/* article.css — Actual Maths long-form Learn article (Aurora Glass) */
:root {
  --bg-0:#0a0a1a; --bg-1:#0e0c24;
  --ink-0:#f5f3ff;
  --ink-1:rgba(245,243,255,.80);
  --ink-2:rgba(245,243,255,.55);
  --ink-3:rgba(245,243,255,.32);
  --line:rgba(255,255,255,.08);
  --line-2:rgba(255,255,255,.14);
  --glass:rgba(255,255,255,.04);
  --glass-2:rgba(255,255,255,.06);
  --glass-hi:rgba(255,255,255,.10);
  --c-invest:oklch(.78 .18 175);
  --c-overpay:oklch(.74 .17 295);
  --c-pcp:oklch(.74 .15 230);
  --c-mortgage:oklch(.75 .15 40);
  --c-good:oklch(.80 .18 145);
  --c-warn:oklch(.78 .18 30);
  --radius:14px; --radius-lg:22px; --radius-xl:30px;
  --font-display:'Geist','Inter Tight',system-ui,sans-serif;
  --font-mono:'Geist Mono',ui-monospace,monospace;
  --global-nav-h:54px;
  --shadow-card:0 12px 40px -16px rgba(0,0,0,.55);
  --accent:var(--c-invest);
}
* { box-sizing:border-box; }
html,body { margin:0; padding:0; }
html { background:var(--bg-0); }
body {
  font-family:var(--font-display); background:var(--bg-0); color:var(--ink-0);
  font-feature-settings:'ss01','cv11'; -webkit-font-smoothing:antialiased; overflow-x:hidden;
}
.num { font-family:var(--font-mono); font-variant-numeric:tabular-nums; }

/* aurora bg */
.aurora { position:fixed; inset:0; z-index:-1; overflow:hidden; pointer-events:none; }
.aurora span { position:absolute; border-radius:50%; filter:blur(120px); opacity:.36; mix-blend-mode:screen; }
.aurora .a { width:58vw;height:58vw;left:-16vw;top:-26vw; background:radial-gradient(circle,oklch(.55 .28 295) 0%,transparent 65%); animation:d1 26s ease-in-out infinite alternate; }
.aurora .b { width:50vw;height:50vw;right:-18vw;top:4vh; background:radial-gradient(circle,oklch(.55 .24 195) 0%,transparent 65%); animation:d2 32s ease-in-out infinite alternate; }
@keyframes d1 { to { transform:translate(8vw,6vh); } }
@keyframes d2 { to { transform:translate(-6vw,8vh); } }
@media (prefers-reduced-motion:reduce){ .aurora span{ animation:none; } }

.wrap { max-width:760px; margin:0 auto; padding:0 28px; }

/* breadcrumb */
.crumbs { display:flex; align-items:center; gap:8px; font-size:13px; color:var(--ink-3); padding:34px 0 0; flex-wrap:wrap; }
.crumbs a { color:var(--ink-2); text-decoration:none; }
.crumbs a:hover { color:var(--ink-0); }
.crumbs .sep { opacity:.5; }

/* article header */
.art-head { padding:20px 0 8px; }
.art-kicker { display:inline-flex; align-items:center; gap:9px; font-size:12px; text-transform:uppercase; letter-spacing:.1em; font-weight:600; color:var(--accent); margin-bottom:16px; }
.art-kicker .sw { width:9px; height:9px; border-radius:50%; background:var(--accent); box-shadow:0 0 8px var(--accent); }
.art-head h1 { font-size:clamp(32px,4.6vw,46px); line-height:1.08; letter-spacing:-0.025em; font-weight:700; margin:0 0 16px; text-wrap:balance; }
.art-head .standfirst { font-size:19px; line-height:1.6; color:var(--ink-1); margin:0; text-wrap:pretty; }
.art-meta { display:flex; align-items:center; gap:14px; margin-top:20px; font-size:13px; color:var(--ink-3); font-family:var(--font-mono); flex-wrap:wrap; }
.art-meta .dot { width:4px; height:4px; border-radius:50%; background:var(--ink-3); }

/* answer box — the "featured snippet" target */
.answer { margin:30px 0 8px; border:1px solid var(--line-2); border-radius:var(--radius-lg);
  background:linear-gradient(180deg,var(--glass-2),var(--glass)); box-shadow:var(--shadow-card); padding:24px 26px; position:relative; overflow:hidden; }
.answer::before { content:""; position:absolute; left:0; top:0; bottom:0; width:3px; background:var(--accent); }
.answer .lbl { font-size:11px; text-transform:uppercase; letter-spacing:.11em; color:var(--accent); font-weight:600; margin-bottom:10px; }
.answer p { font-size:17px; line-height:1.6; color:var(--ink-0); margin:0; text-wrap:pretty; }
.answer p + p { margin-top:12px; font-size:15px; color:var(--ink-1); }

/* prose */
.prose { padding:14px 0 8px; }
.prose h2 { font-size:27px; letter-spacing:-0.015em; font-weight:680; margin:40px 0 12px; line-height:1.2; scroll-margin-top:74px; }
.prose h3 { font-size:19px; font-weight:640; margin:28px 0 8px; }
.prose p { font-size:17px; line-height:1.72; color:var(--ink-1); margin:0 0 16px; text-wrap:pretty; }
.prose ul, .prose ol { margin:0 0 18px; padding-left:4px; list-style:none; display:grid; gap:11px; }
.prose ol { counter-reset:li; }
.prose ul li, .prose ol li { position:relative; padding-left:24px; font-size:16.5px; line-height:1.6; color:var(--ink-1); }
.prose ul li::before { content:""; position:absolute; left:3px; top:10px; width:6px; height:6px; border-radius:50%; background:var(--accent); }
.prose ol li { counter-increment:li; }
.prose ol li::before { content:counter(li); position:absolute; left:0; top:1px; font-family:var(--font-mono); font-size:13px; color:var(--accent); font-weight:600; }
.prose a { color:var(--accent); text-decoration:none; border-bottom:1px solid color-mix(in oklab,var(--accent) 40%,transparent); }
.prose a:hover { border-bottom-color:var(--accent); }
.prose strong { color:var(--ink-0); font-weight:600; }
.prose em { color:var(--ink-0); font-style:italic; }

/* pull example / scenario card */
.example { margin:22px 0; border:1px solid var(--line); border-radius:var(--radius-lg); background:var(--glass); padding:22px 24px; box-shadow:var(--shadow-card); }
.example .ex-lbl { font-size:11px; text-transform:uppercase; letter-spacing:.1em; color:var(--ink-3); font-weight:600; margin-bottom:14px; }
.ex-rows { display:grid; gap:1px; }
.ex-row { display:flex; align-items:baseline; justify-content:space-between; gap:14px; padding:9px 0; border-top:1px solid var(--line); font-size:15px; }
.ex-row:first-child { border-top:none; }
.ex-row span { color:var(--ink-2); }
.ex-row b { font-family:var(--font-mono); font-variant-numeric:tabular-nums; color:var(--ink-0); font-weight:600; }
.ex-row.win b { color:var(--accent); font-size:17px; }

/* callout */
.callout { display:flex; gap:14px; align-items:flex-start; padding:16px 18px; border-radius:var(--radius);
  background:var(--glass); border-left:3px solid var(--accent); margin:22px 0; }
.callout .ico { flex:0 0 auto; font-size:18px; line-height:1.4; }
.callout p { margin:0; font-size:15px; color:var(--ink-1); line-height:1.6; }
.callout.warn { border-left-color:var(--c-warn); }

/* inline CTA to calculator */
.tool-cta { margin:30px 0; border:1px solid var(--line-2); border-radius:var(--radius-lg);
  background:linear-gradient(135deg,color-mix(in oklab,var(--accent) 14%,transparent),var(--glass));
  padding:24px 26px; display:flex; align-items:center; justify-content:space-between; gap:20px; flex-wrap:wrap; }
.tool-cta h3 { margin:0 0 5px; font-size:19px; font-weight:650; }
.tool-cta p { margin:0; font-size:14.5px; color:var(--ink-2); max-width:46ch; }
.btn { display:inline-flex; align-items:center; gap:9px; border:1px solid transparent; padding:13px 22px; border-radius:999px;
  font-family:inherit; font-weight:600; font-size:15px; cursor:pointer; text-decoration:none; white-space:nowrap;
  transition:filter .15s,transform .15s; flex:0 0 auto; }
.btn-primary { background:linear-gradient(135deg,var(--accent),color-mix(in oklab,var(--accent) 70%,#000)); color:#06231c; }
.btn-primary:hover { filter:brightness(1.08); transform:translateY(-1px); }
.btn .arr { transition:transform .15s; }
.btn:hover .arr { transform:translateX(3px); }

/* FAQ */
.faq { margin:18px 0 8px; }
.faq details { border:1px solid var(--line); border-radius:var(--radius); background:var(--glass); margin-bottom:10px; overflow:hidden; }
.faq summary { list-style:none; cursor:pointer; padding:16px 18px; font-size:16.5px; font-weight:600; color:var(--ink-0);
  display:flex; align-items:center; justify-content:space-between; gap:14px; }
.faq summary::-webkit-details-marker { display:none; }
.faq summary::after { content:"+"; font-family:var(--font-mono); font-size:20px; color:var(--accent); transition:transform .2s; flex:0 0 auto; }
.faq details[open] summary::after { transform:rotate(45deg); }
.faq .faq-body { padding:0 18px 16px; }
.faq .faq-body p { margin:0; font-size:15.5px; line-height:1.65; color:var(--ink-1); }

/* related */
.related { margin:36px 0 0; padding-top:28px; border-top:1px solid var(--line); }
.related h2 { font-size:15px; text-transform:uppercase; letter-spacing:.08em; color:var(--ink-2); font-weight:600; margin:0 0 16px; }
.related-grid { display:grid; grid-template-columns:repeat(2,minmax(0,1fr)); gap:12px; }
.related-card { display:block; border:1px solid var(--line); border-radius:var(--radius); background:var(--glass); padding:16px 18px; text-decoration:none; transition:background .15s,border-color .15s,transform .15s; }
.related-card:hover { background:var(--glass-2); border-color:var(--line-2); transform:translateY(-2px); }
.related-card .rc-kick { font-size:11px; text-transform:uppercase; letter-spacing:.08em; color:var(--ink-3); font-weight:600; margin-bottom:7px; }
.related-card .rc-title { font-size:15.5px; font-weight:600; color:var(--ink-0); line-height:1.35; }

.disclaim { margin:36px 0 0; padding:16px 18px; border:1px dashed var(--line-2); border-radius:var(--radius);
  background:var(--glass); color:var(--ink-3); font-size:13px; line-height:1.6; }

/* footer */
footer { border-top:1px solid var(--line); margin-top:52px; padding:40px 0 60px; }
.foot-inner { display:flex; align-items:center; justify-content:space-between; gap:20px; flex-wrap:wrap; max-width:760px; margin:0 auto; padding:0 28px; }
.foot-brand { display:flex; align-items:center; gap:11px; }
.foot-mark { width:30px; height:30px; border-radius:9px;
  background:radial-gradient(circle at 30% 30%,oklch(.85 .18 295),transparent 60%),
            radial-gradient(circle at 70% 70%,oklch(.85 .18 195),transparent 60%),
            linear-gradient(135deg,oklch(.4 .15 295),oklch(.4 .15 195));
  box-shadow:inset 0 0 0 1px rgba(255,255,255,.25); }
.foot-links { display:flex; gap:22px; flex-wrap:wrap; }
.foot-links a { color:var(--ink-2); text-decoration:none; font-size:14px; }
.foot-links a:hover { color:var(--ink-0); }
.foot-note { color:var(--ink-3); font-size:12px; margin:18px auto 0; max-width:760px; padding:0 28px; line-height:1.5; }

@media (max-width:680px){ .related-grid { grid-template-columns:minmax(0,1fr); } .tool-cta { flex-direction:column; align-items:flex-start; } }