/*
  Tandem protocol dossier.

  The visual system carries one idea: a Tandem record is two halves that mean
  nothing apart. Side A and side B each own a colour and keep it on every page,
  so a reader can always tell which half of a pair they are looking at. Colour
  is never the only signal: every side is also labelled A or B in text.
*/

:root {
  --side-a: #a82f11;
  --side-a-bright: #ff4f2e;
  --side-a-wash: #fbe8e2;
  --side-b: #1e3a8f;
  --side-b-bright: #4a67e0;
  --side-b-wash: #e6ebf9;
  --inert: #7d7d73;
  --inert-wash: #e7e5db;
  --seam: #10120f;
  --header-height: 76px;
  --dossier-max: 1180px;
}

/* ---------------------------------------------------------------- shell -- */

.dossier {
  background: var(--paper);
}

.dossier-hero {
  max-width: var(--dossier-max);
  margin: 0 auto;
  padding: 3.5rem 1.5rem 2rem;
}

.dossier-hero .eyebrow {
  color: var(--muted);
}

.dossier-hero h1 {
  font-family: var(--display);
  font-size: clamp(2.1rem, 5.4vw, 3.4rem);
  line-height: 1.05;
  letter-spacing: -0.02em;
  margin-bottom: 1rem;
}

.dossier-hero h1 em {
  font-style: italic;
}

.dossier-lede {
  max-width: 60ch;
  font-size: 1.08rem;
  color: var(--ink-soft);
}

.dossier-status {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  margin-top: 1.4rem;
  padding: 0.55rem 0.95rem;
  border: 2px solid var(--ink);
  background: var(--paper-bright);
  font-size: 0.82rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.dossier-status i {
  width: 0.6rem;
  height: 0.6rem;
  background: var(--side-a-bright);
  border-radius: 50%;
}

.dossier-shell {
  max-width: var(--dossier-max);
  margin: 0 auto;
  padding: 0 1.5rem 4rem;
  display: grid;
  gap: 2.5rem;
  grid-template-columns: 15rem minmax(0, 1fr);
  align-items: start;
}

/* The site header is sticky and 76px tall, so anything else that sticks or
   scrolls into view has to clear it. */
.dossier-side {
  position: sticky;
  top: calc(var(--header-height) + 1rem);
  max-height: calc(100vh - var(--header-height) - 2rem);
  overflow-y: auto;
  overscroll-behavior: contain;
  border: 2px solid var(--ink);
  background: var(--paper-bright);
  padding: 1.1rem;
}

.dossier-side p {
  margin: 0 0 0.6rem;
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--muted);
}

.dossier-side a {
  display: block;
  padding: 0.32rem 0;
  font-size: 0.9rem;
  text-decoration: none;
  border-bottom: 1px solid transparent;
}

.dossier-side a:hover,
.dossier-side a:focus-visible {
  border-bottom-color: var(--ink);
}

.dossier-side hr {
  border: 0;
  border-top: 1px solid var(--line);
  margin: 0.9rem 0;
}

.dossier-main {
  min-width: 0;
}

.dossier-main section {
  margin-bottom: 3.25rem;
  scroll-margin-top: calc(var(--header-height) + 1rem);
}

[id] {
  scroll-margin-top: calc(var(--header-height) + 1rem);
}

.dossier-main h2 {
  font-family: var(--display);
  font-size: clamp(1.5rem, 3.2vw, 2.1rem);
  line-height: 1.15;
  letter-spacing: -0.01em;
  padding-top: 1.1rem;
  border-top: 3px solid var(--ink);
}

.dossier-main h3 {
  font-size: 1.08rem;
  letter-spacing: -0.005em;
  margin: 1.9rem 0 0.6rem;
}

.dossier-main h4 {
  font-size: 0.95rem;
  margin: 1.4rem 0 0.5rem;
}

.dossier-main p,
.dossier-main li {
  max-width: 74ch;
}

.dossier-main ul,
.dossier-main ol {
  padding-left: 1.15rem;
}

.dossier-main li {
  margin-bottom: 0.35rem;
}

.kicker {
  margin: 0 0 0.35rem;
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--muted);
}

.lede {
  font-size: 1.03rem;
  color: var(--ink-soft);
}

/* ------------------------------------------------------------ two sides -- */

.side-tag {
  display: inline-block;
  padding: 0.06rem 0.42rem;
  border: 2px solid currentColor;
  font-family: var(--mono);
  font-size: 0.74rem;
  font-weight: 700;
  line-height: 1.5;
  white-space: nowrap;
}

.side-tag.a {
  color: var(--side-a);
  background: var(--side-a-wash);
}

.side-tag.b {
  color: var(--side-b);
  background: var(--side-b-wash);
}

.side-tag.inert {
  color: var(--inert);
  background: var(--inert-wash);
  border-style: dashed;
}

/* The seam: two panels that only read as one thing when both are filled. */
.pair-band {
  display: grid;
  grid-template-columns: 1fr 1fr;
  border: 2px solid var(--ink);
  background: var(--paper-bright);
  margin: 1.4rem 0;
}

.pair-band > div {
  padding: 1.1rem 1.2rem;
  min-width: 0;
}

.pair-band > div:first-child {
  border-right: 2px dashed var(--seam);
  box-shadow: inset 0.35rem 0 0 -0.1rem var(--side-a-bright);
}

.pair-band > div:last-child {
  box-shadow: inset -0.35rem 0 0 -0.1rem var(--side-b-bright);
}

.pair-band h4 {
  margin: 0 0 0.5rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.pair-band p:last-child,
.pair-band ul:last-child {
  margin-bottom: 0;
}

/* ------------------------------------------------------------ notations -- */

.dossier-main code {
  font-family: var(--mono);
  font-size: 0.88em;
  background: var(--inert-wash);
  padding: 0.08rem 0.3rem;
  word-break: break-word;
}

.code {
  border: 2px solid var(--ink);
  background: var(--paper-bright);
  padding: 0.9rem 1rem;
  overflow-x: auto;
  margin: 1rem 0;
}

.code pre {
  margin: 0;
  font-family: var(--mono);
  font-size: 0.85rem;
  line-height: 1.6;
  white-space: pre;
}

.code code {
  background: none;
  padding: 0;
  font-size: inherit;
}

.code-label {
  display: block;
  margin-bottom: 0.55rem;
  font-size: 0.7rem;
  font-weight: 800;
  letter-spacing: 0.13em;
  text-transform: uppercase;
  color: var(--muted);
}

.scroll-x {
  overflow-x: auto;
  margin: 1.1rem 0;
  border: 2px solid var(--ink);
  background: var(--paper-bright);
}

table.tbl {
  border-collapse: collapse;
  width: 100%;
  min-width: 30rem;
  font-size: 0.88rem;
}

table.tbl caption {
  text-align: left;
  padding: 0.7rem 0.85rem 0;
  font-size: 0.78rem;
  font-weight: 700;
  color: var(--muted);
}

table.tbl th,
table.tbl td {
  padding: 0.5rem 0.85rem;
  text-align: left;
  vertical-align: top;
  border-bottom: 1px solid var(--line);
}

table.tbl thead th {
  border-bottom: 2px solid var(--ink);
  font-size: 0.74rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  white-space: nowrap;
}

table.tbl tbody tr:last-child th,
table.tbl tbody tr:last-child td {
  border-bottom: 0;
}

table.tbl td code,
table.tbl th code {
  white-space: nowrap;
}

/* ---------------------------------------------------------------- rules -- */

.rule {
  border-left: 4px solid var(--ink);
  padding: 0.1rem 0 0.1rem 0.95rem;
  margin: 1.1rem 0;
}

.rule > p:last-child {
  margin-bottom: 0;
}

.rule-id {
  display: inline-block;
  margin-bottom: 0.3rem;
  font-family: var(--mono);
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.03em;
  color: var(--ink);
  background: var(--acid);
  padding: 0.05rem 0.4rem;
}

.rule-src {
  display: block;
  margin-top: 0.35rem;
  font-size: 0.78rem;
  color: var(--muted);
}

.note {
  border: 2px solid var(--ink);
  background: var(--paper-bright);
  padding: 0.95rem 1.1rem;
  margin: 1.3rem 0;
}

.note > :last-child {
  margin-bottom: 0;
}

.note strong:first-child {
  display: block;
  margin-bottom: 0.35rem;
}

.note.warn {
  border-color: var(--side-a);
  background: var(--side-a-wash);
}

.note.errata {
  border-style: dashed;
}

/* ------------------------------------------------------------- diagrams -- */

figure.diagram {
  margin: 1.6rem 0;
  border: 2px solid var(--ink);
  background: var(--paper-bright);
  padding: 1.1rem;
}

figure.diagram svg {
  width: 100%;
  height: auto;
}

figure.diagram figcaption {
  margin-top: 0.8rem;
  font-size: 0.85rem;
  color: var(--muted);
  max-width: 70ch;
}

.legend {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1rem;
  margin-top: 0.7rem;
  font-size: 0.8rem;
  color: var(--ink-soft);
}

.legend span {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
}

.legend i {
  width: 0.85rem;
  height: 0.85rem;
  border: 2px solid var(--ink);
}

.legend i.a { background: var(--side-a-bright); }
.legend i.b { background: var(--side-b-bright); }
.legend i.inert { background: var(--inert-wash); border-style: dashed; }

/* ----------------------------------------------------------- link cards -- */

.card-grid {
  display: grid;
  gap: 1rem;
  grid-template-columns: repeat(auto-fit, minmax(15rem, 1fr));
  margin: 1.4rem 0;
}

.card-grid a,
.card-grid article {
  display: block;
  border: 2px solid var(--ink);
  background: var(--paper-bright);
  padding: 1rem 1.05rem;
  text-decoration: none;
}

.card-grid a:hover,
.card-grid a:focus-visible {
  background: var(--acid);
}

.card-grid strong {
  display: block;
  margin-bottom: 0.25rem;
}

.card-grid small {
  color: var(--muted);
  font-size: 0.83rem;
  line-height: 1.5;
  display: block;
}

.page-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  justify-content: space-between;
  border-top: 3px solid var(--ink);
  padding-top: 1.1rem;
  margin-top: 2.5rem;
}

.page-nav a {
  font-weight: 700;
  text-decoration: none;
  border-bottom: 2px solid var(--ink);
}

/* ------------------------------------------------------------ the tool --- */

.tool {
  border: 3px solid var(--ink);
  background: var(--paper-bright);
  margin: 1.5rem 0;
}

.tool-head {
  padding: 1rem 1.15rem;
  border-bottom: 2px solid var(--ink);
}

.tool-head h3 {
  margin: 0 0 0.3rem;
}

.tool-head p {
  margin: 0;
  font-size: 0.9rem;
  color: var(--ink-soft);
}

.tool-sides {
  display: grid;
  grid-template-columns: 1fr 1fr;
}

.tool-sides > div {
  padding: 1rem 1.15rem;
  min-width: 0;
}

.tool-sides > div:first-child {
  border-right: 2px dashed var(--seam);
}

.tool label {
  display: block;
  margin-bottom: 0.4rem;
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.tool textarea,
.tool input[type="text"],
.tool select {
  width: 100%;
  border: 2px solid var(--ink);
  background: var(--white);
  color: var(--ink);
  padding: 0.55rem 0.6rem;
  font-family: var(--mono);
  font-size: 0.82rem;
  line-height: 1.5;
}

.tool textarea {
  min-height: 5.5rem;
  resize: vertical;
  word-break: break-all;
}

.tool .hint {
  margin: 0.45rem 0 0;
  font-size: 0.78rem;
  color: var(--muted);
  font-family: var(--body);
}

.tool-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  align-items: center;
  padding: 0 1.15rem 1.15rem;
}

.tool button {
  border: 2px solid var(--ink);
  background: var(--ink);
  color: var(--paper-bright);
  padding: 0.5rem 1rem;
  font-weight: 700;
  cursor: pointer;
}

.tool button.ghost {
  background: var(--paper-bright);
  color: var(--ink);
}

.tool button:hover {
  background: var(--side-a);
  border-color: var(--side-a);
  color: var(--white);
}

.tool button.ghost:hover {
  background: var(--acid);
  color: var(--ink);
  border-color: var(--ink);
}

.verdict {
  border-top: 2px solid var(--ink);
  padding: 1rem 1.15rem;
}

.verdict-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0.6rem;
  margin-bottom: 0.7rem;
}

.verdict-flag {
  font-family: var(--mono);
  font-weight: 700;
  font-size: 0.82rem;
  padding: 0.15rem 0.55rem;
  border: 2px solid var(--ink);
}

.verdict-flag.pass {
  background: var(--acid);
}

.verdict-flag.fail {
  background: var(--side-a-wash);
  border-color: var(--side-a);
  color: var(--side-a);
}

.verdict-flag.idle {
  background: var(--inert-wash);
  border-style: dashed;
  color: var(--inert);
}

.verdict-note {
  font-size: 0.9rem;
  color: var(--ink-soft);
  margin: 0;
}

ol.checks {
  list-style: none;
  padding: 0;
  margin: 0.9rem 0 0;
  border-top: 1px solid var(--line);
}

ol.checks li {
  display: grid;
  grid-template-columns: 1.6rem minmax(0, 1fr);
  gap: 0.7rem;
  padding: 0.55rem 0;
  border-bottom: 1px solid var(--line);
  max-width: none;
  margin: 0;
}

ol.checks li > b {
  font-family: var(--mono);
  font-weight: 700;
  font-size: 0.9rem;
  text-align: center;
}

ol.checks li.ok > b { color: var(--side-b); }
ol.checks li.bad > b { color: var(--side-a); }
ol.checks li.skip > b { color: var(--inert); }

ol.checks .check-rule {
  font-family: var(--mono);
  font-size: 0.74rem;
  color: var(--muted);
  display: block;
  margin-top: 0.2rem;
}

ol.checks .check-detail {
  font-family: var(--mono);
  font-size: 0.78rem;
  word-break: break-all;
  display: block;
  margin-top: 0.2rem;
}

.derived {
  margin: 0.9rem 0 0;
}

.derived div {
  display: grid;
  grid-template-columns: 11rem minmax(0, 1fr);
  gap: 0.7rem;
  padding: 0.35rem 0;
  border-bottom: 1px solid var(--line);
}

.derived dt {
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--muted);
}

.derived dd {
  margin: 0;
  font-family: var(--mono);
  font-size: 0.79rem;
  word-break: break-all;
}

.selftest {
  border: 2px solid var(--ink);
  background: var(--paper-bright);
  padding: 1rem 1.15rem;
  margin: 1.4rem 0;
}

.selftest ul {
  list-style: none;
  padding: 0;
  margin: 0.7rem 0 0;
  font-family: var(--mono);
  font-size: 0.82rem;
}

.selftest li {
  padding: 0.25rem 0;
  border-bottom: 1px solid var(--line);
  max-width: none;
}

.selftest li:last-child { border-bottom: 0; }
.selftest li b { display: inline-block; width: 2.2rem; }
.selftest li.ok b { color: var(--side-b); }
.selftest li.bad b { color: var(--side-a); }

.noscript-note {
  border: 2px dashed var(--ink);
  padding: 0.9rem 1.1rem;
  margin: 1.3rem 0;
  background: var(--inert-wash);
}

/* --------------------------------------------------------- responsive --- */

@media (max-width: 62rem) {
  .dossier-shell {
    grid-template-columns: minmax(0, 1fr);
  }

  .dossier-side {
    position: static;
    max-height: none;
    overflow-y: visible;
  }
}

@media (max-width: 44rem) {
  .pair-band,
  .tool-sides {
    grid-template-columns: minmax(0, 1fr);
  }

  .pair-band > div:first-child,
  .tool-sides > div:first-child {
    border-right: 0;
    border-bottom: 2px dashed var(--seam);
  }

  .pair-band > div:first-child {
    box-shadow: inset 0 0.35rem 0 -0.1rem var(--side-a-bright);
  }

  .pair-band > div:last-child {
    box-shadow: inset 0 -0.35rem 0 -0.1rem var(--side-b-bright);
  }

  .derived div {
    grid-template-columns: minmax(0, 1fr);
    gap: 0.15rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
}