.ie-breadcrumb{display:flex;gap:8px;align-items:center;margin-bottom:18px;font-size:.86rem}.ie-breadcrumb a{color:var(--teal2)}.ie-breadcrumb span{color:#87949a}.ie-breadcrumb strong{color:var(--muted)}
.ie-hero-skills{display:flex;gap:7px;flex-wrap:wrap;margin-top:18px}.ie-hero-skills span,.ie-row-skills em{border:1px solid #cadad6;background:#f3f8f6;border-radius:999px;padding:5px 9px;font-size:.73rem;font-style:normal;color:#3f5a62}
.ie-hero-grid{display:grid;grid-template-columns:minmax(0,1.18fr) minmax(340px,.82fr);gap:52px;align-items:center}.ie-hero-graph{background:#fbfcfa;border:1px solid #cfdbd8;border-radius:18px;padding:18px;box-shadow:0 18px 45px rgba(30,56,63,.08)}.ie-hero-graph svg{display:block;width:100%;height:auto}.ie-hero-graph .axis{fill:none;stroke:#73878c;stroke-width:2}.ie-hero-graph .grid{fill:none;stroke:#dce4e2;stroke-width:1}.ie-hero-graph polyline{fill:none;stroke:var(--teal2);stroke-width:3}.ie-hero-graph circle{fill:#fff;stroke:var(--navy);stroke-width:2}.ie-hero-graph text{font-size:12px;fill:#4e646b;text-anchor:middle}
.ie-picker{padding-top:56px}.ie-tool-list{display:grid;gap:11px}.ie-tool-row{display:grid;grid-template-columns:auto minmax(260px,1.2fr) minmax(260px,.9fr) auto;gap:18px;align-items:center;padding:17px 19px;border:1px solid #cddad7;background:#fff;border-radius:15px;text-decoration:none;color:var(--ink);transition:transform .15s,border-color .15s,box-shadow .15s}.ie-tool-row:hover{transform:translateY(-2px);border-color:#9ab9b2;box-shadow:0 10px 25px rgba(29,59,65,.08)}.ie-tool-row.is-advanced{background:linear-gradient(90deg,#fff,#f5f3fa)}.ie-row-icon .tool-icon{width:34px;height:34px}.ie-row-copy{display:grid;gap:5px}.ie-row-copy strong{font-size:1.03rem;color:var(--navy)}.ie-row-copy small{line-height:1.45;color:var(--muted)}.ie-row-skills{display:flex;gap:6px;flex-wrap:wrap}.ie-tool-row>b{white-space:nowrap;color:var(--teal2)}
.ie-concepts-grid{display:grid;grid-template-columns:1.2fr .8fr;gap:38px;align-items:center}.ie-concepts-grid h2,.ie-advanced-note h2{font-family:Georgia,"Times New Roman",serif;color:var(--navy)}.ie-jump-card{display:grid;grid-template-columns:repeat(4,1fr);gap:8px;align-items:end;border:1px solid #cbd8d5;background:#fff;border-radius:16px;padding:20px}.ie-jump-card>strong,.ie-jump-card>small{grid-column:1/-1}.ie-jump-card span{display:grid;place-items:center;height:55px;background:#edf4f2;border-radius:9px;color:var(--navy);font-weight:800}.ie-jump-card span.jump{height:115px;background:#e7ecf5;border-top:4px solid #4f6386}.ie-jump-card small{color:var(--muted);line-height:1.4}.ie-advanced-note{display:flex;gap:32px;align-items:center;justify-content:space-between}.ie-advanced-note>div{max-width:780px}
.ie-practice-shell{padding-top:54px}.ie-app{max-width:1020px;margin:auto;padding:0;overflow:hidden}.ie-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}.ie-app-header h2{font-family:Georgia,"Times New Roman",serif;color:var(--navy);margin:.1em 0 0}.ie-session-summary{display:flex;gap:9px}.ie-session-summary span{min-width:104px;display:grid;text-align:center;border:1px solid #d2dfdc;background:#fff;border-radius:12px;padding:8px 10px}.ie-session-summary strong{font-size:1.3rem;color:var(--navy)}.ie-session-summary small{font-size:.68rem;color:var(--muted)}
.ie-toolbar{display:flex;gap:14px;align-items:end;flex-wrap:wrap;padding:18px 30px;background:#f3f7f5;border-bottom:1px solid var(--line)}.ie-toolbar label{display:grid;gap:5px;font-size:.82rem;font-weight:750;color:var(--navy)}.ie-toolbar label small{max-width:24rem;color:var(--muted);font-weight:500;line-height:1.3}.ie-toolbar select{min-width:175px;background:#fff;border:1px solid #a9b8b5;border-radius:9px;padding:8px 10px}.ie-toolbar .button{margin-left:auto}
.ie-question-stage{padding:28px 30px 32px}.ie-question-meta{display:flex;gap:7px;flex-wrap:wrap;margin-bottom:15px}.ie-question-meta span{background:#edf3f1;border:1px solid #d2ddda;border-radius:999px;padding:4px 9px;font-size:.74rem;font-weight:750;color:#415862}.ie-question{background:#f7f8f5;border:1px solid #e0e4df;border-radius:15px;padding:22px 24px;line-height:1.55}.ie-question>p:first-child{margin-top:0}.ie-question>p:last-child{margin-bottom:0}
.ie-table-scroll{overflow-x:auto;margin:15px 0}.ie-data-table{width:100%;border-collapse:collapse;background:#fff;min-width:500px}.ie-data-table th,.ie-data-table td{padding:9px 10px;border:1px solid #d1d9d7;text-align:center}.ie-data-table th{background:#edf3f1;color:var(--navy);font-weight:800}.ie-choice-symbols{display:flex;gap:10px;margin:16px 0 4px}.ie-choice-symbols span{display:grid;place-items:center;width:48px;height:48px;border:1px solid #c9d5d2;border-radius:10px;background:#fff;font-size:1.2rem;font-weight:800;color:var(--navy)}
.ie-answer{display:flex;gap:15px;align-items:end;flex-wrap:wrap;margin:22px 0 8px}.ie-answer>#ie-answer-control{flex:1;min-width:270px}.ie-options{border:0;padding:0;display:grid;gap:9px}.ie-options label{display:grid;grid-template-columns:auto 1fr;gap:10px;padding:11px 13px;border:1px solid #c8d3d0;border-radius:10px;background:#fff;cursor:pointer}.ie-options label:has(input:checked){border-color:#6e9890;background:#f0f8f5}.ie-number-answer,.ie-written-answer{display:grid;gap:7px;color:var(--navy);font-weight:750}.ie-number-entry{display:flex;align-items:center;border:1px solid #9eaeaa;border-radius:10px;background:#fff;overflow:hidden;max-width:390px}.ie-number-entry input{width:100%;border:0;padding:11px 12px;outline:0}.ie-number-entry b{padding:0 12px;color:var(--muted);white-space:nowrap}.ie-written-answer textarea{width:100%;resize:vertical;border:1px solid #9eaeaa;border-radius:10px;padding:12px 13px;font:inherit;line-height:1.5;background:#fff}.ie-help-row{display:flex;gap:18px;margin-top:8px}
.ie-equation-builder{display:flex;gap:9px;align-items:center;flex-wrap:wrap;border:1px solid #c7d2cf;border-radius:12px;background:#fff;padding:14px 16px;font-size:1.05rem}.ie-equation-builder .species{display:flex;gap:5px;align-items:center}.ie-equation-builder select{border:1px solid #b4c1be;border-radius:7px;padding:7px 8px;background:#fff}.ie-equation-builder .arrow{font-size:1.25rem;color:var(--teal2)}.ie-equation-line{font-family:Georgia,"Times New Roman",serif;font-size:1.12rem;text-align:center;padding:12px;border:1px solid #d7dfdd;background:#fff;border-radius:10px}.ie-orbitals{display:flex;gap:12px;flex-wrap:wrap;margin:10px 0}.ie-orbitals>span{display:flex;gap:5px;align-items:center;background:#fff;border:1px solid #d1dbd8;border-radius:9px;padding:9px}.ie-orbitals i{font-style:normal;border:1px solid #aebbb8;min-width:30px;text-align:center;padding:2px}
.ie-mark-points{display:grid;gap:8px}.ie-mark-points label{display:grid;grid-template-columns:auto 1fr;gap:10px;align-items:start;border:1px solid #d1d9d6;background:#fff;border-radius:9px;padding:9px 11px}.ie-mark-points input{margin-top:4px}.ie-plot-control{display:flex;gap:14px;align-items:center;flex-wrap:wrap}.ie-plot-control span{color:var(--muted)}
.ie-graph-wrap{margin:18px auto 4px;max-width:820px;background:#fff;border:1px solid #d2dcda;border-radius:12px;padding:8px}.ie-graph-wrap.is-interactive{touch-action:none}.ie-line-graph{display:block;width:100%;height:auto;min-height:260px;user-select:none}.ie-grid line{stroke:#dfe6e4;stroke-width:1}.ie-axis line{stroke:#536a70;stroke-width:1.8}.ie-ylabels text,.ie-xlabels text{font-size:12px;fill:#465e65}.ie-ytitle{font-size:12px;fill:#465e65;text-anchor:middle}.ie-series polyline{fill:none;stroke:#425f68;stroke-width:2.4}.ie-series circle{fill:#fff;stroke:#223f4a;stroke-width:2}.ie-faint-line{fill:none;stroke:#9fb0ad;stroke-width:1.3;stroke-dasharray:5 5;opacity:.38}.ie-target-column{fill:#fff;stroke:#3b8b7f;stroke-width:2;stroke-dasharray:3 2}.ie-user-point circle{fill:#e9f6f2;stroke:#136d61;stroke-width:2}.ie-user-point path{stroke:#136d61;stroke-width:2}.ie-missing-base .missing{fill:#fff;stroke:#75958e;stroke-width:2;stroke-dasharray:3 2}
.ie-solution h3{font-family:Georgia,"Times New Roman",serif;color:var(--navy)}.ie-next-step,.ie-progress-nudge{display:flex;justify-content:space-between;gap:22px;align-items:center;margin-top:20px;padding:18px 20px;border:1px solid #bed4ce;border-radius:14px;background:#f2f8f5}.ie-next-step[hidden],.ie-progress-nudge[hidden]{display:none}.ie-next-step h3{margin:0 0 .3rem;color:var(--navy);font-family:Georgia,"Times New Roman",serif}.ie-next-step p,.ie-progress-nudge p{margin:.2rem 0 0;color:var(--muted)}.ie-app-footer{display:flex;justify-content:space-between;gap:18px;border-top:1px solid var(--line);padding:17px 30px;background:#fbfcfa;font-size:.88rem}.ie-app-footer>span{color:var(--muted);text-align:right}.ie-related-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:13px}.ie-related-grid a{display:grid;gap:5px;border:1px solid #cad8d4;border-radius:13px;background:#fff;padding:17px 18px;text-decoration:none;color:var(--ink)}.ie-related-grid strong{color:var(--navy)}.ie-related-grid small{color:var(--muted)}
@media(max-width:850px){.ie-hero-grid,.ie-concepts-grid{grid-template-columns:1fr}.ie-hero-graph{max-width:620px}.ie-tool-row{grid-template-columns:auto 1fr auto}.ie-row-skills{grid-column:2/4}.ie-related-grid{grid-template-columns:1fr 1fr}.ie-advanced-note{align-items:flex-start;flex-direction:column}.ie-toolbar .button{margin-left:0}}
@media(max-width:620px){.ie-hero-grid{gap:26px}.ie-hero-graph{padding:8px}.ie-tool-row{grid-template-columns:auto 1fr;padding:14px}.ie-tool-row>b{grid-column:2}.ie-row-skills{grid-column:2}.ie-app-header{align-items:flex-start;flex-direction:column;padding:22px 18px 16px}.ie-session-summary{width:100%}.ie-session-summary span{flex:1;min-width:0}.ie-toolbar,.ie-question-stage{padding-left:16px;padding-right:16px}.ie-toolbar{align-items:stretch}.ie-toolbar label,.ie-toolbar select,.ie-toolbar .button{width:100%}.ie-question{padding:17px 14px}.ie-answer{align-items:stretch}.ie-answer>#ie-answer-control,.ie-answer>.button{width:100%;min-width:0}.ie-equation-builder{gap:6px;padding:10px}.ie-equation-builder .species{display:grid;grid-template-columns:auto 1fr;grid-template-areas:'symbol charge' 'symbol state'}.ie-equation-builder .species b{grid-area:symbol;align-self:center}.ie-equation-builder .species select:first-of-type{grid-area:charge}.ie-equation-builder .species select:last-of-type{grid-area:state}.ie-line-graph{min-height:220px}.ie-related-grid{grid-template-columns:1fr}.ie-next-step,.ie-progress-nudge{align-items:flex-start;flex-direction:column}.ie-app-footer{flex-direction:column;padding:15px 16px}.ie-app-footer>span{text-align:left}.ie-jump-card{grid-template-columns:repeat(4,minmax(0,1fr));padding:14px}}

/* Ionisation-energy data explorer */
.ie-tool-row.is-explorer{background:linear-gradient(90deg,#fff,#f2f8f7)}
.ie-plotter-app{max-width:1120px;margin:auto;padding:0;overflow:hidden}.ie-plotter-header{padding:25px 30px 19px;border-bottom:1px solid var(--line);background:#fbfcfa}.ie-plotter-header h2{margin:0 0 6px;font-family:Georgia,"Times New Roman",serif;color:var(--navy)}.ie-plotter-header p{margin:0;color:var(--muted);max-width:820px}
.ie-plotter-toolbar{display:grid;grid-template-columns:repeat(6,minmax(135px,1fr));gap:13px;align-items:end;padding:18px 30px;background:#f3f7f5;border-bottom:1px solid var(--line)}.ie-plotter-toolbar label{display:grid;gap:5px;font-size:.82rem;font-weight:750;color:var(--navy)}.ie-plotter-toolbar select{width:100%;background:#fff;border:1px solid #a9b8b5;border-radius:9px;padding:8px 10px}.ie-plotter-toolbar [hidden]{display:none!important}.ie-plotter-check{display:flex!important;grid-template-columns:auto 1fr!important;gap:8px!important;align-items:center;padding:8px 0;font-weight:650!important}.ie-plotter-check input{width:18px;height:18px;margin:0}
.ie-plotter-stage{padding:27px 30px 30px}.ie-plotter-title-row{display:flex;align-items:start;justify-content:space-between;gap:22px}.ie-plotter-title-row h2{margin:0;color:var(--navy);font-family:Georgia,"Times New Roman",serif}.ie-plotter-title-row p{margin:5px 0 0;color:var(--muted)}.ie-explorer-graph{max-width:940px;padding:10px 12px}.ie-explorer-point{cursor:pointer;outline:none}.ie-explorer-point circle{transition:r .12s,fill .12s}.ie-explorer-point:hover circle,.ie-explorer-point:focus circle{r:8;fill:#e9f6f2}.ie-value-label{font-size:10px;fill:#304a52;font-weight:700}.ie-xtitle{font-size:12px;fill:#465e65}.ie-plot-readout{max-width:940px;margin:10px auto 0;border-left:3px solid var(--teal2);padding:9px 12px;background:#f3f8f6;color:#3c535b}.ie-plot-note{max-width:940px;margin:10px auto 0;color:var(--muted);font-size:.88rem;line-height:1.45}.ie-plotter-data{max-width:940px;margin:17px auto 0}.ie-plotter-data summary{cursor:pointer;color:var(--teal2);font-weight:750}.ie-plotter-data .ie-table-scroll{margin-bottom:0}
@media(max-width:960px){.ie-plotter-toolbar{grid-template-columns:repeat(3,minmax(0,1fr))}}
@media(max-width:620px){.ie-plotter-header,.ie-plotter-stage{padding-left:16px;padding-right:16px}.ie-plotter-toolbar{grid-template-columns:1fr 1fr;padding-left:16px;padding-right:16px}.ie-plotter-check{grid-column:1/-1}.ie-explorer-graph{padding:5px}.ie-explorer-graph .ie-line-graph{min-height:260px}.ie-value-label{font-size:9px}}
@media(max-width:420px){.ie-plotter-toolbar{grid-template-columns:1fr}}