/* libfido2 developer reference
   Design tokens are defined once. Each component has one primary rule.
   Breakpoint rules modify layout only; typography is not scaled down on mobile. */

/* 1. Design system */
:root {
  color-scheme: dark;
  --page: #101317;
  --sidebar: #13171b;
  --surface: #13191d;
  --surface-raised: #171d21;
  --code-surface: #1b2328;
  --text: #d8dde1;
  --text-secondary: #c3cbd1;
  --text-muted: #a8b3bc;
  --text-emphasis: #eef1f4;
  --link: #b2ccd9;
  --link-strong: #d6e3ff;
  --rule: #343c42;
  --rule-strong: #415059;
  --active: #26313a;
  --selection: #38577d;
  --font-prose: Georgia, "Times New Roman", serif;
  --font-ui:
    ui-monospace, SFMono-Regular, Consolas, "Liberation Mono", monospace;
  --size-prose: 20px;
  --size-reference: 18px;
  --size-caption: 17px;
  --size-label: 16px;
  --size-nav: 17px;
  --size-heading-1: clamp(38px, 19.5px + 3.08vw, 46px);
  --size-heading-2: clamp(28px, 18.8px + 1.54vw, 32px);
  --size-heading-3: 23px;
  --sidebar-width: 294px;
  --content-width: 980px;
  --text-label: #b9cad1;
  --rule-line: 1px solid var(--rule);
  --rule-strong-line: 1px solid var(--rule-strong);
  --pad-block: clamp(17px, 10.21px + 1.2cqi, 20px);
  --pad-inline: clamp(17px, 5.68px + 2cqi, 22px);
  --pad-block-end: clamp(17px, 7.94px + 1.6cqi, 21px);
  --op-gap: clamp(6px, -18.9px + 4.4cqi, 17px);
}

/* 2. Document and navigation */
* {
  box-sizing: border-box;
}
html {
  scroll-behavior: smooth;
}
body {
  margin: 0;
  background: var(--page);
  color: var(--text);
  font-family: var(--font-prose);
  font-weight: 600;
  font-size: var(--size-prose);
  line-height: 1.63;
}
a {
  color: var(--link);
  text-decoration: none;
}
a:hover {
  text-decoration: underline;
}
::selection {
  background: var(--selection);
  color: white;
}
strong {
  color: var(--text-emphasis);
}

aside {
  position: fixed;
  inset: 0 auto 0 0;
  width: var(--sidebar-width);
  padding: 28px 19px;
  overflow-y: auto;
  background: var(--sidebar);
  border-right: var(--rule-line);
  font-family: var(--font-ui);
  @media (width <= 860px) {
    display: flex;
    align-items: center;
    justify-content: space-between;
    position: static;
    width: auto;
    padding: 18px 20px;
    border-right: 0;
    border-bottom: var(--rule-line);
  }
}
.brand {
  font-family: var(--font-ui);
  font-size: 19px;
  font-weight: 900;
  color: var(--text-emphasis);
  letter-spacing: -0.4px;
}
.nav-toggle {
  display: none;
  @media (width <= 860px) {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border: var(--rule-line);
    border-radius: 8px;
    background: var(--surface);
    color: var(--text);
    font-size: 20px;
    line-height: 1;
    cursor: pointer;
  }
}
dialog.site-nav {
  display: contents;
  @media (width <= 860px) {
    display: none;
  }
}
.nav-close {
  display: none;
  @media (width <= 860px) {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    align-self: flex-end;
    width: 40px;
    height: 40px;
    margin-bottom: 4px;
    border: var(--rule-line);
    border-radius: 8px;
    background: var(--surface);
    color: var(--text);
    font-size: 18px;
    line-height: 1;
    cursor: pointer;
  }
}
nav {
  margin-top: 20px;
  font-family: var(--font-ui);
}
nav a {
  display: block;
  padding: 7px 9px;
  color: var(--text-muted);
  font-size: var(--size-nav);
  line-height: 1.45;
}
nav a:hover,
nav a[aria-current="page"],
nav a.active {
  background: var(--active);
  color: var(--text-emphasis);
  text-decoration: none;
}
.nav-label {
  margin: 22px 10px 10px;
  color: var(--text-muted);
  font-size: var(--size-label);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  text-decoration: underline;
}
.nav-group {
  margin-bottom: 12px;
}
.nav-sep {
  border-top: var(--rule-line);
  margin: 13px 8px;
}
@media (width <= 860px) {
  dialog.site-nav[open] {
    display: flex;
    flex-direction: column;
    position: fixed;
    inset-block: 0;
    inset-inline-start: 0;
    width: min(85vw, 320px);
    max-width: none;
    max-height: none;
    height: 100dvh;
    margin: 0;
    padding: 18px 19px;
    border: 0;
    border-inline-end: var(--rule-line);
    background: var(--sidebar);
    color: var(--text);
    overflow-y: auto;
    translate: 0 0;
    transition:
      translate 250ms ease,
      display 250ms allow-discrete,
      overlay 250ms allow-discrete;
    @starting-style {
      translate: -100% 0;
    }
  }
  dialog.site-nav::backdrop {
    background: rgb(0 0 0 / 0.55);
  }
}
body:has(dialog.site-nav[open]) {
  overflow: hidden;
}

main {
  margin-left: var(--sidebar-width);
  max-width: 1400px;
  padding: 54px 62px 110px;
  @media (width <= 860px) {
    margin-left: 0;
  }
}
header {
  padding-bottom: 0;
}
.breadcrumbs {
  margin-bottom: 20px;
  color: var(--text-muted);
  font: 500 var(--size-caption)/1.5 var(--font-ui);
}
.overline {
  color: var(--text-muted);
  font: 500 var(--size-label)/1.5 var(--font-ui);
  text-transform: uppercase;
  letter-spacing: 0.09em;
}
.meta {
  margin-top: 24px;
  color: var(--text-muted);
  font: 500 var(--size-caption)/1.5 var(--font-ui);
}
header p {
  max-width: 760px;
  margin: 12px 0 0;
  color: var(--text-secondary);
  font-size: var(--size-prose);
}
section {
  max-width: var(--content-width);
  container-type: inline-size;
  padding: 0;
  scroll-margin-top: 24px;
  @media (width <= 860px) {
    padding: 38px 0;
  }
}
h1,
h2,
h3 {
  font-family: var(--font-prose);
  font-weight: 800;
  letter-spacing: 0;
}
h1 {
  margin: 13px 0;
  font-size: var(--size-heading-1);
  line-height: 1.18;
}
h2 {
  margin: 0 0 14px;
  padding-top: 15px;
  border-top: var(--rule-line);
  font-size: var(--size-heading-2);
  line-height: 1.3;
}
h3 {
  margin: 31px 0 10px;
  font-size: var(--size-heading-3);
}
p {
  max-width: 82ch;
  margin: 12px 0 20px;
  color: var(--text-secondary);
}

/* 3. Reference content */
table {
  width: 100%;
  margin: 24px 0 25px;
  border-collapse: collapse;
  font-family: var(--font-ui);
  font-size: var(--size-reference);
  line-height: 1.6;
  @media (width <= 860px) {
    display: block;
    overflow-x: auto;
  }
}
th {
  padding: 14px 13px;
  border-bottom: var(--rule-line);
  background: var(--sidebar);
  color: var(--text-muted);
  font-size: var(--size-label);
  font-weight: 700;
  text-align: left;
}
td {
  padding: 17px 13px;
  border-bottom: var(--rule-line);
  color: var(--text-secondary);
  vertical-align: top;
  @media (width <= 860px) {
    min-width: 170px;
  }
}
td:first-child {
  min-width: 120px;
  color: var(--text-emphasis);
}
tr:last-child td {
  border-bottom-color: var(--rule-strong);
}
code {
  font-family: var(--font-ui);
  font-size: var(--size-reference);
  line-height: 1.6;
  color: var(--text-emphasis);
  overflow-wrap: anywhere;
}
pre {
  font-family: var(--font-ui);
}
.api {
  white-space: normal;
}
.api code {
  color: #b8d0fb;
}
.api span {
  color: var(--text-muted);
  font-size: var(--size-label);
}
.note {
  margin-top: 26px;
  padding: 16px 19px;
  border-left: 2px solid #8da8bb;
  background: var(--surface);
  color: var(--text-secondary);
  font-size: var(--size-reference);
}
.note strong {
  color: var(--text-emphasis);
}
.foot {
  margin-top: 20px;
  color: var(--text-muted);
  font-size: var(--size-caption);
}
.subtle {
  color: var(--text-muted);
  font-size: var(--size-reference);
}
.spec-ref {
  margin-left: 5px;
  border-bottom: 1px dotted var(--rule-strong);
  color: var(--link);
  font: 500 var(--size-label)/1.5 var(--font-ui);
  white-space: nowrap;
}
.spec-ref:hover {
  color: var(--link-strong);
  border-bottom-color: var(--link-strong);
  text-decoration: none;
}
.spec-local {
  margin-left: 5px;
  color: var(--text-muted);
  font: 500 var(--size-label)/1.5 var(--font-ui);
  white-space: nowrap;
}
.spec-legend {
  margin: 13px 0;
  color: var(--text-muted);
  font-size: var(--size-caption);
}
.spec-legend a {
  margin-right: 12px;
}
.ref-links {
  max-width: 820px;
  color: var(--text-muted);
  font: 500 var(--size-caption)/1.6 var(--font-ui);
}
.ref-links a {
  margin-right: 16px;
}

.error-table td {
  padding: 12px 13px;
}
.error-table td:first-child {
  min-width: 240px;
}
.error-table code {
  font-size: var(--size-caption);
}
.function-table td:first-child {
  width: 42%;
  white-space: normal;
  overflow-wrap: anywhere;
}
.index-grid {
  columns: 2;
  column-gap: 24px;
  @container (width <= 566px) {
    columns: 1;
  }
}
.index-grid li {
  margin: 7px 0;
  break-inside: avoid;
  font-size: var(--size-reference);
}
.index-grid a {
  font-family: var(--font-ui);
}
.section-index {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(225px, 1fr));
  gap: 0 24px;
  max-width: 920px;
  padding: 0;
  list-style: none;
}
.section-index li {
  padding: 12px 0;
  border-bottom: var(--rule-line);
  font: 600 var(--size-reference)/1.55 var(--font-ui);
}
.section-index small {
  display: block;
  margin-top: 3px;
  color: var(--text-muted);
  font-size: var(--size-caption);
}
.count {
  color: var(--text-muted);
  font-size: var(--size-caption);
}

/* 4. Operation composition: layout and decisions */
.contract-intro {
  max-width: 78ch;
  color: var(--text-muted);
}
.op-lede {
  max-width: 74ch;
}
.op-toc {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0 clamp(12px, -10.64px + 4cqi, 22px);
  margin: 20px 0 38px;
  padding: 0;
  border-top: var(--rule-line);
  list-style: none;
  @container (width <= 602px) {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}
.op-toc li {
  margin: 0;
  border-bottom: var(--rule-line);
}
.op-toc a {
  display: block;
  padding: 11px 2px;
  color: var(--text);
  font: 500 var(--size-reference)/1.5 var(--font-ui);
}
.op-toc small {
  display: block;
  margin-top: 2px;
  color: var(--text-muted);
  font: 500 var(--size-caption)/1.5 var(--font-ui);
}
.op-sheet {
  max-width: 1050px;
  margin: 0 0 57px;
  padding: 0 0 38px;
  scroll-margin-top: 22px;
}
.op-sheet h3 {
  margin: 0 0 5px;
  font-size: clamp(27px, 17.94px + 1.6cqi, 31px);
  line-height: 1.25;
}
.op-board {
  border: var(--rule-strong-line);
  background: var(--surface);
}
.op-entry,
.op-outcome {
  display: grid;
  grid-template-columns: 142px minmax(0, 1fr);
  column-gap: var(--op-gap);
  padding: var(--pad-block) var(--pad-inline);
  @container (width <= 566px) {
    grid-template-columns: 1fr;
  }
}
.op-entry {
  border-bottom: var(--rule-strong-line);
}
.op-outcome {
  border-top: var(--rule-strong-line);
}
:is(.op-field-label, .op-core h4, .contract-cell h4, .dep-map h4) {
  color: var(--text-label);
  font: 700 var(--size-label)/1.5 var(--font-ui);
  text-transform: uppercase;
}
.op-field-label,
.op-core h4 {
  margin: 0 0 14px;
  letter-spacing: 0.025em;
}
.op-field-text {
  margin: 0;
  color: var(--text);
  font-size: var(--size-prose);
}
.op-minor {
  margin: 6px 0 0;
  color: var(--text-muted);
  font-size: var(--size-caption);
}
.op-core {
  display: grid;
  grid-template-columns: minmax(0, 1.18fr) minmax(0, 0.82fr);
  @container (width <= 602px) {
    grid-template-columns: 1fr;
  }
}
:is(.op-decisions, .op-execution) {
  padding: var(--pad-block) var(--pad-inline) var(--pad-block-end);
}
.op-decisions {
  border-right: var(--rule-strong-line);
  @container (width <= 602px) {
    border-right: 0;
    border-bottom: var(--rule-strong-line);
  }
}
.op-question {
  padding: 9px 0 12px;
  border-top: var(--rule-line);
}
.op-question:first-of-type {
  padding-top: 0;
  border-top: 0;
}
.op-condition {
  margin: 0 0 3px;
  color: var(--text);
  font-size: var(--size-prose);
  font-weight: 700;
}
.op-consequence {
  margin: 0;
  color: var(--text-secondary);
  font-size: var(--size-reference);
}
.op-consequence::before {
  content: "Then: ";
  color: #9cb5c5;
  font: 500 var(--size-label)/1.5 var(--font-ui);
}
.op-callgroup {
  padding: 0 0 17px;
}
.op-callgroup + .op-callgroup {
  padding-top: 15px;
  border-top: var(--rule-line);
}
.op-call-label {
  display: block;
  margin-bottom: 7px;
  color: var(--text-muted);
  font: 500 var(--size-label)/1.5 var(--font-ui);
}
.op-callgroup code {
  color: var(--text-emphasis);
  font-size: var(--size-reference);
  line-height: 1.75;
}
.op-device code {
  color: #b9d8e9;
  font-weight: 700;
}
.op-call-note {
  margin: 8px 0 0;
  color: var(--text-muted);
  font-size: var(--size-reference);
}
.op-next {
  margin: 8px 0 0;
  color: var(--text-muted);
  font: 500 var(--size-caption)/1.65 var(--font-ui);
}
.op-next a {
  display: inline-block;
  margin: 0 10px 1px 0;
}
.op-failure {
  display: grid;
  grid-template-columns: 142px minmax(0, 1fr);
  gap: var(--op-gap);
  padding: clamp(16px, 13.69px + 0.38vw, 17px) var(--pad-inline);
  border-top: var(--rule-line);
  background: var(--surface-raised);
  @container (width <= 566px) {
    grid-template-columns: 1fr;
  }
}
.op-failure p {
  margin: 0;
  color: var(--text-secondary);
  font-size: var(--size-reference);
}

/* 5. Expanded contracts and dependencies */
.reference-detail {
  margin: 0;
  border: var(--rule-line);
  border-top: 0;
  background: var(--sidebar);
}
.reference-detail summary {
  padding: 15px 21px;
  color: var(--text);
  cursor: pointer;
  font: 500 var(--size-reference)/1.5 var(--font-ui);
  list-style-position: inside;
}
.reference-detail[open] summary {
  border-bottom: var(--rule-line);
}
.reference-detail .original-content {
  padding: clamp(15px, 12.69px + 0.38vw, 16px)
    clamp(15px, -1.15px + 2.69vw, 22px) clamp(15px, -8.08px + 3.85vw, 25px);
}
.reference-detail .original-content > p {
  margin: 9px 0 18px;
  font-size: var(--size-reference);
  line-height: 1.7;
}
.reference-detail .original-content .operation-contract {
  margin: 20px 0 0;
}
.reference-detail .original-content h4 {
  font-family: var(--font-ui);
}
.original-note {
  margin: 8px 0 0;
  color: var(--text-muted);
  font: 500 var(--size-caption)/1.6 var(--font-ui);
}
.operation-contract {
  margin: 14px 0 40px;
  border: var(--rule-line);
  background: var(--surface);
}
.contract-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
  padding: 15px 17px;
  border-bottom: var(--rule-line);
}
.contract-head strong {
  color: var(--text);
  font: 700 var(--size-reference)/1.5 var(--font-ui);
}
.contract-head span {
  color: var(--text-muted);
  font: 500 var(--size-caption)/1.5 var(--font-ui);
}
.contract-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  @media (width <= 860px) {
    grid-template-columns: 1fr;
  }
}
.contract-cell {
  min-width: 0;
  padding: 17px;
  border-inline-end: var(--rule-line);
  border-block-end: var(--rule-line);
  @media (width <= 860px) {
    border-inline-end: 0;
  }
}
.contract-cell:nth-child(2n) {
  border-inline-end: 0;
}
.contract-cell h4,
.dep-map h4 {
  margin: 0 0 10px;
  letter-spacing: 0.04em;
}
.contract-cell p,
.contract-cell ul {
  margin: 0;
  color: var(--text);
  font-size: var(--size-reference);
  line-height: 1.6;
}
.contract-cell ul {
  padding-inline-start: 22px;
}
.dep-map {
  padding: 18px 17px;
}
.dep-rows {
  display: grid;
  grid-template-columns: 118px minmax(0, 1fr);
  border-top: var(--rule-line);
  @media (width <= 860px) {
    grid-template-columns: 105px minmax(0, 1fr);
  }
}
.dep-type {
  padding: 12px 10px 12px 0;
  border-bottom: var(--rule-line);
  color: var(--text-muted);
  font: 500 var(--size-label)/1.55 var(--font-ui);
  text-transform: uppercase;
}
.dep-detail {
  padding: 12px 0 12px 13px;
  border-bottom: var(--rule-line);
  font-size: var(--size-reference);
}
.dep-detail code {
  font-size: var(--size-reference);
}
.dep-note {
  margin-top: 12px;
  color: var(--text-muted);
  font-size: var(--size-caption);
}
.keyline {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  padding: 10px 0 4px;
  color: var(--text-muted);
  font: 500 var(--size-caption)/1.5 var(--font-ui);
}
.keyline b {
  color: var(--text);
  font-weight: 700;
}

/* 6. Responsive layout is nested within each component above. */