:root {
    --bg: #E8EBE5;
    --surface: #F7F8F4;
    --ink: #1C2230;
    --muted: #5D6472;
    --line: #CCD1C8;
    --accent: #2F3F9E;
    --accent-ink: #FFFFFF;
    --mark-bg: #F4D35E;
    --mark-ink: #1C2230;
    --error: #A2331F;
    --shadow: 0 1px 0 rgba(28, 34, 48, .04), 0 10px 30px -18px rgba(28, 34, 48, .35);
    --serif: "Instrument Serif", Georgia, "Times New Roman", serif;
    --sans: "Instrument Sans", system-ui, -apple-system, "Segoe UI", sans-serif;
    --mono: "IBM Plex Mono", ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
}
@media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) {
        color-scheme: dark;
        --bg: #10131A; --surface: #171B24; --ink: #DCE0E7; --muted: #8E95A3; --line: #2B313D;
        --accent: #9CA9F6; --accent-ink: #10131A; --mark-bg: #E2C04A; --mark-ink: #10131A; --error: #F08A74;
        --shadow: 0 10px 30px -18px rgba(0, 0, 0, .8);
    }
}
:root[data-theme="dark"] {
    color-scheme: dark;
    --bg: #10131A; --surface: #171B24; --ink: #DCE0E7; --muted: #8E95A3; --line: #2B313D;
    --accent: #9CA9F6; --accent-ink: #10131A; --mark-bg: #E2C04A; --mark-ink: #10131A; --error: #F08A74;
    --shadow: 0 10px 30px -18px rgba(0, 0, 0, .8);
}

/* Base */
* { box-sizing: border-box; }
[hidden] { display: none !important; }
html { scroll-behavior: smooth; }
body {
    margin: 0;
    background: var(--bg);
    color: var(--ink);
    font-family: var(--sans);
    font-size: 15px;
    line-height: 1.55;
    padding-inline: 16px;
    padding-block: 28px 56px;
}
.wrap { max-width: 900px; margin: 0 auto; display: flex; flex-direction: column; gap: 28px; }
main { display: flex; flex-direction: column; gap: 28px; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
a { color: var(--accent); text-underline-offset: 3px; }
a:hover { text-decoration-thickness: 2px; }
code { font-family: var(--mono); font-size: .9em; color: var(--ink); }
mark { background: var(--mark-bg); color: var(--mark-ink); border-radius: 2px; padding: 0; }
b { font-weight: 600; }
sup { line-height: 0; }

/* Site header */
header.site { display: flex; flex-direction: column; gap: 6px; }
h1 { font-family: var(--serif); font-weight: 400; font-size: clamp(40px, 7vw, 64px); line-height: 1; margin: 0; letter-spacing: -.01em; text-wrap: balance; }
h1 a { color: inherit; text-decoration: none; }
h1 em { color: var(--accent); }
header.site:not(.home) { flex-direction: row; flex-wrap: wrap; align-items: baseline; justify-content: space-between; gap: 8px 22px; }
header.site:not(.home) h1 { font-size: clamp(32px, 5vw, 40px); }
.topnav { display: flex; gap: 18px; font-weight: 500; font-size: 14px; }
.topnav a { color: var(--muted); text-decoration: none; }
.topnav a:hover { color: var(--ink); }
.lede { margin: 0; max-width: 62ch; color: var(--muted); font-size: 16px; }
.spec { font-family: var(--mono); font-size: 12px; color: var(--muted); display: flex; flex-wrap: wrap; gap: 4px 18px; margin-top: 6px; }
.spec b { color: var(--ink); font-weight: 500; }

/* Buttons and forms */
button { font-family: var(--sans); }
.btn { display: inline-block; font: 500 14px/1.5 var(--sans); border-radius: 8px; padding: 8px 14px; cursor: pointer; border: 1px solid var(--line); background: var(--surface); color: var(--ink); text-decoration: none; }
.btn:hover { border-color: var(--muted); text-decoration: none; }
.btn.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); }
.btn.primary:hover { filter: brightness(1.08); }
.controls { display: flex; flex-direction: column; gap: 14px; }
.bar { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; justify-content: space-between; }
.bar form { margin: 0; }
.tabs { display: inline-flex; border: 1px solid var(--line); border-radius: 999px; padding: 3px; background: var(--surface); }
.tab { font: 500 14px var(--sans); color: var(--muted); background: none; border: 0; border-radius: 999px; padding: 7px 14px; cursor: pointer; }
.tab[aria-selected="true"] { background: var(--ink); color: var(--bg); }
.panel { display: flex; flex-direction: column; gap: 10px; margin: 0; }
.row { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; }
.row input { flex: 1 1 260px; }
label.lbl, .lbl { font-size: 12px; font-weight: 600; text-transform: uppercase; letter-spacing: .07em; color: var(--muted); }
input[type=text], input[type=number] { font: 14px/1.5 var(--mono); color: var(--ink); background: var(--surface); border: 1px solid var(--line); border-radius: 8px; padding: 8px 12px; width: 100%; min-width: 0; }
input[type=text]:hover, input[type=number]:hover { border-color: var(--muted); }
.hint { font-size: 13px; color: var(--muted); margin: 0; }
.hint code { word-break: break-all; }
.msg { font-size: 14px; margin: 0; }
.msg.err { color: var(--error); }

/* Page view */
.book { display: flex; flex-direction: column; gap: 12px; }
.found { display: flex; flex-direction: column; gap: 4px; }
.found-text { margin: 0; font: 15px/1.6 var(--mono); word-break: break-all; }
.addr { display: flex; flex-wrap: wrap; gap: 10px 22px; align-items: flex-end; justify-content: space-between; }
.coords { display: flex; flex-wrap: wrap; gap: 8px 22px; font-family: var(--mono); font-variant-numeric: tabular-nums; }
.coord { display: flex; flex-direction: column; gap: 1px; }
.coord span { font: 600 11px var(--sans); text-transform: uppercase; letter-spacing: .08em; color: var(--muted); }
.coord b { font-weight: 500; font-size: 15px; }
.nav { display: flex; gap: 8px; flex-wrap: wrap; }
details.full { font-size: 13px; color: var(--muted); }
details.full summary { cursor: pointer; width: max-content; max-width: 100%; }
details.full .hint { margin-top: 10px; }
.hexbox { margin-top: 8px; font: 12px/1.5 var(--mono); color: var(--ink); background: var(--surface); border: 1px solid var(--line); border-radius: 8px; padding: 10px 12px; max-height: 160px; overflow: auto; word-break: break-all; user-select: all; }
.sheet { background: var(--surface); border: 1px solid var(--line); border-radius: 4px; box-shadow: var(--shadow); overflow-x: auto; }
.sheet-inner { display: flex; width: max-content; min-width: 100%; padding: 22px 26px 26px 14px; font: clamp(10px, 1.3vw, 12.5px)/1.62 var(--mono); }
.gutter { color: var(--muted); opacity: .55; text-align: right; padding-right: 14px; margin-right: 14px; border-right: 1px solid var(--line); user-select: none; white-space: pre; font-variant-numeric: tabular-nums; }
/* One character = 1ch in a monospace font: the text wraps exactly every --cols characters */
.text { width: calc((var(--cols, 101) + .5) * 1ch); word-break: break-all; line-break: anywhere; }
.foot { display: flex; justify-content: space-between; flex-wrap: wrap; gap: 6px 16px; font: 12px var(--mono); color: var(--muted); }
.foot a { color: inherit; }
@media (prefers-reduced-motion: no-preference) {
    .sheet .text { animation: ink .45s ease-out; }
    @keyframes ink { from { opacity: .35; } to { opacity: 1; } }
}

/* Error */
.alert { display: flex; flex-direction: column; align-items: flex-start; gap: 10px; background: var(--surface); border: 1px solid var(--line); border-left: 3px solid var(--error); border-radius: 8px; padding: 18px 20px; }
.alert h2 { color: var(--error); font-size: 28px; }
.alert p { margin: 0; color: var(--muted); word-break: break-word; }
.alert p b { font-family: var(--mono); font-weight: 500; color: var(--ink); word-break: break-all; }

/* How it works */
h2 { font-family: var(--serif); font-weight: 400; font-size: 32px; line-height: 1.1; margin: 0; }
section.how { display: flex; flex-direction: column; gap: 16px; border-top: 1px solid var(--line); padding-top: 24px; }
section.how > p { margin: 0; }
.steps { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 18px 28px; }
.steps li { display: flex; flex-direction: column; gap: 4px; }
.steps h3 { margin: 0; font-size: 15px; font-weight: 600; display: flex; gap: 8px; align-items: baseline; }
.steps h3 i { font: italic 22px var(--serif); color: var(--accent); }
.steps p { margin: 0; color: var(--muted); max-width: 60ch; }
.formula { font: 13px/1.6 var(--mono); background: var(--surface); border: 1px solid var(--line); border-radius: 8px; padding: 14px 16px; overflow-x: auto; white-space: nowrap; margin: 4px 0 16px; }
.prose { max-width: 72ch; }
.prose h2 { margin: 0 0 14px; }
.prose p { margin: 0 0 14px; }
.prose ul { margin: 0 0 14px; padding-left: 22px; }
.prose li { margin-bottom: 4px; }
.prose li::marker { color: var(--accent); }
.prose hr { border: 0; border-top: 1px solid var(--line); margin: 32px 0 24px; }
.prose h3 { margin: 22px 0 10px; font-size: 15px; font-weight: 600; }
.prose pre { font: 13px/1.6 var(--mono); color: var(--ink); background: var(--surface); border: 1px solid var(--line); border-radius: 8px; padding: 12px 16px; overflow-x: auto; margin: 4px 0 16px; }
.prose pre i, .prose code i { color: var(--muted); }
.logo { display: block; width: 120px; max-width: 30%; margin: 40px auto 0; }
.math { font-family: var(--serif); font-style: italic; font-size: 1.15em; color: var(--ink); }
.math sup { font-style: normal; }
.formula .math { font-size: 1.35em; }
span.sum1, span.sum2 { position: relative; font-size: 2.2em; display: inline-block; line-height: .7em; vertical-align: middle; font-style: normal; color: var(--accent); }
span.sum1:before, span.sum2:before { font: 11px var(--mono); color: var(--muted); display: block; text-align: center; }
span.sum1:before { width: 30px; content: "N"; }
span.sum2:before { width: 50px; content: "L(v) - 1"; }
span.sum1:after, span.sum2:after { font: 11px var(--mono); color: var(--muted); display: block; content: "k = 1"; width: 40px; text-align: center; }
.bigger { font-size: 3em; vertical-align: bottom; font-weight: lighter; font-style: normal; color: var(--muted); }

/* Site footer */
.site-foot { display: flex; justify-content: space-between; flex-wrap: wrap; gap: 6px 16px; border-top: 1px solid var(--line); padding-top: 16px; font: 12px var(--mono); color: var(--muted); }
.site-foot a { color: inherit; }

@media (max-width: 640px) {
    .steps { grid-template-columns: 1fr; }
}