:root{--brand:#2f6df6;--apricot:#f08a24;--ink:#1c2430;--muted:#5a6675;--bg:#fbf7f0;--card:#fff;--line:#ececec}
*{box-sizing:border-box}html{-webkit-text-size-adjust:100%}
body{margin:0;font:17px/1.65 -apple-system,Segoe UI,Roboto,sans-serif;color:var(--ink);background:var(--bg)}
.topbar{position:sticky;top:0;z-index:5;display:flex;justify-content:space-between;align-items:center;gap:8px 16px;padding:8px 16px;background:#fff;border-bottom:1px solid var(--line)}
.brand{font-weight:700;color:var(--brand);text-decoration:none;font-size:15px}
.langtoggle{display:flex;gap:4px;flex-shrink:0}
.langtoggle button{border:1px solid var(--line);background:#fff;color:var(--muted);padding:6px 10px;border-radius:999px;cursor:pointer;font-size:14px;white-space:nowrap}
.langtoggle button[aria-pressed=true]{background:var(--brand);color:#fff;border-color:var(--brand)}
main{max-width:760px;margin:0 auto;padding:18px 16px 64px}
h1{font-size:24px;line-height:1.3}.lead{color:var(--muted);margin:6px 0}
.hint{margin:10px 0 18px;background:#fff;border:1px solid var(--line);border-left:3px solid var(--apricot);border-radius:8px;padding:9px 12px;color:var(--muted);font-size:13.5px}
.breadcrumb{color:var(--muted);font-size:14px;margin-bottom:8px}.breadcrumb a{color:var(--brand)}
.article{background:var(--card);border:1px solid var(--line);border-radius:14px;padding:16px 18px;margin:14px 0}
.article-title{font-weight:600;margin:0 0 8px}
.part{margin:10px 0}.part-no{color:var(--apricot);font-weight:700}
.part p{margin:0}
.seg{cursor:pointer;border-radius:4px;padding:0 2px;transition:background .12s}
.seg:hover,.seg:focus-visible{background:#fdebcf;outline:none}
.seg.active{background:var(--apricot);color:#fff}
.tooltip{position:fixed;max-width:min(92vw,440px);background:#1c2430;color:#fff;padding:9px 12px;border-radius:9px;font-size:15.5px;line-height:1.45;box-shadow:0 8px 28px rgba(0,0,0,.28);z-index:50;display:none}
.tooltip.show{display:block}
.toc{list-style:none;padding:0}.toc li{margin:6px 0}
.toc a{display:block;background:#fff;border:1px solid var(--line);border-radius:12px;padding:12px 14px;text-decoration:none;color:var(--ink)}
.toc .ch-num{display:block;color:var(--brand);font-size:13px;font-weight:700}
.toc .prev{color:var(--muted);font-weight:400;font-size:.92em}
.chapter-nav{display:flex;justify-content:space-between;margin-top:20px;gap:12px}.chapter-nav a{color:var(--brand);text-decoration:none}
.preamble{background:#fff;border:1px solid var(--line);border-radius:14px;padding:16px}
.site-footer{max-width:760px;margin:0 auto;padding:20px 16px 40px;color:var(--muted);font-size:13px}
/* one language at a time — the other stays in the DOM for SEO */
body.show-ru .hy{display:none}
body.show-hy .ru{display:none}