:root{--bg:#f4f3ee;--surface:#fff;--sidebar:#e8ecd9;--sidebar2:#f1f3e7;--nav:#e1e5de;--ink:#202722;--muted:#687169;--link:#28665e;--accent:#7c9172;--line:#d7dcd4}*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;background:var(--bg);color:var(--ink);font:15px/1.55 Arial,helvetica neue,sans-serif}a{color:inherit;text-decoration:none}img{max-width:100%;display:block}.wrap{width:min(1130px,calc(100% - 32px));margin:auto}.skip{position:absolute;left:-999px}.skip:focus{left:12px;top:12px;background:#fff;padding:10px;z-index:99}.site-header{position:sticky;top:0;z-index:20;background:var(--nav);border-bottom:1px solid #cbd1c9}.header-inner{height:62px;display:flex;align-items:center}.brand{font-weight:800;letter-spacing:.065em;white-space:nowrap}.brand span{color:var(--link)}.header-inner nav{height:100%;display:flex;align-items:center;gap:4px;margin-left:58px}.header-inner nav>a,.nav-dropdown>button{height:100%;display:flex;align-items:center;padding:0 16px;border:0;background:0 0;font:700 .82rem Arial,sans-serif;color:#354038}.header-inner nav>a:hover,.nav-dropdown>button:hover{background:#d5dbd2}.search-link{margin-left:auto;color:var(--link);font-size:.82rem;font-weight:700}.menu-button{display:none;background:0 0;border:0}.menu-button i{display:block;width:24px;height:2px;background:var(--ink);margin:5px}.nav-dropdown{height:100%;position:relative}.dropdown-menu{display:none;position:absolute;top:61px;left:0;width:210px;background:#fff;border:1px solid var(--line);box-shadow:0 8px 18px #27352c1a;padding:7px}.nav-dropdown.open .dropdown-menu,.nav-dropdown:hover .dropdown-menu{display:block}.dropdown-menu a{display:block;padding:8px 10px;font-size:.85rem}.dropdown-menu a:hover{background:var(--sidebar2)}.site-shell{display:grid;grid-template-columns:195px minmax(0,680px)220px;gap:17px;align-items:start;padding-top:20px}.home-content,.article,.section-main{background:var(--surface);border:1px solid var(--line);padding:0 28px 32px;min-width:0}.breadcrumbs{font-size:.75rem;color:var(--muted);padding:16px 0;border-bottom:1px solid #edf0ec;margin-bottom:22px}.breadcrumbs span{margin:0 7px}.knowledge,.right-rail{position:sticky;top:82px}.knowledge{background:var(--sidebar);border:1px solid #d2d8c4}.knowledge-toggle{display:none}.knowledge-body{padding:17px 16px 20px}.knowledge-title,.rail-widget h2{font:800 .69rem/1.25 Arial,sans-serif;letter-spacing:.095em;margin:0}.knowledge-title{padding-bottom:13px;border-bottom:1px solid #cbd2bd}.knowledge section{padding:13px 0 8px;border-bottom:1px solid #d1d7c7}.knowledge section:last-child{border:0}.knowledge h3{font-size:.77rem;letter-spacing:.08em;text-transform:uppercase;margin:0 0 7px}.knowledge h4{font-size:.68rem;letter-spacing:.08em;text-transform:uppercase;color:var(--muted);margin:8px 0 3px;padding-left:8px}.knowledge a{display:block;padding:3px 5px 3px 17px;font-size:.79rem;color:#445047}.knowledge a:hover{color:var(--link);text-decoration:underline}.right-rail{display:grid;gap:12px}.rail-widget{background:var(--surface);border:1px solid var(--line);padding:14px}.rail-widget h2{background:var(--sidebar2);margin:-14px -14px 9px;padding:10px 12px;border-bottom:1px solid var(--line)}.rail-widget a{display:block;padding:7px 1px;border-bottom:1px solid #ecefea;font-size:.79rem;line-height:1.35}.rail-widget a:last-child{border:0}.rail-widget a:hover{color:var(--link)}.rail-widget span{display:block;color:var(--muted);font-size:.72rem;margin-top:2px}.rail-start{border-top:3px solid var(--accent)}.rail-tools a{color:var(--link);font-weight:700}.eyebrow{font:800 .68rem/1.2 Arial,sans-serif;letter-spacing:.12em;color:var(--link);margin:0 0 7px}.home-intro{padding-bottom:25px}.home-intro h1,.article h1,.section-intro h1{font:700 2.25rem/1.12 Georgia,serif;letter-spacing:-.02em;margin:0 0 10px}.home-subtitle,.article-deck{font-size:1.06rem;line-height:1.5;color:#4f5d54;margin:0 0 16px}.home-intro>p:not(.eyebrow){margin:0 0 10px}.info-note{margin-top:18px;background:var(--sidebar2);border-left:4px solid var(--accent);padding:12px 14px;font-size:.85rem}.info-note a,.prose a{color:var(--link);text-decoration:underline}.topic-list{border-top:1px solid var(--line)}.topic-row{display:grid;grid-template-columns:210px 1fr;gap:22px;padding:24px 0;border-bottom:1px solid var(--line);align-items:center}.topic-row:nth-child(even){grid-template-columns:1fr 210px}.topic-row:nth-child(even) .topic-image{order:2}.topic-image{height:145px;background-image:url(../images/technical-topics.jpg);background-size:300% 200%;background-repeat:no-repeat;border:1px solid var(--line)}.topic-pressure{background-position:0 0}.topic-basics{background-position:50% 0}.topic-calibration{background-position:100% 0}.topic-howto{background-position:0 100%}.topic-trouble{background-position:50% 100%}.topic-tools{background-position:100% 100%}.topic-row h2{font:700 1.45rem/1.2 Georgia,serif;margin:0 0 6px}.topic-row p:not(.eyebrow){color:var(--muted);margin:0 0 10px}.topic-link{font-size:.82rem;font-weight:800;color:var(--link)}.article header{padding-bottom:18px;border-bottom:1px solid var(--line)}.prose{font:16px/1.67 Georgia,serif}.prose h2{font-size:1.55rem;line-height:1.25;margin:1.65em 0 .45em}.prose h3{font-size:1.2rem}.prose img{margin:18px 0}.toc{position:static}.toc nav a{padding-left:8px}.toc ul{list-style:none;padding:0;margin:0}.toc ul ul{padding-left:8px}.related{margin:38px 0 0;border-top:1px solid var(--line);padding-top:25px}.related h2{font:700 1.35rem Georgia,serif}.related-grid{display:grid;grid-template-columns:1fr;gap:8px}.related-grid a{border:1px solid var(--line);padding:11px;display:flex;flex-direction:column}.related-grid span{color:var(--muted);font-size:.78rem}.section-intro{padding:0 0 18px;border-bottom:1px solid var(--line)}.section-intro p{color:var(--muted)}.list-label{margin-top:28px}.article-list a{display:block;border-top:1px solid var(--line);padding:15px 0}.article-list h2{font:700 1.25rem Georgia,serif;margin:3px 0}.article-list p{color:var(--muted);margin:3px 0}.article-list span{color:var(--link);font-size:.8rem;font-weight:700}.calculator{background:var(--sidebar2);border:1px solid var(--line);padding:20px;display:grid;gap:10px;max-width:600px;font-family:Arial,sans-serif}.calculator label{display:grid;gap:4px;font-weight:700}.calculator input,.calculator select{padding:10px;border:1px solid var(--line);font:inherit}.calculator button{background:var(--link);color:#fff;border:0;padding:11px}.tool-output{background:#fff;padding:13px;min-height:50px}.site-footer{background:#313a34;color:#e2e8e3;margin-top:45px;padding:38px 0 18px}.footer-grid{display:grid;grid-template-columns:2fr repeat(3,1fr);gap:30px}.footer-grid div{display:flex;flex-direction:column}.footer-grid a{color:#bac5bd}.footer-bottom{border-top:1px solid #536059;margin-top:28px;padding-top:15px}@media(max-width:1040px){.site-shell{grid-template-columns:185px minmax(0,1fr);gap:16px}.right-rail{grid-column:2;position:static;grid-template-columns:repeat(2,1fr)}.article-rail{grid-column:2}.header-inner nav{margin-left:25px}.header-inner nav>a,.nav-dropdown>button{padding:0 10px}}@media(max-width:899px){.wrap{width:min(720px,calc(100% - 24px))}.header-inner{height:58px}.header-inner nav{display:none;position:absolute;top:58px;left:0;right:0;height:auto;margin:0;background:var(--nav);padding:8px 12px;flex-direction:column;align-items:stretch;border-bottom:1px solid var(--line)}.header-inner nav.open{display:flex}.header-inner nav>a,.nav-dropdown>button{height:auto;padding:11px;text-align:left}.nav-dropdown{height:auto}.dropdown-menu{position:static;width:auto;box-shadow:none;border:0;background:#eef0eb}.nav-dropdown:hover .dropdown-menu{display:none}.nav-dropdown.open .dropdown-menu{display:block}.menu-button{display:block;margin-left:auto}.search-link{margin-left:15px}.site-shell{grid-template-columns:1fr;padding-top:12px}.knowledge{position:static}.knowledge-toggle{display:flex;justify-content:space-between;width:100%;padding:12px 14px;background:var(--sidebar);border:0;font-weight:800;color:var(--ink)}.knowledge-body{display:none}.knowledge.open .knowledge-body{display:block}.home-content,.article,.section-main{grid-column:1}.right-rail,.article-rail{grid-column:1;grid-template-columns:repeat(2,1fr)}.home-content,.article,.section-main{padding:0 22px 28px}.footer-grid{grid-template-columns:1fr 1fr}}@media(max-width:599px){.home-content,.article,.section-main{padding:0 16px 22px}.home-intro h1,.article h1,.section-intro h1{font-size:1.85rem}.topic-row,.topic-row:nth-child(even){grid-template-columns:1fr;gap:13px}.topic-row:nth-child(even) .topic-image{order:0}.topic-image{height:175px}.right-rail,.article-rail{grid-template-columns:1fr}.footer-grid{grid-template-columns:1fr}}