/* ============================================================
   I-Tech blog — shared stylesheet for /blog/
   Every blog page links this. Change once, changes everywhere.
   ============================================================ */
:root{
  --ink:#FFFFFF;
  --ink-2:#0D2438;
  --on-ink:#0E1C2A;
  --on-ink-2:#55697D;
  --signal:#F2570C;
  --signal-hi:#FF6D1F;
  --steel:#0E6FE8;

  --bg:#FFFFFF;
  --bg-2:#FFF5EE;
  --bg-cool:#EFF6FF;
  --surface:#FFFFFF;
  --text:#0E1C2A;
  --text-2:#54677A;
  --text-3:#8496A8;
  --border:#F0E5DC;
  --border-2:#E0D2C6;
  --accent-text:#D2470A;

  --maxw:1180px;
  --r:6px;
  --r-lg:14px;
}
@media (prefers-color-scheme: dark){
  :root:not([data-theme="light"]){
    --ink:#0B1723; --on-ink:#F2F6FA; --on-ink-2:#93A7BA;
    --bg:#0B1723; --bg-2:#12212F; --bg-cool:#0E1E30; --surface:#142433;
    --text:#EEF3F8; --text-2:#9DAFBF; --text-3:#75879A;
    --border:#22333F; --border-2:#2E4150; --accent-text:#FF8A45;
  }
}
:root[data-theme="dark"]{
  --ink:#0B1723; --on-ink:#F2F6FA; --on-ink-2:#93A7BA;
  --bg:#0B1723; --bg-2:#12212F; --bg-cool:#0E1E30; --surface:#142433;
  --text:#EEF3F8; --text-2:#9DAFBF; --text-3:#75879A;
  --border:#22333F; --border-2:#2E4150; --accent-text:#FF8A45;
}

*,*::before,*::after{box-sizing:border-box;}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth;}
@media (prefers-reduced-motion: reduce){
  html{scroll-behavior:auto;}
  *,*::before,*::after{animation-duration:.01ms !important;transition-duration:.01ms !important;}
}
body{
  margin:0;background:var(--bg);color:var(--text);
  font-family:"Source Sans 3","Segoe UI",system-ui,sans-serif;
  font-size:17px;line-height:1.65;-webkit-font-smoothing:antialiased;
}
h1,h2,h3,h4{
  font-family:Archivo,"Segoe UI",system-ui,sans-serif;
  font-weight:700;line-height:1.15;letter-spacing:-.02em;
  text-wrap:balance;margin:0;
}
p{margin:0;}
a{color:inherit;}
img{display:block;max-width:100%;height:auto;}
:focus-visible{outline:2.5px solid var(--signal-hi);outline-offset:3px;border-radius:2px;}

.wrap{width:100%;max-width:var(--maxw);margin:0 auto;padding:0 28px;}
.eyebrow{
  font-family:"IBM Plex Mono",ui-monospace,monospace;
  font-size:.72rem;font-weight:600;letter-spacing:.16em;
  text-transform:uppercase;color:var(--accent-text);
  display:block;margin-bottom:14px;
}

/* ---------- buttons ---------- */
.btn{
  display:inline-flex;align-items:center;gap:9px;
  font-family:Archivo,sans-serif;font-weight:600;font-size:.95rem;
  padding:13px 24px;border-radius:var(--r);border:1.5px solid transparent;
  text-decoration:none;cursor:pointer;
  transition:background-color .18s,border-color .18s,color .18s,transform .18s;
}
.btn-primary{background:var(--signal);color:#fff;box-shadow:0 10px 22px -10px rgba(242,87,12,.7);}
.btn-primary:hover{background:var(--signal-hi);transform:translateY(-1px);}
.btn-outline{background:transparent;color:var(--text);border-color:var(--border-2);}
.btn-outline:hover{border-color:var(--steel);color:var(--steel);}
.btn svg{width:15px;height:15px;flex:none;}

/* ---------- header ---------- */
.site-head{
  position:sticky;top:0;z-index:100;
  background:rgba(255,255,255,.9);
  backdrop-filter:saturate(160%) blur(12px);
  -webkit-backdrop-filter:saturate(160%) blur(12px);
  border-bottom:1px solid var(--border);
}
:root[data-theme="dark"] .site-head{background:rgba(11,23,35,.9);}
@media (prefers-color-scheme: dark){
  :root:not([data-theme="light"]) .site-head{background:rgba(11,23,35,.9);}
}
.head-in{display:flex;align-items:center;gap:28px;height:70px;}
.brand{display:flex;align-items:center;gap:11px;text-decoration:none;flex:none;}
.brand-mark{
  width:34px;height:34px;flex:none;display:flex;align-items:center;justify-content:center;
  background:linear-gradient(140deg,var(--signal-hi),var(--signal));
  border-radius:3px;box-shadow:0 6px 14px -6px rgba(242,87,12,.75);
}
.brand-mark span{font-family:Archivo,sans-serif;font-weight:800;font-size:1rem;color:#fff;letter-spacing:-.04em;}
.brand-text{display:block;}
.brand-name{display:block;font-family:Archivo,sans-serif;font-weight:700;font-size:1.04rem;color:var(--on-ink);letter-spacing:-.02em;line-height:1.2;white-space:nowrap;}
.brand-sub{display:block;font-family:"IBM Plex Mono",monospace;font-size:.58rem;letter-spacing:.12em;text-transform:uppercase;color:var(--on-ink-2);line-height:1.3;white-space:nowrap;}
.site-nav{display:flex;gap:22px;margin-left:auto;align-items:center;}
.site-nav a{
  font-size:.9rem;font-weight:500;color:var(--on-ink-2);text-decoration:none;white-space:nowrap;
  padding:6px 0;border-bottom:2px solid transparent;transition:color .16s,border-color .16s;
}
.site-nav a:hover,.site-nav a[aria-current="page"]{color:var(--on-ink);border-bottom-color:var(--signal);}
.head-cta{flex:none;}
.nav-toggle{
  display:none;background:none;border:1px solid var(--border-2);border-radius:var(--r);
  padding:12px;color:var(--on-ink);margin-left:auto;cursor:pointer;
  min-width:44px;min-height:44px;align-items:center;justify-content:center;
}

/* ---------- blog index ---------- */
.blog-hero{
  background:linear-gradient(168deg,#FFFBF8 0%,#FFF3EA 48%,#F4F8FF 100%);
  border-bottom:1px solid var(--border);padding:64px 0 56px;
}
:root[data-theme="dark"] .blog-hero{background:linear-gradient(168deg,#101F2E 0%,#12212F 50%,#0E1E30 100%);}
@media (prefers-color-scheme: dark){
  :root:not([data-theme="light"]) .blog-hero{background:linear-gradient(168deg,#101F2E 0%,#12212F 50%,#0E1E30 100%);}
}
.blog-hero h1{font-size:clamp(2rem,4.2vw,3rem);margin-bottom:16px;letter-spacing:-.03em;}
.blog-hero p{font-size:1.12rem;color:var(--text-2);max-width:62ch;}

.filters{display:flex;flex-wrap:wrap;gap:8px;margin:38px 0 34px;}
.filter{
  font-family:Archivo,sans-serif;font-weight:600;font-size:.87rem;
  padding:9px 17px;border-radius:100px;cursor:pointer;
  background:transparent;color:var(--text-2);border:1.5px solid var(--border-2);
  transition:all .16s ease;
}
.filter:hover{color:var(--text);border-color:var(--steel);}
.filter[aria-pressed="true"]{background:var(--signal);color:#fff;border-color:var(--signal);box-shadow:0 8px 18px -8px rgba(242,87,12,.65);}

.post-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:22px;padding-bottom:80px;}
.card{
  display:flex;flex-direction:column;
  background:var(--surface);border:1px solid var(--border);border-radius:var(--r-lg);
  padding:24px;text-decoration:none;
  transition:border-color .18s ease,transform .18s ease,box-shadow .18s ease;
}
.card:hover{border-color:var(--signal);transform:translateY(-3px);box-shadow:0 18px 40px -24px rgba(14,28,42,.3);}
.card-tag{
  font-family:"IBM Plex Mono",monospace;font-size:.62rem;font-weight:600;
  letter-spacing:.13em;text-transform:uppercase;color:var(--accent-text);margin-bottom:12px;
}
.card h2{font-size:1.18rem;margin-bottom:10px;line-height:1.3;}
.card p{font-size:.94rem;color:var(--text-2);line-height:1.55;flex:1;}
.card-meta{
  display:flex;gap:10px;align-items:center;margin-top:16px;
  font-family:"IBM Plex Mono",monospace;font-size:.68rem;color:var(--text-3);letter-spacing:.06em;
}
.empty{
  grid-column:1/-1;padding:52px 24px;text-align:center;
  color:var(--text-2);border:1px dashed var(--border-2);border-radius:var(--r-lg);
}

/* ---------- article ---------- */
.article-head{
  background:linear-gradient(168deg,#FFFBF8 0%,#FFF3EA 100%);
  border-bottom:1px solid var(--border);padding:52px 0 44px;
}
:root[data-theme="dark"] .article-head{background:linear-gradient(168deg,#101F2E 0%,#12212F 100%);}
@media (prefers-color-scheme: dark){
  :root:not([data-theme="light"]) .article-head{background:linear-gradient(168deg,#101F2E 0%,#12212F 100%);}
}
.breadcrumb{font-family:"IBM Plex Mono",monospace;font-size:.7rem;letter-spacing:.1em;text-transform:uppercase;color:var(--text-3);margin-bottom:20px;}
.breadcrumb a{color:var(--accent-text);text-decoration:none;}
.breadcrumb a:hover{text-decoration:underline;}
.article-head h1{font-size:clamp(1.9rem,4vw,2.85rem);letter-spacing:-.03em;max-width:22ch;margin-bottom:18px;}
.article-meta{display:flex;flex-wrap:wrap;gap:16px;font-family:"IBM Plex Mono",monospace;font-size:.7rem;letter-spacing:.08em;text-transform:uppercase;color:var(--text-3);}

/* article pages use a narrower container so the measure stays readable
   and the sidebar balances the page instead of leaving dead space */
.article-head .wrap,
.article .wrap{max-width:1010px;}

.article{padding:52px 0 72px;}
.article .wrap{display:grid;grid-template-columns:minmax(0,1fr) 244px;gap:58px;align-items:start;}
.article-main{min-width:0;}
.article-body{max-width:68ch;min-width:0;}

/* ---------- sticky sidebar ---------- */
.article-side{position:sticky;top:96px;display:flex;flex-direction:column;gap:20px;}
.toc-title{
  font-family:"IBM Plex Mono",monospace;font-size:.66rem;font-weight:600;
  letter-spacing:.13em;text-transform:uppercase;color:var(--text-3);
  padding-bottom:10px;border-bottom:1px solid var(--border);margin-bottom:4px;
}
.toc{list-style:none;margin:0;padding:0;display:flex;flex-direction:column;gap:2px;}
.toc a{
  display:block;text-decoration:none;font-size:.88rem;line-height:1.4;
  color:var(--text-2);padding:7px 0 7px 13px;
  border-left:2px solid var(--border);transition:color .15s,border-color .15s;
}
.toc a:hover{color:var(--text);border-left-color:var(--border-2);}
.toc a.is-active{color:var(--accent-text);border-left-color:var(--signal);font-weight:600;}

.side-cta{
  background:var(--bg-2);border:1px solid var(--border-2);
  border-radius:var(--r-lg);padding:20px;
}
.side-cta h4{font-size:.98rem;margin-bottom:8px;line-height:1.35;}
.side-cta p{font-size:.85rem;color:var(--text-2);line-height:1.5;margin-bottom:14px;}
.side-cta .btn{width:100%;justify-content:center;font-size:.86rem;padding:11px 14px;}
.article-body > *+*{margin-top:22px;}
.article-body p{font-size:1.08rem;color:var(--text);line-height:1.72;}
.article-body h2{font-size:1.6rem;margin-top:52px;letter-spacing:-.02em;}
.article-body h3{font-size:1.22rem;margin-top:38px;}
.article-body strong{font-weight:600;}
.article-body a{color:var(--accent-text);text-decoration:underline;text-underline-offset:2px;}
.article-body ul,.article-body ol{padding-left:24px;color:var(--text);}
.article-body li{margin-bottom:9px;line-height:1.65;}
.article-body li::marker{color:var(--signal);}
.lede{font-size:1.24rem !important;color:var(--text-2) !important;line-height:1.6 !important;}

.callout{
  background:var(--bg-2);border-left:3px solid var(--signal);
  border-radius:0 var(--r-lg) var(--r-lg) 0;padding:20px 24px;
}
.callout p{font-size:1rem;}
.callout .callout-label{
  font-family:"IBM Plex Mono",monospace;font-size:.66rem;font-weight:600;
  letter-spacing:.13em;text-transform:uppercase;color:var(--accent-text);
  display:block;margin-bottom:8px;
}

/* ---------- diagrams ---------- */
.figure{margin:38px 0;}
.figure-scroll{
  overflow-x:auto;
  border:1px solid var(--border);border-radius:var(--r-lg);
  background:var(--surface);padding:24px 22px;
}
.figure svg{display:block;width:100%;min-width:520px;height:auto;}
.figcap{
  margin-top:12px;font-size:.86rem;color:var(--text-3);line-height:1.5;
  font-family:"IBM Plex Mono",monospace;letter-spacing:.02em;
}
.figcap b{color:var(--text-2);font-weight:600;}
.d-label{font-family:"IBM Plex Mono",monospace;font-size:11px;font-weight:600;letter-spacing:1.4px;text-transform:uppercase;}
.d-head{font-family:Archivo,sans-serif;font-size:15px;font-weight:700;}
.d-txt{font-family:"Source Sans 3",sans-serif;font-size:13.5px;}
.d-num{font-family:"IBM Plex Mono",monospace;font-size:15px;font-weight:600;}

.article-body table{width:100%;border-collapse:collapse;font-size:.96rem;}
.table-scroll{overflow-x:auto;}
.article-body th,.article-body td{padding:12px 14px;border-bottom:1px solid var(--border);text-align:left;}
.article-body th{
  font-family:"IBM Plex Mono",monospace;font-size:.68rem;letter-spacing:.1em;
  text-transform:uppercase;color:var(--text-3);font-weight:600;background:var(--bg-2);
}

.article-cta{
  margin-top:56px;max-width:68ch;
  background:var(--bg-2);border:1px solid var(--border-2);border-radius:var(--r-lg);
  padding:30px;
}
.article-cta h3{font-size:1.28rem;margin-bottom:10px;}
.article-cta p{font-size:1rem;color:var(--text-2);margin-bottom:20px;}

/* ---------- footer ---------- */
.site-foot{
  --on-ink-2:#9DB4CA;
  background:linear-gradient(160deg,#123049 0%,#0D2438 100%);
  color:var(--on-ink-2);padding:48px 0 24px;
}
.foot-grid{display:grid;grid-template-columns:1.5fr 1fr 1fr;gap:36px;margin-bottom:32px;}
.foot-grid h4{
  font-family:"IBM Plex Mono",monospace;font-size:.66rem;font-weight:600;
  letter-spacing:.12em;text-transform:uppercase;color:#fff;margin-bottom:14px;
}
.foot-grid p{font-size:.9rem;line-height:1.6;}
.foot-links{list-style:none;margin:0;padding:0;display:flex;flex-direction:column;gap:9px;}
.foot-links a{font-size:.9rem;color:var(--on-ink-2);text-decoration:none;}
.foot-links a:hover{color:#fff;}
.foot-bar{
  border-top:1px solid rgba(255,255,255,.09);padding-top:20px;
  display:flex;flex-wrap:wrap;gap:14px;justify-content:space-between;font-size:.84rem;
}

/* ---------- responsive ---------- */
@media (max-width:1120px){ .head-cta{display:none;} }
@media (max-width:1000px){
  .post-grid{grid-template-columns:repeat(2,1fr);}
  /* sidebar drops away — article gets the full column */
  .article .wrap{grid-template-columns:1fr;gap:0;}
  .article-side{display:none;}
  .article-body{max-width:none;}
}
@media (max-width:940px){
  .site-nav{
    display:none;position:absolute;top:70px;left:0;right:0;
    flex-direction:column;gap:0;background:var(--bg);
    border-bottom:1px solid var(--border);padding:8px 20px 16px;align-items:stretch;
  }
  .site-nav[data-open="true"]{display:flex;}
  .site-nav a{padding:11px 0;border-bottom:1px solid var(--border);font-size:.95rem;}
  .nav-toggle{display:flex;}
}
@media (max-width:720px){
  body{font-size:16px;}
  .wrap{padding:0 20px;}
  .blog-hero{padding:44px 0 38px;}
  .article-head{padding:36px 0 32px;}
  .article{padding:38px 0 56px;}
  .post-grid{grid-template-columns:1fr;}
  .foot-grid{grid-template-columns:1fr;}
  .article-body p{font-size:1.03rem;}
  .btn{padding:15px 24px;}
  .filter{padding:12px 18px;}
}