#ptc{--ink:#12262f;--steel:#1d4d5f;--wall:#2a7b93;--mist:#eef3f5;--line:#cbd8de;--muted:#566b75;--signal:#f0b90b;--ok:#1f7a4d;--bad:#b3352b;--warn:#8a5a00;
  --serif:"Iowan Old Style","Palatino Linotype",Palatino,"Book Antiqua",Georgia,serif;
  font:16px/1.5 "Segoe UI",system-ui,-apple-system,Roboto,"Helvetica Neue",Arial,sans-serif;color:var(--ink);
  max-width:860px;margin:0 auto;border:1px solid var(--line);border-radius:10px;overflow:hidden;background:#fff;text-align:left}
#ptc *,#ptc *::before,#ptc *::after{box-sizing:border-box}
#ptc h2,#ptc h3,#ptc p,#ptc ol,#ptc ul,#ptc table,#ptc fieldset,#ptc legend{margin:0;padding:0;border:0;background:none;text-transform:none;letter-spacing:normal}
#ptc button,#ptc input,#ptc select{font:inherit;color:inherit}

/* header with the equation as the hero */
#ptc .ptc-head{background-color:var(--ink);color:#fff;padding:26px 26px 22px;
  background-image:linear-gradient(rgba(255,255,255,.045) 1px,transparent 1px),linear-gradient(90deg,rgba(255,255,255,.045) 1px,transparent 1px);background-size:22px 22px}
#ptc .ptc-head h2{font:600 22px/1.25 "Segoe UI",system-ui,sans-serif;color:#fff;margin-bottom:4px}
#ptc .ptc-head p{color:#b9cbd3;font-size:14px}
#ptc .ptc-eq{font-family:var(--serif);font-size:30px;line-height:1.3;margin:20px 0 6px;display:flex;align-items:center;flex-wrap:wrap;gap:10px;color:#fff}
#ptc .ptc-eq i{font-style:italic;padding:0 2px;border-radius:3px;transition:background-color .15s,color .15s}
#ptc .ptc-eq i.on{background:var(--signal);color:var(--ink)}
#ptc .ptc-frac{display:inline-flex;flex-direction:column;align-items:center;text-align:center;font-size:.9em}
#ptc .ptc-frac>span:first-child{border-bottom:1.5px solid #fff;padding:0 8px 3px}
#ptc .ptc-frac>span:last-child{padding:3px 8px 0}
#ptc .ptc-eq2{font-family:var(--serif);font-size:17px;color:#d5e2e8;display:flex;flex-wrap:wrap;gap:4px 26px}
#ptc .ptc-eq2 i{font-style:italic;padding:0 2px;border-radius:3px;transition:background-color .15s,color .15s}
#ptc .ptc-eq2 i.on{background:var(--signal);color:var(--ink)}

/* form */
#ptc .ptc-body{padding:22px 26px 8px}
#ptc .ptc-sec{margin:0 0 22px;padding:0 0 0 16px;border-left:3px solid var(--wall)}
#ptc .ptc-sec>legend,#ptc .ptc-sec>h3{font-size:17px;font-weight:650;color:var(--steel);padding:0;margin:0 0 10px;float:none;width:auto}
#ptc .ptc-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(270px,1fr));gap:14px 20px}
#ptc .ptc-field{min-width:0}
#ptc .ptc-field>label{display:block;font-size:14px;font-weight:600;margin-bottom:5px}
#ptc .ptc-field>label small{font-weight:400;color:var(--muted)}
#ptc .ptc-ctl{display:flex}
#ptc .ptc-ctl>input,#ptc .ptc-ctl>select,#ptc .ptc-field>select,#ptc .ptc-field>input{height:44px;border:1px solid var(--line);background:#fff;padding:0 10px;width:100%;min-width:0;border-radius:6px;font-size:16px;font-variant-numeric:tabular-nums;margin:0;box-shadow:none}
#ptc .ptc-ctl>input{border-radius:6px 0 0 6px;flex:1 1 auto}
#ptc .ptc-ctl>select{border-radius:0 6px 6px 0;margin-left:-1px;flex:0 0 auto;width:auto;max-width:44%;background:var(--mist);cursor:pointer;padding:0 6px}
#ptc .ptc-field .ptc-sub{margin-top:8px}
#ptc input:focus-visible,#ptc select:focus-visible,#ptc button:focus-visible{outline:2px solid var(--wall);outline-offset:1px;position:relative;z-index:1}
#ptc .ptc-hint{font-size:12.5px;color:var(--muted);margin-top:4px;line-height:1.4}
#ptc .ptc-readout{display:inline-block;margin-top:8px;font-family:var(--serif);font-size:16px;background:var(--mist);border-radius:5px;padding:2px 10px}
#ptc .ptc-hide{display:none!important}
#ptc .ptc-actions{display:flex;flex-wrap:wrap;gap:10px;margin:2px 0 20px}
#ptc .ptc-btn{height:44px;padding:0 16px;border-radius:6px;border:1px solid var(--steel);background:var(--steel);color:#fff;cursor:pointer;font-size:14px;font-weight:600}
#ptc .ptc-btn.alt{background:#fff;color:var(--steel)}
#ptc .ptc-btn:hover{filter:brightness(1.12)}

/* results */
#ptc .ptc-res{min-height:460px;background:var(--mist);border-top:1px solid var(--line);padding:24px 26px 26px}
#ptc .ptc-wait{color:var(--muted);font-size:15px}
#ptc .ptc-wait ul{margin:6px 0 0 18px;padding:0;list-style:disc}
#ptc .ptc-hero{display:grid;grid-template-columns:1fr 1fr;gap:14px;margin-bottom:16px}
#ptc .ptc-card{background:var(--ink);color:#fff;border-radius:8px;padding:16px 18px}
#ptc .ptc-card.pick{background:var(--steel);border-bottom:4px solid var(--signal)}
#ptc .ptc-card .lbl{font-size:13.5px;color:#b9cbd3}
#ptc .ptc-card .big{font-family:var(--serif);font-size:34px;line-height:1.15;margin:4px 0 2px;font-variant-numeric:tabular-nums}
#ptc .ptc-card .big.long{font-size:24px}
#ptc .ptc-card .big small{font-size:.5em;color:#b9cbd3;margin-left:2px}
#ptc .ptc-card .alt{font-size:14.5px;color:#dbe7ec;font-variant-numeric:tabular-nums}
#ptc .ptc-note{background:#fff;border:1px solid var(--line);border-radius:8px;padding:11px 14px;font-size:14.5px;margin-bottom:14px}
#ptc .ptc-note.warn{border-color:#e2b04a;background:#fff8e8}
#ptc .ptc-note.bad{border-color:#d98b85;background:#fdf0ee}
#ptc .ptc-res h3{font-size:16px;font-weight:650;color:var(--steel);margin:22px 0 8px}

/* thickness bar */
#ptc .ptc-bar{position:relative;height:24px;background:#dfe8ec;border-radius:4px;margin:26px 0 30px;}
#ptc .ptc-bar .seg{position:absolute;top:0;bottom:0}
#ptc .ptc-bar .s1{background:var(--wall);border-radius:4px 0 0 4px}
#ptc .ptc-bar .s2{background:var(--signal)}
#ptc .ptc-bar .s3{background:repeating-linear-gradient(45deg,#8fa4ae,#8fa4ae 4px,#b4c4cb 4px,#b4c4cb 8px)}
#ptc .ptc-bar .mk{position:absolute;top:-8px;bottom:-8px;width:3px;background:var(--ink)}
#ptc .ptc-bar .mk span{position:absolute;top:100%;margin-top:3px;white-space:nowrap;font-size:12.5px;font-weight:600;left:6px}
#ptc .ptc-bar .mk.r span{left:auto;right:6px}
#ptc .ptc-legend{display:flex;flex-wrap:wrap;gap:6px 18px;font-size:13.5px;margin-top:-10px}
#ptc .ptc-legend b{display:inline-block;width:12px;height:12px;border-radius:2px;margin-right:6px;vertical-align:-1px}

/* working steps */
#ptc ol.ptc-steps{list-style:none;counter-reset:st}
#ptc .ptc-steps li{counter-increment:st;position:relative;padding:0 0 12px 40px;margin:0}
#ptc .ptc-steps li::before{content:counter(st);position:absolute;left:0;top:0;width:26px;height:26px;border-radius:50%;background:var(--steel);color:#fff;font-size:13px;font-weight:700;display:flex;align-items:center;justify-content:center}
#ptc .ptc-steps li::after{content:"";position:absolute;left:12px;top:28px;bottom:2px;width:2px;background:var(--line)}
#ptc .ptc-steps li:last-child::after{display:none}
#ptc .ptc-steps .t{font-weight:600;font-size:14.5px}
#ptc .ptc-steps .m{font-family:var(--serif);font-size:16.5px;background:#fff;border:1px solid var(--line);border-radius:6px;padding:6px 12px;margin-top:5px;overflow-x:auto;font-variant-numeric:tabular-nums;line-height:1.7}
#ptc .ptc-steps .m i{font-style:italic}
#ptc .ptc-steps .m .r{font-weight:700}
#ptc .ptc-steps .d{font-size:13px;color:var(--muted);margin-top:3px}

/* table */
#ptc .ptc-tw{overflow-x:auto;background:#fff;border:1px solid var(--line);border-radius:8px}
#ptc table{width:100%;border-collapse:collapse;font-size:14.5px;font-variant-numeric:tabular-nums}
#ptc th{text-align:left;font-weight:600;font-size:13px;color:var(--muted);padding:9px 12px;border-bottom:1px solid var(--line);white-space:nowrap}
#ptc td{padding:0;border-bottom:1px solid #e6edf0}
#ptc td>*,#ptc td.p{padding:8px 12px}
#ptc td button{display:block;width:100%;min-height:40px;text-align:left;background:none;border:0;cursor:pointer;font-weight:600;padding:8px 12px}
#ptc td button:hover{background:var(--mist)}
#ptc tr:last-child td{border-bottom:0}
#ptc tr.no td{color:#7d8e96}
#ptc tr.sel td{background:#fff6d6}
#ptc tr.sel td:first-child{box-shadow:inset 4px 0 0 var(--signal)}
#ptc .tag{display:inline-block;font-size:12.5px;font-weight:600;border-radius:4px;padding:1px 8px}
#ptc .tag.ok{background:#dcf0e5;color:var(--ok)}
#ptc .tag.no{background:#f4e1de;color:var(--bad)}
#ptc .tag.pk{background:var(--signal);color:var(--ink)}

/* checks */
#ptc ul.ptc-chk{list-style:none}
#ptc .ptc-chk li{display:flex;gap:10px;align-items:baseline;padding:6px 0;font-size:14.5px;border-bottom:1px solid #dbe5e9}
#ptc .ptc-chk li:last-child{border-bottom:0}
#ptc .ptc-chk .tag{flex:0 0 auto;min-width:54px;text-align:center}
#ptc .tag.wn{background:#fbecc8;color:var(--warn)}

#ptc .ptc-about{padding:14px 26px;border-top:1px solid var(--line);font-size:14.5px;background:#fff}
#ptc .ptc-about summary{cursor:pointer;font-weight:600;color:var(--steel);min-height:32px}
#ptc .ptc-about p{margin:8px 0 0}
#ptc .ptc-foot{padding:14px 26px 18px;font-size:12.5px;color:var(--muted);border-top:1px solid var(--line);background:#fff}
#ptc .ptc-foot a{color:var(--wall);text-decoration:underline}

@media (max-width:600px){
  #ptc .ptc-head,#ptc .ptc-body,#ptc .ptc-res,#ptc .ptc-foot,#ptc .ptc-about{padding-left:16px;padding-right:16px}
  #ptc .ptc-eq{font-size:24px}
  #ptc .ptc-hero{grid-template-columns:1fr}
}
@media (prefers-reduced-motion:reduce){#ptc *{transition:none!important}}