@import url("../../labs/assets/palette.css");
@import url("https://fonts.googleapis.com/css2?family=Source+Sans+3:wght@400;500;600;650;700&family=Source+Serif+4:opsz,wght@8..60,400;8..60,600&display=swap");

:root {
  --ink: var(--palette-graphite);
  --muted: color-mix(in srgb, var(--palette-slate) 75%, var(--palette-graphite));
  --border: var(--palette-mist);
  --paper: var(--palette-paper);
  --teal: var(--palette-teal);
  --amber: var(--palette-amber);
  --soft-teal: color-mix(in srgb, var(--teal) 7%, white);
  --soft-sand: color-mix(in srgb, var(--palette-sand) 25%, white);
  font-family: "Source Sans 3", "Segoe UI", sans-serif;
  color: var(--ink);
  background: var(--paper);
  font-size: 17px;
  line-height: 1.5;
}

* { box-sizing: border-box; }
body { margin: 0; }
a { color: var(--teal); text-underline-offset: 3px; }
a:hover { text-decoration-thickness: 2px; }
button, input, select, textarea { font: inherit; color: inherit; }
button, input, select, textarea, summary { border-radius: 6px; }
button, select { min-height: 46px; }
button { cursor: pointer; padding: 10px 16px; font-weight: 600; }
button:disabled { cursor: default; opacity: .5; }
button, input, select, textarea { border: 1px solid var(--border); }
input, select, textarea { background: white; border-color: var(--palette-slate); padding: 11px 12px; width: 100%; min-width: 0; }
input { min-height: 46px; }
input[type="file"] { max-width: 330px; }
textarea { resize: vertical; line-height: 1.6; }
input[aria-invalid="true"] { border-color: var(--palette-rust); outline: 1px solid var(--palette-rust); }
:focus-visible { outline: 3px solid var(--teal); outline-offset: 3px; }
[hidden] { display: none !important; }
label { display: block; font-weight: 600; margin-bottom: 7px; }
label span { color: var(--muted); font-size: .88em; font-weight: 400; }
h1, h2, h3, p { margin-top: 0; }
h1 { font-family: "Source Serif 4", Georgia, serif; font-size: clamp(2rem, 3.4vw, 3rem); font-weight: 600; line-height: 1.13; letter-spacing: -.025em; margin-bottom: 16px; }
h2 { font-size: 1.36rem; line-height: 1.2; letter-spacing: -.02em; margin-bottom: 0; }
h3 { font-size: 1.05rem; margin-bottom: 10px; }
p { margin-bottom: 14px; }
sub, sup { font-size: .73em; }

.skip-link { position: absolute; top: -100px; left: 14px; padding: 12px; background: white; z-index: 5; }
.skip-link:focus { top: 12px; }
.site-header, .site-footer { display: flex; align-items: center; justify-content: space-between; gap: 20px; padding: 20px max(24px, calc((100vw - 1240px) / 2)); }
.site-header { border-bottom: 1px solid var(--border); background: white; }
.brand { color: var(--ink); font-size: 1.15rem; font-weight: 700; text-decoration: none; white-space: nowrap; }
.brand span { font-weight: 400; margin-left: 8px; }
.site-header nav { display: flex; gap: 24px; font-size: .9rem; }
.site-footer { font-size: .85rem; color: var(--muted); margin-top: 28px; }
.page { max-width: 1288px; margin: 0 auto; padding: 28px 24px 18px; }
.page-intro { display: flex; justify-content: space-between; align-items: center; gap: 40px; margin-bottom: 22px; }
.page-intro > div { max-width: 830px; }
.eyebrow { color: var(--teal); font-weight: 600; font-size: .9rem; letter-spacing: .025em; margin-bottom: 10px; }
.intro-copy { font-size: 1.07rem; max-width: 720px; margin-bottom: 0; }
.preview-note { flex-shrink: 0; font-size: .87rem; color: var(--muted); margin: 0; border-left: 2px solid var(--amber); padding-left: 14px; }
.starter { display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: 16px 26px; background: white; border: 1px solid var(--border); border-radius: 10px; padding: 19px 24px; margin-bottom: 22px; }
.starter-label { display: flex; flex-direction: column; font-size: .93rem; }
.starter-label span { color: var(--muted); font-size: .9em; }
.case-buttons { display: flex; flex-wrap: wrap; gap: 8px; }
.case-buttons button { background: white; border-color: var(--palette-slate); font-size: .93rem; }
.case-buttons button[aria-pressed="true"] { border-color: var(--teal); background: var(--soft-teal); color: var(--teal); }
.case-buttons button:hover { border-color: var(--teal); }
.experiment-grid { display: grid; grid-template-columns: 1fr 1fr; align-items: start; gap: 22px; }
.panel { background: white; border: 1px solid var(--border); border-radius: 10px; padding: 26px; min-width: 0; }
.panel-heading { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 8px 16px; margin-bottom: 14px; }
.condition { font-size: .9rem; color: var(--muted); }
.section-help { font-size: .92rem; color: var(--muted); }
.cell-bridge { margin: 24px 24px 0; border: 2px solid var(--border); border-bottom: 0; border-radius: 12px 12px 0 0; height: 25px; text-align: center; }
.cell-bridge span { position: relative; top: -15px; background: white; padding: 0 10px; font-size: .8rem; color: var(--muted); }
.solution-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; }
.solution { min-width: 0; margin: 0; padding: 18px 16px 10px; border: 1px solid var(--border); border-top: 3px solid var(--ink); border-radius: 0 0 22px 22px; background: linear-gradient(white 55%, var(--soft-teal)); }
.solution legend { padding: 0 7px; font-weight: 600; margin-left: -5px; }
.electrode { width: 48px; height: 42px; border: 3px solid var(--ink); border-bottom-width: 8px; margin: 0 auto 12px; display: flex; align-items: center; justify-content: center; background: var(--paper); font-size: .83rem; }
.solution label { font-size: .91rem; }
.quantity-input { position: relative; }
.quantity-input input { padding-right: 54px; font-size: 1.1rem; font-variant-numeric: tabular-nums; }
.quantity-input span { position: absolute; right: 11px; top: 15px; font-size: .83rem; color: var(--muted); pointer-events: none; }
.activity-value { display: flex; justify-content: space-between; gap: 10px; font-size: .87rem; color: var(--muted); margin: 12px 0 5px; }
.activity-value output { color: var(--ink); font-variant-numeric: tabular-nums; }
.cell-direction { text-align: center; margin: 16px 0 23px; font-size: .9rem; min-height: 1.5em; }
.advanced { border-top: 1px solid var(--border); padding: 12px 0; font-size: .92rem; }
.advanced summary { cursor: pointer; padding: 5px 2px; font-weight: 600; min-height: 38px; }
.advanced p { margin-top: 12px; }
.coefficient-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; }
.secondary-cases button { font-size: .86rem; }
.prediction-row { display: grid; grid-template-columns: 1fr 1fr; align-items: center; gap: 12px; margin: 18px 0 14px; }
.prediction-row label { margin: 0; }
.primary-button { background: var(--teal); color: white; border-color: var(--teal); }
.primary-button:hover:not(:disabled) { background: var(--ink); border-color: var(--ink); }
.secondary-button { background: white; border-color: var(--teal); color: var(--teal); }
.calculate-button { width: 100%; min-height: 52px; }
.calculate-button + .advanced { margin-top: 22px; }
.error-summary { color: var(--ink); background: var(--soft-sand); border: 2px solid var(--palette-rust); padding: 14px; margin-bottom: 20px; }
.field-error { color: var(--ink); font-weight: 600; font-size: .85rem; margin-top: 8px; margin-bottom: 0; }
.result-placeholder { padding: 52px 20px; text-align: center; border-bottom: 1px solid var(--border); margin-bottom: 24px; }
.placeholder-voltage { display: block; font-family: "Source Serif 4", Georgia, serif; color: var(--teal); font-size: 3.6rem; margin-bottom: 12px; }
.voltage-result { padding: 18px 0 12px; }
.voltage-result > span { font-size: .93rem; color: var(--muted); }
.voltage-result > div { display: flex; align-items: baseline; gap: 12px; }
#result-E { font-size: clamp(2.5rem, 4.8vw, 4.3rem); line-height: 1.2; letter-spacing: -.04em; font-variant-numeric: tabular-nums; }
.voltage-unit { font-size: 1.4rem; color: var(--muted); }
.direction-result { font-weight: 600; }
.prediction-feedback { border-left: 3px solid var(--amber); padding-left: 12px; font-size: .93rem; }
.prediction-feedback:empty { display: none; }
.result-metrics { margin: 22px 0; }
.result-metrics > div { display: flex; justify-content: space-between; align-items: baseline; gap: 16px; padding: 11px 0; border-top: 1px solid var(--border); }
.result-metrics dt { font-size: .91rem; }
.result-metrics dt span { display: block; color: var(--muted); font-size: .9em; }
.result-metrics dd { margin: 0; font-size: 1.1rem; font-weight: 600; font-variant-numeric: tabular-nums; }
.calculation-check { padding: 18px; border-radius: 6px; background: var(--soft-teal); margin-bottom: 24px; }
.reaction { font-size: .94rem; overflow-wrap: anywhere; }
#calc-steps { padding-left: 22px; margin: 14px 0 0; font-size: .94rem; }
#calc-steps li + li { margin-top: 10px; }
.save-case-row { display: grid; grid-template-columns: 1fr; gap: 10px; }
.save-case-row label { margin-bottom: -4px; }
.result-panel:has(#results[hidden]) .save-case-row { display: none; }
.comparison-panel { margin-top: 22px; }
.table-scroll { width: 100%; overflow-x: auto; border: 1px solid var(--border); border-radius: 6px; }
table { border-collapse: collapse; width: 100%; font-size: .91rem; }
th, td { text-align: right; white-space: nowrap; padding: 13px 14px; border-bottom: 1px solid var(--border); font-variant-numeric: tabular-nums; }
th { background: var(--paper); font-size: .86rem; font-weight: 600; }
th:first-child, td:first-child { text-align: left; white-space: normal; min-width: 120px; }
td button { background: white; font-size: .85rem; min-height: 42px; padding: 7px 12px; }
tbody tr:last-child td { border-bottom: 0; }
.empty-state { border: 1px dashed var(--border); border-radius: 6px; padding: 22px; color: var(--muted); }
.reflection-label { margin-top: 26px; }
.study-actions { display: flex; flex-wrap: wrap; align-items: end; gap: 24px; margin-top: 20px; }
.file-control label { font-size: .91rem; }
.file-control input { font-size: .85rem; }
.study-status { margin: 16px 0 0; font-weight: 600; color: var(--teal); overflow-wrap: anywhere; }
.privacy-note { color: var(--muted); font-size: .85rem; margin-top: 12px; }
.visually-hidden { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0; }

.design-page { max-width: 1080px; }
.design-intro { max-width: 800px; margin: 20px 0 40px; }
.design-intro h1 { font-size: clamp(2.2rem, 4.8vw, 3.9rem); }
.design-intro p { font-size: 1.1rem; }
.design-intro .primary-button { display: inline-flex; align-items: center; text-decoration: none; margin-top: 10px; }
.design-section { margin: 30px 0; }
.design-section h2 { margin-bottom: 18px; }
.design-section li + li { margin-top: 12px; }
.principles-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; }
.principle { border-top: 3px solid var(--teal); padding-top: 18px; }
.principle h3 { font-size: 1.15rem; }
.principle p { font-size: .95rem; }
.roadmap td, .roadmap th { text-align: left; white-space: normal; vertical-align: top; }
.roadmap td:first-child { min-width: 175px; }
.roadmap td:last-child { min-width: 220px; }
.plan-note { padding: 18px 22px; background: var(--soft-sand); border-left: 3px solid var(--amber); }

@media (max-width: 950px) {
  .page-intro { align-items: start; }
  .preview-note { max-width: 160px; }
  .starter { align-items: start; }
  .experiment-grid { grid-template-columns: 1fr; }
  .result-placeholder { padding: 25px 20px; }
  .panel { padding: 24px; }
}

@media (max-width: 600px) {
  :root { font-size: 16px; }
  .site-header { padding: 16px; flex-wrap: wrap; gap: 12px; }
  .site-header nav { gap: 20px; font-size: .87rem; }
  .brand { white-space: normal; }
  .page { padding: 26px 14px 10px; }
  .page-intro { display: block; margin-bottom: 24px; }
  .preview-note { margin-top: 20px; max-width: none; }
  .starter { padding: 18px; }
  .case-buttons { width: 100%; }
  .case-buttons button { flex: 1 1 100%; text-align: left; }
  .panel { padding: 20px 16px; }
  .solution-grid { gap: 10px; }
  .solution { padding: 15px 10px 10px; }
  .quantity-input input { padding: 11px 8px; }
  .quantity-input span { position: static; display: block; padding: 3px 0 0; font-size: .8rem; }
  .solution legend { font-size: .95rem; padding: 0 3px; }
  .solution label { font-size: .84rem; }
  .activity-value { display: block; }
  .activity-value output { display: block; }
  .cell-bridge { margin-left: 15px; margin-right: 15px; }
  .cell-bridge span { font-size: .72rem; padding: 0 5px; }
  .coefficient-grid { grid-template-columns: 1fr; }
  .prediction-row { grid-template-columns: 1fr; }
  .study-actions, .file-control { width: 100%; }
  .study-actions > button { width: 100%; }
  input[type="file"] { max-width: 100%; }
  .site-footer { padding: 20px 16px; flex-direction: column; align-items: start; gap: 8px; }
  .principles-grid { grid-template-columns: 1fr; }
  .design-intro { margin-top: 10px; }
}

@media print {
  .site-header, .site-footer, .starter, #cell-form, .save-case-row, .study-actions, .preview-note { display: none; }
  .experiment-grid { display: block; }
  .setup-panel { display: none; }
  .panel { break-inside: avoid; }
  .page { padding: 0; }
  body { background: white; }
}