/* ==========================================================================
   Tide Window — chart-desk surface.
   Dark navy base, sea-glass accent, brass numerals, 1px hairlines, 2px radii.
   No gradient, no photograph, no webfont, no remote asset.
   Mobile-first: the base rules are the 390px layout; wider layouts are added
   with min-width in this order: 390 (base) -> 640 -> 768 -> 1024 -> 1200.
   Budget held at 390x844: h1 <= 30px, section 1 <= 360px, no sideways scroll.
   ========================================================================== */
:root {
  --deep: #071A26;
  --panel: #0C2533;
  --panel-2: #10303F;
  --line: rgba(232, 241, 242, 0.16);
  --line-strong: rgba(232, 241, 242, 0.34);
  --ink: #E8F1F2;
  --muted: #9DB4C0;
  --sea: #58C9B9;
  --brass: #C9A227;
  --signal: #D8553F;
  --display: "Iowan Old Style", Georgia, "Times New Roman", serif;
  --body: system-ui, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --mono: ui-monospace, "Cascadia Mono", Consolas, "Liberation Mono", monospace;
  --header-h: 56px;
  --radius: 2px;
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--deep);
  color: var(--ink);
  font-family: var(--body);
  font-size: 16px;
  line-height: 1.6;
  overflow-x: hidden;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  background-image:
    linear-gradient(to right, rgba(232, 241, 242, 0.05) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(232, 241, 242, 0.05) 1px, transparent 1px);
  background-size: 24px 24px;
  z-index: 0;
}

img { max-width: 100%; height: auto; display: block; }

a { color: var(--sea); text-decoration: none; }

h1, h2, h3, h4 {
  font-family: var(--display);
  font-weight: 600;
  letter-spacing: 0.01em;
  line-height: 1.15;
  margin: 0 0 0.5em;
}

p { margin: 0 0 1em; }

.container {
  width: 100%;
  max-width: 1180px;
  margin: 0 auto;
  padding: 0 14px;
}

.icon { display: inline-block; vertical-align: middle; }

.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;
}

.skip {
  position: absolute;
  left: 12px; top: -48px;
  z-index: 100;
  background: var(--brass);
  color: var(--deep);
  padding: 8px 14px;
  border-radius: var(--radius);
  font-weight: 600;
}
.skip:focus { top: 12px; }

/* ---- header: one row at every width ------------------------------------ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  height: var(--header-h);
  background: rgba(7, 26, 38, 0.94);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(6px);
}

.header-inner {
  display: flex;
  flex-wrap: nowrap;
  align-items: center;
  gap: 10px;
  height: var(--header-h);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--ink);
  flex: 0 0 auto;
}

.brand-mark { color: var(--sea); }
.brand-mark .icon { width: 24px; height: 24px; }

.brand-text { display: flex; flex-direction: column; line-height: 1.05; }
.brand-text strong {
  font-family: var(--display);
  font-size: 16px;
  letter-spacing: 0.04em;
  white-space: nowrap;
}
.brand-text small {
  display: none;
  font-family: var(--mono);
  font-size: 10px;
  color: var(--muted);
  letter-spacing: 0.16em;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 10px;
  flex: 1 1 auto;
  min-width: 0;
  margin-left: auto;
  overflow-x: auto;
  scrollbar-width: none;
  white-space: nowrap;
}
.site-nav::-webkit-scrollbar { display: none; }

.nav-link {
  color: var(--muted);
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 4px 0;
  border-bottom: 1px solid transparent;
  flex: 0 0 auto;
}
/* at 390 the full nav cannot fit; the deeper sections stay reachable from
   the home page and footer, exactly as before the mobile-first rewrite */
.site-nav .nav-link:nth-child(n+3) { display: none; }
.nav-link:hover, .nav-link.is-active {
  color: var(--ink);
  border-bottom-color: var(--sea);
}

.nav-search {
  flex: 0 0 auto;
  color: var(--muted);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  width: 34px; height: 34px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}
.nav-search:hover { color: var(--sea); border-color: var(--sea); }

/* ---- section 1: text mast (mobile budget: <= 360px tall) --------------- */
.s1 {
  position: relative;
  border-bottom: 1px solid var(--line);
  background: var(--deep);
}

.s1-mast { padding: 20px 0 16px; }

.s1-mast-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 16px;
  align-items: start;
}

.eyebrow {
  display: block;
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--brass);
  margin-bottom: 8px;
}

.mast-main h1 {
  font-size: 30px;
  letter-spacing: -0.01em;
  margin: 0 0 8px;
  text-wrap: balance;
}

.mast-deck {
  color: var(--muted);
  font-size: 14.5px;
  max-width: 34em;
  margin-bottom: 10px;
  display: -webkit-box;
  -webkit-line-clamp: 1;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.mast-actions { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 10px; }

.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 9px 13px;
  border-radius: var(--radius);
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  border: 1px solid var(--line-strong);
  color: var(--ink);
  transition: background-color 0.18s ease, color 0.18s ease, border-color 0.18s ease;
}
.btn-solid { background: var(--sea); border-color: var(--sea); color: #04201f; font-weight: 700; }
.btn-solid:hover { background: var(--ink); border-color: var(--ink); }
.btn-ghost:hover { border-color: var(--sea); color: var(--sea); }

.mast-lead {
  display: flex;
  align-items: baseline;
  gap: 8px;
  border-left: 2px solid var(--brass);
  padding: 5px 0 5px 10px;
  color: var(--ink);
}
.mast-lead-kicker {
  display: block;
  font-family: var(--mono);
  font-size: 9px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--brass);
  flex: 0 0 auto;
}
.mast-lead-title {
  display: block;
  font-family: var(--display);
  font-size: 16px;
  margin-top: 2px;
}
.mast-lead-desc { display: none; color: var(--muted); font-size: 14px; }
.mast-lead:hover .mast-lead-title { color: var(--sea); }

.mast-side {
  display: flex;
  gap: 8px;
  overflow-x: auto;
  border-top: 2px solid var(--sea);
  padding-top: 10px;
  scrollbar-width: none;
}
.mast-side::-webkit-scrollbar { display: none; }
.mast-side-title {
  display: none;
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--muted);
  font-weight: 400;
  margin-bottom: 6px;
}
.mast-row {
  display: grid;
  flex: 0 0 auto;
  width: 226px;
  grid-template-columns: 24px minmax(0, 1fr);
  align-items: baseline;
  gap: 6px;
  padding: 7px 9px;
  border: 1px solid var(--line);
  color: var(--ink);
}
.mast-row:hover { background: rgba(88, 201, 185, 0.06); }
.mast-row:hover .mast-row-title { color: var(--sea); }
.mast-num { font-family: var(--mono); color: var(--brass); font-size: 11px; }
.mast-row-title { font-family: var(--display); font-size: 15px; }
.mast-row-cat { display: none; font-family: var(--mono); font-size: 10px; letter-spacing: 0.1em; text-transform: uppercase; color: var(--muted); }
.mast-row-arrow { display: none; color: var(--muted); }
.mast-row:hover .mast-row-arrow { color: var(--sea); }

/* ---- modules ------------------------------------------------------------ */
.module {
  position: relative;
  padding: 34px 0;
  border-bottom: 1px solid var(--line);
}

.section-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 8px 20px;
  margin-bottom: 16px;
  border-bottom: 1px solid var(--line);
  padding-bottom: 10px;
}
.section-head h2 { font-size: 22px; margin: 0; }
.section-link {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted);
  display: inline-flex;
  align-items: center;
  gap: 6px;
  white-space: nowrap;
}
.section-link:hover { color: var(--sea); }

.module-note { color: var(--muted); max-width: 46em; font-size: 14px; }

/* ---- cards -------------------------------------------------------------- */
.tool-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
}

.card {
  display: flex;
  flex-direction: column;
  gap: 8px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 12px;
  color: var(--ink);
  position: relative;
  transition: border-color 0.18s ease, transform 0.18s ease;
}
.card:hover { border-color: var(--sea); transform: translateY(-2px); }

.tool-card { min-height: 0; }
.card-art {
  display: block;
  background: var(--panel-2);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  aspect-ratio: 4 / 3;
}
.card-art img { width: 100%; height: 100%; object-fit: cover; }
.card-body { display: block; }
.card-kicker {
  display: block;
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--brass);
  margin-bottom: 3px;
}
.card-title {
  display: block;
  font-family: var(--display);
  font-size: 17px;
  line-height: 1.25;
  margin-bottom: 4px;
}
.card-desc { display: block; color: var(--muted); font-size: 13px; line-height: 1.45; }
.card-go {
  margin-top: auto;
  display: inline-flex;
  align-items: center;
  gap: 5px;
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--muted);
}
.card:hover .card-go { color: var(--sea); }

.cat-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 10px; }
.cat-card { gap: 6px; min-height: 0; }
.card-icon { color: var(--sea); }
.card-icon .icon { width: 26px; height: 26px; }
.card-meta { margin-top: auto; font-family: var(--mono); font-size: 10px; letter-spacing: 0.12em; text-transform: uppercase; color: var(--brass); }

.calc-band { display: grid; grid-template-columns: minmax(0, 1fr); gap: 12px; }
.calc-card { min-height: 0; }
.calc-card .card-go { color: var(--sea); }

.post-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 10px; }
.post-grid.wide { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.post-card { min-height: 0; }
.post-meta {
  display: flex;
  gap: 12px;
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--brass);
  margin-bottom: 6px;
}

/* ---- reference table ---------------------------------------------------- */
.ref-wrap { overflow-x: auto; border: 1px solid var(--line); border-radius: var(--radius); }
.ref-table, .data-table {
  width: 100%;
  border-collapse: collapse;
  background: var(--panel);
  font-size: 14px;
}
.ref-table th, .ref-table td,
.data-table th, .data-table td {
  text-align: left;
  padding: 11px 14px;
  border-bottom: 1px solid var(--line);
  vertical-align: top;
}
.ref-table th, .data-table th {
  background: var(--panel-2);
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--muted);
  font-weight: 400;
}
.ref-table .num, .data-table .num { font-family: var(--mono); color: var(--brass); white-space: nowrap; }

.stage-grid { display: grid; grid-template-columns: minmax(0, 1fr); gap: 14px; }
.stage-item { border-top: 2px solid var(--brass); padding-top: 12px; }
.stage-no { font-family: var(--mono); color: var(--brass); font-size: 12px; }
.stage-item h3 { font-size: 19px; margin: 4px 0 6px; }
.stage-item p { color: var(--muted); font-size: 14px; margin: 0; }

/* ---- page hero ---------------------------------------------------------- */
.page-hero { padding: 26px 0 22px; border-bottom: 1px solid var(--line); position: relative; }
.page-hero h1 { font-size: 30px; margin-bottom: 10px; }
.lede { color: var(--muted); font-size: 16px; max-width: 48em; }
.hero-meta { font-family: var(--mono); font-size: 11px; letter-spacing: 0.14em; text-transform: uppercase; color: var(--brass); }

.crumbs ol { list-style: none; display: flex; flex-wrap: wrap; gap: 8px; padding: 0; margin: 0 0 14px; }
.crumbs li { font-family: var(--mono); font-size: 10.5px; letter-spacing: 0.1em; text-transform: uppercase; color: var(--muted); }
.crumbs li + li::before { content: "/"; margin-right: 8px; color: var(--line-strong); }
.crumbs a { color: var(--muted); }
.crumbs a:hover { color: var(--sea); }
.crumbs span[aria-current] { color: var(--ink); }

.chip-row { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 16px; }
.chip {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 6px 12px;
  color: var(--muted);
}
.chip:hover { border-color: var(--sea); color: var(--sea); }

.filter-bar { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 18px; }
.filter-btn {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  background: transparent;
  color: var(--muted);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 7px 12px;
  cursor: pointer;
}
.filter-btn:hover { color: var(--sea); border-color: var(--sea); }
.filter-btn.is-on { background: var(--sea); border-color: var(--sea); color: #04201f; font-weight: 700; }

/* ---- detail ------------------------------------------------------------- */
.detail-hero { padding: 26px 0 0; }
.detail-head {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 18px;
  align-items: start;
  padding-bottom: 20px;
  border-bottom: 1px solid var(--line);
}
.detail-title h1 { font-size: 30px; margin: 6px 0 10px; }
.detail-art {
  margin: 0;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
  overflow: hidden;
  max-width: 100%;
  justify-self: start;
}
.detail-body { padding: 30px 0 40px; }

.detail-cols { display: grid; gap: 32px; grid-template-columns: minmax(0, 1fr); }
.detail-cols.with-rail { grid-template-columns: minmax(0, 1fr); }
.detail-cols.stacked { grid-template-columns: minmax(0, 1fr); max-width: 820px; margin: 0 auto; }

.detail-main h2 { font-size: 20px; margin-top: 26px; }
.detail-main h2:first-child { margin-top: 0; }

.summary-list { list-style: none; padding: 0; margin: 0 0 8px; }
.summary-list li {
  border-left: 2px solid var(--sea);
  padding: 4px 0 4px 14px;
  margin-bottom: 10px;
  color: var(--ink);
}
.note-list { padding-left: 20px; margin: 0 0 8px; }
.note-list li { margin-bottom: 10px; color: var(--ink); }
.note-list li::marker { font-family: var(--mono); color: var(--brass); }
.safety-list { list-style: none; padding: 0; margin: 0; }
.safety-list li {
  display: flex;
  gap: 10px;
  align-items: flex-start;
  border-left: 3px solid var(--signal);
  padding: 8px 0 8px 14px;
  margin-bottom: 10px;
  color: var(--ink);
}
.safety-list .icon { color: var(--signal); flex: 0 0 auto; }

.detail-return { margin-top: 26px; }

.mini-link {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 10px 0;
  border-bottom: 1px solid var(--line);
  color: var(--ink);
  font-size: 14px;
}
.mini-link:hover { color: var(--sea); }
.mini-link .icon { color: var(--muted); }

.detail-rail {
  position: static;
  display: flex;
  flex-direction: column;
  gap: 14px;
}
.rail-block {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 14px 16px;
}
.rail-block h3 {
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--brass);
  font-weight: 400;
  margin-bottom: 8px;
}
.spec-table { width: 100%; border-collapse: collapse; font-size: 13px; }
.spec-table th {
  text-align: left;
  font-family: var(--mono);
  font-size: 10.5px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--muted);
  font-weight: 400;
  padding: 6px 0;
  width: 42%;
  vertical-align: top;
  border-bottom: 1px solid var(--line);
}
.spec-table td { padding: 6px 0; border-bottom: 1px solid var(--line); vertical-align: top; }
.spec-table tr:last-child th, .spec-table tr:last-child td { border-bottom: 0; }
.rail-text { font-size: 13px; color: var(--muted); margin-bottom: 6px; }

/* ---- calculators -------------------------------------------------------- */
.calc-panel {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 18px;
  border: 1px solid var(--line);
  background: var(--panel);
  border-radius: var(--radius);
  padding: 16px;
  margin-bottom: 26px;
}
.calc-form { display: flex; flex-direction: column; gap: 14px; }
.field { display: flex; flex-direction: column; gap: 5px; }
.field label {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
}
.unit { color: var(--brass); }
.field input {
  font-family: var(--mono);
  font-size: 15px;
  padding: 9px 12px;
  background: var(--panel-2);
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  color: var(--ink);
}
.field input:focus { outline: 2px solid var(--brass); outline-offset: 1px; border-color: var(--brass); }
.calc-out { border-left: 0; padding-left: 0; border-top: 1px solid var(--line); padding-top: 18px; }
.calc-out h2 { font-size: 18px; margin-bottom: 12px; }
.out-list { margin: 0; }
.out-list div {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  padding: 10px 0;
  border-bottom: 1px solid var(--line);
}
.out-list dt { color: var(--muted); font-size: 13px; }
.out-list dd { margin: 0; font-family: var(--mono); color: var(--brass); font-size: 15px; text-align: right; }
.calc-note { font-size: 12px; color: var(--muted); margin-top: 14px; }

/* ---- blog / prose ------------------------------------------------------- */
.post-wrap { max-width: 760px; }
.post h1 { font-size: 28px; }
.post h2 { font-size: 21px; margin-top: 28px; }
.post-meta {
  display: flex;
  gap: 16px;
  font-family: var(--mono);
  font-size: 10.5px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 16px 0 20px;
}
.post-art {
  margin: 0 0 26px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--panel);
}
.post-foot { margin-top: 30px; padding-top: 14px; border-top: 1px solid var(--line); }
.prose { max-width: 760px; }
.prose p { color: var(--ink); }
.prose h2 { font-size: 21px; margin-top: 26px; }

/* ---- search ------------------------------------------------------------- */
.search-form { margin: 18px 0 10px; max-width: 520px; }
.search-form input {
  width: 100%;
  font-family: var(--mono);
  font-size: 15px;
  padding: 12px 14px;
  background: var(--panel);
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  color: var(--ink);
}
.search-form input:focus { outline: 2px solid var(--brass); outline-offset: 1px; }
.search-count { font-family: var(--mono); font-size: 11px; letter-spacing: 0.1em; text-transform: uppercase; color: var(--muted); }
.search-results { list-style: none; padding: 0; margin: 0; }
.search-results li { border-bottom: 1px solid var(--line); }
.search-results a { display: block; padding: 12px 0; color: var(--ink); }
.search-results a:hover .r-title { color: var(--sea); }
.r-title { font-family: var(--display); font-size: 17px; }
.r-desc { display: block; font-size: 13px; color: var(--muted); }
.r-tag { font-family: var(--mono); font-size: 10px; letter-spacing: 0.12em; text-transform: uppercase; color: var(--brass); }
.search-again { display: flex; gap: 12px; margin-top: 22px; }

/* ---- 404 ---------------------------------------------------------------- */
.cat-icon-lg { display: inline-flex; color: var(--sea); margin-bottom: 8px; }
.cat-icon-lg .icon { width: 34px; height: 34px; }

/* ---- footer ------------------------------------------------------------- */
.site-footer {
  position: relative;
  background: #05141D;
  border-top: 1px solid var(--line);
  padding: 32px 0 22px;
}
.footer-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: 22px;
  padding-bottom: 22px;
  border-bottom: 1px solid var(--line);
}
.footer-about { grid-column: 1 / -1; }
.footer-about h4 { font-size: 19px; margin-bottom: 6px; }
.footer-grid h4 {
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--brass);
  font-weight: 400;
  margin: 0 0 10px;
}
.footer-grid ul { list-style: none; padding: 0; margin: 0; }
.footer-grid li { margin-bottom: 7px; }
.footer-grid a { color: var(--muted); font-size: 13.5px; }
.footer-grid a:hover { color: var(--sea); }
.footer-about p { color: var(--muted); font-size: 13.5px; }
.footer-note { font-size: 12px; color: var(--muted); opacity: 0.8; max-width: 30em; }
.footer-legal { padding-top: 16px; display: flex; flex-wrap: wrap; flex-direction: column; gap: 12px; justify-content: space-between; }
.footer-legal p { font-size: 11.5px; color: var(--muted); margin: 0; max-width: 62em; }

/* ---- 640: two-up cards, wider mast rows -------------------------------- */
@media (min-width: 640px) {
  :root { --header-h: 60px; }
  .container { padding: 0 20px; }
  .header-inner { gap: 14px; }
  .brand-text strong { font-size: 18px; }
  .brand-text small { display: block; }
  .site-nav { gap: 14px; }
  .nav-link { font-size: 11px; }
  .site-nav .nav-link:nth-child(n+3) { display: inline-flex; }
  .s1-mast { padding: 26px 0 22px; }
  .s1-mast-grid { gap: 20px; }
  .mast-main h1 { font-size: 34px; }
  .mast-deck { font-size: 15px; -webkit-line-clamp: 2; }
  .mast-actions { gap: 10px; margin-bottom: 14px; }
  .btn { padding: 10px 16px; font-size: 12px; letter-spacing: 0.1em; }
  .mast-lead { display: block; padding: 8px 0 8px 14px; }
  .mast-lead-title { font-size: 19px; }
  .mast-side { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: 0 18px; border-top: 2px solid var(--sea); padding-top: 12px; overflow: visible; }
  .mast-side-title { display: block; grid-column: 1 / -1; }
  .mast-row { width: auto; grid-template-columns: 28px minmax(0, 1fr) auto 18px; gap: 10px; padding: 9px 2px; border: 0; border-bottom: 1px solid var(--line); }
  .mast-row-cat, .mast-row-arrow { display: inline; }
  .module { padding: 38px 0; }
  .section-head h2 { font-size: 24px; }
  .tool-grid { gap: 12px; }
  .card { padding: 14px; }
  .card-title { font-size: 18px; }
  .card-desc { font-size: 13.5px; }
  .cat-grid { gap: 12px; }
  .calc-band { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .post-grid, .post-grid.wide { gap: 12px; }
  .stage-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .page-hero { padding: 30px 0 26px; }
  .page-hero h1 { font-size: 36px; }
  .detail-hero { padding: 30px 0 0; }
  .detail-title h1 { font-size: 34px; }
  .detail-main h2 { font-size: 21px; }
  .footer-grid { grid-template-columns: 1.2fr 1fr 1fr; }
  .footer-about { grid-column: auto; }
  .footer-legal { flex-direction: row; }
  .calc-panel { padding: 20px; }
  .post h1 { font-size: 34px; }
  .prose h2 { font-size: 22px; }
}

/* ---- 768: mast side becomes a vertical list, three-up directory -------- */
@media (min-width: 768px) {
  .container { padding: 0 24px; }
  .s1-mast { padding: 32px 0 28px; }
  .s1-mast-grid { grid-template-columns: minmax(0, 1.25fr) minmax(0, 0.9fr); gap: 30px; }
  .mast-main h1 { font-size: clamp(34px, 5.4vw, 66px); }
  .mast-deck { font-size: 16px; }
  .mast-lead-desc { display: block; }
  .mast-side { display: block; }
  .mast-side-title { margin-bottom: 6px; }
  .mast-row { padding: 11px 2px; }
  .tool-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .cat-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .post-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .post-grid.wide { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .detail-head { grid-template-columns: minmax(0, 1fr) 300px; gap: 28px; padding-bottom: 24px; align-items: end; }
  .detail-art { max-width: 300px; justify-self: end; }
  .detail-cols { gap: 36px; }
  .detail-cols.stacked .detail-rail { display: grid; grid-template-columns: 1.3fr 1fr 1fr; border: 1px solid var(--line); background: var(--panel); }
  .detail-cols.stacked .rail-block { border: 0; border-right: 1px solid var(--line); border-bottom: 0; background: transparent; padding: 12px 14px; }
  .detail-cols.stacked .rail-block:last-child { border-right: 0; }
  .detail-main h2 { font-size: 23px; }
  .post h1 { font-size: clamp(28px, 4vw, 42px); }
  .footer-grid { grid-template-columns: 1.2fr 1fr 1fr; }
  .tool-card { min-height: 200px; }
  .cat-card { min-height: 160px; }
  .calc-card { min-height: 140px; }
  .post-card { min-height: 160px; }
  .calc-panel { grid-template-columns: minmax(0, 1fr) 300px; }
  .calc-out { border-left: 1px solid var(--line); border-top: 0; padding-left: 18px; padding-top: 0; }
}

/* ---- 1024: side rail, four-up footer ----------------------------------- */
@media (min-width: 1024px) {
  .s1-mast { padding: 40px 0 34px; }
  .s1-mast-grid { gap: 40px; }
  .mast-deck { font-size: 16.5px; }
  .mast-lead-title { font-size: 21px; }
  .module { padding: 48px 0; }
  .section-head h2 { font-size: 26px; }
  .detail-head { grid-template-columns: minmax(0, 1fr) 360px; gap: 36px; }
  .detail-art { max-width: 360px; }
  .detail-body { padding: 38px 0 56px; }
  .detail-cols.with-rail { grid-template-columns: minmax(0, 1fr) 320px; }
  .detail-cols.with-rail .detail-rail { position: sticky; top: calc(var(--header-h) + 18px); align-self: start; }
  .calc-panel { grid-template-columns: minmax(0, 1fr) 340px; }
  .footer-grid { grid-template-columns: 1.4fr 1fr 1fr 1fr; }
  .tool-card { min-height: 210px; }
  .cat-card { min-height: 170px; }
  .post-card { min-height: 165px; }
}

/* ---- 1200: four-up directory, five-up categories ----------------------- */
@media (min-width: 1200px) {
  .s1-mast { padding: 46px 0 40px; }
  .s1-mast-grid { gap: 48px; }
  .tool-grid { grid-template-columns: repeat(4, minmax(0, 1fr)); }
  .cat-grid { grid-template-columns: repeat(5, minmax(0, 1fr)); }
  .calc-band { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .calc-card { min-height: 150px; }
  .stage-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}

@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; animation: none !important; }
  .card:hover { transform: none; }
}