/* Layout: dark indigo masthead band, then a light reading surface; one column for reading, two-up grids for paths and offers. The gradient lives only on the dot, primary buttons and the qubit demo. */
:root {
  --indigo: #1E1B4B;
  --violet: #7C3AED;
  --cyan: #22D3EE;
  --bg: #F8F7FF;
  --surface: #FFFFFF;
  --fg: #1E1B4B;
  --muted: #5B5880;
  --line: #E3E0F5;
  --soft: #EFECFD;
  --band: #1E1B4B;
  --band-fg: #F5F3FF;
  --band-muted: #B9B4E8;
  --link: #6D28D9;
  --grad: linear-gradient(135deg, var(--violet), var(--cyan));
  --f-display: "Poppins", "Avenir Next", "Segoe UI", system-ui, sans-serif;
  --f-body: "Source Serif 4", Georgia, "Times New Roman", serif;
  --f-mono: "IBM Plex Mono", ui-monospace, "SFMono-Regular", Menlo, monospace;
  --wrap: 1120px;
  --read: 68ch;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #12102E; --surface: #1A1740; --fg: #EEEBFF; --muted: #A9A4D6;
    --line: #2E2A63; --soft: #221E52; --band: #0C0A24; --band-fg: #F5F3FF;
    --band-muted: #A9A4D6; --link: #67E8F9; color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #12102E; --surface: #1A1740; --fg: #EEEBFF; --muted: #A9A4D6;
  --line: #2E2A63; --soft: #221E52; --band: #0C0A24; --band-fg: #F5F3FF;
  --band-muted: #A9A4D6; --link: #67E8F9; color-scheme: dark;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } * { transition: none !important; animation: none !important; } }
body { background: var(--bg); color: var(--fg); font-family: var(--f-body); font-size: 18px; line-height: 1.6; }
a { color: var(--link); text-underline-offset: 3px; }
a:focus-visible, button:focus-visible, input:focus-visible, select:focus-visible, textarea:focus-visible { outline: 3px solid var(--cyan); outline-offset: 2px; border-radius: 6px; }
h1, h2, h3, h4 { font-family: var(--f-display); font-weight: 600; line-height: 1.15; text-wrap: balance; margin: 0; letter-spacing: -0.01em; }
h1 { font-size: clamp(2.1rem, 5.2vw, 3.6rem); }
h2 { font-size: clamp(1.6rem, 3.4vw, 2.3rem); }
h3 { font-size: 1.2rem; }
p { margin: 0; }
.wrap { max-width: var(--wrap); margin: 0 auto; padding-inline: 20px; }
.eyebrow { font-family: var(--f-mono); font-size: 0.78rem; letter-spacing: 0.12em; text-transform: uppercase; color: var(--muted); }
.mono { font-family: var(--f-mono); }
.stack { display: flex; flex-direction: column; gap: 16px; }
.lede { font-size: 1.2rem; color: var(--muted); max-width: 58ch; }

/* header */
.top { background: var(--band); color: var(--band-fg); position: sticky; top: env(safe-area-inset-top, 0px); z-index: 10; border-bottom: 1px solid rgba(255,255,255,0.08); }
.top .wrap { display: flex; align-items: center; justify-content: space-between; gap: 16px; padding-block: 14px; }
.brand { display: flex; align-items: center; gap: 12px; color: var(--band-fg); text-decoration: none; font-family: var(--f-display); font-weight: 500; letter-spacing: 0.18em; font-size: 0.95rem; }
.brand svg { flex: none; }
nav.main { display: flex; gap: 4px; flex-wrap: wrap; justify-content: flex-end; }
nav.main a { color: var(--band-muted); text-decoration: none; font-family: var(--f-display); font-size: 0.9rem; padding: 6px 10px; border-radius: 999px; }
nav.main a:hover { color: var(--band-fg); }
nav.main a[aria-current="page"] { color: var(--band-fg); background: rgba(255,255,255,0.1); }
.menu-btn { display: none; background: none; border: 1px solid rgba(255,255,255,0.25); color: var(--band-fg); font-family: var(--f-display); font-size: 0.9rem; padding: 6px 12px; border-radius: 999px; cursor: pointer; }
@media (max-width: 760px) {
  .menu-btn { display: block; }
  nav.main { display: none; position: absolute; left: 0; right: 0; top: 100%; background: var(--band); flex-direction: column; padding: 8px 20px 16px; }
  nav.main.open { display: flex; }
  nav.main a { padding: 10px 0; border-radius: 0; }
  nav.main a[aria-current="page"] { background: none; }
}

/* buttons */
.btn { display: inline-flex; align-items: center; gap: 8px; font-family: var(--f-display); font-weight: 500; font-size: 0.98rem; padding: 12px 20px; border-radius: 999px; border: 0; cursor: pointer; text-decoration: none; }
.btn-primary { background: var(--grad); color: #fff; }
.btn-ghost { background: transparent; color: inherit; border: 1px solid currentColor; }
.btn-row { display: flex; gap: 12px; flex-wrap: wrap; }

/* band (hero) */
.band { background: var(--band); color: var(--band-fg); }
.band .lede, .band .eyebrow { color: var(--band-muted); }
.hero { display: grid; grid-template-columns: 1.1fr 0.9fr; gap: 48px; align-items: center; padding-block: 64px 72px; }
.hero > * { min-width: 0; }
@media (max-width: 880px) { .hero { grid-template-columns: 1fr; padding-block: 40px 48px; gap: 32px; } }

/* qubit demo */
.demo { background: rgba(255,255,255,0.05); border: 1px solid rgba(255,255,255,0.12); border-radius: 20px; padding: 22px; display: flex; flex-direction: column; gap: 16px; }
.demo-head { display: flex; justify-content: space-between; align-items: baseline; gap: 12px; flex-wrap: wrap; }
.ket { font-family: var(--f-mono); font-size: 1.05rem; color: var(--band-fg); overflow-wrap: anywhere; }
.ket b { font-weight: 500; color: var(--cyan); }
.orb-row { display: grid; grid-template-columns: 120px 1fr; gap: 20px; align-items: center; }
.orb { width: 120px; height: 120px; border-radius: 50%; position: relative; background: conic-gradient(var(--cyan) 0 var(--p1, 50%), var(--violet) var(--p1, 50%) 100%); box-shadow: 0 0 40px rgba(124,58,237,0.35); transition: background 0.2s; }
.orb::after { content: ""; position: absolute; inset: 22px; border-radius: 50%; background: var(--band); }
.orb span { position: absolute; inset: 0; display: grid; place-items: center; z-index: 1; font-family: var(--f-mono); font-size: 1.5rem; color: var(--band-fg); }
.orb.flash { animation: pop 0.35s ease-out; }
@keyframes pop { 0% { transform: scale(0.9); } 60% { transform: scale(1.06); } 100% { transform: scale(1); } }
.demo label { font-family: var(--f-display); font-size: 0.85rem; color: var(--band-muted); display: block; margin-bottom: 6px; }
.demo input[type=range] { width: 100%; accent-color: var(--cyan); }
.tally { display: flex; flex-direction: column; gap: 8px; font-family: var(--f-mono); font-size: 0.85rem; color: var(--band-muted); }
.bar { display: grid; grid-template-columns: 36px 1fr 48px; gap: 10px; align-items: center; }
.bar i { display: block; height: 10px; border-radius: 6px; background: rgba(255,255,255,0.1); overflow: hidden; }
.bar i em { display: block; height: 100%; width: 0; transition: width 0.3s; }
.bar.zero i em { background: var(--violet); }
.bar.one i em { background: var(--cyan); }
.bar span:last-child { text-align: right; font-variant-numeric: tabular-nums; }
.demo .btn { font-size: 0.9rem; padding: 10px 16px; }
.demo .btn-ghost { color: var(--band-fg); border-color: rgba(255,255,255,0.35); }
.demo-note { font-family: var(--f-body); font-size: 0.92rem; color: var(--band-muted); }

/* sections */
section.block { padding-block: 64px; }
section.block + section.block { border-top: 1px solid var(--line); }
.section-head { display: flex; flex-direction: column; gap: 10px; margin-bottom: 32px; max-width: 70ch; }

/* learning path — a real sequence, so numbered */
.path { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 320px), 1fr)); gap: 0; border-top: 1px solid var(--line); }
.path li { border-bottom: 1px solid var(--line); }
.path a { display: grid; grid-template-columns: 56px 1fr; gap: 12px; padding: 22px 8px 22px 0; text-decoration: none; color: var(--fg); }
.path a:hover h3 { color: var(--link); }
.path .ketnum { font-family: var(--f-mono); color: var(--muted); font-size: 0.95rem; padding-top: 2px; }
.path p { color: var(--muted); font-size: 1rem; margin-top: 4px; }
.path .meta { font-family: var(--f-mono); font-size: 0.75rem; color: var(--muted); margin-top: 8px; letter-spacing: 0.04em; }

/* myths */
.myths { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 300px), 1fr)); gap: 20px; }
.myth { background: var(--surface); border: 1px solid var(--line); border-radius: 16px; padding: 22px; display: flex; flex-direction: column; gap: 10px; }
.myth .said { font-family: var(--f-display); font-weight: 500; font-size: 1.05rem; }
.myth .said s { text-decoration-color: var(--violet); text-decoration-thickness: 2px; }
.myth p { font-size: 1rem; color: var(--muted); }
.tag { font-family: var(--f-mono); font-size: 0.72rem; letter-spacing: 0.1em; text-transform: uppercase; }
.tag.no { color: var(--violet); }
:root[data-theme="dark"] .tag.no { color: #A78BFA; }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .tag.no { color: #A78BFA; } }

/* split */
.split { display: grid; grid-template-columns: 1fr 1fr; gap: 48px; align-items: start; }
.split > * { min-width: 0; }
@media (max-width: 820px) { .split { grid-template-columns: 1fr; gap: 28px; } }

/* signup */
.signup { background: var(--soft); border-radius: 20px; padding: 32px; display: grid; grid-template-columns: 1.2fr 1fr; gap: 32px; align-items: center; }
.signup > * { min-width: 0; }
@media (max-width: 820px) { .signup { grid-template-columns: 1fr; padding: 24px; } }
form.inline { display: flex; gap: 10px; flex-wrap: wrap; }
form.inline input { flex: 1 1 220px; min-width: 0; }
input[type=email], input[type=text], select, textarea { font: inherit; font-size: 1rem; padding: 12px 14px; border-radius: 12px; border: 1px solid var(--line); background: var(--surface); color: var(--fg); width: 100%; }
.form-msg { font-family: var(--f-display); font-size: 0.9rem; color: var(--muted); margin-top: 10px; min-height: 1.4em; }
.small { font-size: 0.88rem; color: var(--muted); }

/* author strip */
.author { display: grid; grid-template-columns: 96px 1fr; gap: 24px; align-items: start; }
.avatar { width: 96px; height: 96px; border-radius: 50%; background: var(--band); display: grid; place-items: center; color: var(--band-fg); font-family: var(--f-display); font-weight: 500; font-size: 1.6rem; letter-spacing: 0.04em; position: relative; }
.avatar img { width: 100%; height: 100%; object-fit: cover; border-radius: 50%; display: block; }
.avatar.avatar-lg { width: 168px; height: 168px; }
.avatar.avatar-lg::after { width: 32px; height: 32px; right: 6px; bottom: 8px; border-color: var(--band); }
.about-head { grid-template-columns: 168px 1fr; align-items: center; }
@media (max-width: 560px) { .about-head { grid-template-columns: 1fr; } }
.avatar::after { content: ""; position: absolute; width: 22px; height: 22px; border-radius: 50%; background: var(--grad); right: 2px; bottom: 4px; border: 3px solid var(--bg); }
.creds { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 4px; }
.creds span { font-family: var(--f-mono); font-size: 0.78rem; padding: 4px 10px; border: 1px solid var(--line); border-radius: 999px; color: var(--muted); }

/* offers */
.offers { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 300px), 1fr)); gap: 20px; }
.offer { background: var(--surface); border: 1px solid var(--line); border-radius: 18px; padding: 26px; display: flex; flex-direction: column; gap: 14px; }
.offer.feature { border-color: transparent; background: linear-gradient(var(--surface), var(--surface)) padding-box, var(--grad) border-box; border: 2px solid transparent; }
.price { font-family: var(--f-display); font-size: 2rem; font-weight: 600; font-variant-numeric: tabular-nums; }
.price small { font-size: 0.95rem; font-weight: 400; color: var(--muted); }
.offer ul { margin: 0; padding-left: 1.1em; display: flex; flex-direction: column; gap: 6px; font-size: 1rem; }
.offer .btn { align-self: flex-start; margin-top: auto; }

/* article */
.article { max-width: var(--read); margin: 0 auto; padding-block: 48px 72px; }
.article h1 { font-size: clamp(2rem, 4.6vw, 3rem); margin: 12px 0 16px; }
.article .byline { font-family: var(--f-display); font-size: 0.9rem; color: var(--muted); display: flex; gap: 14px; flex-wrap: wrap; }
.article h2 { font-size: 1.5rem; margin: 40px 0 12px; }
.article p + p { margin-top: 18px; }
.article figure { margin: 28px 0; background: var(--soft); border-radius: 16px; padding: 22px; }
.article figcaption { font-family: var(--f-display); font-size: 0.85rem; color: var(--muted); margin-top: 12px; }
.coins { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; text-align: center; }
.coins div { display: flex; flex-direction: column; align-items: center; gap: 8px; font-family: var(--f-display); font-size: 0.9rem; }
.coin { width: 72px; height: 72px; border-radius: 50%; display: grid; place-items: center; font-family: var(--f-mono); font-size: 1.2rem; color: #fff; }
.coin.classic { background: var(--indigo); border: 2px solid var(--line); }
.coin.q { background: conic-gradient(var(--cyan) 0 50%, var(--violet) 50% 100%); }
.callout { border-left: 3px solid var(--violet); padding: 4px 0 4px 18px; margin: 24px 0; font-style: italic; color: var(--muted); }
.takeaways { background: var(--surface); border: 1px solid var(--line); border-radius: 16px; padding: 22px 24px; margin-top: 40px; }
.takeaways ul { margin: 10px 0 0; padding-left: 1.1em; display: flex; flex-direction: column; gap: 8px; }
.next-read { display: flex; justify-content: space-between; gap: 16px; flex-wrap: wrap; margin-top: 40px; padding-top: 24px; border-top: 1px solid var(--line); font-family: var(--f-display); }

/* article list */
.list { display: flex; flex-direction: column; border-top: 1px solid var(--line); }
.list a { display: grid; grid-template-columns: 1fr auto; gap: 8px 24px; padding: 22px 0; border-bottom: 1px solid var(--line); text-decoration: none; color: var(--fg); }
.list a:hover h3 { color: var(--link); }
.list p { grid-column: 1; color: var(--muted); font-size: 1rem; }
.list .meta { font-family: var(--f-mono); font-size: 0.78rem; color: var(--muted); white-space: nowrap; grid-row: 1; grid-column: 2; }
@media (max-width: 560px) { .list a { grid-template-columns: 1fr; } .list .meta { grid-column: 1; grid-row: auto; } }
.filters { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 20px; }
.chip { font-family: var(--f-display); font-size: 0.85rem; padding: 6px 14px; border-radius: 999px; border: 1px solid var(--line); background: var(--surface); color: var(--fg); cursor: pointer; }
.chip[aria-pressed="true"] { background: var(--fg); color: var(--bg); border-color: var(--fg); }

/* course */
.days { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 240px), 1fr)); gap: 12px; }
.days li { background: var(--surface); border: 1px solid var(--line); border-radius: 14px; padding: 16px 18px; }
.days .d { font-family: var(--f-mono); font-size: 0.75rem; color: var(--muted); letter-spacing: 0.08em; }
.days h3 { font-size: 1.02rem; margin-top: 6px; }
.days p { font-size: 0.95rem; color: var(--muted); margin-top: 4px; }

/* form grid */
.form-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.form-grid .full { grid-column: 1 / -1; }
.form-grid label { font-family: var(--f-display); font-size: 0.85rem; color: var(--muted); display: flex; flex-direction: column; gap: 6px; }
@media (max-width: 560px) { .form-grid { grid-template-columns: 1fr; } }

/* timeline for PQC */
.dates { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 200px), 1fr)); gap: 0; border-top: 2px solid var(--fg); margin-top: 8px; }
.dates div { padding: 14px 14px 0 0; }
.dates .y { font-family: var(--f-mono); font-size: 1.3rem; font-weight: 500; }
.dates p { font-size: 0.95rem; color: var(--muted); margin-top: 4px; }

/* footer */
footer { background: var(--band); color: var(--band-muted); font-size: 0.9rem; }
footer .wrap { padding-block: 40px; display: grid; grid-template-columns: 1.4fr 1fr 1fr; gap: 32px; }
footer .wrap > * { min-width: 0; }
footer a { color: var(--band-fg); text-decoration: none; display: block; padding: 3px 0; }
footer h4 { color: var(--band-fg); font-size: 0.85rem; letter-spacing: 0.1em; text-transform: uppercase; margin-bottom: 10px; font-weight: 500; }
footer .legal { grid-column: 1 / -1; border-top: 1px solid rgba(255,255,255,0.1); padding-top: 20px; font-size: 0.82rem; line-height: 1.5; }
@media (max-width: 760px) { footer .wrap { grid-template-columns: 1fr 1fr; } footer .wrap > :first-child { grid-column: 1 / -1; } }

/* article figures */
.wave { width: 100%; height: auto; display: block; }
.wave text { font-family: var(--f-mono); font-size: 12px; fill: var(--muted); }
.gb { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.gb > div { min-width: 0; }
.gb ul { margin: 8px 0 0; padding-left: 1.1em; font-size: 0.98rem; display: flex; flex-direction: column; gap: 6px; }
@media (max-width: 560px) { .gb { grid-template-columns: 1fr; } }
.tbl-wrap { overflow-x: auto; }
table.pairs { border-collapse: collapse; width: 100%; font-size: 0.95rem; min-width: 360px; }
table.pairs th, table.pairs td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--line); }
table.pairs th { font-family: var(--f-display); font-weight: 500; font-size: 0.85rem; color: var(--muted); }
table.pairs td { font-family: var(--f-mono); font-variant-numeric: tabular-nums; }
.mosca { display: flex; flex-direction: column; gap: 10px; font-family: var(--f-display); font-size: 0.85rem; }
.mosca .row { display: grid; grid-template-columns: 130px 1fr; gap: 12px; align-items: center; }
.mosca .track { position: relative; height: 26px; background: var(--surface); border-radius: 8px; border: 1px solid var(--line); overflow: hidden; }
.mosca .seg { position: absolute; top: 0; bottom: 0; display: grid; place-items: center; color: #fff; font-size: 0.75rem; white-space: nowrap; overflow: hidden; }
.mosca .x { background: var(--violet); }
.mosca .y { background: var(--indigo); }
.mosca .z { background: var(--cyan); color: var(--indigo); }
.mosca .gap { background: repeating-linear-gradient(45deg, #DC2626 0 6px, #F87171 6px 12px); }
@media (max-width: 480px) { .mosca .row { grid-template-columns: 1fr; gap: 4px; } }
.std { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 190px), 1fr)); gap: 12px; }
.std div { background: var(--surface); border: 1px solid var(--line); border-radius: 12px; padding: 14px; }
.std b { font-family: var(--f-mono); font-weight: 500; display: block; }
.std span { font-size: 0.92rem; color: var(--muted); }
.qs { margin: 10px 0 0; padding-left: 1.3em; display: flex; flex-direction: column; gap: 8px; }

.proto { background: var(--soft); color: var(--muted); font-family: var(--f-display); font-size: 0.8rem; text-align: center; padding: 6px 16px; }
.page { display: block; }

[hidden]{display:none!important}
body{margin:0}
img{max-width:100%}

/* table of contents */
.toc { margin: 24px 0 8px; border: 1px solid var(--line); border-radius: 14px; background: var(--surface); }
.toc summary { cursor: pointer; padding: 12px 18px; font-family: var(--f-display); font-weight: 500; font-size: 0.95rem; }
.toc ol { margin: 0; padding: 0 18px 16px 2.4em; display: flex; flex-direction: column; gap: 6px; font-size: 0.98rem; }
.toc a { text-decoration: none; }
.toc a:hover { text-decoration: underline; }
.article h2[id] { scroll-margin-top: 80px; }

/* sources */
.sources { margin-top: 48px; padding-top: 28px; border-top: 1px solid var(--line); }
.sources h2 { margin-top: 0; }
.sources ol { margin: 18px 0 0; padding-left: 1.4em; display: flex; flex-direction: column; gap: 14px; font-size: 0.98rem; }
.sources li { padding-left: 4px; }
.sources a { overflow-wrap: anywhere; }
.sources .kind { display: inline-block; font-family: var(--f-mono); font-size: 0.68rem; letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); border: 1px solid var(--line); border-radius: 999px; padding: 1px 8px; margin-right: 8px; vertical-align: 2px; }
.sources .by { display: block; color: var(--muted); font-size: 0.9rem; }
@media (max-width: 480px) {
  table.pairs { min-width: 0; font-size: 0.85rem; }
  table.pairs th, table.pairs td { padding: 6px 6px; }
}