/* Energy Cost Modeller - styles. Light/dark via prefers-color-scheme. No inline styles (CSP). */
:root {
  color-scheme: light;
  --bg: #f4f4f1;
  --surface: #fcfcfb;
  --surface-2: #f0efec;
  --border: #dddcd6;
  --text: #0b0b0b;
  --text-2: #52514e;
  --text-3: #75746f;
  --accent: #256abf;
  --accent-hover: #184f95;
  --accent-text: #ffffff;
  --accent-soft: #e6f0fc;
  --good: #0a6b3d;
  --good-bg: #e3f4ea;
  --warn: #8a5a00;
  --warn-bg: #fdf1d6;
  --bad: #b3261e;
  --bad-bg: #fbe5e3;
  --series-1: #2a78d6; --series-2: #eb6834; --series-3: #1baf7a; --series-4: #eda100;
  --series-5: #e87ba4; --series-6: #008300; --series-7: #4a3aa7; --series-8: #e34948;
  --grid: #e7e6e1;
  --radius: 10px;
  --shadow: 0 1px 2px rgba(0,0,0,.05);
  --font: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    color-scheme: dark;
    --bg: #121211; --surface: #1a1a19; --surface-2: #242423; --border: #353533;
    --text: #f4f4f1; --text-2: #c3c2b7; --text-3: #9a9990;
    --accent: #3987e5; --accent-hover: #6da7ec; --accent-text: #0b0b0b; --accent-soft: #14253a;
    --good: #6fd29b; --good-bg: #12301f; --warn: #f0c060; --warn-bg: #33270b; --bad: #f19b95; --bad-bg: #3a1714;
    --series-1: #3987e5; --series-2: #d95926; --series-3: #199e70; --series-4: #c98500;
    --series-5: #d55181; --series-6: #008300; --series-7: #9085e9; --series-8: #e66767;
    --grid: #2c2c2a; --shadow: none;
  }
}
:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: #121211; --surface: #1a1a19; --surface-2: #242423; --border: #353533;
  --text: #f4f4f1; --text-2: #c3c2b7; --text-3: #9a9990;
  --accent: #3987e5; --accent-hover: #6da7ec; --accent-text: #0b0b0b; --accent-soft: #14253a;
  --good: #6fd29b; --good-bg: #12301f; --warn: #f0c060; --warn-bg: #33270b; --bad: #f19b95; --bad-bg: #3a1714;
  --series-1: #3987e5; --series-2: #d95926; --series-3: #199e70; --series-4: #c98500;
  --series-5: #d55181; --series-6: #008300; --series-7: #9085e9; --series-8: #e66767;
  --grid: #2c2c2a; --shadow: none;
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; font: 15px/1.5 var(--font); background: var(--bg); color: var(--text); }
a { color: var(--accent); text-decoration-thickness: 1px; text-underline-offset: 2px; }
a:hover { color: var(--accent-hover); }
h1, h2, h3 { line-height: 1.25; margin: 0 0 .5rem; }
h1 { font-size: 1.6rem; letter-spacing: -.01em; }
h2 { font-size: 1.2rem; }
h3 { font-size: 1rem; }
p { margin: 0 0 .75rem; }
small, .small { font-size: .85rem; }
.muted { color: var(--text-2); }
.faint { color: var(--text-3); }
.num { font-variant-numeric: tabular-nums; text-align: right; }
.nowrap { white-space: nowrap; }
.hidden { display: none !important; }
.mt { margin-top: 14px; }
.mt-0 { margin-top: 0; }
.right { text-align: right; }

/* ---- layout ---- */
.wrap { max-width: 1120px; margin: 0 auto; padding: 0 16px; }
.site-header { background: var(--surface); border-bottom: 1px solid var(--border); }
.site-header .wrap { display: flex; align-items: center; gap: 20px; min-height: 56px; flex-wrap: wrap; }
.brand { font-weight: 700; color: var(--text); text-decoration: none; letter-spacing: -.01em; display: flex; align-items: center; gap: 8px; }
.brand svg { width: 22px; height: 22px; }
.site-nav { display: flex; gap: 4px; flex: 1; flex-wrap: wrap; }
.site-nav a { color: var(--text-2); text-decoration: none; padding: 6px 10px; border-radius: 6px; }
.site-nav a:hover { background: var(--surface-2); color: var(--text); }
.site-nav a[aria-current="page"] { color: var(--text); background: var(--surface-2); font-weight: 600; }
.userbox { display: flex; align-items: center; gap: 10px; color: var(--text-2); font-size: .9rem; }
main { padding: 24px 0 64px; }
.page-head { display: flex; justify-content: space-between; align-items: flex-start; gap: 16px; flex-wrap: wrap; margin-bottom: 18px; }
.page-head p { margin: 0; }
.crumbs { font-size: .85rem; color: var(--text-2); margin-bottom: 4px; }
.crumbs a { color: var(--text-2); }
.actions { display: flex; gap: 8px; flex-wrap: wrap; align-items: center; }
.grid { display: grid; gap: 16px; }
.grid.cols-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid.cols-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid.cols-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
@media (max-width: 860px) { .grid.cols-3, .grid.cols-4 { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
@media (max-width: 600px) { .grid.cols-2, .grid.cols-3 { grid-template-columns: 1fr; } .grid.cols-4 { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 10px; } .tile .value { font-size: 1.35rem; } }
.stack > * + * { margin-top: 16px; }

/* ---- cards ---- */
.card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 16px 18px; box-shadow: var(--shadow); min-width: 0; }
.card > h2:first-child, .card > h3:first-child { margin-bottom: .6rem; }
.card.flush { padding: 0; overflow: hidden; }
.card-head { display: flex; justify-content: space-between; align-items: center; gap: 12px; margin-bottom: 8px; flex-wrap: wrap; }
.card-head h2, .card-head h3 { margin: 0; }

/* ---- stat tiles ---- */
.tile { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 14px 16px; }
.tile .label { font-size: .8rem; color: var(--text-2); text-transform: uppercase; letter-spacing: .04em; }
.tile .value { font-size: 1.7rem; font-weight: 700; letter-spacing: -.02em; font-variant-numeric: tabular-nums; line-height: 1.2; margin-top: 2px; }
.tile .sub { font-size: .85rem; color: var(--text-2); margin-top: 2px; }
.tile .value.good { color: var(--good); }
.tile .value.bad { color: var(--bad); }

/* ---- buttons ---- */
.btn { display: inline-flex; align-items: center; gap: 6px; font: inherit; font-weight: 600; font-size: .9rem; padding: 8px 14px; border-radius: 8px; border: 1px solid var(--border); background: var(--surface); color: var(--text); cursor: pointer; text-decoration: none; line-height: 1.2; }
.btn:hover { background: var(--surface-2); color: var(--text); }
.btn.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-text); }
.btn.primary:hover { background: var(--accent-hover); border-color: var(--accent-hover); color: var(--accent-text); }
.btn.danger { color: var(--bad); border-color: var(--bad); }
.btn.danger:hover { background: var(--bad-bg); color: var(--bad); }
.btn.small { padding: 4px 10px; font-size: .82rem; }
.btn.link { border: none; background: none; color: var(--accent); padding: 4px 6px; font-weight: 500; }
.btn.link:hover { text-decoration: underline; background: none; }
form.inline { display: inline; margin: 0; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; border-radius: 4px; }

/* ---- forms ---- */
fieldset { border: 0; margin: 0; padding: 0; min-width: 0; }
.form-section { margin-bottom: 16px; }
.form-section legend { font-size: 1.05rem; font-weight: 700; padding: 0; margin-bottom: 8px; float: left; width: 100%; }
.form-section legend + * { clear: both; }
.section-help { font-size: .88rem; margin-bottom: 10px; }
.field-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 14px 18px; }
@media (max-width: 700px) { .field-grid { grid-template-columns: 1fr; } }
.field { display: flex; flex-direction: column; gap: 4px; min-width: 0; }
.field.wide { grid-column: 1 / -1; }
.field label { font-weight: 600; font-size: .9rem; }
.field .help { color: var(--text-2); font-size: .82rem; }
.field .error-text, .error-text { color: var(--bad); font-size: .85rem; font-weight: 500; }
.field.has-error input, .field.has-error select { border-color: var(--bad); }
input[type=text], input[type=email], input[type=password], input[type=number], input[type=time], select, textarea {
  font: inherit; width: 100%; padding: 8px 10px; border: 1px solid var(--border); border-radius: 8px; background: var(--surface); color: var(--text); min-height: 38px;
}
textarea { resize: vertical; }
input:focus, select:focus, textarea:focus { outline: 2px solid var(--accent); outline-offset: 0; border-color: var(--accent); }
.with-unit { display: flex; align-items: center; gap: 8px; }
.with-unit input { flex: 1; min-width: 0; }
.unit { color: var(--text-2); font-size: .85rem; white-space: nowrap; }
.check { display: flex; gap: 8px; align-items: flex-start; font-weight: 500 !important; cursor: pointer; }
.check input { margin-top: 4px; }
.form-actions { position: sticky; bottom: 0; background: var(--bg); padding: 12px 0; border-top: 1px solid var(--border); display: flex; gap: 10px; align-items: center; z-index: 5; }
.auth-card { max-width: 420px; margin: 8vh auto 0; }
.auth-card .field { margin-bottom: 14px; }

/* ---- tables ---- */
.table-wrap { overflow-x: auto; }
table { border-collapse: collapse; width: 100%; font-size: .92rem; }
th, td { padding: 8px 12px; text-align: left; border-bottom: 1px solid var(--border); vertical-align: top; }
th { font-weight: 600; color: var(--text-2); font-size: .8rem; text-transform: uppercase; letter-spacing: .03em; white-space: nowrap; background: var(--surface); }
td.num, th.num { text-align: right; font-variant-numeric: tabular-nums; }
tbody tr:last-child td { border-bottom: 0; }
tr.heading th { background: var(--surface-2); color: var(--text); text-transform: none; font-size: .88rem; letter-spacing: 0; padding: 6px 12px; }
tr.base td, tr.base th { background: color-mix(in srgb, var(--accent-soft) 60%, transparent); }
td.best { font-weight: 700; color: var(--good); }
.compare-table th:first-child, .compare-table td:first-child { position: sticky; left: 0; background: var(--surface); min-width: 220px; z-index: 1; }
.compare-table tr.heading th:first-child { background: var(--surface-2); }
.delta { display: block; font-size: .78rem; font-weight: 500; color: var(--text-2); }
.delta.good { color: var(--good); }
.delta.bad { color: var(--bad); }

/* ---- badges & alerts ---- */
.badge { display: inline-block; padding: 2px 8px; border-radius: 99px; font-size: .75rem; font-weight: 600; background: var(--surface-2); color: var(--text-2); white-space: nowrap; }
.badge.good { background: var(--good-bg); color: var(--good); }
.badge.warn { background: var(--warn-bg); color: var(--warn); }
.badge.bad { background: var(--bad-bg); color: var(--bad); }
.badge.accent { background: var(--accent-soft); color: var(--accent); }
.alert { padding: 10px 14px; border-radius: 8px; margin-bottom: 14px; border: 1px solid transparent; }
.alert.success { background: var(--good-bg); color: var(--good); border-color: color-mix(in srgb, var(--good) 30%, transparent); }
.alert.error { background: var(--bad-bg); color: var(--bad); border-color: color-mix(in srgb, var(--bad) 30%, transparent); }
.alert.warn { background: var(--warn-bg); color: var(--warn); border-color: color-mix(in srgb, var(--warn) 30%, transparent); }
.alert.info { background: var(--accent-soft); color: var(--text); border-color: color-mix(in srgb, var(--accent) 30%, transparent); }
.alert ul { margin: 4px 0 0; padding-left: 18px; }
.alert p:last-child { margin-bottom: 0; }

/* ---- lists ---- */
.kv { display: grid; grid-template-columns: max-content 1fr; gap: 4px 16px; margin: 0; }
.kv dt { color: var(--text-2); }
.kv dd { margin: 0; font-variant-numeric: tabular-nums; }
.scenario-row { display: grid; grid-template-columns: minmax(0, 2fr) repeat(4, minmax(0, 1fr)) auto; gap: 12px; align-items: center; padding: 12px 16px; border-bottom: 1px solid var(--border); }
.scenario-row:last-child { border-bottom: 0; }
.scenario-row .name { font-weight: 600; }
.scenario-row .metric .l { font-size: .75rem; color: var(--text-2); text-transform: uppercase; letter-spacing: .03em; }
.scenario-row .metric .v { font-variant-numeric: tabular-nums; font-weight: 600; }
@media (max-width: 860px) { .scenario-row { grid-template-columns: 1fr 1fr; } .scenario-row .name { grid-column: 1 / -1; } }
.checks { display: flex; flex-wrap: wrap; gap: 6px 16px; }
details > summary { cursor: pointer; font-weight: 600; }
details[open] > summary { margin-bottom: 8px; }

/* ---- appliance table ---- */
.appliance-table td { vertical-align: middle; padding: 6px 10px; }
.appliance-table input { min-height: 32px; padding: 4px 8px; }
.appliance-table input.qty { width: 64px; }
.appliance-table input.kw { width: 84px; }
.appliance-table tr.group th { background: var(--surface-2); color: var(--text); text-transform: none; letter-spacing: 0; font-size: .85rem; }

/* ---- tariff bands editor ---- */
.band-row { display: grid; grid-template-columns: 1fr 1fr 1fr auto; gap: 8px; margin-bottom: 8px; align-items: center; }
.tariff-strip { display: block; width: 100%; max-width: 288px; height: 22px; }
.tariff-strip rect { fill: var(--accent); }
.strip-legend { display: flex; justify-content: space-between; font-size: .7rem; color: var(--text-3); max-width: 288px; }

/* ---- supply check ---- */
.meter { height: 10px; border-radius: 99px; background: var(--surface-2); overflow: hidden; position: relative; min-width: 80px; }
.meter > span { display: block; height: 100%; background: var(--good); border-radius: 99px; }
.meter > span.tight { background: var(--series-4); }
.meter > span.exceeds { background: var(--bad); }

/* ---- charts ---- */
.chart { position: relative; width: 100%; }
.chart svg { display: block; width: 100%; height: auto; overflow: visible; }
.chart text { fill: var(--text-2); font: 11px var(--font); }
.chart .grid-line { stroke: var(--grid); stroke-width: 1; }
.chart .axis-line { stroke: var(--border); stroke-width: 1; }
.chart .zero-line { stroke: var(--text-3); stroke-width: 1; }
.chart .line { fill: none; stroke-width: 2; stroke-linejoin: round; stroke-linecap: round; }
.chart .area { stroke: none; }
.chart .dash { stroke-dasharray: 5 4; }
.chart .crosshair { stroke: var(--text-3); stroke-width: 1; stroke-dasharray: 3 3; }
.chart .bar { stroke: var(--surface); stroke-width: 2; paint-order: stroke; }
.chart .hit { fill: transparent; }
.chart .dot { stroke: var(--surface); stroke-width: 2; }
.legend { display: flex; flex-wrap: wrap; gap: 6px 16px; margin-top: 8px; font-size: .85rem; color: var(--text-2); }
.legend span { display: inline-flex; align-items: center; gap: 6px; }
.legend i { width: 12px; height: 12px; border-radius: 3px; display: inline-block; }
.legend i.line-key { height: 3px; border-radius: 2px; width: 16px; }
.tooltip { position: absolute; pointer-events: none; background: var(--surface); border: 1px solid var(--border); border-radius: 8px; padding: 8px 10px; font-size: .82rem; box-shadow: 0 4px 14px rgba(0,0,0,.18); z-index: 20; min-width: 130px; display: none; }
.tooltip .t-title { font-weight: 700; margin-bottom: 4px; }
.tooltip .t-row { display: flex; justify-content: space-between; gap: 14px; align-items: center; }
.tooltip .t-row i { width: 10px; height: 10px; border-radius: 2px; display: inline-block; margin-right: 6px; }
.tooltip .t-row b { font-variant-numeric: tabular-nums; }
.chart-controls { display: flex; gap: 10px; align-items: center; margin-bottom: 8px; flex-wrap: wrap; }
.chart-controls select { width: auto; min-height: 32px; padding: 4px 8px; }
.seg { display: inline-flex; border: 1px solid var(--border); border-radius: 8px; overflow: hidden; }
.seg button { font: inherit; font-size: .82rem; border: 0; background: var(--surface); color: var(--text-2); padding: 5px 10px; cursor: pointer; }
.seg button[aria-pressed="true"] { background: var(--accent-soft); color: var(--text); font-weight: 600; }

.footer { color: var(--text-3); font-size: .8rem; padding: 24px 0; }
.footer .wrap { border-top: 1px solid var(--border); padding-top: 14px; }

@media print {
  .site-header, .actions, .form-actions, .footer, .no-print, .chart-controls { display: none !important; }
  body { background: #fff; color: #000; }
  .card, .tile { box-shadow: none; break-inside: avoid; }
  main { padding: 0; }
}

.card.narrow { max-width: 560px; }
.card.narrow.wide { max-width: 720px; }

@media (max-width: 640px) {
  .site-header .wrap { gap: 6px 12px; padding-top: 8px; padding-bottom: 8px; }
  .brand { order: 1; }
  .userbox { order: 2; margin-left: auto; }
  .site-nav { order: 3; flex-basis: 100%; }
  h1 { font-size: 1.35rem; }
  .form-actions { flex-wrap: wrap; }
}

details.advanced { margin-top: 14px; border-top: 1px dashed var(--border); padding-top: 10px; }
details.advanced > summary { font-weight: 600; color: var(--text-2); }
details.advanced[open] > summary { margin-bottom: 12px; }

.checklist { list-style: none; padding: 0; margin: 0; }
.check-item { padding: 10px 0; border-bottom: 1px solid var(--border); }
.check-item:last-child { border-bottom: 0; }
.check-item .badge { margin-right: 6px; }
.check-item .small { margin-top: 2px; }

/* ---------- simple ("starter") mode ---------- */
.starter-layout { display: grid; grid-template-columns: minmax(0, 1.05fr) minmax(0, 1fr); gap: 16px; align-items: start; }
@media (max-width: 900px) { .starter-layout { grid-template-columns: 1fr; } }
.q { margin-bottom: 16px; }
.q-label { display: block; font-weight: 600; font-size: .92rem; margin-bottom: 6px; }
.q-row { display: flex; gap: 18px; flex-wrap: wrap; align-items: flex-start; }
.q-row > .q { flex: 1 1 200px; }
.btn-group { display: flex; flex-wrap: wrap; gap: 6px; }
.btn-group .choice { font: inherit; font-size: .9rem; padding: 8px 13px; border-radius: 999px; border: 1px solid var(--border); background: var(--surface); color: var(--text); cursor: pointer; line-height: 1.2; }
.btn-group .choice:hover { background: var(--surface-2); }
.btn-group .choice[aria-pressed="true"] { background: var(--accent); border-color: var(--accent); color: var(--accent-text); font-weight: 600; }
.mini { display: flex; flex-direction: column; gap: 4px; font-size: .88rem; font-weight: 600; min-width: 140px; }
.mini input, .mini select { font-weight: 400; }
.have { align-items: flex-end; }
.stepper { display: inline-flex; align-items: center; gap: 0; border: 1px solid var(--border); border-radius: 10px; overflow: hidden; background: var(--surface); }
.stepper button { font: inherit; font-size: 1.1rem; width: 38px; height: 38px; border: 0; background: var(--surface-2); color: var(--text); cursor: pointer; }
.stepper button:hover { background: var(--border); }
.stepper input { width: 64px; min-height: 38px; border: 0; border-radius: 0; text-align: center; padding: 0 4px; }
.stepper input:focus { outline-offset: -2px; }
.tariff-line { margin: 4px 0 10px; color: var(--text-2); }
details.refine { margin-top: 6px; border-top: 1px dashed var(--border); padding-top: 10px; }
details.refine > summary { font-weight: 600; color: var(--text-2); }
details.refine[open] > summary { margin-bottom: 10px; }
.plan-tabs { display: flex; gap: 6px; flex-wrap: wrap; margin-bottom: 12px; }
.plan-tabs .tab { font: inherit; font-size: .9rem; padding: 7px 14px; border: 1px solid var(--border); background: var(--surface); color: var(--text-2); border-radius: 8px 8px 0 0; cursor: pointer; }
.plan-tabs .tab[aria-selected="true"] { color: var(--text); font-weight: 700; background: var(--accent-soft); border-color: var(--accent); }
.upgrade { padding: 12px 0; border-top: 1px solid var(--border); }
.upgrade-head { margin-bottom: 8px; }
.compare-cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); gap: 14px; margin-top: 4px; }
.compare-card { border: 1px solid var(--border); border-radius: var(--radius); padding: 14px 16px; background: var(--surface); display: flex; flex-direction: column; gap: 8px; min-width: 0; }
.compare-card.now { background: var(--surface-2); }
.cc-head { display: flex; justify-content: space-between; align-items: center; gap: 8px; }
.cc-head h3 { margin: 0; }
.bigcost .amount { font-size: 2rem; font-weight: 800; letter-spacing: -.02em; font-variant-numeric: tabular-nums; }
.bigcost .per { color: var(--text-2); }
.stackbar { display: flex; height: 14px; border-radius: 99px; overflow: hidden; background: var(--surface-2); gap: 2px; }
.seg { display: block; height: 100%; }
.seg1, .legend i.seg1 { background: var(--series-1); } .seg2, .legend i.seg2 { background: var(--series-2); }
.seg3, .legend i.seg3 { background: var(--series-4); } .seg4, .legend i.seg4 { background: var(--text-3); }
.compare-card .legend { margin-top: 0; font-size: .78rem; gap: 4px 10px; }
.saving { font-weight: 700; font-size: 1.05rem; }
.saving.good { color: var(--good); } .saving.bad { color: var(--bad); }
.upfront strong { font-size: 1.05rem; }
.compare-card .alert { margin: 0; }
.compare-card p { margin: 0; }
.notes { margin: 6px 0 0; padding-left: 18px; }
.barset h3 { font-size: .95rem; }
.barrow { display: grid; grid-template-columns: 110px 1fr 70px; gap: 10px; align-items: center; margin: 6px 0; font-size: .88rem; }
.barname { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.bartrack { background: var(--surface-2); border-radius: 6px; height: 16px; overflow: hidden; }
.bar { height: 100%; border-radius: 6px; }
.bar.c0 { background: var(--text-3); } .bar.c1 { background: var(--series-1); } .bar.c2 { background: var(--series-2); } .bar.c3 { background: var(--series-3); }
.barval { text-align: right; font-variant-numeric: tabular-nums; font-weight: 600; }
.house-pair:empty { display: none; }

/* simple mode: view toggles, payback horizon */
.results-toolbar { display: flex; flex-wrap: wrap; gap: 14px 20px; align-items: center; margin-bottom: 14px; }
.results-toolbar .check { font-weight: 500; }
#results-card[data-view="running"] .only-full { display: none; }
#results-card:not([data-carbon="1"]) .only-carbon { display: none; }
.block { display: flex; flex-direction: column; gap: 8px; }
.payback { font-size: .95rem; }
.horizon { margin-top: 2px; }
.hz-track { position: relative; height: 12px; background: var(--surface-2); border-radius: 99px; overflow: hidden; }
.hz-range { position: absolute; top: 0; height: 100%; background: var(--good); border-radius: 99px; }
.hz-ticks { display: flex; justify-content: space-between; font-size: .7rem; color: var(--text-3); margin-top: 3px; }

/* ---------- isometric house drawings ---------- */
:root {
  --hs-ground: #dfeadb; --hs-wall-l: #efdfc9; --hs-wall-r: #d2bfa4; --hs-edge: #7d6e5c;
  --hs-roof-l: #b9604f; --hs-roof-r: #a39d99; --hs-roof-top: #a9a39b; --hs-gable: #d2bfa4; --hs-glass: #a9cfec; --hs-glass2: #cfe9fb; --hs-door: #4c6f93;
  --hs-panel: #1f3a63; --hs-panel-line: #8eaed6; --hs-batt-l: #f3f6f9; --hs-batt-r: #cfd7df; --hs-batt-t: #ffffff; --hs-led: #34c77b;
  --hs-hp-l: #dde3e8; --hs-hp-r: #b9c2ca; --hs-hp-t: #eef1f4; --hs-fan: #5d6b78; --hs-tank-l: #8fa396; --hs-tank-r: #6f8276; --hs-tank-t: #a9bbaf;
  --hs-flue-l: #f2f2f2; --hs-flue-r: #c9c9c9; --hs-flue-t: #ffffff; --hs-rad-l: #f7f7f7; --hs-rad-r: #d6d6d6; --hs-rad-t: #ffffff;
  --hs-chim-l: #9c5a4d; --hs-chim-r: #7e473c; --hs-chim-t: #b3685a; --hs-quilt: #f2c94c; --hs-new: #14a05b; --hs-tag: #14a05b; --hs-tag-text: #ffffff;
  --hs-render-l: #f6f2ea; --hs-render-r: #ddd5c6;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --hs-ground: #25302a; --hs-wall-l: #b9a58a; --hs-wall-r: #8f7d66; --hs-edge: #15130f; --hs-roof-l: #8c4538; --hs-roof-r: #7f7a76; --hs-roof-top: #6f6a63; --hs-gable: #8f7d66;
    --hs-glass: #6d94b5; --hs-glass2: #9ec2de; --hs-door: #38546f; --hs-panel: #162b4b; --hs-panel-line: #5f7fa8;
    --hs-batt-l: #dfe5ea; --hs-batt-r: #aeb7bf; --hs-hp-l: #c5ccd2; --hs-hp-r: #99a2aa; --hs-hp-t: #d8dde1; --hs-tank-l: #6f8276; --hs-tank-r: #566a5d; --hs-tank-t: #849a8b;
    --hs-chim-l: #75443a; --hs-chim-r: #5c342c; --hs-chim-t: #8b5144; --hs-new: #3ddc8b; --hs-tag: #3ddc8b; --hs-tag-text: #08210f; --hs-render-l: #d9d1c0; --hs-render-r: #b3ab9b;
  }
}
:root[data-theme="dark"] {
  --hs-ground: #25302a; --hs-wall-l: #b9a58a; --hs-wall-r: #8f7d66; --hs-edge: #15130f; --hs-roof-l: #8c4538; --hs-roof-r: #7f7a76; --hs-roof-top: #6f6a63; --hs-gable: #8f7d66;
  --hs-glass: #6d94b5; --hs-glass2: #9ec2de; --hs-door: #38546f; --hs-panel: #162b4b; --hs-panel-line: #5f7fa8;
  --hs-batt-l: #dfe5ea; --hs-batt-r: #aeb7bf; --hs-hp-l: #c5ccd2; --hs-hp-r: #99a2aa; --hs-hp-t: #d8dde1; --hs-tank-l: #6f8276; --hs-tank-r: #566a5d; --hs-tank-t: #849a8b;
  --hs-chim-l: #75443a; --hs-chim-r: #5c342c; --hs-chim-t: #8b5144; --hs-new: #3ddc8b; --hs-tag: #3ddc8b; --hs-tag-text: #08210f; --hs-render-l: #d9d1c0; --hs-render-r: #b3ab9b;
}
svg.hs { display: block; width: 100%; height: auto; }
.hs polygon { stroke: var(--hs-edge); stroke-width: .9px; stroke-linejoin: round; vector-effect: non-scaling-stroke; }
.hs-thumb polygon { stroke-width: .6px; }
.hs .hs-ground { fill: var(--hs-ground); stroke: none; }
.hs .hs-wall-l { fill: var(--hs-wall-l); } .hs .hs-wall-r { fill: var(--hs-wall-r); } .hs .hs-gable { fill: var(--hs-gable); }
.hs.hs-ins-wall .hs-wall-l { fill: var(--hs-render-l); } .hs.hs-ins-wall .hs-wall-r, .hs.hs-ins-wall .hs-gable { fill: var(--hs-render-r); }
.hs .hs-mine.hs-unit .hs-cavity { stroke: none; opacity: .55; } .hs .hs-hatchline { stroke: var(--hs-edge); stroke-width: .7; opacity: .55; }
.hs .hs-roof-l { fill: var(--hs-roof-l); } .hs .hs-roof-r { fill: var(--hs-roof-r); } .hs .hs-roof-top { fill: var(--hs-roof-top); }
.hs .hs-quilt { fill: var(--hs-quilt); opacity: .9; }
.hs .hs-chim-l { fill: var(--hs-chim-l); } .hs .hs-chim-r { fill: var(--hs-chim-r); } .hs .hs-chim-t { fill: var(--hs-chim-t); }
.hs .hs-glass { fill: var(--hs-glass); } .hs .hs-glass2 { fill: var(--hs-glass2); stroke-width: 1.8px; } .hs .hs-glass3 { stroke-width: 2.6px; }
.hs .hs-door { fill: var(--hs-door); }
.hs .hs-panel { fill: var(--hs-panel); stroke: var(--hs-panel-line); stroke-width: .8px; }
.hs .hs-batt-l { fill: var(--hs-batt-l); } .hs .hs-batt-r { fill: var(--hs-batt-r); } .hs .hs-batt-t { fill: var(--hs-batt-t); } .hs .hs-led { fill: var(--hs-led); stroke: none; }
.hs .hs-hp-l { fill: var(--hs-hp-l); } .hs .hs-hp-r { fill: var(--hs-hp-r); } .hs .hs-hp-t { fill: var(--hs-hp-t); } .hs .hs-fan { fill: var(--hs-fan); }
.hs .hs-tank-l { fill: var(--hs-tank-l); } .hs .hs-tank-r { fill: var(--hs-tank-r); } .hs .hs-tank-t { fill: var(--hs-tank-t); }
.hs .hs-flue-l { fill: var(--hs-flue-l); } .hs .hs-flue-r { fill: var(--hs-flue-r); } .hs .hs-flue-t { fill: var(--hs-flue-t); }
.hs .hs-rad-l { fill: var(--hs-rad-l); } .hs .hs-rad-r { fill: var(--hs-rad-r); } .hs .hs-rad-t { fill: var(--hs-rad-t); }
.hs .hs-dim { opacity: .5; }
.hs .hs-new polygon { stroke: var(--hs-new); stroke-width: 2.2px; }
.hs .hs-tag line { stroke: var(--hs-tag); stroke-width: 1.4px; }
.hs .hs-tag rect { fill: var(--hs-tag); } .hs .hs-tag text { fill: var(--hs-tag-text); font: 600 8.5px system-ui, sans-serif; }

/* ---------- step pages ---------- */
.steps { display: flex; gap: 6px; flex-wrap: wrap; margin: 0 0 16px; padding: 0; list-style: none; }
.steps button { font: inherit; font-size: .85rem; display: flex; align-items: center; gap: 8px; padding: 7px 12px; border: 1px solid var(--border); background: var(--surface); color: var(--text-2); border-radius: 999px; cursor: pointer; }
.steps button .n { display: inline-grid; place-items: center; width: 20px; height: 20px; border-radius: 50%; background: var(--surface-2); font-size: .75rem; font-weight: 700; }
.steps button[aria-current="step"] { color: var(--text); font-weight: 700; border-color: var(--accent); background: var(--accent-soft); }
.steps button[aria-current="step"] .n { background: var(--accent); color: var(--accent-text); }
.step-layout { display: grid; grid-template-columns: minmax(0, 1.2fr) minmax(260px, .8fr); gap: 16px; align-items: start; }
@media (max-width: 900px) { .step-layout { grid-template-columns: 1fr; } .step-art { order: -1; } }
.step-art { position: sticky; top: 12px; z-index: 4; }
/* the sticky picture never takes more than 40% of the screen height; on small screens it also drops its heading and chips */
.step-art svg.hs, .house-pair svg.hs { max-height: 40vh; }
@media (max-width: 900px) {
  .step-art { top: 6px; }
  .step-art .art-card { padding: 8px 10px; }
  .step-art .art-card h3, .step-art .chips, .step-art .heat-loss { display: none; }
}
.art-card h3 { margin-bottom: 6px; }
.chips { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 8px; }
.chip { font-size: .78rem; background: var(--surface-2); border-radius: 99px; padding: 3px 10px; color: var(--text-2); }
.chip.new { background: color-mix(in srgb, var(--hs-new) 20%, transparent); color: var(--text); font-weight: 600; }
.step-nav { display: flex; justify-content: space-between; align-items: center; gap: 12px; margin-top: 16px; flex-wrap: wrap; }
.step-nav .today { color: var(--text-2); font-size: .9rem; }
.btn-group .choice.tile { display: flex; flex-direction: column; align-items: center; gap: 2px; padding: 8px 10px 6px; border-radius: 12px; min-width: 96px; }
.choice.tile svg.hs { width: 84px; }
.choice.tile[aria-pressed="true"] .hs-wall-l { filter: none; }
.house-pair { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
@media (max-width: 700px) {
  .house-pair { gap: 8px; }
  .house-pair figcaption { font-size: .85rem; }
  .house-pair .chips { gap: 4px; justify-content: center; }
  .house-pair .chip { font-size: .68rem; padding: 2px 7px; }
}
.house-pair figure { margin: 0; text-align: center; }
.house-pair figcaption { font-weight: 700; margin-bottom: 4px; }
.results-col .compare-cards { grid-template-columns: 1fr; }
@media (min-width: 1100px) { .plan-layout { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1.1fr); gap: 16px; align-items: start; } }

.mb { margin-bottom: 16px; }
.btn-group.stacked { flex-direction: column; align-items: stretch; gap: 6px; }
.btn-group.stacked .choice { border-radius: 10px; text-align: left; padding: 9px 14px; }
.btn-group.tiles { gap: 8px; }
.btn-group .choice.tile { border-radius: 14px; }
.btn-group .choice.tile[aria-pressed="true"] svg.hs .hs-ground { fill: color-mix(in srgb, var(--accent) 30%, var(--hs-ground)); }

.btn-group .choice:disabled { opacity: .4; cursor: not-allowed; }

/* sliders that move between set values (solar panels, battery size) */
.stops { margin: 8px 0 26px; padding-inline: 14px; }
.stops-value { font-weight: 700; margin-bottom: 6px; }
.stops input[type="range"] { width: 100%; margin: 0; accent-color: var(--accent); cursor: pointer; }
.stops input[type="range"]:disabled { cursor: not-allowed; opacity: .6; }
.stops-ticks { display: flex; justify-content: space-between; margin-top: 2px; }
.stops-ticks .tick { width: 0; display: flex; justify-content: center; }
.stops-ticks .tick span { white-space: nowrap; font-size: .75rem; color: var(--text-2); }
/* tick boxes for insulation (also used in the detailed forms) */
.check-list { display: flex; flex-direction: column; gap: 10px; margin-top: 4px; }
.check-list .check { align-items: flex-start; }
.check.locked { opacity: .7; }
.check.locked > span::after { content: " (you have this)"; color: var(--text-2); font-size: .85em; }
.field > .label { font-weight: 600; font-size: .9rem; }
.field .check-list .check { font-weight: 400; font-size: .95rem; }

/* a turning arrow on every expandable heading, so it is clear it can be opened */
details > summary { list-style: none; }
details > summary::-webkit-details-marker { display: none; }
details > summary::before { content: ""; display: inline-block; flex: none; width: .5em; height: .5em; margin-right: .6em; border-right: 2px solid currentColor; border-bottom: 2px solid currentColor; transform: translateY(-.1em) rotate(-45deg); transition: transform .15s ease; }
details[open] > summary::before { transform: translateY(-.15em) rotate(45deg); }
@media (prefers-reduced-motion: reduce) { details > summary::before { transition: none; } }

/* small screens: one step per line, and Back and Next side by side with the running total above them */
@media (max-width: 700px) {
  .steps { flex-direction: column; flex-wrap: nowrap; gap: 2px; }
  .step-nav { flex-wrap: wrap; }
  .step-nav .today { order: -1; flex: 1 0 100%; }
  .step-nav [data-next] { margin-left: auto; }
}
.heat-loss { margin: 10px 0 0; }
.heat-loss:empty { display: none; }
.house-pair .heat-loss { margin: 6px 0 0; }