rotate(90deg)}}
@media(max-width:700px){.ep-commercial-tabs{grid-template-columns:1fr}.ep-commercial-tabs button{border-right:0;border-bottom:1px solid var(--line);text-align:left}.ep-commercial-tabs button:last-child{border-bottom:0}.ep-commercial-stage{padding:22px 20px}.ep-commercial-controls{align-items:stretch;flex-direction:column}.ep-commercial-controls label,.ep-toggle-pair{width:100%}.ep-toggle-pair button{flex:1}.ep-commercial-cell-head{flex-direction:column}.ep-emf-badge{width:100%}.ep-commercial-practice .ep-toolbar label:first-child{min-width:0}}
/* Pass E: generated multi-part exam sets. */
.ep-exam-shell{padding-top:48px}.ep-exam-app{max-width:1060px}.ep-exam-header{align-items:flex-start}.ep-exam-header>div:first-child{max-width:690px}.ep-exam-header p:last-child{margin:.55rem 0 0;color:var(--muted);line-height:1.45}.ep-exam-score{display:flex;gap:9px}.ep-exam-score span{min-width:112px;display:grid;text-align:center;border:1px solid #c6d8d3;background:#fff;border-radius:12px;padding:9px 11px}.ep-exam-score strong{font-size:1.35rem;color:var(--navy)}.ep-exam-score small{font-size:.67rem;color:var(--muted)}.ep-exam-paper{padding:28px 30px 34px}.ep-exam-paper-head{display:flex;justify-content:space-between;gap:20px;align-items:start;margin-bottom:14px}.ep-exam-paper-head>div:last-child{display:grid;text-align:right;gap:4px}.ep-exam-paper-head>div:last-child strong{font-family:Georgia,"Times New Roman",serif;color:var(--navy);font-size:1.12rem}.ep-exam-paper-head>div:last-child span{font-size:.75rem;color:var(--muted);font-weight:800}.ep-exam-stem{padding:22px 24px;border:1px solid #d6e0dd;border-radius:15px;background:#f7f8f5;line-height:1.5}.ep-exam-stem>p:first-child{margin-top:0}.ep-exam-stem>p:last-child{margin-bottom:0}.ep-exam-stem .ep-data-table{margin-bottom:0}.ep-exam-parts{display:grid;gap:14px;margin-top:18px}.ep-exam-part{border:1px solid #ccd9d6;border-radius:14px;background:#fff;overflow:hidden}.ep-exam-part.is-complete{border-color:#b8d2ca}.ep-exam-part-head{display:grid;grid-template-columns:auto 1fr auto;gap:12px;align-items:start;padding:16px 18px;border-bottom:1px solid #e0e6e4;background:#fbfcfa}.ep-exam-part-letter{display:grid;place-items:center;width:30px;height:30px;border-radius:50%;background:#e9f3ef;color:var(--teal2);font-weight:900}.ep-exam-part-head p{margin:.25rem 0 0;line-height:1.45}.ep-exam-part-mark{white-space:nowrap;font-weight:900;color:#586d75;font-size:.78rem;padding-top:6px}.ep-exam-part-body{padding:18px}.ep-exam-response{display:grid;gap:12px}.ep-exam-response textarea{min-height:108px;width:100%;resize:vertical;padding:12px 13px;border:1px solid #a9b8b5;border-radius:10px;font:inherit;line-height:1.45}.ep-exam-response .ep-number-entry{max-width:430px}.ep-exam-action-row{display:flex;gap:12px;align-items:center;flex-wrap:wrap}.ep-exam-action-row .text-button{margin-right:auto}.ep-exam-feedback{margin-top:12px}.ep-exam-markpoints{margin-top:15px;padding:16px;border:1px solid #c9d9d5;border-radius:12px;background:#f4f8f6}.ep-exam-markpoints>strong{display:block;color:var(--navy);margin-bottom:9px}.ep-exam-markpoints>p{color:var(--muted);font-size:.82rem}.ep-exam-markpoints label{display:grid;grid-template-columns:auto 1fr;gap:10px;padding:9px 0;border-top:1px solid #dbe4e1;line-height:1.4}.ep-exam-markpoints label:first-of-type{border-top:0}.ep-exam-markpoints input{margin-top:.2rem}.ep-exam-model{margin-top:15px;padding:15px 17px;border-left:4px solid var(--teal);background:#edf7f3}.ep-exam-model strong{display:block;color:var(--navy);margin-bottom:5px}.ep-exam-model p{margin:.3rem 0;line-height:1.48}.ep-exam-summary{margin-top:20px;padding:20px;border:1px solid #b8d2ca;border-radius:14px;background:#edf7f3}.ep-exam-summary h3{font-family:Georgia,"Times New Roman",serif;color:var(--navy);margin:0 0 .45rem}.ep-exam-summary p{margin:.35rem 0}.ep-exam-summary .button-row{margin-top:13px}.ep-exam-part .ep-options label span sub,.ep-exam-part .ep-options label span sup{line-height:0}.ep-exam-part .ep-data-table{margin-top:10px}.ep-exam-clue{margin-top:12px;padding:11px 13px;border-left:3px solid #c79062;background:#fbf6f0;color:#5b4b42}.ep-exam-clue strong{color:#81573b}.ep-exam-supported{font-size:.72rem;color:#9a5c3e;font-weight:800}.ep-exam-paper .matching-member-note{margin-top:18px}
@media(max-width:720px){.ep-exam-header{flex-direction:column}.ep-exam-score{width:100%}.ep-exam-score span{flex:1}.ep-exam-paper{padding:22px 20px}.ep-exam-paper-head{display:grid}.ep-exam-paper-head>div:last-child{text-align:left}.ep-exam-part-head{grid-template-columns:auto 1fr}.ep-exam-part-mark{grid-column:2}.ep-exam-action-row{align-items:stretch;flex-direction:column}.ep-exam-action-row .button,.ep-exam-action-row .text-button{width:100%;text-align:left}.ep-exam-toolbar label{width:100%}}