:root {
  --bg: #f6f4ef; --panel: #ffffff; --ink: #1f2430; --muted: #5d6472; --line: #e2ddd3;
  --accent: #9a2f3b; --accent-ink: #ffffff; --soft: #f1ebe3; --link: #8a2b36;
  --g: #2f8a4a; --y: #c9950c; --r: #c3352b;
  --imp: #fff4e5; --imp-b: #f0a33a; --warn: #fdecec; --warn-b: #d9534f; --note: #eef4fb; --note-b: #4f83c9; --tip: #eef8f0; --tip-b: #3d9a5a; --why: #f3effa; --why-b: #7d5fc7;
  --radius: 12px; --sans: -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif; --mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  --navw: 300px;
}
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) {
  --bg: #16181d; --panel: #1f2229; --ink: #e8e6e1; --muted: #a2a7b2; --line: #2f333c; --accent: #d05c6a; --link: #e2818d; --soft: #262a33;
  --imp: #3a2d18; --imp-b: #d9962e; --warn: #3d2020; --warn-b: #e06661; --note: #1f2a3a; --note-b: #6b9be0; --tip: #1c3123; --tip-b: #4fb573; --why: #2a2338; --why-b: #a58ae6;
}}
:root[data-theme="dark"] {
  --bg: #16181d; --panel: #1f2229; --ink: #e8e6e1; --muted: #a2a7b2; --line: #2f333c; --accent: #d05c6a; --link: #e2818d; --soft: #262a33;
  --imp: #3a2d18; --imp-b: #d9962e; --warn: #3d2020; --warn-b: #e06661; --note: #1f2a3a; --note-b: #6b9be0; --tip: #1c3123; --tip-b: #4fb573; --why: #2a2338; --why-b: #a58ae6;
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--bg); color: var(--ink); font: 16px/1.6 var(--sans); }
a { color: var(--link); }
code, kbd { font-family: var(--mono); font-size: .9em; background: var(--soft); padding: .1em .35em; border-radius: 5px; }
kbd { border: 1px solid var(--line); border-bottom-width: 2px; background: var(--panel); }
pre { background: var(--soft); padding: 12px; border-radius: var(--radius); overflow: auto; }
h1 { font-size: 1.9rem; line-height: 1.2; margin: .3em 0 .4em; letter-spacing: -.01em; }
h2 { font-size: 1.35rem; margin: 1.8em 0 .5em; padding-top: .6em; border-top: 1px solid var(--line); }
h3 { font-size: 1.08rem; margin: 1.4em 0 .4em; }
h4 { font-size: 1rem; margin: 1.2em 0 .3em; color: var(--muted); text-transform: uppercase; letter-spacing: .04em; font-size: .82rem; }
p { margin: .6em 0; }
ol, ul { padding-left: 1.4em; } li { margin: .25em 0; } li > ol, li > ul { margin-top: .25em; }
hr { border: 0; border-top: 1px solid var(--line); margin: 1.5em 0; }
.small { font-size: .85rem; color: var(--muted); }
.lead { font-size: 1.1rem; color: var(--muted); margin: .2em 0 1em; }
.source { font-size: .8rem; color: var(--muted); word-break: break-all; }

.topbar { position: sticky; top: 0; z-index: 30; display: flex; align-items: center; gap: 12px; padding: 10px 16px; background: var(--panel); border-bottom: 1px solid var(--line); }
.topbar .brand, .sidenav .brand { font-weight: 700; text-decoration: none; color: var(--ink); letter-spacing: -.01em; }
.spacer { flex: 1; }
.menubtn, .themebtn { font: inherit; background: none; border: 1px solid var(--line); color: var(--ink); border-radius: 8px; padding: 4px 10px; cursor: pointer; }
.menubtn { display: none; }

.layout { display: grid; grid-template-columns: var(--navw) minmax(0, 1fr); min-height: calc(100vh - 53px); }
.sidenav { position: sticky; top: 53px; height: calc(100vh - 53px); overflow-y: auto; padding: 14px 12px 24px; border-right: 1px solid var(--line); background: var(--panel); font-size: .92rem; }
.sidenav .brand { display: none; }
.navsearch { position: relative; margin-bottom: 12px; }
.navsearch input { width: 100%; font: inherit; padding: 8px 10px; border: 1px solid var(--line); border-radius: 8px; background: var(--bg); color: var(--ink); }
.results { position: absolute; left: 0; right: 0; top: 100%; z-index: 40; background: var(--panel); border: 1px solid var(--line); border-radius: 8px; box-shadow: 0 10px 30px rgba(0,0,0,.15); max-height: 60vh; overflow: auto; }
.results a { display: block; padding: 8px 10px; text-decoration: none; color: var(--ink); border-bottom: 1px solid var(--line); }
.results a:hover, .results a.active { background: var(--soft); }
.results .rt { font-weight: 600; } .results .rs { font-size: .8rem; color: var(--muted); }
.results mark { background: #ffe58a; color: #222; border-radius: 3px; padding: 0 2px; }
.navmod summary { list-style: none; cursor: pointer; padding: 6px 6px; border-radius: 8px; display: flex; align-items: center; }
.navmod summary::-webkit-details-marker { display: none; }
.navmod summary a { color: var(--ink); text-decoration: none; font-weight: 600; display: flex; align-items: center; gap: 8px; flex: 1; }
.navmod summary::after { content: "›"; color: var(--muted); transition: transform .15s; margin-left: 6px; }
.navmod[open] summary::after { transform: rotate(90deg); }
.navmod ul { list-style: none; margin: 0 0 8px; padding: 0 0 0 10px; border-left: 2px solid var(--line); margin-left: 15px; }
.navmod li a { display: flex; gap: 6px; align-items: flex-start; padding: 4px 8px; color: var(--muted); text-decoration: none; border-radius: 6px; line-height: 1.35; }
.navmod li a:hover { background: var(--soft); color: var(--ink); }
.navmod li.current a { background: var(--soft); color: var(--ink); font-weight: 600; }
.num { display: inline-grid; place-items: center; width: 22px; height: 22px; border-radius: 6px; background: var(--accent); color: var(--accent-ink); font-size: .75rem; font-weight: 700; flex: none; }
.num.big { width: 34px; height: 34px; font-size: 1rem; margin-right: 12px; vertical-align: middle; border-radius: 9px; }
.navfoot { margin-top: 14px; padding-top: 10px; border-top: 1px solid var(--line); font-size: .85rem; color: var(--muted); }
.tick { width: 14px; height: 14px; border-radius: 50%; border: 1.5px solid var(--line); flex: none; margin-top: 4px; }
[data-done="1"] .tick, .tick.done { background: var(--g); border-color: var(--g); }

.content { padding: 28px clamp(16px, 4vw, 56px) 48px; max-width: 900px; }
.crumbs { font-size: .85rem; color: var(--muted); margin-bottom: 4px; } .crumbs a { color: var(--muted); }
.meta { display: flex; flex-wrap: wrap; gap: 8px 12px; align-items: center; margin: 0 0 12px; }
.pill { display: inline-block; font-size: .75rem; font-weight: 600; padding: 2px 9px; border-radius: 999px; background: var(--soft); color: var(--muted); text-transform: uppercase; letter-spacing: .04em; }
.pill.doc { background: var(--accent); color: var(--accent-ink); letter-spacing: 0; text-transform: none; font-family: var(--mono); }
.pill.s-current { background: #e2f3e6; color: #1f6b35; } .pill.s-draft { background: #fff1d6; color: #8a5a00; } .pill.s-shelved, .pill.s-superseded { background: #fde8e8; color: #9a2f2f; }
:root[data-theme="dark"] .pill.s-current, :root:not([data-theme="light"]) .pill.s-current { background: #1f3a27; color: #8fd8a5; }
.studied { font-size: .85rem; color: var(--muted); display: inline-flex; gap: 6px; align-items: center; cursor: pointer; margin-left: auto; }
.toc { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 10px 14px; margin: 12px 0 18px; font-size: .9rem; }
.toc ul { margin: 4px 0 0; padding-left: 1.2em; columns: 2; column-gap: 24px; } .toc li { break-inside: avoid; }
.callout { border-left: 4px solid var(--line); background: var(--soft); border-radius: 0 var(--radius) var(--radius) 0; padding: 10px 14px; margin: 14px 0; }
.callout .label { display: block; font-size: .75rem; font-weight: 700; text-transform: uppercase; letter-spacing: .06em; margin-bottom: 2px; }
.callout p:first-of-type { margin-top: 0; } .callout p:last-child { margin-bottom: 0; }
.callout.important { background: var(--imp); border-color: var(--imp-b); } .callout.important .label { color: var(--imp-b); }
.callout.warning { background: var(--warn); border-color: var(--warn-b); } .callout.warning .label { color: var(--warn-b); }
.callout.note { background: var(--note); border-color: var(--note-b); } .callout.note .label { color: var(--note-b); }
.callout.tip { background: var(--tip); border-color: var(--tip-b); } .callout.tip .label { color: var(--tip-b); }
.callout.why { background: var(--why); border-color: var(--why-b); } .callout.why .label { color: var(--why-b); }
blockquote { margin: 12px 0; padding: 6px 14px; border-left: 3px solid var(--line); color: var(--muted); }
.tablewrap { overflow-x: auto; margin: 12px 0; border: 1px solid var(--line); border-radius: var(--radius); background: var(--panel); }
table { border-collapse: collapse; width: 100%; font-size: .92rem; }
th, td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--line); vertical-align: top; }
th { background: var(--soft); font-size: .8rem; text-transform: uppercase; letter-spacing: .04em; color: var(--muted); }
tr:last-child td { border-bottom: 0; }
.lock { display: inline-block; font-size: .78rem; font-weight: 700; padding: 1px 8px; border-radius: 999px; color: #fff; vertical-align: baseline; }
.lock.g { background: var(--g); } .lock.y { background: var(--y); } .lock.r { background: var(--r); }
a.doc, abbr.doc { font-family: var(--mono); font-size: .9em; text-decoration: none; border-bottom: 1px dotted currentColor; }
a.doc { color: var(--link); border-bottom-style: solid; } abbr.doc.ext { color: var(--muted); cursor: help; }
.reflist { list-style: none; padding: 0; } .reflist li { padding: 6px 0; border-bottom: 1px solid var(--line); }

.cards { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 14px; margin: 18px 0; }
.card { position: relative; display: block; background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 14px 16px 12px; text-decoration: none; color: var(--ink); transition: transform .12s, box-shadow .12s; }
.card:hover { transform: translateY(-2px); box-shadow: 0 8px 24px rgba(0,0,0,.08); }
.card .tick { position: absolute; top: 12px; right: 12px; margin: 0; }
.card p { color: var(--muted); font-size: .92rem; margin: 6px 0 0; }
.cardhead { display: flex; flex-direction: column; gap: 6px; padding-right: 20px; } .cardhead .pill { align-self: flex-start; }
.card.mod { display: flex; gap: 6px; align-items: flex-start; } .card.mod strong { font-size: 1.05rem; }

.auto { margin-top: 28px; }
.qq { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 12px 14px; margin: 12px 0; }
.qt { margin: 0 0 8px; font-weight: 600; } .qn { color: var(--muted); font-weight: 700; margin-right: 4px; }
.opts { display: grid; gap: 6px; }
.opt { font: inherit; text-align: left; display: flex; gap: 10px; align-items: flex-start; padding: 8px 10px; background: var(--bg); border: 1px solid var(--line); border-radius: 8px; color: var(--ink); cursor: pointer; line-height: 1.4; }
.opt:hover { border-color: var(--accent); }
.ol { flex: none; width: 22px; height: 22px; border-radius: 6px; background: var(--soft); display: grid; place-items: center; font-size: .75rem; font-weight: 700; color: var(--muted); }
.qq.answered .opt { cursor: default; opacity: .75; }
.qq .opt.right { border-color: var(--g); background: color-mix(in srgb, var(--g) 14%, var(--panel)); opacity: 1; } .qq .opt.right .ol { background: var(--g); color: #fff; }
.qq .opt.wrong { border-color: var(--r); background: color-mix(in srgb, var(--r) 12%, var(--panel)); opacity: 1; } .qq .opt.wrong .ol { background: var(--r); color: #fff; }
.qq.nokey .opt.picked { border-color: var(--y); }
.score { margin-top: 10px; font-weight: 600; }
.prevnext { display: flex; justify-content: space-between; gap: 12px; margin-top: 36px; padding-top: 16px; border-top: 1px solid var(--line); font-size: .92rem; }
.prevnext a { text-decoration: none; max-width: 48%; } .prevnext .next { text-align: right; }
.pagefoot { margin-top: 40px; font-size: .78rem; color: var(--muted); border-top: 1px solid var(--line); padding-top: 12px; }
.body ol ol { list-style: lower-alpha; } .body ol ol ol { list-style: lower-roman; }
.body table th:first-child { white-space: nowrap; }

@media (max-width: 860px) {
  .layout { grid-template-columns: 1fr; }
  .menubtn { display: inline-block; }
  .sidenav { position: fixed; top: 53px; left: 0; bottom: 0; width: min(88vw, 340px); transform: translateX(-105%); transition: transform .18s; z-index: 25; box-shadow: 0 0 40px rgba(0,0,0,.25); }
  body.navopen .sidenav { transform: none; }
  .content { padding: 18px 16px 40px; }
  h1 { font-size: 1.5rem; } .toc ul { columns: 1; } .lead { font-size: 1rem; }
  .prevnext { flex-direction: column; } .prevnext a { max-width: none; } .prevnext .next { text-align: left; }
  .studied { margin-left: 0; }
}
@media print {
  .topbar, .sidenav, .studied, .prevnext, .quiz .opts, .toc { display: none !important; }
  .layout { display: block; } .content { max-width: none; padding: 0; } body { background: #fff; color: #000; }
  .card, .qq, .tablewrap, .callout { break-inside: avoid; }
}

/* ---- accounts: user menu, sign-in card, account and admin pages */
.usermenu { display: flex; align-items: center; gap: 10px; font-size: .85rem; color: var(--muted); }
.usermenu .uname { font-weight: 600; color: var(--ink); }
.usermenu a { color: var(--muted); text-decoration: none; } .usermenu a:hover { color: var(--ink); }
.usermenu form { margin: 0; display: inline; }
.usermenu button, .btn { font: inherit; font-size: .85rem; line-height: 1.4; display: inline-block; background: none; border: 1px solid var(--line); color: var(--ink); border-radius: 8px; padding: 4px 10px; cursor: pointer; text-decoration: none; }
.btn.primary { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); font-weight: 600; padding: 8px 16px; }
.btn.danger { color: var(--r); border-color: var(--r); }
body.auth { display: grid; place-items: center; min-height: 100vh; padding: 16px; }
.authcard { width: min(100%, 400px); background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 28px 26px; box-shadow: 0 10px 40px rgba(0,0,0,.08); }
.authcard h1 { margin: 12px 0 4px; font-size: 1.6rem; } .authcard .lead { margin-bottom: 12px; }
.authhead { display: flex; align-items: flex-start; justify-content: space-between; }
.brandmark .num.big { width: 44px; height: 44px; font-size: 1.05rem; margin: 0; }
form.stack { display: grid; gap: 12px; margin: 14px 0; }
form.stack label { display: grid; gap: 4px; font-size: .85rem; font-weight: 600; color: var(--muted); }
form.stack input, form.stack select { font: inherit; padding: 9px 11px; border: 1px solid var(--line); border-radius: 8px; background: var(--bg); color: var(--ink); width: 100%; }
form.stack input:focus, form.stack select:focus { outline: 2px solid var(--accent); outline-offset: 1px; border-color: transparent; }
.content.solo { max-width: 960px; margin: 0 auto; width: 100%; }
.flash { border-radius: var(--radius); padding: 10px 14px; margin: 0 0 14px; background: var(--tip); border-left: 4px solid var(--tip-b); }
.flash.error { background: var(--warn); border-left-color: var(--warn-b); }
.panel { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 16px 18px; margin: 14px 0; }
.stats { display: grid; grid-template-columns: repeat(auto-fit, minmax(140px, 1fr)); gap: 12px; margin: 14px 0; }
.stat { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 12px 14px; }
.stat b { display: block; font-size: 1.5rem; line-height: 1.2; } .stat span { font-size: .8rem; color: var(--muted); }
.inline-form { display: inline-block; margin: 4px 6px 4px 0; }
.bar { height: 6px; background: var(--soft); border-radius: 3px; overflow: hidden; margin: 6px 0 14px; } .bar i { display: block; height: 100%; background: var(--g); }
.qhist { font-size: .85rem; color: var(--muted); margin: -4px 0 10px; }
.yourprogress { margin: -4px 0 8px; }
table.users td { vertical-align: middle; } tr.disabled td { opacity: .6; }
@media (max-width: 860px) { .usermenu .uname, .usermenu a.acct { display: none; } }
@media print { .usermenu { display: none !important; } }