/* RectangleFlow design system */
:root{
  --ink:#0b1220; --ink-2:#1e293b; --muted:#5b6b84; --line:#e3e8f0;
  --bg:#f7f9fc; --card:#ffffff; --brand:#3b82f6; --brand-2:#8b5cf6;
  --ok:#10b981; --warn:#f59e0b; --danger:#ef4444;
  --radius:16px; --shadow:0 1px 2px rgba(16,24,40,.05),0 12px 32px -16px rgba(16,24,40,.22);
  --wrap:1140px; --read:760px;
  --sans:"Inter",ui-sans-serif,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;
  --mono:ui-monospace,SFMono-Regular,"SF Mono",Menlo,monospace;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--ink);font-family:var(--sans);
  font-size:17px;line-height:1.68;-webkit-font-smoothing:antialiased}
img,svg{max-width:100%;height:auto;display:block}
a{color:var(--brand)}
.wrap{max-width:var(--wrap);margin:0 auto;padding:0 20px}
.read{max-width:var(--read);margin:0 auto;padding:0 20px}
.skip{position:absolute;left:-9999px}
.skip:focus{left:12px;top:12px;background:#fff;padding:10px 16px;border-radius:8px;z-index:99}

/* header */
.site-head{position:sticky;top:0;z-index:50;background:rgba(247,249,252,.85);
  backdrop-filter:saturate(180%) blur(14px);border-bottom:1px solid var(--line)}
.head-in{max-width:var(--wrap);margin:0 auto;padding:12px 20px;display:flex;
  align-items:center;justify-content:space-between;gap:16px}
.brand{display:flex;align-items:center;gap:10px;text-decoration:none;color:var(--ink);font-weight:800;letter-spacing:-.02em}
.brand img{width:34px;height:34px;border-radius:10px}
.nav{display:flex;gap:4px;align-items:center;flex-wrap:wrap}
.nav a{padding:8px 13px;border-radius:10px;text-decoration:none;color:var(--muted);
  font-weight:600;font-size:.95rem}
.nav a:hover{background:#eef2f9;color:var(--ink)}
.nav a.active{background:var(--ink);color:#fff}
.nav a.cta{background:linear-gradient(135deg,var(--brand),var(--brand-2));color:#fff}

/* hero */
.hero{background:radial-gradient(1000px 480px at 12% -10%,#1e3a8a 0%,transparent 60%),
  linear-gradient(135deg,#0b1220,#182a4a);color:#fff;padding:76px 0 68px}
.hero h1{font-size:clamp(2rem,5vw,3.2rem);line-height:1.1;margin:0 0 18px;letter-spacing:-.03em}
.hero p{font-size:1.15rem;color:#c3d0e6;max-width:640px;margin:0 0 26px}
.pill{display:inline-flex;align-items:center;gap:8px;background:rgba(255,255,255,.1);
  border:1px solid rgba(255,255,255,.18);color:#dbe6f7;padding:6px 14px;border-radius:999px;
  font-size:.82rem;font-weight:600;margin-bottom:20px}
.btn{display:inline-block;padding:13px 24px;border-radius:12px;text-decoration:none;
  font-weight:700;font-size:.98rem;transition:transform .15s ease,box-shadow .15s ease}
.btn:hover{transform:translateY(-2px)}
.btn-p{background:#fff;color:var(--ink);box-shadow:0 10px 30px -12px rgba(0,0,0,.6)}
.btn-s{background:rgba(255,255,255,.12);color:#fff;border:1px solid rgba(255,255,255,.28)}
.btn-row{display:flex;gap:12px;flex-wrap:wrap}
.hero-grid{display:grid;grid-template-columns:1.05fr .95fr;gap:44px;align-items:center}
@media(max-width:900px){.hero-grid{grid-template-columns:1fr}}

/* sections */
section.band{padding:64px 0}
.band h2{font-size:clamp(1.5rem,3vw,2rem);letter-spacing:-.02em;margin:0 0 8px}
.band .lede{color:var(--muted);margin:0 0 32px;max-width:620px}
.grid{display:grid;gap:20px}
.g3{grid-template-columns:repeat(3,1fr)}
.g2{grid-template-columns:repeat(2,1fr)}
.g4{grid-template-columns:repeat(4,1fr)}
@media(max-width:900px){.g3,.g4{grid-template-columns:repeat(2,1fr)}}
@media(max-width:620px){.g2,.g3,.g4{grid-template-columns:1fr}}
.card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);
  padding:24px;box-shadow:var(--shadow)}
.card h3{margin:0 0 8px;font-size:1.08rem;letter-spacing:-.01em}
.card p{margin:0;color:var(--muted);font-size:.96rem}
.ico{width:42px;height:42px;border-radius:12px;display:grid;place-items:center;
  background:linear-gradient(135deg,#eff6ff,#f5f3ff);font-size:1.2rem;margin-bottom:14px}

/* article cards */
.post-card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);
  overflow:hidden;box-shadow:var(--shadow);display:flex;flex-direction:column;
  transition:transform .18s ease,box-shadow .18s ease}
.post-card:hover{transform:translateY(-3px);box-shadow:0 18px 40px -20px rgba(16,24,40,.4)}
.post-card .thumb{background:#0b1220;padding:0;line-height:0}
.post-card .body{padding:20px 22px 24px;display:flex;flex-direction:column;gap:9px;flex:1}
.tag{display:inline-block;background:#eef2ff;color:#4338ca;border-radius:999px;
  padding:3px 11px;font-size:.75rem;font-weight:700;letter-spacing:.01em}
.post-card h3{margin:0;font-size:1.09rem;line-height:1.35;letter-spacing:-.01em}
.post-card h3 a{color:var(--ink);text-decoration:none}
.post-card h3 a:hover{color:var(--brand)}
.post-card p{margin:0;color:var(--muted);font-size:.93rem}
.meta{color:#8494ad;font-size:.8rem;margin-top:auto;padding-top:6px}

/* article */
.post-hero{background:linear-gradient(135deg,#0b1220,#1b2f52);color:#fff;padding:60px 0 52px}
.post-hero .kicker{color:#93b4f0;font-weight:700;font-size:.82rem;letter-spacing:.08em;
  text-transform:uppercase}
.post-hero h1{font-size:clamp(1.75rem,4vw,2.7rem);line-height:1.15;margin:12px 0 14px;
  letter-spacing:-.03em;max-width:820px}
.post-hero .sub{color:#c3d0e6;font-size:1.1rem;max-width:700px;margin:0}
.post-hero .bits{color:#8ea6c9;font-size:.86rem;margin-top:18px}
article{padding:44px 0 20px}
article h2{font-size:1.5rem;letter-spacing:-.02em;margin:2.6rem 0 1rem;scroll-margin-top:84px}
article h3{font-size:1.16rem;margin:2rem 0 .8rem;scroll-margin-top:84px}
article p{margin:0 0 1.4rem}
article ul,article ol{margin:0 0 1.5rem;padding-left:1.3rem}
article li{margin-bottom:.6rem}
article kbd{background:var(--ink);color:#fff;border-radius:6px;padding:2px 7px;
  font-family:var(--mono);font-size:.82em;white-space:nowrap}
.rl{color:#1d4ed8;font-weight:600;text-decoration:underline;text-underline-offset:3px;
  text-decoration-thickness:1.5px;text-decoration-color:#bfd3f6}
.rl:hover{text-decoration-color:#1d4ed8}
.figure{margin:2rem 0}
.figure figcaption{color:var(--muted);font-size:.87rem;margin-top:10px;text-align:center}
.toc{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);
  padding:20px 24px;margin:0 0 34px;box-shadow:var(--shadow)}
.toc h4{margin:0 0 10px;font-size:.76rem;letter-spacing:.09em;text-transform:uppercase;color:var(--muted)}
.toc ol{margin:0;padding-left:1.1rem}
.toc li{margin:.3rem 0}
.toc a{color:var(--ink-2);text-decoration:none;font-size:.95rem}
.toc a:hover{color:var(--brand);text-decoration:underline}
.box{border-radius:0 14px 14px 0;padding:16px 20px;margin:1.8rem 0;font-size:.97rem}
.box p:last-child{margin-bottom:0}
.box.info{background:#eff6ff;border-left:4px solid var(--brand)}
.box.tip{background:#ecfdf5;border-left:4px solid var(--ok)}
.box.warn{background:#fff7ed;border-left:4px solid var(--warn)}
.keys{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin:1.7rem 0}
@media(max-width:620px){.keys{grid-template-columns:1fr}}
.key{background:var(--card);border:1px solid var(--line);border-radius:12px;
  padding:12px 15px;display:flex;align-items:center;gap:12px;font-size:.93rem;box-shadow:var(--shadow)}
.key kbd{background:var(--ink);color:#fff;font-family:var(--mono);font-size:.82rem;
  padding:4px 9px;border-radius:6px;white-space:nowrap}
table{width:100%;border-collapse:collapse;margin:1.8rem 0;background:var(--card);
  border-radius:14px;overflow:hidden;box-shadow:var(--shadow);font-size:.94rem}
th{background:var(--ink);color:#fff;text-align:left;padding:12px 16px;font-weight:600}
td{padding:12px 16px;border-bottom:1px solid var(--line)}
tr:last-child td{border-bottom:none}
.cta{background:linear-gradient(135deg,#0b1220,#22407a);color:#fff;border-radius:20px;
  padding:34px 30px;text-align:center;margin:2.6rem 0}
.cta h3{margin:0 0 8px;font-size:1.35rem;color:#fff;letter-spacing:-.02em}
.cta p{color:#c3d0e6;margin:0 0 18px}
.faq details{background:var(--card);border:1px solid var(--line);border-radius:14px;
  padding:14px 20px;margin-bottom:10px;box-shadow:var(--shadow)}
.faq summary{cursor:pointer;font-weight:650;list-style:none}
.faq summary::-webkit-details-marker{display:none}
.faq summary::after{content:"+";float:right;color:var(--muted);font-weight:400}
.faq details[open] summary::after{content:"\2212"}
.faq p{margin:.8rem 0 .2rem;color:var(--muted);font-size:.96rem}
.next{display:grid;grid-template-columns:1fr 1fr;gap:16px;margin:2.4rem 0}
@media(max-width:620px){.next{grid-template-columns:1fr}}
.next a{display:block;background:var(--card);border:1px solid var(--line);border-radius:14px;
  padding:16px 20px;text-decoration:none;color:var(--ink);box-shadow:var(--shadow)}
.next a:hover{border-color:var(--brand)}
.next span{display:block;font-size:.75rem;text-transform:uppercase;letter-spacing:.08em;color:var(--muted)}
.crumbs{font-size:.85rem;color:var(--muted);padding:16px 0 0}
.crumbs a{color:var(--muted);text-decoration:none}
.crumbs a:hover{text-decoration:underline}
dl.gloss{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);
  padding:24px;box-shadow:var(--shadow)}
dl.gloss dt{font-weight:700;margin-top:14px}
dl.gloss dt:first-child{margin-top:0}
dl.gloss dd{margin:4px 0 0;color:var(--muted);font-size:.95rem}
.filters{display:flex;gap:8px;flex-wrap:wrap;margin-bottom:26px}
.filters button{border:1px solid var(--line);background:var(--card);color:var(--ink-2);
  border-radius:999px;padding:8px 16px;font:inherit;font-size:.9rem;font-weight:600;cursor:pointer}
.filters button[aria-pressed="true"]{background:var(--ink);color:#fff;border-color:var(--ink)}
.form-row{display:flex;flex-direction:column;gap:6px;margin-bottom:16px}
.form-row label{font-weight:650;font-size:.92rem}
.form-row input,.form-row textarea{font:inherit;padding:11px 14px;border:1px solid var(--line);
  border-radius:10px;background:#fff}
.form-row input:focus,.form-row textarea:focus{outline:2px solid var(--brand);border-color:var(--brand)}

/* footer */
.site-foot{background:#0b1220;color:#9fb0c9;margin-top:70px;padding:52px 0 26px}
.foot-grid{display:grid;grid-template-columns:1.6fr 1fr 1fr 1fr;gap:30px}
@media(max-width:820px){.foot-grid{grid-template-columns:1fr 1fr}}
@media(max-width:520px){.foot-grid{grid-template-columns:1fr}}
.site-foot h4{color:#fff;font-size:.95rem;margin:0 0 12px}
.site-foot a{display:block;color:#9fb0c9;text-decoration:none;font-size:.92rem;margin-bottom:8px}
.site-foot a:hover{color:#fff}
.site-foot p{font-size:.9rem;margin:0 0 10px}
.foot-bottom{border-top:1px solid rgba(255,255,255,.1);margin-top:34px;padding-top:20px;
  font-size:.84rem;display:flex;justify-content:space-between;gap:14px;flex-wrap:wrap}