/* ==========================================================================
   Both Ways — unit conversion
   Direction: two number lines laid side by side. A conversion is a mapping
   between scales, so the page shows the mapping, not just one answer.
   ========================================================================== */

:root {
  --ink:        #0E1A28;
  --ink-2:      #3B4E60;
  --ink-3:      #6E8093;
  --paper:      #E7ECEF;
  --panel:      #FFFFFF;
  --rule:       #C0CBD3;
  --rule-soft:  #DBE2E7;
  --signal:     #D1402A;
  --signal-tint:#FBEDEA;
  --slate:      #24435C;

  --shadow: 0 1px 2px rgba(14,26,40,.06), 0 10px 28px -18px rgba(14,26,40,.34);
  --radius: 2px;
  --measure: 66ch;

  --display: "Archivo", "Helvetica Neue", Arial, sans-serif;
  --body:    "Atkinson Hyperlegible", "Helvetica Neue", Arial, sans-serif;
  --num:     "Martian Mono", ui-monospace, "SF Mono", Menlo, monospace;
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--body);
  font-size: 1.0625rem;
  line-height: 1.62;
  overflow-wrap: break-word;
}

.wrap { width: 100%; max-width: 1080px; margin-inline: auto; padding-inline: 20px; }

/* --- masthead --------------------------------------------------------- */
.masthead { background: var(--ink); color: #E7ECEF; }
.masthead__inner {
  display: flex; align-items: center; justify-content: space-between;
  gap: 20px; flex-wrap: wrap; min-height: 60px;
}
.wordmark {
  font-family: var(--display); font-weight: 700; font-size: 1.0625rem;
  letter-spacing: -0.025em; color: #fff; text-decoration: none;
  display: inline-flex; align-items: center; gap: 9px; padding-block: 12px;
}
.wordmark i {
  font-style: normal; font-family: var(--num); font-size: .75rem;
  color: var(--signal); letter-spacing: -0.05em;
}
.nav { display: flex; gap: 18px; flex-wrap: wrap; padding-block: 8px; }
.nav a {
  font-family: var(--display); font-size: .875rem; font-weight: 500;
  color: #B6C4CF; text-decoration: none; padding-block: 3px;
  border-bottom: 2px solid transparent;
}
.nav a:hover, .nav a[aria-current="page"] { color: #fff; border-bottom-color: var(--signal); }

@media (max-width: 620px) {
  .masthead__inner { min-height: 0; gap: 2px; padding-block: 6px 4px; }
  .wordmark { padding-block: 6px; }
  .nav { gap: 5px 13px; padding-block: 0 6px; }
  .nav a { font-size: .8125rem; }
}

/* --- page head -------------------------------------------------------- */
.pagehead { padding-block: 40px 24px; }
@media (max-width: 620px) { .pagehead { padding-block: 26px 18px; } }
.eyebrow {
  font-family: var(--num); font-size: .625rem; letter-spacing: .1em;
  text-transform: uppercase; color: var(--ink-3); margin: 0 0 13px;
}
h1 {
  font-family: var(--display); font-weight: 700;
  font-size: clamp(1.875rem, 5vw, 2.875rem); line-height: 1.06;
  letter-spacing: -0.035em; margin: 0 0 .48em; max-width: 20ch;
}
.lede { font-size: 1.125rem; color: var(--ink-2); max-width: 56ch; margin: 0; }

/* --- the converter ---------------------------------------------------- */
.converter {
  background: var(--panel); border: 1px solid var(--rule);
  border-radius: var(--radius); box-shadow: var(--shadow);
  padding: 24px 24px 28px; margin-bottom: 36px;
}
@media (max-width: 620px) { .converter { padding: 18px 16px 22px; } }

.leg { display: grid; grid-template-columns: minmax(0,1fr) minmax(0,190px); gap: 12px; }
@media (max-width: 520px) { .leg { grid-template-columns: 1fr; gap: 8px; } }

.leg label {
  grid-column: 1 / -1;
  font-family: var(--display); font-size: .6875rem; font-weight: 600;
  letter-spacing: .1em; text-transform: uppercase; color: var(--ink-3);
  margin-bottom: 2px;
}

.leg input[type="number"] {
  width: 100%; font-family: var(--num); font-weight: 500;
  font-size: clamp(1.375rem, 5.2vw, 1.875rem); letter-spacing: -0.05em;
  color: var(--ink); background: var(--panel);
  border: 1px solid var(--rule); border-radius: var(--radius);
  padding: 12px 14px; appearance: none; -moz-appearance: textfield;
}
.leg input::-webkit-outer-spin-button,
.leg input::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }

.leg select {
  width: 100%; font-family: var(--display); font-weight: 500; font-size: 1rem;
  color: var(--ink); background-color: #F4F7F9;
  border: 1px solid var(--rule); border-radius: var(--radius);
  padding: 12px 34px 12px 12px; appearance: none;
  background-image: url("data:image/svg+xml;charset=UTF-8,%3Csvg width='11' height='7' viewBox='0 0 11 7' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M1 1l4.5 4.5L10 1' stroke='%236E8093' stroke-width='1.5' fill='none' stroke-linecap='round'/%3E%3C/svg%3E");
  background-repeat: no-repeat; background-position: right 12px center;
}

input:focus-visible, select:focus-visible, button:focus-visible, a:focus-visible {
  outline: 2px solid var(--signal); outline-offset: 2px;
}

/* swap control sits on the rule between the two legs */
.swapbar { display: flex; align-items: center; gap: 14px; margin: 16px 0; }
.swapbar::before, .swapbar::after {
  content: ""; flex: 1; height: 1px; background: var(--rule-soft);
}
.swap {
  font-family: var(--display); font-size: .75rem; font-weight: 600;
  letter-spacing: .08em; text-transform: uppercase;
  color: var(--slate); background: var(--panel);
  border: 1px solid var(--rule); border-radius: 999px;
  padding: 7px 15px; cursor: pointer; display: inline-flex; align-items: center; gap: 7px;
}
.swap:hover { border-color: var(--slate); color: var(--ink); }
.swap span { font-family: var(--num); font-size: .875rem; line-height: 1; }

/* --- quick-pick chips -------------------------------------------------- */
.chips { display: flex; flex-wrap: wrap; gap: 7px; margin: 18px 0 0; }
.chip {
  font-family: var(--num); font-size: .75rem; letter-spacing: -0.04em;
  color: var(--slate); background: #F4F7F9;
  border: 1px solid var(--rule-soft); border-radius: 999px;
  padding: 6px 12px; cursor: pointer; white-space: nowrap;
}
.chip:hover { border-color: var(--slate); background: #fff; color: var(--ink); }

/* --- result row -------------------------------------------------------- */
.resultbar {
  display: flex; align-items: center; justify-content: space-between;
  gap: 14px; flex-wrap: wrap;
  margin: 22px 0 0; padding-top: 18px; border-top: 1px solid var(--rule-soft);
}
.copy {
  font-family: var(--display); font-size: .75rem; font-weight: 600;
  letter-spacing: .06em; text-transform: uppercase;
  color: var(--slate); background: var(--panel);
  border: 1px solid var(--rule); border-radius: 999px;
  padding: 7px 14px; cursor: pointer; flex: none;
}
.copy:hover { border-color: var(--slate); color: var(--ink); }

/* --- related converters ------------------------------------------------ */
.related { margin: 8px 0 44px; padding-top: 20px; border-top: 1px solid var(--rule); }
.related h2 {
  font-family: var(--display); font-weight: 700; font-size: 1.125rem;
  letter-spacing: -0.02em; margin: 0 0 14px;
}
.related ul {
  list-style: none; margin: 0; padding: 0;
  display: grid; grid-template-columns: repeat(auto-fit, minmax(196px, 1fr)); gap: 1px;
  background: var(--rule); border: 1px solid var(--rule); border-radius: var(--radius);
  overflow: hidden;
}
.related a {
  display: block; background: var(--panel); padding: 14px 15px;
  text-decoration: none; color: var(--ink);
  font-family: var(--display); font-size: .9375rem; font-weight: 600;
}
.related a:hover { background: #F4F7F9; color: var(--slate); }
.related span {
  display: block; font-family: var(--num); font-size: .6875rem; font-weight: 400;
  letter-spacing: -0.04em; color: var(--ink-3); margin-top: 3px;
}

/* --- the equation line ------------------------------------------------ */
.equation {
  margin: 0; flex: 1 1 auto; min-width: 0;
  font-family: var(--num); font-size: clamp(.8125rem, 3.1vw, 1rem);
  font-weight: 500; letter-spacing: -0.04em; color: var(--ink-2);
}
.equation b { color: var(--ink); font-weight: 500; }

/* --- SIGNATURE: parallel scales --------------------------------------- */
.scales { margin: 26px 0 0; }
.scales__title {
  font-family: var(--display); font-size: .6875rem; font-weight: 600;
  letter-spacing: .1em; text-transform: uppercase; color: var(--ink-3);
  margin: 0 0 14px; display: flex; align-items: center; gap: 10px;
}
.scales__title::after { content: ""; flex: 1; height: 1px; background: var(--rule-soft); }

.scales__body { position: relative; padding: 4px 0 2px; }
.axis { position: relative; height: 34px; }
.axis__line { position: absolute; left: 0; right: 0; height: 1px; background: var(--rule); }
.axis--from .axis__line { bottom: 0; }
.axis--to   .axis__line { top: 0; }

.tick { position: absolute; width: 1px; background: var(--rule); }
.axis--from .tick { bottom: 0; height: 6px; }
.axis--to   .tick { top: 0; height: 6px; }
.tick--major { background: var(--ink-3); }
.axis--from .tick--major { height: 11px; }
.axis--to   .tick--major { height: 11px; }

.tlabel {
  position: absolute; transform: translateX(-50%);
  font-family: var(--num); font-size: .625rem; font-weight: 400;
  letter-spacing: -0.04em; color: var(--ink-3); white-space: nowrap;
}
.axis--from .tlabel { bottom: 13px; }
.axis--to   .tlabel { top: 13px; }

.unitcap {
  font-family: var(--display); font-size: .6875rem; font-weight: 600;
  letter-spacing: .04em; color: var(--ink-2); margin: 0;
}
.unitcap--to { text-align: right; }

/* the shared marker: one vertical line crossing both scales.
   Inset top and bottom so it spans the ticks and the band without striking
   through the tick labels sitting above and below. */
.marker {
  position: absolute; top: 22px; bottom: 22px; width: 2px;
  background: var(--signal); transform: translateX(-1px);
  transition: left .3s cubic-bezier(.22,1,.36,1); z-index: 2; pointer-events: none;
}
.marker::before, .marker::after {
  content: ""; position: absolute; left: 50%; width: 7px; height: 7px;
  background: var(--signal); border-radius: 50%; transform: translateX(-50%);
}
.marker::before { top: -3px; }
.marker::after  { bottom: -3px; }
.scales__mid {
  height: 26px; background: var(--signal-tint);
  border-block: 1px solid #F0D9D4;
}
@media (prefers-reduced-motion: reduce) { .marker { transition: none; } }

/* --- reference table -------------------------------------------------- */
.reftable { width: 100%; border-collapse: collapse; font-size: .9375rem; margin: 0 0 1.4em; }
.reftable th, .reftable td {
  text-align: left; padding: 9px 12px; border-bottom: 1px solid var(--rule-soft);
}
.reftable th {
  font-family: var(--display); font-size: .6875rem; font-weight: 700;
  letter-spacing: .07em; text-transform: uppercase; color: var(--ink-3);
  border-bottom-color: var(--rule);
}
.reftable td { font-family: var(--num); font-size: .8125rem; letter-spacing: -0.04em; }
@media (max-width: 620px) {
  .reftable { display: block; overflow-x: auto; }
  .reftable th, .reftable td { padding: 8px 9px; }
}

/* --- article ---------------------------------------------------------- */
.layout {
  display: grid; grid-template-columns: minmax(0,1fr) 300px;
  gap: 46px; align-items: start; padding-bottom: 52px;
}
@media (max-width: 940px) { .layout { grid-template-columns: minmax(0,1fr); gap: 30px; } }

.article { max-width: var(--measure); min-width: 0; }
.article h2 {
  font-family: var(--display); font-weight: 700; font-size: 1.4375rem;
  letter-spacing: -0.028em; line-height: 1.18; margin: 2.1em 0 .5em;
  padding-top: .85em; border-top: 1px solid var(--rule);
}
.article h3 {
  font-family: var(--display); font-weight: 700; font-size: 1.0625rem;
  letter-spacing: -0.015em; margin: 1.65em 0 .35em;
}
.article p { margin: 0 0 1.05em; }
.article ul, .article ol { margin: 0 0 1.15em; padding-left: 1.25em; }
.article li { margin-bottom: .4em; }
.article a { color: var(--slate); text-underline-offset: 2px; }
.article code {
  font-family: var(--num); font-size: .8125em; letter-spacing: -0.04em;
  background: #F1F5F7; padding: 1px 5px; border-radius: 2px;
}

.note {
  border-left: 3px solid var(--signal); background: var(--signal-tint);
  padding: 15px 17px; margin: 0 0 1.35em; font-size: .9375rem;
}
.note p:last-child { margin-bottom: 0; }
.note strong { font-family: var(--display); }

/* --- ad slots ---------------------------------------------------------
   Policy note: slots sit below content, never adjacent to the converter
   controls, and always carry a label. Heights are reserved to avoid CLS. */
.adslot {
  margin: 30px 0; padding: 10px 0; min-height: 100px;
  display: flex; flex-direction: column; justify-content: center; align-items: center;
  gap: 8px; border-block: 1px solid var(--rule-soft); color: var(--ink-3);
}
.adslot::before {
  content: "Advertisement"; font-family: var(--display); font-size: .625rem;
  font-weight: 600; letter-spacing: .14em; text-transform: uppercase;
}
.adslot--rail {
  border: 1px dashed var(--rule); min-height: 600px; margin: 0; padding: 10px;
}
.rail { position: sticky; top: 22px; }
@media (max-width: 940px) { .rail { position: static; } }

/* --- hub grid --------------------------------------------------------- */
.grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 1px; background: var(--rule); border: 1px solid var(--rule);
  border-radius: var(--radius); overflow: hidden; margin-bottom: 36px;
}
.card {
  background: var(--panel); padding: 22px 20px 24px; text-decoration: none;
  color: inherit; display: flex; flex-direction: column; gap: 7px;
}
.card:hover { background: #F4F7F9; }
.card__eq {
  font-family: var(--num); font-size: .6875rem; letter-spacing: -0.04em;
  color: var(--signal);
}
.card h2 {
  font-family: var(--display); font-weight: 700; font-size: 1.0625rem;
  letter-spacing: -0.02em; margin: 0;
}
.card p { margin: 0; font-size: .9375rem; color: var(--ink-2); }
.card__go {
  margin-top: auto; padding-top: 11px;
  font-family: var(--display); font-size: .8125rem; font-weight: 600; color: var(--slate);
}

.sechead {
  display: flex; align-items: baseline; justify-content: space-between;
  gap: 18px; margin: 40px 0 18px; padding-top: 16px;
  border-top: 1px solid var(--rule); flex-wrap: wrap;
}
.sechead h2 {
  font-family: var(--display); font-weight: 700; font-size: 1.4375rem;
  letter-spacing: -0.028em; margin: 0;
}
.sechead p { margin: 0; color: var(--ink-2); font-size: .9375rem; max-width: 44ch; }

/* --- profit margin calculator ---------------------------------------- */
.profit-form {
  display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 16px;
}
.profit-field label {
  display: block; font-family: var(--display); font-size: .6875rem; font-weight: 600;
  letter-spacing: .08em; text-transform: uppercase; color: var(--ink-3); margin-bottom: 5px;
}
.profit-field input {
  width: 100%; font-family: var(--num); font-size: 1.125rem; color: var(--ink);
  background: var(--panel); border: 1px solid var(--rule); border-radius: var(--radius);
  padding: 11px 12px; appearance: none; -moz-appearance: textfield;
}
.profit-field input::-webkit-outer-spin-button,
.profit-field input::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }
.profit-field small { display: block; color: var(--ink-3); font-size: .75rem; margin-top: 4px; }
.profit-results {
  display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 1px;
  margin-top: 22px; background: var(--rule); border: 1px solid var(--rule);
}
.profit-result { background: #F7F9FA; padding: 16px; min-width: 0; }
.profit-result--primary { background: var(--signal-tint); }
.profit-result span {
  display: block; font-family: var(--display); font-size: .6875rem; font-weight: 600;
  letter-spacing: .08em; text-transform: uppercase; color: var(--ink-3); margin-bottom: 5px;
}
.profit-result strong {
  display: block; font-family: var(--num); font-size: clamp(1rem, 3.2vw, 1.35rem);
  letter-spacing: -.05em; overflow-wrap: anywhere;
}
.profit-summary { margin: 18px 0 0; color: var(--ink-2); font-size: .9375rem; }
.profit-summary strong { color: var(--ink); }
.profit-meter { height: 12px; display: flex; background: var(--rule-soft); margin-top: 18px; overflow: hidden; }
.profit-meter span { min-width: 0; transition: width .25s ease; }
.profit-meter__cost { background: var(--slate); }
.profit-meter__fees { background: #8B9CAB; }
.profit-meter__profit { background: var(--signal); }
.profit-legend { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 7px; font-size: .75rem; color: var(--ink-3); }
.profit-legend i { display: inline-block; width: 8px; height: 8px; margin-right: 5px; }
.profit-legend .cost { background: var(--slate); }
.profit-legend .fees { background: #8B9CAB; }
.profit-legend .profit { background: var(--signal); }
.target-box { margin-top: 22px; padding-top: 18px; border-top: 1px solid var(--rule-soft); }
.target-box h2 { font-family: var(--display); font-size: 1rem; margin: 0 0 10px; }
.target-row { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1.4fr); gap: 12px; align-items: end; }
.target-output { background: #F4F7F9; border-left: 3px solid var(--signal); padding: 10px 13px; }
.target-output span { display: block; color: var(--ink-3); font-size: .75rem; }
.target-output strong { font-family: var(--num); font-size: 1.125rem; }
@media (max-width: 680px) {
  .profit-form { grid-template-columns: 1fr; gap: 12px; }
  .profit-results { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .target-row { grid-template-columns: 1fr; }
}
@media (max-width: 390px) { .profit-results { grid-template-columns: 1fr; } }

/* --- footer ----------------------------------------------------------- */
.footer { background: var(--ink); color: #A9BAC7; padding: 38px 0 44px; font-size: .875rem; }
.footer a { color: #DCE5EB; }
.footer__grid {
  display: grid; grid-template-columns: minmax(0,1.4fr) repeat(2, minmax(0,1fr)); gap: 30px;
}
@media (max-width: 700px) { .footer__grid { grid-template-columns: 1fr; } }
.footer h3 {
  font-family: var(--display); font-size: .6875rem; font-weight: 600;
  letter-spacing: .14em; text-transform: uppercase; color: #7C8FA0; margin: 0 0 11px;
}
.footer ul { list-style: none; margin: 0; padding: 0; }
.footer li { margin-bottom: 6px; }
.smallprint {
  margin-top: 28px; padding-top: 18px; border-top: 1px solid #1F3346;
  font-size: .8125rem; color: #8496A5; max-width: 74ch;
}
.resource-actions{display:flex;gap:10px;flex-wrap:wrap;margin:18px 0}.resource-actions button{border:1px solid var(--ink);background:var(--ink);color:#fff;padding:10px 14px;border-radius:4px;font:600 .875rem var(--display);cursor:pointer}.factbox{border:1px solid var(--rule);border-left:4px solid var(--signal);background:var(--panel);padding:18px 20px;margin:22px 0}.mini-converter{display:grid;grid-template-columns:1fr 1fr;gap:16px;background:var(--panel);border:1px solid var(--rule);padding:20px;border-radius:var(--radius);box-shadow:var(--shadow);margin:22px 0}.mini-converter label{font-family:var(--display);font-weight:600}.mini-converter input{display:block;width:100%;margin-top:7px;padding:12px;border:1px solid var(--rule);font:1rem var(--num)}@media(max-width:600px){.mini-converter{grid-template-columns:1fr}}@media print{.masthead,.footer,.resource-actions,.adslot{display:none!important}.wrap{max-width:none}.reftable{break-inside:avoid}a{color:#000;text-decoration:none}}

.sr-only {
  position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0;
}