/* self-hosted fonts (Fontsource, latin subsets, OFL) */
@font-face{font-family:'Archivo';font-style:normal;font-weight:400;font-display:swap;src:url('/assets/fonts/archivo-latin-400-normal.woff2') format('woff2')}
@font-face{font-family:'Archivo';font-style:normal;font-weight:500;font-display:swap;src:url('/assets/fonts/archivo-latin-500-normal.woff2') format('woff2')}
@font-face{font-family:'Archivo';font-style:normal;font-weight:600;font-display:swap;src:url('/assets/fonts/archivo-latin-600-normal.woff2') format('woff2')}
@font-face{font-family:'JetBrains Mono';font-style:normal;font-weight:400;font-display:swap;src:url('/assets/fonts/jetbrains-mono-latin-400-normal.woff2') format('woff2')}
@font-face{font-family:'JetBrains Mono';font-style:normal;font-weight:500;font-display:swap;src:url('/assets/fonts/jetbrains-mono-latin-500-normal.woff2') format('woff2')}
@font-face{font-family:'JetBrains Mono';font-style:normal;font-weight:700;font-display:swap;src:url('/assets/fonts/jetbrains-mono-latin-700-normal.woff2') format('woff2')}
@font-face{font-family:'Bricolage Grotesque';font-style:normal;font-weight:500;font-display:swap;src:url('/assets/fonts/bricolage-grotesque-latin-500-normal.woff2') format('woff2')}
@font-face{font-family:'Bricolage Grotesque';font-style:normal;font-weight:700;font-display:swap;src:url('/assets/fonts/bricolage-grotesque-latin-700-normal.woff2') format('woff2')}
@font-face{font-family:'Bricolage Grotesque';font-style:normal;font-weight:800;font-display:swap;src:url('/assets/fonts/bricolage-grotesque-latin-800-normal.woff2') format('woff2')}
/* tankvolumecalc.com — theme: engineering drawing sheet. REV A */
:root{
  --paper:#f2f0ea;--panel:#faf9f5;--ink:#1b2733;--ink-soft:#46535f;
  --hairline:#cdc9bd;--hairline-dark:#9a9587;
  --liquid:#0e7c86;--liquid-deep:#0a5a62;--liquid-pale:#d7ecee;
  --amber:#e8930c;--amber-deep:#b96f00;
  --mono:'JetBrains Mono',ui-monospace,monospace;
  --body:'Archivo',system-ui,sans-serif;
  --display:'Bricolage Grotesque',var(--body);
}
*{margin:0;padding:0;box-sizing:border-box}
html{scroll-behavior:smooth}
body{font-family:var(--body);color:var(--ink);background:var(--paper);
  background-image:linear-gradient(var(--hairline) 1px,transparent 1px),linear-gradient(90deg,var(--hairline) 1px,transparent 1px);
  background-size:48px 48px;background-position:-1px -1px;line-height:1.62;font-size:17px}
a{color:var(--liquid-deep)}
.wrap{max-width:1180px;margin:0 auto;padding:0 24px}
.toprule{height:6px;background:repeating-linear-gradient(90deg,var(--ink) 0 36px,var(--amber) 36px 48px)}
header{background:var(--panel);border-bottom:1.5px solid var(--ink)}
.hd{display:flex;align-items:center;justify-content:space-between;gap:20px;padding:13px 0;flex-wrap:wrap}
.brand{display:flex;align-items:center;gap:12px;text-decoration:none;color:var(--ink)}
.brand-mark{width:36px;height:36px;border:2px solid var(--ink);position:relative;background:var(--panel)}
.brand-mark::after{content:"";position:absolute;left:3px;right:3px;bottom:3px;height:55%;background:var(--liquid);animation:slosh 5s ease-in-out infinite}
@keyframes slosh{0%,100%{height:48%}50%{height:62%}}
.brand-name{font-family:var(--display);font-weight:800;font-size:20px;letter-spacing:-.01em}
.brand-name span{color:var(--liquid)}
.brand-tld{font-family:var(--mono);font-size:12px;color:var(--ink-soft)}
nav.main{display:flex;gap:4px;flex-wrap:wrap}
nav.main a{font-family:var(--mono);font-size:12px;text-transform:uppercase;letter-spacing:.06em;text-decoration:none;color:var(--ink);padding:8px 11px;border:1px solid transparent}
nav.main a:hover{border-color:var(--ink);background:var(--paper)}
.navtoggle{display:none}
@media(max-width:900px){
  .navtoggle{display:block;appearance:none;background:var(--ink);color:var(--panel);border:0;font-family:var(--mono);font-size:12px;letter-spacing:.08em;padding:9px 14px;cursor:pointer}
  nav.main{display:none;width:100%;flex-direction:column;border-top:1px solid var(--hairline)}
  nav.main.open{display:flex}
  nav.main a{border:0;border-bottom:1px solid var(--hairline);padding:12px 4px}
}
main{min-height:60vh}
.crumbs{font-family:var(--mono);font-size:11px;text-transform:uppercase;letter-spacing:.08em;color:var(--ink-soft);padding:18px 0 0}
.crumbs a{color:var(--ink-soft);text-decoration:none}.crumbs a:hover{color:var(--liquid-deep)}
.hero{padding:34px 0 8px}
.eyebrow{display:inline-flex;align-items:center;gap:10px;font-family:var(--mono);font-size:11.5px;text-transform:uppercase;letter-spacing:.14em;color:var(--ink-soft);margin-bottom:14px}
.eyebrow::before{content:"";width:34px;height:2px;background:var(--amber)}
h1{font-family:var(--display);font-weight:800;font-size:clamp(30px,4.6vw,50px);line-height:1.06;letter-spacing:-.02em;max-width:22ch}
h1 em{font-style:normal;color:var(--liquid);position:relative}
h1 em::after{content:"";position:absolute;left:0;right:0;bottom:4px;height:9px;background:var(--liquid-pale);z-index:-1}
.lede{margin-top:14px;max-width:62ch;font-size:17.5px;color:var(--ink-soft)}
.lede strong{color:var(--ink)}
h2{font-family:var(--display);font-weight:800;font-size:clamp(22px,3vw,30px);letter-spacing:-.015em;margin:34px 0 12px}
h3{font-family:var(--display);font-weight:700;font-size:18px;margin:22px 0 8px}
.prose{max-width:74ch}
.prose p{margin:0 0 14px;color:var(--ink-soft)}
.prose p b,.prose p strong{color:var(--ink)}
.prose code{font-family:var(--mono);font-size:.92em;background:var(--panel);border:1px solid var(--hairline);padding:1px 5px;color:var(--liquid-deep)}
.prose pre{background:var(--panel);border:1.5px solid var(--ink);padding:14px;font-family:var(--mono);font-size:13px;overflow-x:auto;margin:0 0 16px;color:var(--liquid-deep)}
.badges{display:flex;margin-top:18px;flex-wrap:wrap}
.badges span{font-family:var(--mono);font-size:11px;text-transform:uppercase;letter-spacing:.08em;border:1px solid var(--ink);padding:6px 11px;margin:-1px 0 0 -1px;background:var(--panel)}
.badges span b{color:var(--amber-deep)}

/* calculator sheet */
.sheet{margin:26px 0 12px;background:var(--panel);border:1.5px solid var(--ink);box-shadow:8px 8px 0 rgba(27,39,51,.12)}
.sheet-head{display:flex;justify-content:space-between;border-bottom:1.5px solid var(--ink)}
.sheet-title{padding:11px 16px;font-family:var(--mono);font-size:11.5px;text-transform:uppercase;letter-spacing:.12em}
.sheet-title b{color:var(--liquid-deep)}
.sheet-no{padding:11px 16px;border-left:1.5px solid var(--ink);font-family:var(--mono);font-size:11.5px;color:var(--ink-soft);display:flex;align-items:center;gap:12px}
.sheet-no i{font-style:normal;color:var(--amber-deep)}
.sheet-grid{display:grid;grid-template-columns:370px 1fr 290px}
@media(max-width:1020px){.sheet-grid{grid-template-columns:1fr 1fr}.col-out{grid-column:1/-1;border-top:1.5px solid var(--ink);border-left:none!important}}
@media(max-width:680px){.sheet-grid{grid-template-columns:1fr}.col-viz{border-left:none!important;border-top:1.5px solid var(--ink)}}
.col-in{padding:20px 20px 24px}
.col-viz{border-left:1.5px solid var(--ink);background:repeating-linear-gradient(0deg,transparent 0 23px,rgba(27,39,51,.07) 23px 24px),repeating-linear-gradient(90deg,transparent 0 23px,rgba(27,39,51,.07) 23px 24px),var(--panel);display:flex;flex-direction:column}
.col-out{border-left:1.5px solid var(--ink);background:var(--ink);color:#eef0ee;padding:20px}
fieldset{border:none;margin-bottom:16px}
legend,label.lbl{display:block;font-family:var(--mono);font-size:10.5px;text-transform:uppercase;letter-spacing:.12em;color:var(--ink-soft);margin-bottom:7px}
.shape-grid{display:grid;grid-template-columns:repeat(3,1fr)}
.shape-grid button{appearance:none;border:1px solid var(--hairline-dark);background:var(--panel);margin:-1px 0 0 -1px;padding:9px 3px 7px;cursor:pointer;font-family:var(--mono);font-size:9.5px;text-transform:uppercase;letter-spacing:.03em;color:var(--ink-soft);display:flex;flex-direction:column;align-items:center;gap:5px;transition:background .12s}
.shape-grid button svg{width:32px;height:22px;stroke:var(--ink-soft);fill:none;stroke-width:1.6}
.shape-grid button:hover{background:var(--liquid-pale)}
.shape-grid button.on{background:var(--ink);color:var(--panel);border-color:var(--ink);position:relative;z-index:1}
.shape-grid button.on svg{stroke:var(--amber)}
.dims{display:grid;grid-template-columns:1fr 1fr;gap:11px}
.field{display:flex;flex-direction:column}
.field input,.field select{font-family:var(--mono);font-size:16px;padding:9px 10px;border:1px solid var(--hairline-dark);background:var(--paper);color:var(--ink);width:100%}
.field input:focus,.field select:focus{outline:2px solid var(--liquid);outline-offset:-1px}
.field .err{font-family:var(--mono);font-size:10.5px;color:#b3261e;margin-top:4px;display:none}
.field.bad input{outline:2px solid #b3261e;outline-offset:-1px}
.field.bad .err{display:block}
.unit-row{display:grid;grid-template-columns:1fr 1fr;gap:11px;margin-top:13px}
.fill-block{margin-top:16px}
.fill-head{display:flex;justify-content:space-between;align-items:baseline}
.fill-head output{font-family:var(--mono);font-size:13px;font-weight:700;color:var(--liquid-deep)}
input[type=range]{width:100%;accent-color:var(--liquid);margin-top:6px;cursor:pointer}
.viz-stage{flex:1;display:flex;align-items:center;justify-content:center;padding:16px;min-height:280px}
.viz-foot{border-top:1px solid var(--hairline-dark);display:grid;grid-template-columns:1fr 1fr 1fr;font-family:var(--mono);font-size:10px}
.viz-foot div{padding:7px 10px;border-left:1px solid var(--hairline-dark)}
.viz-foot div:first-child{border-left:none}
.viz-foot b{display:block;font-size:12px;color:var(--liquid-deep)}
.viz-foot small{text-transform:uppercase;letter-spacing:.08em;color:var(--ink-soft)}
.out-big{border-bottom:1px solid rgba(238,240,238,.25);padding-bottom:14px;margin-bottom:14px}
.out-big small{font-family:var(--mono);font-size:10px;text-transform:uppercase;letter-spacing:.14em;color:#c4d3d9;display:block;margin-bottom:5px}
.out-big .num{font-family:var(--mono);font-weight:700;font-size:32px;line-height:1;color:#fff}
.out-big .num em{font-style:normal;font-size:15px;color:var(--amber);margin-left:6px}
.out-row{display:flex;justify-content:space-between;gap:10px;padding:6px 0;border-bottom:1px dashed rgba(238,240,238,.18);font-size:14px}
.out-row span{color:#c4d3d9;font-family:var(--mono);font-size:11px;text-transform:uppercase;letter-spacing:.08em;padding-top:2px}
.out-row b{font-family:var(--mono);font-weight:500;text-align:right;color:#fff}
.out-note{margin-top:12px;font-size:11px;color:#9fb3ba;font-family:var(--mono);line-height:1.6}
.out-note a{color:var(--amber)}

/* ad stubs */
#ad-desktop{width:728px;max-width:100%;height:90px}
#ad-mobile{width:320px;height:50px;display:none}
@media(max-width:760px){#ad-desktop{display:none}#ad-mobile{display:flex}}

/* sections / cards / chips */
section{padding:34px 0}
.sec-head{display:flex;align-items:baseline;justify-content:space-between;gap:18px;margin-bottom:20px;flex-wrap:wrap}
.sec-head .idx{font-family:var(--mono);font-size:11.5px;color:var(--amber-deep);letter-spacing:.1em}
.cards{display:grid;grid-template-columns:repeat(auto-fill,minmax(245px,1fr))}
.card{border:1px solid var(--ink);margin:-1px 0 0 -1px;background:var(--panel);padding:17px;text-decoration:none;display:block;transition:background .12s;position:relative;color:var(--ink)}
.card:hover{background:var(--liquid-pale)}
.card .k{font-family:var(--mono);font-size:10px;color:var(--ink-soft);text-transform:uppercase;letter-spacing:.1em}
.card h3{margin:5px 0 5px;font-size:16.5px}
.card p{font-size:13.5px;color:var(--ink-soft)}
.card .vol{position:absolute;top:13px;right:13px;font-family:var(--mono);font-size:9.5px;border:1px solid var(--amber-deep);color:var(--amber-deep);padding:2px 6px}
.chips{display:flex;flex-wrap:wrap}
.chips a{font-family:var(--mono);font-size:12px;text-decoration:none;color:var(--ink);border:1px solid var(--hairline-dark);padding:8px 13px;margin:-1px 0 0 -1px;background:var(--panel)}
.chips a:hover{background:var(--liquid);border-color:var(--liquid);color:#fff}
.chips a b{color:var(--amber-deep)}
.chips a:hover b{color:#ffd9a0}
.dark{background:var(--ink);color:#eef0ee;border-top:6px solid var(--amber)}
.dark h2{color:#fff}.dark .lede{color:#9fb3ba}
.dark .chips a{color:#eef0ee;border-color:#44535f;background:transparent}
.dark .chips a b{color:var(--amber)}

/* dip chart table */
.stick{display:flex;gap:12px;align-items:flex-end;flex-wrap:wrap;background:var(--panel);border:1.5px solid var(--ink);padding:16px;box-shadow:6px 6px 0 rgba(27,39,51,.12);margin:20px 0}
.stick .field{min-width:140px}
.stick .res{font-family:var(--mono);font-size:15px;padding:9px 14px;background:var(--ink);color:#fff}
.stick .res b{color:var(--amber)}
table.chart{border-collapse:collapse;width:100%;max-width:680px;margin:18px 0;background:var(--panel);font-family:var(--mono);font-size:13px}
table.chart caption{text-align:left;font-family:var(--mono);font-size:11px;text-transform:uppercase;letter-spacing:.1em;color:var(--ink-soft);padding:8px 0}
table.chart th{background:var(--ink);color:#fff;font-weight:500;text-transform:uppercase;font-size:10.5px;letter-spacing:.08em;padding:8px 10px;text-align:right}
table.chart th:first-child{text-align:left}
table.chart td{border:1px solid var(--hairline);padding:6px 10px;text-align:right;color:var(--ink-soft)}
table.chart td:first-child{text-align:left;color:var(--ink);font-weight:700}
table.chart tr:nth-child(even) td{background:var(--paper)}
table.chart tr.hl td{background:var(--liquid-pale);color:var(--ink)}
.btnrow{display:flex;gap:10px;margin:14px 0;flex-wrap:wrap}
.btn{appearance:none;cursor:pointer;text-decoration:none;font-family:var(--mono);font-size:12px;text-transform:uppercase;letter-spacing:.08em;padding:10px 16px;border:1.5px solid var(--ink);background:var(--ink);color:var(--panel)}
.btn:hover{background:var(--amber);border-color:var(--amber);color:var(--ink)}
.btn.ghost{background:transparent;color:var(--ink)}
.btn.ghost:hover{background:var(--liquid-pale);color:var(--ink)}

/* formula block, ticklist, faq */
.formula{border:1.5px solid var(--ink);background:var(--panel);padding:16px;font-family:var(--mono);font-size:13px;box-shadow:6px 6px 0 rgba(27,39,51,.12);margin:16px 0}
.formula .fhead{font-size:10px;text-transform:uppercase;letter-spacing:.12em;color:var(--amber-deep);margin-bottom:8px}
.formula code{display:block;background:var(--paper);border:1px solid var(--hairline);padding:11px;font-size:13px;color:var(--liquid-deep);overflow-x:auto}
.formula small{display:block;margin-top:8px;color:var(--ink-soft);font-size:11px;line-height:1.6}
.ticklist{list-style:none;margin:8px 0 16px}
.ticklist li{padding:7px 0 7px 25px;position:relative;font-size:14px;color:var(--ink-soft);border-bottom:1px dashed var(--hairline)}
.ticklist li::before{content:"";position:absolute;left:0;top:12px;width:11px;height:11px;border:2px solid var(--liquid);background:var(--liquid-pale)}
.ticklist li b{color:var(--ink)}
details.faq{border:1px solid var(--ink);background:var(--panel);margin:-1px 0 0;max-width:74ch}
details.faq summary{cursor:pointer;font-family:var(--display);font-weight:700;font-size:16.5px;padding:13px 16px;list-style:none;position:relative}
details.faq summary::after{content:"+";position:absolute;right:16px;font-family:var(--mono);color:var(--amber-deep)}
details.faq[open] summary::after{content:"−"}
details.faq div{padding:0 16px 14px;color:var(--ink-soft);font-size:15.5px}
.note{border-left:4px solid var(--amber);background:var(--panel);padding:12px 14px;font-size:14.5px;color:var(--ink-soft);margin:16px 0;max-width:74ch}
.note b{color:var(--ink)}

/* footer */
footer{border-top:1.5px solid var(--ink);background:var(--panel);margin-top:34px}
.ft{display:grid;grid-template-columns:2fr 1fr 1fr 1fr;gap:28px;padding:32px 0}
@media(max-width:820px){.ft{grid-template-columns:1fr 1fr}}
.ft h4{font-family:var(--mono);font-size:10.5px;text-transform:uppercase;letter-spacing:.12em;color:var(--amber-deep);margin-bottom:11px}
.ft a{display:block;font-size:13px;text-decoration:none;color:var(--ink-soft);padding:3px 0}
.ft a:hover{color:var(--liquid-deep)}
.ft p{font-size:12.5px;color:var(--ink-soft);max-width:38ch}
.legal{border-top:1px solid var(--hairline);padding:13px 0;display:flex;justify-content:space-between;gap:14px;flex-wrap:wrap;font-family:var(--mono);font-size:10.5px;color:var(--ink-soft)}

/* result actions in dark output panel */
.out-actions{display:flex;gap:8px;margin-top:14px;flex-wrap:wrap}
.btn.act{flex:1;text-align:center;background:transparent;color:#eef0ee;border-color:#44535f;font-size:11px;padding:9px 10px}
.btn.act:hover{background:var(--amber);border-color:var(--amber);color:var(--ink)}

/* cross-field validation message (themed, no native alerts) */
.calc-err{display:none;margin-top:14px;border-left:4px solid #b3261e;background:var(--paper);padding:10px 12px;font-family:var(--mono);font-size:11.5px;line-height:1.55;color:#8c1d16}

/* dip chart step selector in dark output panel */
.stepsel{flex:1;font-family:var(--mono);font-size:11px;padding:9px 8px;background:transparent;color:#eef0ee;border:1.5px solid #44535f;cursor:pointer}
.stepsel option{color:var(--ink)}

/* free-tools: visible bold URL line on cards */
.toolurl{font-family:var(--mono);font-size:12px;margin:2px 0 6px;color:var(--teal-deep);letter-spacing:.02em;word-break:break-all}