/* rrefcalculator.io — calm mathematics notebook.
   Tokens from DESIGN-SYSTEM.md. System font stacks only: no remote fonts, no layout shift. */
:root {
  --ink: #222339;
  --muted: #606278;
  --paper: #f7f7f2;
  --surface: #ffffff;
  --line: #dddde7;
  --violet: #5b43d6;
  --violet-dark: #4932bf;
  --pale: #efebff;
  --soft: #eeedf5;
  --lime: #dcf5a3;
  --lime-ink: #294100;
  --error: #aa2035;
  --field: #fafafd;
  --result-line: #4a4c64;
  --result-muted: #c1c1d6;
  --focus: #7a5cff;
  --serif: Georgia, 'Times New Roman', 'DejaVu Serif', serif;
  --sans: Arial, Helvetica, 'Liberation Sans', sans-serif;
  --mono: Consolas, 'DejaVu Sans Mono', 'Liberation Mono', Menlo, monospace;
  --shell: 1240px;
  --gutter: 20px;
  --radius-lg: 20px;
  --radius-md: 14px;
  --radius-sm: 8px;
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font: 400 16px/1.6 var(--sans);
  font-synthesis: none;
  overflow-wrap: break-word;
}
img { max-width: 100%; height: auto; }
a { color: inherit; }
button, input, select, textarea { font: inherit; color: inherit; }
button, select, summary { cursor: pointer; }
:focus-visible { outline: 3px solid var(--focus); outline-offset: 3px; }
main:focus { outline: none; }

.visually-hidden {
  position: absolute !important; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0;
}

.skip-link {
  position: absolute; left: 12px; top: -80px; z-index: 10;
  padding: 12px 16px; border: 2px solid var(--violet); border-radius: var(--radius-sm);
  background: var(--surface); color: var(--ink); font-weight: 700;
}
.skip-link:focus { top: 12px; }

/* ---------- Header ---------- */
.site-header { border-bottom: 1px solid var(--line); }
.header-inner {
  max-width: 1440px; margin: 0 auto; padding: 18px var(--gutter) 0;
  display: flex; flex-wrap: wrap; align-items: center; column-gap: 40px;
}
.brand { display: inline-flex; align-items: center; gap: 10px; text-decoration: none; white-space: nowrap; }
.brand-mark { display: block; width: 26px; height: 30px; }
.brand-text { font-size: 21px; letter-spacing: -0.5px; line-height: 1; }
.brand-text b { font-weight: 800; }
.brand-tld { color: var(--violet); font-size: 14px; margin-left: 1px; }
.site-nav { width: 100%; }
.site-nav ul { list-style: none; margin: 0; padding: 0; display: flex; justify-content: space-between; gap: 12px; }
.site-nav a {
  display: inline-flex; align-items: center; min-height: 48px; padding: 0 2px;
  font-size: 13px; font-weight: 700; text-decoration: none;
  border-bottom: 3px solid transparent;
}
.site-nav a:hover { color: var(--violet); }
.site-nav a.is-active { color: var(--violet); border-bottom-color: var(--violet); }
.header-note { display: none; margin: 0 0 0 auto; font: italic 13px var(--serif); color: var(--muted); }

/* ---------- Layout ---------- */
main { display: block; max-width: var(--shell); margin: 0 auto; padding: 28px var(--gutter) 56px; }

.breadcrumb ol { list-style: none; margin: 0 0 18px; padding: 0; display: flex; flex-wrap: wrap; gap: 4px 0; font-size: 13px; color: var(--muted); }
.breadcrumb li + li::before { content: '/'; margin: 0 8px; color: #9a9cb0; }
.breadcrumb a { text-underline-offset: 3px; }
.breadcrumb a:hover { color: var(--violet); }

.eyebrow {
  display: flex; align-items: center; gap: 9px; margin: 0;
  font-size: 11px; font-weight: 700; letter-spacing: 1.4px; text-transform: uppercase;
}
.eyebrow::before { content: ''; width: 7px; height: 7px; flex: none; border-radius: 50%; background: var(--violet); }

.hero { margin-bottom: 32px; }
.hero h1 {
  margin: 14px 0 0; font: 400 43px/1.08 var(--serif); letter-spacing: -1.6px;
}
.h1-line { display: block; }
.hero h1 em { font-style: normal; color: var(--violet); }
.lede { margin: 22px 0 0; max-width: 720px; color: var(--muted); font-size: 15px; line-height: 1.7; }

.section-title { margin: 12px 0 18px; font: 400 26px/1.25 var(--serif); letter-spacing: -0.4px; }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  min-height: 44px; padding: 10px 18px; border-radius: var(--radius-sm);
  border: 1px solid var(--line); background: var(--surface); color: var(--ink);
  font-size: 14px; font-weight: 700; text-decoration: none; line-height: 1.2;
  transition: background-color .15s ease, border-color .15s ease;
}
.btn:hover { background: var(--pale); }
.btn-primary { background: var(--violet); border-color: var(--violet); color: #fff; }
.btn-primary:hover { background: var(--violet-dark); border-color: var(--violet-dark); }
.btn-secondary { background: var(--surface); }
.btn-grow { flex: 1; justify-content: flex-start; padding-left: 16px; }
.btn-block { display: flex; width: 100%; justify-content: flex-start; }
.btn-small { min-height: 40px; padding: 8px 14px; font-size: 13px; }
.text-button {
  border: 0; background: none; padding: 8px 2px; min-height: 40px;
  color: var(--violet); font-size: 13px; text-decoration: underline; text-underline-offset: 4px;
}

/* ---------- Workspace ---------- */
.workspace {
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius-lg);
  overflow: hidden; box-shadow: 0 15px 40px rgba(36, 36, 57, .03);
}
.worktop { display: flex; align-items: center; justify-content: space-between; gap: 12px; padding: 0 18px; border-bottom: 1px solid var(--line); }
.tabs { display: flex; gap: 22px; }
.tab {
  display: flex; align-items: center; min-height: 54px; padding: 0 2px;
  font-size: 13px; font-weight: 700; text-decoration: none; color: var(--muted);
  border-bottom: 3px solid transparent; margin-bottom: -1px;
}
.tab:hover { color: var(--violet); }
.tab.is-active { color: var(--violet); border-bottom-color: var(--violet); }
.local-note { display: none; margin: 0; font-size: 12px; color: var(--muted); }
.workgrid { display: grid; grid-template-columns: minmax(0, 1fr); }
.workgrid > * { min-width: 0; }

.editor { padding: 24px 18px 26px; }
.panel-head { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-bottom: 16px; }
.panel-title { margin: 0; font: 700 16px/1.3 var(--sans); letter-spacing: -0.2px; }
.step-dot { margin-right: 8px; }

.controls { display: flex; flex-wrap: wrap; align-items: flex-end; gap: 12px; }
.field { display: flex; flex-direction: column; gap: 6px; }
.field label, .field-label { font-size: 12px; color: var(--muted); }
.field select, .static-field {
  min-width: 72px; min-height: 44px; padding: 8px 10px;
  border: 1px solid var(--line); border-radius: 7px; background: var(--surface);
}
.static-field { display: flex; align-items: center; color: var(--ink); background: var(--field); }
.field-form { margin-left: auto; }

.matrix-wrap {
  display: flex; justify-content: safe center; max-width: 100%;
  overflow-x: auto; overscroll-behavior-x: contain;
  padding: 24px 2px 18px;
  /* Scroll shadows reveal overflow without extra markup. */
  background:
    linear-gradient(90deg, var(--bg-wrap, #fff) 30%, transparent) left / 24px 100% no-repeat local,
    linear-gradient(270deg, var(--bg-wrap, #fff) 30%, transparent) right / 24px 100% no-repeat local,
    radial-gradient(farthest-side at 0 50%, rgba(34, 35, 57, .18), transparent) left / 10px 100% no-repeat scroll,
    radial-gradient(farthest-side at 100% 50%, rgba(34, 35, 57, .18), transparent) right / 10px 100% no-repeat scroll;
}
.matrix-wrap.is-scrollable { justify-content: flex-start; }
.matrix-wrap.is-scrollable:focus-visible { outline-offset: -3px; }

.matrix { position: relative; flex: none; border-collapse: separate; border-spacing: 7px; padding: 0 8px; }
.matrix::before, .matrix::after {
  content: ''; position: absolute; top: -6px; bottom: -6px; width: 9px;
  border: 2px solid currentColor; opacity: .6;
}
.matrix::before { left: 0; border-right: 0; }
.matrix::after { right: 0; border-left: 0; }
.matrix td { padding: 0; text-align: center; white-space: nowrap; font-family: var(--mono); }
.matrix td.aug { border-left: 2px solid #b5a5e9; padding-left: 8px; }
.matrix td.pivot { color: var(--violet); font-weight: 700; }

.matrix-input .cell {
  width: 56px; height: 44px; padding: 0 4px; text-align: center;
  border: 1px solid var(--line); border-radius: 7px; background: var(--field);
  font: 16px var(--mono);
}
.matrix-input .cell:focus { background: var(--pale); border-color: var(--violet); }
.matrix-input .cell[aria-invalid='true'] { border: 2px solid var(--error); background: #fff0f2; }

.entry-note { margin: 0 0 18px; font-size: 12px; line-height: 1.6; color: var(--muted); }
.actions { display: flex; gap: 10px; }
.error { margin: 12px 0 0; color: var(--error); font-size: 13px; line-height: 1.5; }
.error:empty { display: none; }

.paste { margin-top: 12px; font-size: 13px; }
.paste summary { display: inline-flex; align-items: center; min-height: 36px; color: var(--violet); list-style: none; }
.paste summary::-webkit-details-marker { display: none; }
.paste[open] summary { font-weight: 700; }
.paste-label { display: block; margin: 6px 0 8px; color: var(--muted); line-height: 1.6; }
.paste textarea {
  display: block; width: 100%; min-height: 96px; margin-bottom: 10px; padding: 10px;
  border: 1px solid var(--line); border-radius: var(--radius-sm); background: var(--field);
  font: 14px/1.5 var(--mono); resize: vertical;
}

/* Result panel */
.result { --bg-wrap: var(--ink); background: var(--ink); color: #fff; padding: 24px 18px 26px; }
.result .panel-head { margin-bottom: 8px; }
.badge {
  flex: none; padding: 5px 8px; border-radius: 5px; background: var(--lime); color: var(--lime-ink);
  font-size: 10px; font-weight: 700; letter-spacing: .4px; text-transform: uppercase;
}
.result-sub { margin: 0; font-size: 12px; color: var(--result-muted); }
.matrix-result { padding: 22px 2px 20px; }
.matrix-result .matrix { border-spacing: 14px 8px; padding: 0 10px; }
.matrix-result td { min-width: 36px; font-size: 19px; }
.result .matrix td.pivot { color: var(--lime); font-weight: 400; }
.result .matrix td.aug { border-left-color: #8f80d8; padding-left: 14px; }
.result-meta {
  display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 12px;
  margin: 0; padding-top: 16px; border-top: 1px solid var(--result-line);
}
.result-meta dt { font-size: 11px; color: #b8bbd0; line-height: 1.4; }
.result-meta dd { margin: 6px 0 0; font-size: 16px; }
.solution { margin-top: 18px; padding: 14px 16px; border: 1px solid #62627b; border-radius: 10px; background: #292a44; }
.solution h3 { margin: 0 0 8px; font-size: 14px; color: var(--lime); }
.equations { list-style: none; margin: 0; padding: 0; font: 14px/1.9 var(--mono); overflow-wrap: anywhere; }
.solution-note { margin: 6px 0 0; font-size: 12px; color: var(--result-muted); }
.result-bottom { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 12px; margin-top: 20px; }
.display-field { display: flex; align-items: center; gap: 8px; font-size: 13px; }
.display-field select {
  min-height: 40px; padding: 6px 8px; border: 1px solid #686a83; border-radius: 6px;
  background: #32334d; color: #fff; font-size: 13px;
}
.btn-outline-light {
  min-height: 40px; padding: 8px 12px; border: 1px solid #686a83; border-radius: 7px;
  background: transparent; color: #fff; font-size: 13px; font-weight: 700;
}
.btn-outline-light:hover { background: #32334d; }
.copy-status { margin-top: 10px; font-size: 13px; line-height: 1.5; color: var(--lime); }
.copy-status:empty { display: none; }
.copy-fallback-label { display: block; color: #fff; }
.copy-fallback {
  display: block; width: 100%; margin-top: 8px; padding: 10px;
  border: 1px solid var(--line); border-radius: 6px; background: #fff; color: var(--ink);
  font: 14px/1.5 var(--mono);
}
.empty { padding: 36px 8px; text-align: center; color: var(--result-muted); }
.empty-icon { margin: 0; font: 48px var(--serif); color: #8c80c8; }
.empty h3 { margin: 10px 0 6px; font: 400 20px var(--serif); color: #fff; }
.empty p:last-child { margin: 0; font-size: 13px; line-height: 1.7; }

.trustline {
  list-style: none; margin: 0; padding: 14px 18px; border-top: 1px solid var(--line); background: #fcfcfd;
  display: flex; flex-wrap: wrap; gap: 6px 18px; font-size: 12px; color: var(--muted);
}
.trustline li::before { content: '✓'; margin-right: 6px; color: var(--violet); }

/* ---------- Steps ---------- */
.steps { padding-top: 36px; }
.section-head { display: flex; flex-wrap: wrap; align-items: baseline; justify-content: space-between; gap: 6px 16px; margin-bottom: 16px; }
.section-head h2 { margin: 0; font: 400 25px/1.25 var(--serif); }
.section-head span { font-size: 12px; color: var(--muted); }
.steps-note { margin: 0; color: var(--muted); font-size: 14px; }
.step-list { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: minmax(0, 1fr); gap: 12px; align-items: start; }
.step-list > li { min-width: 0; }
.operation { border: 1px solid var(--line); border-radius: 12px; background: var(--surface); }
.operation summary { display: flex; align-items: center; gap: 12px; min-height: 52px; padding: 8px 16px; font: 12px/1.5 var(--mono); list-style: none; }
.operation summary::-webkit-details-marker { display: none; }
.operation summary::after { content: '+'; margin-left: auto; color: var(--muted); font: 16px var(--sans); }
.operation[open] summary::after { content: '−'; }
.op-num { flex: none; color: var(--violet); font: 11px var(--sans); }
.op-label { min-width: 0; overflow-wrap: anywhere; }
.matrix-step { padding: 6px 2px 16px; }
.matrix-step .matrix { border-spacing: 10px 3px; }
.matrix-step td { font-size: 13px; min-width: 22px; }

/* ---------- Content sections ---------- */
.how-to, .learn-strip, .guide, .faq, .cta-band { margin-top: 44px; }
.how-grid { list-style: none; margin: 0; padding: 0; display: grid; gap: 14px; counter-reset: how; }
.how-grid li { counter-increment: how; padding: 20px; border: 1px solid var(--line); border-radius: var(--radius-md); background: var(--surface); }
.how-grid li::before { content: '0' counter(how); display: block; margin-bottom: 8px; font-size: 11px; color: var(--violet); }
.how-grid h3 { margin: 0 0 8px; font-size: 16px; font-weight: 700; }
.how-grid p { margin: 0; font-size: 14px; line-height: 1.7; color: var(--muted); }

.card-grid { display: grid; grid-template-columns: minmax(0, 1fr); gap: 14px; }
.link-card {
  position: relative; display: flex; flex-direction: column; align-items: flex-start; gap: 8px;
  padding: 20px 22px; border-radius: var(--radius-md); text-decoration: none;
  transition: transform .15s ease, box-shadow .15s ease;
}
.link-card:hover { box-shadow: 0 8px 24px rgba(36, 36, 57, .08); }
.link-card:hover .card-title { text-decoration: underline; text-underline-offset: 4px; }
.link-card-soft { background: var(--soft); }
.link-card-plain { background: var(--surface); border: 1px solid var(--line); }
.card-kicker { font-size: 11px; letter-spacing: .5px; text-transform: uppercase; color: var(--violet); }
.card-title { margin: 0; font: 400 18px/1.35 var(--sans); }
.card-desc { font-size: 13px; line-height: 1.7; color: var(--muted); }
.card-arrow { align-self: flex-end; color: var(--violet); font-size: 20px; line-height: 1; }
.link-card-soft .card-arrow { position: absolute; right: 20px; bottom: 18px; font-size: 14px; }
.link-card-soft .card-desc { padding-right: 28px; }
.hub-grid .link-card-plain { min-height: 210px; padding: 24px; }
.hub-grid .card-title { margin-top: 18px; font: 400 25px/1.25 var(--serif); }
.hub-grid .card-arrow { margin-top: auto; }

.guide-body { max-width: 820px; }
.guide-body h3 { margin: 28px 0 8px; font-size: 18px; }
.guide-body p, .guide-body li { color: #51546a; font-size: 15px; line-height: 1.8; }
.outcome-grid { display: grid; grid-template-columns: minmax(0, 1fr); gap: 14px; margin: 16px 0 8px; }
.outcome { min-width: 0; padding: 20px; border: 1px solid var(--line); border-radius: var(--radius-md); background: var(--surface); }
.outcome h4 { margin: 0 0 8px; font-size: 16px; }
.outcome p { margin: 0; font-size: 14px; line-height: 1.7; color: #51546a; }
.outcome-system { font-family: var(--mono); color: var(--ink) !important; }
.outcome .math-block { margin: 12px 0; padding: 12px 8px; }
.equations-light { margin-bottom: 10px; font-size: 13px; }

.faq { max-width: 860px; }
.faq-item { border-bottom: 1px solid var(--line); }
.faq-item summary { display: flex; align-items: center; gap: 12px; min-height: 56px; padding: 10px 0; list-style: none; }
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after { content: '+'; margin-left: auto; color: var(--violet); font-size: 20px; }
.faq-item[open] summary::after { content: '−'; }
.faq-q { margin: 0; font-size: 15px; font-weight: 700; }
.faq-a p { margin: 0 0 16px; color: var(--muted); font-size: 14px; line-height: 1.8; }
.faq-a a, .guide-body a, .article a:not(.btn) { color: var(--violet); text-decoration: underline; text-underline-offset: 3px; }

.cta-band .cta-actions { display: flex; flex-wrap: wrap; gap: 12px; }

/* ---------- Articles ---------- */
.article-layout { display: grid; grid-template-columns: minmax(0, 1fr); gap: 32px; }
.article { min-width: 0; font-size: 15px; line-height: 1.8; }
.byline { margin: 0 0 18px; font-size: 12px; color: var(--muted); }
.article-intro { margin-top: 0; }
.article p, .article li { color: #51546a; }
.article h2 { margin: 36px 0 12px; font: 400 26px/1.3 var(--serif); letter-spacing: -.3px; color: var(--ink); }
.article h2.step-heading { margin: 28px 0 10px; font: 400 21px/1.35 var(--sans); letter-spacing: 0; }
.article h3 { margin: 22px 0 6px; font-size: 17px; }
.article ul, .article ol { padding-left: 22px; }
.article li { margin: 6px 0; }
.article code { padding: 2px 6px; border-radius: 4px; background: var(--pale); font: 14px var(--mono); color: var(--ink); }
kbd {
  display: inline-block; padding: 1px 6px; border: 1px solid var(--line); border-bottom-width: 3px;
  border-radius: 5px; background: #fff; color: var(--ink); font: 12px/1.6 var(--mono); white-space: nowrap;
}
.math-block { margin: 22px 0; padding: 18px 20px; border: 1px solid var(--line); border-radius: var(--radius-md); background: var(--surface); }
.math-label { font-size: 11px; letter-spacing: 1px; text-transform: uppercase; color: var(--muted); }
.math-block .matrix-wrap { padding: 18px 2px 8px; }
.math-block .matrix { border-spacing: 22px 8px; }
.math-block td { font-size: 18px; min-width: 20px; }

.table-scroll { max-width: 100%; overflow-x: auto; }
.compare-table { width: 100%; min-width: 420px; border-collapse: collapse; font-size: 14px; }
.compare-table th, .compare-table td { padding: 13px 10px; text-align: left; border-bottom: 1px solid var(--line); color: var(--ink); }
.compare-table thead th { background: var(--pale); font-weight: 700; }
.compare-table thead th:first-child { border-radius: 8px 0 0 8px; }
.compare-table thead th:last-child { border-radius: 0 8px 8px 0; }
.compare-table tbody th { font-weight: 400; }

.callout { margin: 32px 0 20px; padding: 18px 20px; border-radius: var(--radius-md); background: var(--pale); }
.callout p { margin: 0; }
.callout-title { font-size: 18px; color: var(--ink) !important; }
.callout-link { display: inline-block; margin-top: 6px; font-size: 14px; }
.source-note { margin-top: 18px; font-size: 12px; line-height: 1.7; color: var(--muted) !important; }

.side-card {
  align-self: start; padding: 22px; border: 1px solid var(--line); border-radius: var(--radius-md); background: var(--surface);
}
.side-card-title { margin: 14px 0 10px; font: 400 25px/1.3 var(--serif); }
.side-card-title span { display: block; }
.side-card > p:not(.eyebrow) { margin: 0 0 18px; font-size: 13px; line-height: 1.7; color: var(--muted); }
.side-links { list-style: none; margin: 16px 0 0; padding: 0; }
.side-links a { display: flex; gap: 6px; min-height: 44px; align-items: center; border-top: 1px solid var(--line); font-size: 13px; text-decoration: none; }
.side-links a:hover { color: var(--violet); }

/* ---------- Footer ---------- */
.site-footer { border-top: 1px solid var(--line); }
.footer-inner { max-width: var(--shell); margin: 0 auto; padding: 32px var(--gutter) 40px; display: grid; gap: 24px; }
.brand-footer .brand-text, .brand-footer .brand-tld { font-weight: 800; color: var(--ink); font-size: 18px; }
.footer-brand p { margin: 8px 0 0; font-size: 13px; color: var(--muted); }
.footer-groups { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 20px 24px; }
.footer-heading { margin: 0 0 4px; font-size: 11px; font-weight: 700; letter-spacing: 1.2px; text-transform: uppercase; }
.footer-group ul { list-style: none; margin: 0; padding: 0; }
.footer-group a, .footer-button {
  display: inline-flex; align-items: center; min-height: 36px; padding: 0;
  font-size: 13px; text-underline-offset: 3px; color: var(--ink);
}
.footer-button { border: 0; background: none; text-decoration: underline; }
.footer-group a:hover, .footer-button:hover { color: var(--violet); }
.footer-note { margin: 0; padding-top: 18px; border-top: 1px solid var(--line); font-size: 12px; color: var(--muted); }

/* ---------- Content pages (about, contact, legal) ---------- */
.doc h2 { margin-top: 34px; }
.doc > h2:first-of-type, .doc > .byline + h2 { margin-top: 0; }
.doc .compare-table { margin: 8px 0 12px; }
.doc .compare-table td, .doc .compare-table th { font-size: 14px; line-height: 1.6; vertical-align: top; }
.related-card .side-links { margin-top: 8px; }

/* ---------- Forms ---------- */
.contact-form { margin: 18px 0 8px; padding: 22px; border: 1px solid var(--line); border-radius: var(--radius-md); background: var(--surface); }
.form-note { margin: 0 0 14px; font-size: 13px; color: var(--muted) !important; }
.form-field { margin-bottom: 18px; }
.form-field > label { display: block; margin-bottom: 4px; font-size: 14px; font-weight: 700; color: var(--ink); }
.field-hint { margin: 0 0 6px; font-size: 13px; line-height: 1.5; color: var(--muted) !important; }
.form-field input[type='text'], .form-field input[type='email'], .form-field select, .form-field textarea {
  display: block; width: 100%; min-height: 46px; padding: 10px 12px;
  border: 1px solid #b9bacb; border-radius: var(--radius-sm); background: var(--field); color: var(--ink);
  font-size: 16px; line-height: 1.5;
}
.form-field textarea { min-height: 160px; resize: vertical; }
.form-field input:focus, .form-field select:focus, .form-field textarea:focus { background: #fff; border-color: var(--violet); }
.form-field [aria-invalid='true'], .form-field input[aria-invalid='true'], .form-field select[aria-invalid='true'], .form-field textarea[aria-invalid='true'] { border: 2px solid var(--error); background: #fff5f6; }
.field-error { margin: 6px 0 0; font-size: 13px; font-weight: 700; color: var(--error) !important; }
.field-error:empty { display: none; }
.form-check { display: grid; grid-template-columns: auto 1fr; gap: 4px 12px; align-items: start; }
.form-check input { width: 22px; height: 22px; margin: 2px 0 0; accent-color: var(--violet); }
.form-check label { font-size: 14px; font-weight: 400; line-height: 1.6; color: var(--ink); }
.form-check .field-error { grid-column: 2; }
.hp-field { position: absolute; left: -10000px; width: 1px; height: 1px; overflow: hidden; }
.error-summary { margin: 18px 0; padding: 16px 18px; border: 2px solid var(--error); border-radius: var(--radius-sm); background: #fff5f6; }
.error-summary:focus { outline: 3px solid var(--focus); outline-offset: 3px; }
.error-summary-title { margin: 0 0 6px; font-weight: 700; color: var(--error) !important; }
.error-summary ul { margin: 0; padding-left: 20px; }
.summary-link { padding: 4px 0; border: 0; background: none; color: var(--error); text-align: left; text-decoration: underline; font-size: 14px; }
.form-success { margin: 18px 0; padding: 22px; border-radius: var(--radius-md); background: var(--pale); border-left: 4px solid var(--violet); }
.form-success h2 { margin-top: 0 !important; }
.form-success h2:focus { outline: none; }
.form-ref { font-family: var(--mono); font-size: 14px; }

/* ---------- Cookie banner + dialog ---------- */
.cookie-banner {
  position: fixed; left: 12px; right: 12px; bottom: 12px; z-index: 20;
  max-width: 620px; max-height: calc(100vh - 24px); overflow-y: auto;
  padding: 18px 20px; border: 1px solid var(--line); border-radius: var(--radius-md);
  background: var(--surface); box-shadow: 0 18px 50px rgba(34, 35, 57, .18);
}
.cookie-banner[hidden], .back-to-top[hidden] { display: none; }
.cookie-title { margin: 0 0 6px; font: 400 21px/1.3 var(--serif); }
.cookie-banner p, .cookie-dialog p { margin: 0 0 14px; font-size: 14px; line-height: 1.6; color: var(--muted); }
.cookie-banner a { color: var(--violet); text-underline-offset: 3px; }
.cookie-actions { display: flex; flex-wrap: wrap; gap: 8px; }
.cookie-actions .btn { flex: 1 1 140px; }
.cookie-dialog {
  width: min(560px, calc(100vw - 24px)); max-height: calc(100vh - 24px); padding: 22px;
  border: 1px solid var(--line); border-radius: var(--radius-md); color: var(--ink); background: var(--surface);
}
.cookie-dialog::backdrop { background: rgba(34, 35, 57, .45); }
.cookie-dialog-head { display: flex; align-items: flex-start; justify-content: space-between; gap: 12px; }
.dialog-close { min-height: 40px; padding: 6px 12px; border: 1px solid var(--line); border-radius: var(--radius-sm); background: var(--surface); font-size: 13px; font-weight: 700; }
.consent-options { margin: 0 0 16px; padding: 0; border: 0; }
.consent-option { display: grid; grid-template-columns: auto 1fr; gap: 12px; padding: 12px 0; border-top: 1px solid var(--line); }
.consent-option input { width: 22px; height: 22px; margin: 2px 0 0; accent-color: var(--violet); }
.consent-name { display: block; font-weight: 700; font-size: 15px; }
.consent-always { margin-left: 6px; padding: 2px 6px; border-radius: 4px; background: var(--lime); color: var(--lime-ink); font-size: 11px; }
.consent-desc { display: block; font-size: 13px; line-height: 1.55; color: var(--muted); }

/* ---------- Back to top ---------- */
.back-to-top {
  position: fixed; right: 16px; bottom: 16px; z-index: 15;
  display: inline-flex; align-items: center; gap: 6px; min-height: 44px; padding: 8px 14px;
  border: 1px solid var(--violet); border-radius: 999px; background: var(--surface); color: var(--violet);
  font-size: 13px; font-weight: 700; box-shadow: 0 6px 20px rgba(34, 35, 57, .15);
}
.back-to-top:hover { background: var(--pale); }
.has-cookie-banner .back-to-top { display: none; }

/* ---------- Tablet ---------- */
@media (min-width: 700px) {
  :root { --gutter: 28px; }
  .header-inner { flex-wrap: nowrap; padding-top: 0; min-height: 78px; }
  .site-nav { width: auto; }
  .site-nav ul { gap: 44px; justify-content: flex-start; }
  .site-nav a { min-height: 78px; border-bottom-width: 3px; }
  .hero h1 { font-size: 56px; letter-spacing: -2.4px; }
  .lede { font-size: 16px; }
  .local-note { display: block; }
  .worktop { padding: 0 24px; }
  .editor, .result { padding: 26px 28px 30px; }
  .step-list, .card-grid-2, .outcome-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .card-grid-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .how-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .footer-inner { grid-template-columns: minmax(200px, 1fr) 3fr; align-items: start; }
  .footer-groups { grid-template-columns: repeat(4, minmax(0, 1fr)); }
  .footer-note { grid-column: 1 / -1; }
  .cookie-banner { left: 24px; bottom: 24px; right: auto; }
  .section-title { font-size: 30px; }
  .section-head h2 { font-size: 27px; }
}

/* ---------- Desktop ---------- */
@media (min-width: 1000px) {
  .header-inner { padding: 0 48px; column-gap: 60px; }
  .site-nav { margin-left: 100px; }
  .site-nav ul { gap: 60px; }
  .header-note { display: block; }
  main { padding-top: 44px; }
  .hero { margin-bottom: 48px; }
  .hero h1 { font-size: 66px; letter-spacing: -2.8px; line-height: 1.06; }
  .lede { margin-top: 48px; }
  .workgrid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .step-list { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .outcome-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .article-layout { grid-template-columns: minmax(0, 800px) 310px; justify-content: space-between; gap: 64px; }
  .side-card { position: sticky; top: 24px; }
}

/* ---------- Print ---------- */
@media print {
  .site-header, .site-footer, .skip-link, .editor, .worktop, .trustline, .result-bottom,
  .learn-strip, .faq, .side-card, .callout, .how-to, .cta-band, .cookie-banner, .back-to-top,
  .cookie-dialog, .contact-form { display: none !important; }
  body, .result { background: #fff; color: #000; }
  .workgrid, .step-list { display: block; }
  .result .matrix td.pivot, .result-meta dt, .result-sub { color: #000; }
  .operation { break-inside: avoid; margin-bottom: 8px; }
  .matrix-wrap { background: none; }
  main { padding: 0; }
  .hero h1 { font-size: 28px; }
}