/* zray — official site
   Design brief: engineering drawing on warm paper. Light, hairline-ruled,
   serif headings against a sans body, one rust accent. No dark terminal,
   no gradient mesh, no glassmorphism. */

:root {
  --paper: #faf8f4;
  --paper-2: #f3efe7;
  --ink: #16202e;
  --ink-2: #4b5563;
  --ink-3: #7a828e;
  --line: #e2dcd0;
  --line-2: #cfc7b8;
  --accent: #b4451e;
  --accent-soft: #f4e5dc;
  --ok: #1f6f5c;

  --serif: "Iowan Old Style", "Palatino Linotype", Palatino, "Source Serif 4",
    Georgia, "Songti SC", "Noto Serif CJK SC", "Noto Serif SC", serif;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans CJK SC", Roboto,
    Helvetica, Arial, sans-serif;
  --mono: ui-monospace, SFMono-Regular, "SF Mono", "JetBrains Mono", Menlo,
    Consolas, "Liberation Mono", monospace;

  --measure: 62ch;
  --page: 1080px;
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.75;
  font-feature-settings: "kern" 1;
  text-rendering: optimizeLegibility;
}

/* language switch: only one of the two variants is laid out */
html[data-lang="zh"] [lang="en"] { display: none !important; }
html[data-lang="en"] [lang="zh"] { display: none !important; }

a { color: var(--ink); text-decoration: none; border-bottom: 1px solid var(--line-2); }
a:hover { border-bottom-color: var(--accent); color: var(--accent); }

h1, h2, h3 {
  font-family: var(--serif);
  font-weight: 600;
  letter-spacing: -0.01em;
  line-height: 1.2;
  margin: 0;
}

p { margin: 0 0 1em; }
p:last-child { margin-bottom: 0; }

code, pre, .num { font-family: var(--mono); font-variant-numeric: tabular-nums; }

/* long shell snippets inside body text must be allowed to break */
code { overflow-wrap: anywhere; }

.wrap {
  width: 100%;
  max-width: var(--page);
  margin: 0 auto;
  padding: 0 28px;
}

/* ---------- header ---------- */

header.site {
  position: sticky;
  top: 0;
  z-index: 20;
  background: color-mix(in srgb, var(--paper) 92%, transparent);
  backdrop-filter: blur(6px);
  border-bottom: 1px solid var(--line);
}

header.site .wrap {
  display: flex;
  align-items: center;
  gap: 22px;
  min-height: 60px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 9px;
  border: 0;
  font-family: var(--mono);
  font-size: 16px;
  letter-spacing: 0.06em;
  color: var(--ink);
}
.brand:hover { color: var(--ink); border: 0; }
.brand svg { display: block; }

nav.main {
  display: flex;
  gap: 18px;
  margin-left: auto;
  font-size: 14px;
}
nav.main a {
  border: 0;
  color: var(--ink-2);
  padding: 4px 0;
}
nav.main a:hover { color: var(--accent); }

.langswitch {
  display: flex;
  border: 1px solid var(--line-2);
  border-radius: 2px;
  overflow: hidden;
  font-family: var(--mono);
  font-size: 12px;
}
.langswitch button {
  appearance: none;
  border: 0;
  background: transparent;
  color: var(--ink-3);
  font: inherit;
  padding: 3px 8px;
  cursor: pointer;
}
.langswitch button[aria-pressed="true"] { background: var(--ink); color: var(--paper); }

@media (max-width: 780px) {
  nav.main { display: none; }
}

/* ---------- hero ---------- */

.hero {
  border-bottom: 1px solid var(--line);
  background-image:
    linear-gradient(var(--paper-2) 1px, transparent 1px),
    linear-gradient(90deg, var(--paper-2) 1px, transparent 1px);
  background-size: 96px 96px, 96px 96px;
  background-position: -1px -1px;
}
.hero .wrap {
  display: grid;
  grid-template-columns: minmax(0, 1.15fr) minmax(0, 0.85fr);
  gap: 64px;
  align-items: start;
  padding-top: 84px;
  padding-bottom: 84px;
}
@media (max-width: 900px) {
  .hero .wrap { grid-template-columns: 1fr; gap: 44px; padding-top: 56px; padding-bottom: 56px; }
}

.eyebrow {
  font-family: var(--mono);
  font-size: 12.5px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-3);
  margin: 0 0 18px;
  display: flex;
  align-items: center;
  gap: 10px;
}
.eyebrow::before {
  content: "";
  width: 26px;
  height: 1px;
  background: var(--accent);
  display: block;
}

.hero h1 {
  font-size: clamp(34px, 4.6vw, 54px);
  margin: 0 0 20px;
}
.hero h1 em {
  font-style: normal;
  border-bottom: 3px solid var(--accent-soft);
  box-shadow: inset 0 -0.32em 0 var(--accent-soft);
}

.lede {
  font-size: 18px;
  color: var(--ink-2);
  max-width: 46ch;
}

.cta {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 30px;
}
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 11px 20px;
  border: 1px solid var(--ink);
  border-radius: 2px;
  font-size: 15px;
  font-weight: 500;
  background: var(--ink);
  color: var(--paper);
  border-bottom-width: 1px;
}
.btn:hover { background: var(--accent); border-color: var(--accent); color: #fff; }
.btn.ghost { background: transparent; color: var(--ink); border-color: var(--line-2); }
.btn.ghost:hover { background: transparent; border-color: var(--accent); color: var(--accent); }

/* the measurement card */
.spec {
  border: 1px solid var(--line-2);
  background: var(--paper);
  padding: 0;
}
.spec-head {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: baseline;
  gap: 4px 12px;
  padding: 12px 18px;
  border-bottom: 1px solid var(--line);
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-3);
}
.spec dl { margin: 0; }
.spec .row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 16px;
  padding: 13px 18px;
  border-bottom: 1px solid var(--line);
}
.spec .row:last-child { border-bottom: 0; }
.spec dt { font-size: 14px; color: var(--ink-2); }
.spec dd {
  margin: 0;
  font-family: var(--mono);
  font-size: 15px;
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}
.spec dd b { font-weight: 600; font-size: 17px; }
.spec-foot {
  padding: 11px 18px 12px;
  border-top: 1px solid var(--line);
  background: var(--paper-2);
  font-size: 12.5px;
  color: var(--ink-3);
  font-family: var(--mono);
}

/* ---------- sections ---------- */

section { border-bottom: 1px solid var(--line); }
section > .wrap { padding-top: 76px; padding-bottom: 76px; }

.sechead {
  display: grid;
  grid-template-columns: 74px minmax(0, 1fr);
  gap: 18px;
  align-items: baseline;
  margin-bottom: 40px;
}
@media (max-width: 620px) {
  .sechead { grid-template-columns: 1fr; gap: 6px; margin-bottom: 28px; }
}
.sechead .n {
  font-family: var(--mono);
  font-size: 13px;
  color: var(--accent);
  letter-spacing: 0.08em;
}
.sechead h2 { font-size: clamp(24px, 3vw, 32px); }
.sechead .sub {
  grid-column: 2;
  color: var(--ink-2);
  max-width: var(--measure);
  margin-top: 10px;
}
@media (max-width: 620px) { .sechead .sub { grid-column: 1; } }

.prose { max-width: var(--measure); color: var(--ink-2); }
.prose strong { color: var(--ink); font-weight: 600; }

/* three constraints */
.constraints {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0;
  border: 1px solid var(--line-2);
}
@media (max-width: 860px) { .constraints { grid-template-columns: 1fr; } }
.constraint {
  padding: 26px 24px 28px;
  border-right: 1px solid var(--line);
}
.constraint:last-child { border-right: 0; }
@media (max-width: 860px) {
  .constraint { border-right: 0; border-bottom: 1px solid var(--line); }
  .constraint:last-child { border-bottom: 0; }
}
.constraint h3 { font-size: 19px; margin-bottom: 10px; }
.constraint .stat {
  font-family: var(--mono);
  font-size: 27px;
  font-variant-numeric: tabular-nums;
  color: var(--accent);
  letter-spacing: -0.02em;
  margin-bottom: 4px;
}
.constraint .unit { font-size: 12.5px; color: var(--ink-3); font-family: var(--mono); letter-spacing: 0.04em; }
.constraint p { font-size: 15px; color: var(--ink-2); margin-top: 12px; }

/* the connection cross-section: a depth spine on the left, full-width prose on the right */
.stack-cap {
  display: grid;
  grid-template-columns: 212px minmax(0, 1fr);
  gap: 0 28px;
  font-family: var(--mono);
  font-size: 11.5px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-3);
  padding-bottom: 11px;
}
.stack-cap .cap-r { opacity: 0.78; text-transform: none; letter-spacing: 0.02em; }
@media (max-width: 720px) {
  .stack-cap { grid-template-columns: 1fr; gap: 3px; }
}

.stack {
  position: relative;
  border-top: 1px solid var(--line-2);
}

/* one continuous spine; depth is the length of each tick */
.stack::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 1px;
  background: var(--line-2);
}

.layer {
  display: grid;
  grid-template-columns: 212px minmax(0, 1fr);
  gap: 0 28px;
  padding: 19px 0 21px;
  border-bottom: 1px solid var(--line);
}

.rail {
  position: relative;
  padding-left: calc(var(--depth) * 18px + 16px);
}
.rail::after {
  content: "";
  position: absolute;
  left: 0;
  top: 9px;
  width: calc(var(--depth) * 18px + 13px);
  height: 1px;
  background: rgba(22, 32, 46, 0.26);
}

.lname {
  font-family: var(--mono);
  font-size: 12.5px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ink);
  line-height: 1.5;
}

.lbody {
  display: flex;
  flex-direction: column;
  gap: 12px;
  min-width: 0;
}

.ldesc {
  max-width: 72ch;
  font-size: 14.5px;
  line-height: 1.8;
  color: var(--ink-2);
  margin: 0;
}
.ldesc code {
  font-size: 13px;
  background: var(--paper-2);
  padding: 1px 4px;
  border-radius: 2px;
}

.lmeta {
  font-family: var(--mono);
  font-size: 10.8px;
  color: #7e848d;
  letter-spacing: 0.02em;
  overflow-wrap: anywhere;
}

/* the one ring where identity is proven */
.layer.is-key {
  background: linear-gradient(90deg, #f7ebe3, rgba(247, 235, 227, 0) 58%);
  box-shadow: inset 0 0 0 1px var(--line-2);
  margin: 8px 0;
  padding-top: 23px;
  padding-bottom: 25px;
}
.layer.is-key .rail::after { background: var(--accent); }
.layer.is-key .lname { color: var(--accent); }

/* innermost ring: the bytes you actually care about */
.layer.is-core {
  background: var(--paper-2);
  box-shadow: inset 0 0 0 1px var(--line-2);
  margin: 8px 0;
  padding-top: 23px;
  padding-bottom: 25px;
}
.layer.is-core .lname { font-weight: 600; }

/* off the data path: same rail language, three callouts */
.bypass {
  margin-top: 66px;
  border-top: 1px solid var(--line-2);
  padding-top: 20px;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 26px 40px;
}
.bypass-cap {
  grid-column: 1 / -1;
  font-family: var(--mono);
  font-size: 11.5px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-3);
  margin-bottom: 4px;
}
.bypass-item {
  position: relative;
  padding-left: 17px;
  border-left: 1px solid var(--line);
}
.bypass-item::before {
  content: "";
  position: absolute;
  left: 0;
  top: 8px;
  width: 9px;
  height: 1px;
  background: var(--line-2);
}
.bypass-item h3 {
  font-family: var(--serif);
  font-size: 17px;
  margin-bottom: 7px;
}
.bypass-item p {
  font-size: 14px;
  line-height: 1.72;
  color: var(--ink-2);
}
.bypass-item p code {
  font-size: 12.5px;
  background: var(--paper-2);
  padding: 1px 4px;
}
.bypass-item .lmeta {
  display: block;
  margin-top: 11px;
  padding-top: 9px;
  border-top: 1px solid var(--line);
}

@media (max-width: 860px) {
  .bypass { grid-template-columns: 1fr; gap: 22px; }
}
@media (max-width: 720px) {
  .layer { grid-template-columns: 1fr; gap: 7px; padding: 17px 0 19px; }
  .rail { padding-left: calc(var(--depth) * 12px + 15px); }
  .rail::after { width: calc(var(--depth) * 12px + 12px); top: 8px; }
  .ldesc { font-size: 14px; line-height: 1.74; }
}

/* data tables */
.tablewrap { overflow-x: auto; border: 1px solid var(--line-2); }
table {
  width: 100%;
  border-collapse: collapse;
  font-size: 14.5px;
  background: var(--paper);
}
thead th {
  text-align: left;
  font-family: var(--mono);
  font-size: 11.5px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-3);
  font-weight: 500;
  padding: 11px 16px;
  border-bottom: 1px solid var(--line-2);
  background: var(--paper-2);
  white-space: nowrap;
}
tbody td, tbody th {
  padding: 13px 16px;
  border-bottom: 1px solid var(--line);
  text-align: left;
  vertical-align: top;
}
tbody th { font-weight: 500; color: var(--ink); }
tbody tr:last-child td, tbody tr:last-child th { border-bottom: 0; }
td.num, th.num { text-align: right; font-family: var(--mono); font-variant-numeric: tabular-nums; white-space: nowrap; }
tbody td code { font-size: 13px; background: var(--paper-2); padding: 1px 5px; border-radius: 2px; }

.note {
  margin-top: 18px;
  font-size: 14px;
  color: var(--ink-3);
  max-width: var(--measure);
}

/* code blocks */
.code {
  border: 1px solid var(--line-2);
  background: #fff;
  margin: 0 0 22px;
}
.code-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 9px 14px;
  border-bottom: 1px solid var(--line);
  background: var(--paper-2);
  font-family: var(--mono);
  font-size: 12px;
  color: var(--ink-3);
  letter-spacing: 0.04em;
}
.copy {
  appearance: none;
  border: 1px solid var(--line-2);
  background: var(--paper);
  color: var(--ink-2);
  font-family: var(--mono);
  font-size: 11.5px;
  padding: 3px 8px;
  border-radius: 2px;
  cursor: pointer;
}
.copy:hover { border-color: var(--accent); color: var(--accent); }
pre {
  margin: 0;
  padding: 16px 18px;
  overflow-x: auto;
  font-size: 13.5px;
  line-height: 1.62;
  color: #24303f;
  background: #fff;
}
pre .c { color: var(--ink-3); }
pre .k { color: var(--accent); }

/* install grid */
.cols2 > * { min-width: 0; }

.cols2 {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: 40px;
  align-items: start;
}
@media (max-width: 860px) { .cols2 { grid-template-columns: 1fr; gap: 28px; } }

h3.blocktitle {
  font-size: 15px;
  font-family: var(--mono);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ink-3);
  font-weight: 500;
  margin: 0 0 14px;
}

.d-v { display: none; }

/* flow diagram */
.diagram { border: 1px solid var(--line-2); background: #fff; padding: 8px; overflow-x: auto; }
.diagram svg { display: block; width: 100%; height: auto; }

/* docs list */
.doclist { list-style: none; padding: 0; margin: 0; border-top: 1px solid var(--line); }
.doclist li { border-bottom: 1px solid var(--line); }
.doclist a {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 16px;
  align-items: baseline;
  padding: 18px 4px;
  border: 0;
}
.doclist .t { font-size: 16.5px; font-weight: 500; }
.doclist .d { display: block; font-size: 14px; color: var(--ink-2); font-weight: 400; margin-top: 3px; }
.doclist .meta { font-family: var(--mono); font-size: 12px; color: var(--ink-3); white-space: nowrap; }
.doclist a:hover .t { color: var(--accent); }

@media (max-width: 640px) {
  .wrap { padding-left: 22px; padding-right: 22px; }
  .doclist a { grid-template-columns: minmax(0, 1fr); gap: 6px; }
  .doclist .meta { white-space: normal; }
  .spec dd { white-space: normal; }
  .spec .row { gap: 10px; }

  /* keep the data tables readable without sideways scrolling */
  table { font-size: 13.5px; }
  thead th { padding: 9px 10px; white-space: normal; }
  tbody td, tbody th { padding: 10px; }
  td.num, th.num { white-space: normal; }
  tbody td code { overflow-wrap: anywhere; }
  .tablewrap { -webkit-overflow-scrolling: touch; }

  /* the diagram gets a vertical layout of its own on phones */
  .d-h { display: none; }
  .d-v { display: block; }

  /* commands wrap instead of scrolling sideways out of view */
  pre { white-space: pre-wrap; overflow-wrap: anywhere; font-size: 12.5px; padding: 14px; }
}

/* footer */
footer.site { background: var(--paper-2); border-top: 1px solid var(--line-2); }
footer.site .wrap {
  display: flex;
  flex-wrap: wrap;
  gap: 16px 28px;
  align-items: baseline;
  padding-top: 34px;
  padding-bottom: 40px;
  font-size: 13.5px;
  color: var(--ink-3);
}
footer.site a { color: var(--ink-2); border-bottom-color: var(--line-2); }
footer .spacer { margin-left: auto; }

.tag {
  display: inline-block;
  font-family: var(--mono);
  font-size: 11.5px;
  letter-spacing: 0.06em;
  padding: 2px 7px;
  border: 1px solid var(--line-2);
  border-radius: 2px;
  color: var(--ink-3);
  vertical-align: middle;
}
.tag.warn { border-color: #d9b9a5; color: var(--accent); background: var(--accent-soft); }

:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

@media (prefers-reduced-motion: no-preference) {
  html { scroll-behavior: smooth; }
}