/* ===========================================================
   Opcio Data — editorial technical reference
   Design: "Slate & Paper" — serif display over warm paper,
   hairline rules, numbered index, no cards, no drop shadows.
   Deliberately unlike a conference/marketing template.
   =========================================================== */

:root {
  --ink:        #1b1b1a;
  --ink-soft:   #4a4f56;
  --ink-faint:  #77808a;

  --slate-900:  #10243a;
  --slate-800:  #1b3a5c;
  --slate-600:  #2f5b85;
  --slate-300:  #97b0c6;

  --paper:      #f7f4ef;
  --paper-2:    #efeae1;
  --paper-3:    #e6dfd3;
  --white:      #ffffff;

  --accent:     #c2703d;
  --accent-dk:  #9d5527;

  --rule:       #d8d0c3;
  --rule-strong:#b9ae9c;

  --measure:    68ch;
  --shell:      1180px;

  --f-display: "Spectral", Georgia, "Times New Roman", serif;
  --f-body:    "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
  --f-mono:    "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, monospace;
}

/* ---- safeguard: content is NEVER hidden waiting on JS ---- */
[data-aos] { opacity: 1 !important; transform: none !important; }

*, *::before, *::after { box-sizing: border-box; }

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

body.od {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--f-body);
  font-size: 1.0625rem;
  line-height: 1.72;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

img { max-width: 100%; height: auto; }

a { color: var(--slate-800); text-decoration-color: var(--slate-300); text-underline-offset: 3px; }
a:hover { color: var(--accent-dk); text-decoration-color: var(--accent); }

.od-shell { width: 100%; max-width: var(--shell); margin: 0 auto; padding: 0 1.5rem; }

.od-skip {
  position: absolute; left: -9999px; top: 0; z-index: 999;
  background: var(--slate-800); color: var(--white); padding: .75rem 1.25rem;
}
.od-skip:focus { left: 0; }

.od-eyebrow {
  font-family: var(--f-mono);
  font-size: .72rem; letter-spacing: .16em; text-transform: uppercase;
  color: var(--accent-dk); margin: 0 0 .85rem;
}

/* ============================ NAV ============================ */
.od-nav {
  background: var(--slate-900);
  border-bottom: 3px solid var(--accent);
  position: relative; z-index: 40;
}
.od-nav__inner {
  display: flex; align-items: center; justify-content: space-between;
  gap: 1rem; min-height: 68px; flex-wrap: wrap;
}
.od-brand {
  display: inline-flex; align-items: center; gap: .6rem;
  text-decoration: none; flex: 0 0 auto; min-width: 0;
}
.od-brand__mark {
  width: 13px; height: 26px; background: var(--accent);
  display: inline-block; flex: 0 0 auto;
}
.od-brand__text {
  font-family: var(--f-display); font-weight: 700; font-size: 1.4rem;
  color: var(--paper); letter-spacing: -0.01em; white-space: nowrap;
}
.od-brand__text em { font-style: italic; font-weight: 400; color: var(--slate-300); }

.od-burger {
  display: none; background: none; border: 1px solid #35516d;
  padding: .55rem .6rem; cursor: pointer; border-radius: 2px;
}
.od-burger span { display: block; width: 20px; height: 2px; background: var(--paper); margin: 4px 0; }

.od-menu { flex: 1 1 auto; min-width: 0; display: flex; justify-content: flex-end; }
.od-menu__list {
  list-style: none; margin: 0; padding: 0;
  display: flex; align-items: center; gap: 1.6rem;
  flex-wrap: wrap; min-width: 0;              /* nav-overflow guard */
  justify-content: flex-end;
}
.od-menu__link, .od-menu__label {
  font-size: .82rem; letter-spacing: .07em; text-transform: uppercase;
  font-weight: 500; color: var(--slate-300); text-decoration: none;
  padding: .35rem 0; display: inline-block; white-space: nowrap; cursor: default;
}
.od-menu__link { cursor: pointer; }
.od-menu__link:hover, .od-menu__label:hover { color: var(--white); }
.od-menu__link.is-current { color: var(--white); box-shadow: inset 0 -2px 0 var(--accent); }

.od-menu__topics { position: relative; }
.od-drop {
  list-style: none; margin: 0; padding: .5rem 0;
  position: absolute; top: 100%; right: 0; min-width: 300px;
  background: var(--slate-900); border: 1px solid #2b4763; border-top: 2px solid var(--accent);
  display: none; z-index: 60;
}
.od-menu__topics:hover .od-drop,
.od-menu__topics:focus-within .od-drop,
.od-menu__topics.is-open .od-drop { display: block; }
.od-drop__link {
  display: flex; gap: .7rem; align-items: baseline;
  padding: .5rem 1.1rem; color: var(--slate-300); text-decoration: none;
  font-size: .9rem; text-transform: none; letter-spacing: 0;
}
.od-drop__link:hover { background: #17324e; color: var(--white); }
.od-drop__link.is-current { color: var(--white); }
.od-drop__num { font-family: var(--f-mono); font-size: .72rem; color: var(--accent); }

/* ============================ HERO ============================ */
.od-hero { position: relative; background: var(--slate-900); overflow: hidden; }
.od-hero__media { position: absolute; inset: 0; }
.od-hero__media img { width: 100%; height: 100%; object-fit: cover; opacity: .5; }
.od-hero__inner { position: relative; padding: 5.5rem 1.5rem 4.5rem; }
.od-hero__panel {
  background: rgba(10, 22, 36, .82);
  border-left: 4px solid var(--accent);
  padding: 2.4rem 2.4rem 2.6rem;
  max-width: 700px;
}
.od-hero__title {
  font-family: var(--f-display); font-weight: 700;
  font-size: clamp(1.95rem, 4.4vw, 3rem); line-height: 1.16;
  color: var(--white); margin: 0 0 1rem; letter-spacing: -0.015em;
}
.od-hero__lede { color: #c9d6e2; font-size: 1.06rem; margin: 0 0 1.7rem; max-width: 56ch; }
.od-cta {
  display: inline-block; font-family: var(--f-mono); font-size: .78rem;
  letter-spacing: .14em; text-transform: uppercase; text-decoration: none;
  color: var(--slate-900); background: var(--accent);
  padding: .8rem 1.5rem; border: 0;
  transition: background .18s ease, transform .18s ease;
}
.od-cta:hover { background: var(--white); color: var(--slate-900); transform: translateY(-1px); }

/* ---- article page header ---- */
.od-phead { background: var(--slate-900); padding: 2.6rem 0 2.4rem; border-bottom: 3px solid var(--accent); }
.od-phead .od-eyebrow { color: var(--accent); margin-bottom: .5rem; }
.od-phead__desc {
  font-family: var(--f-display); font-size: clamp(1.05rem, 2.1vw, 1.3rem);
  font-style: italic; color: #c9d6e2; margin: 0; max-width: 62ch; line-height: 1.55;
}

/* ============================ PROSE ============================ */
/* NB: .od-layout shares an element with .od-shell — it must never set
   horizontal padding, or it clobbers the shell gutter and text runs to
   the viewport edge on narrow screens. Vertical only. */
.od-layout { padding-top: 0; padding-bottom: 0; }
.od-prose { max-width: var(--measure); margin: 0 auto; padding: 3.2rem 0 1rem; }
.od-prose--home { padding-bottom: 2.5rem; }

.od-prose h1 {
  font-family: var(--f-display); font-weight: 700;
  font-size: clamp(2rem, 4.6vw, 2.85rem); line-height: 1.14;
  letter-spacing: -0.02em; margin: 0 0 1.4rem; color: var(--slate-900);
}
.od-prose h2 {
  font-family: var(--f-display); font-weight: 600;
  font-size: clamp(1.35rem, 2.7vw, 1.72rem); line-height: 1.28;
  margin: 2.8rem 0 .9rem; color: var(--slate-800);
  padding-top: 1.4rem; border-top: 1px solid var(--rule);
}
.od-prose h3 {
  font-family: var(--f-body); font-weight: 600;
  font-size: 1.06rem; letter-spacing: .01em;
  margin: 1.9rem 0 .55rem; color: var(--slate-900);
}
.od-prose p { margin: 0 0 1.25rem; }
.od-prose > p:first-of-type {
  font-size: 1.16rem; line-height: 1.66; color: var(--ink-soft);
}
.od-prose ul, .od-prose ol { margin: 0 0 1.35rem; padding-left: 1.3rem; }
.od-prose li { margin-bottom: .6rem; }
.od-prose li::marker { color: var(--accent); }
.od-prose strong { font-weight: 600; color: var(--slate-900); }
.od-prose em { font-style: italic; }
.od-prose a { font-weight: 500; }

.od-figure { margin: 2rem 0 2.4rem; }
.od-figure__img { width: 100%; display: block; border: 1px solid var(--rule-strong); }

/* ============================ INDEX ============================ */
.od-index { background: var(--paper-2); border-top: 1px solid var(--rule); padding: 3.4rem 0 4rem; margin-top: 1rem; }
.od-index__list { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(2, 1fr); gap: 0; }
.od-index__item { border-top: 1px solid var(--rule); }
.od-index__item:nth-child(odd) { border-right: 1px solid var(--rule); }
.od-index__link {
  display: flex; gap: 1.1rem; align-items: baseline;
  padding: 1.4rem 1.6rem 1.4rem 0; text-decoration: none; color: inherit;
  transition: background .16s ease, padding-left .16s ease;
}
.od-index__item:nth-child(odd) .od-index__link { padding-right: 2.2rem; }
.od-index__link:hover { background: var(--paper-3); padding-left: .6rem; }
.od-index__num { font-family: var(--f-mono); font-size: .8rem; color: var(--accent-dk); flex: 0 0 auto; }
.od-index__body { display: block; min-width: 0; }
.od-index__title {
  display: block; font-family: var(--f-display); font-weight: 600;
  font-size: 1.24rem; color: var(--slate-900); margin-bottom: .3rem; line-height: 1.3;
}
.od-index__desc { display: block; font-size: .92rem; color: var(--ink-soft); line-height: 1.6; }

/* ============================ PAGER ============================ */
.od-pager {
  max-width: var(--measure); margin: 2.2rem auto 4rem;
  display: flex; justify-content: space-between; gap: 1rem;
  border-top: 1px solid var(--rule); padding-top: 1.6rem; flex-wrap: wrap;
}
.od-pager__spacer { flex: 1 1 0; }
.od-pager__link {
  flex: 1 1 0; min-width: 0; text-decoration: none;
  font-family: var(--f-display); font-size: 1.1rem; font-weight: 600; color: var(--slate-800);
}
.od-pager__link span {
  display: block; font-family: var(--f-mono); font-size: .68rem;
  letter-spacing: .14em; text-transform: uppercase; color: var(--ink-faint);
  margin-bottom: .3rem; font-weight: 400;
}
.od-pager__link--next { text-align: right; }
.od-pager__link:hover { color: var(--accent-dk); }

/* ============================ FOOTER ============================ */
.od-foot { background: var(--slate-900); color: #a9bccd; padding: 3.4rem 0 2rem; margin-top: 2rem; }
.od-foot__grid {
  display: grid; grid-template-columns: 2.1fr 1fr 1fr 1.2fr;
  gap: 2rem; align-items: start;
}
.od-foot__brand { font-size: 1.3rem; display: inline-block; margin-bottom: .8rem; }
.od-foot__blurb { font-size: .93rem; line-height: 1.65; margin: 0 0 1rem; max-width: 42ch; }
.od-foot__note {
  font-size: .82rem; line-height: 1.6; color: #7d93a8;
  border-left: 2px solid var(--accent); padding-left: .9rem; margin: 0; max-width: 46ch;
}
.od-foot__head {
  font-family: var(--f-mono); font-size: .7rem; letter-spacing: .16em;
  text-transform: uppercase; color: var(--accent); margin: 0 0 .9rem; font-weight: 500;
}
.od-foot__list { list-style: none; margin: 0; padding: 0; }
.od-foot__list li { margin-bottom: .5rem; }
.od-foot__list a { color: #a9bccd; text-decoration: none; font-size: .92rem; }
.od-foot__list a:hover { color: var(--white); text-decoration: underline; }
.od-foot__rule { height: 1px; background: #2b4763; margin: 2.4rem 0 1.2rem; }
.od-foot__copy { font-size: .82rem; color: #6f8599; margin: 0; }

/* ============================ RESPONSIVE ============================ */
@media (max-width: 960px) {
  .od-foot__grid { grid-template-columns: 1fr 1fr; }
  .od-index__list { grid-template-columns: 1fr; }
  .od-index__item:nth-child(odd) { border-right: 0; }
  .od-index__item:nth-child(odd) .od-index__link { padding-right: 1rem; }
}

@media (max-width: 840px) {
  .od-burger { display: block; }
  .od-nav__inner { min-height: 60px; padding-top: .5rem; padding-bottom: .5rem; }
  .od-menu { flex: 1 1 100%; display: none; }
  .od-menu.is-open { display: block; }
  .od-menu__list { flex-direction: column; align-items: stretch; gap: 0; padding: .5rem 0 1rem; }
  .od-menu__list > li { border-top: 1px solid #2b4763; }
  .od-menu__link, .od-menu__label { display: block; padding: .75rem 0; }
  .od-menu__topics { position: static; }
  .od-drop { position: static; display: block; border: 0; border-top: 0; min-width: 0; padding: 0 0 .5rem; background: transparent; }
  .od-drop__link { padding: .45rem 0 .45rem 1rem; }
  .od-hero__inner { padding: 3.2rem 1.5rem 3rem; }
  .od-hero__panel { padding: 1.8rem 1.6rem 2rem; }
}

@media (max-width: 560px) {
  body.od { font-size: 1rem; }
  .od-foot__grid { grid-template-columns: 1fr; gap: 1.8rem; }
  .od-prose { padding-top: 2.4rem; }
  .od-pager { flex-direction: column; }
  .od-pager__link--next { text-align: left; }
}

@media print {
  .od-nav, .od-foot, .od-pager, .od-hero__media { display: none; }
  body.od { background: #fff; }
}