:root {
  --bg: #07080D;
  --bg-deep: #000000;
  --line: rgba(232, 238, 246, 0.09);
  --ink: #E8ECF3;
  --ink-muted: #A3ADC2;
  --cyan: #7DD3FC;
  --paper: #12141D;
  --paper-ink: #E4E8F0;
  --paper-muted: #96A0B8;
  --amber: #E3A85C;
  --font-display: "IBM Plex Mono", ui-monospace, monospace;
  --font-body: "IBM Plex Sans", system-ui, sans-serif;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-body);
  line-height: 1.5;
  min-height: 100vh;
}

/* Title block — three zones: logo (left), section nav (centred),
   Home/Contact quicklinks (right). .titleblock-left uses display:contents so
   its children become direct grid items. On wide screens all three sit on one
   row with the nav dead-centred (equal minmax(0,1fr) side tracks); below
   1360px the nav drops to its own full-width row beneath logo + quicklinks. */
.titleblock {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto minmax(0, 1fr);
  align-items: center;
  column-gap: 1.5rem;
  row-gap: 0.85rem;
  padding: 1.5rem 2rem;
  border-bottom: 1px solid var(--line);
}

.eyebrow {
  display: block;
  font-family: var(--font-display);
  font-size: 0.7rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--cyan);
  margin-bottom: 0.35rem;
}

.titleblock-left {
  display: contents;
}

.titleblock-name {
  grid-column: 1;
  grid-row: 1;
  min-width: 0;
}

.titleblock-quicklinks {
  grid-column: 3;
  grid-row: 1;
  justify-self: end;
  display: flex;
  flex-direction: row;
  align-items: center;
  gap: 1.25rem;
  font-family: var(--font-display);
}

/* Divider grouping Home/Contact as a utility cluster on the right. */
.titleblock-quicklinks::before {
  content: "";
  align-self: stretch;
  width: 1px;
  min-height: 1.3em;
  background: var(--line);
}

.titleblock-name h1 {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1.5rem;
  letter-spacing: 0.02em;
}

.titleblock-tagline {
  margin: 0.2rem 0 0;
  font-size: 0.75rem;
  color: var(--ink-muted);
  letter-spacing: 0.01em;
}

.site-nav {
  grid-column: 2;
  grid-row: 1;
  justify-self: center;
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  justify-content: center;
  row-gap: 0.5rem;
  gap: 1.6rem;
  font-family: var(--font-display);
}

/* Below 1360px the three zones no longer fit comfortably on one line, so the
   section nav gets its own full-width centred row under logo + Home/Contact. */
@media (max-width: 1360px) {
  .titleblock {
    grid-template-columns: 1fr auto;
  }
  .titleblock-quicklinks {
    grid-column: 2;
  }
  .site-nav {
    grid-column: 1 / -1;
    grid-row: 2;
    justify-self: stretch;
  }
}

/* Cyan divider between the Industrial dropdown and the Calculators link. */
.site-nav > a:last-of-type {
  position: relative;
  padding-left: 1.6rem;
}

.site-nav > a:last-of-type::before {
  content: "";
  position: absolute;
  left: 0;
  top: 50%;
  width: 1px;
  height: 1.5em;
  transform: translateY(-50%);
  background: var(--cyan);
}

/* When active, underline only the word, not the padding lane before it. */
.site-nav > a:last-of-type.active {
  border-bottom-color: transparent;
}

.site-nav > a:last-of-type.active::after {
  content: "";
  position: absolute;
  left: 1.6rem;
  right: 0;
  bottom: 0;
  height: 2px;
  background: var(--cyan);
}

.site-nav a,
.titleblock-quicklinks a {
  color: var(--ink-muted);
  text-decoration: none;
  font-size: 0.8rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding-bottom: 0.25rem;
  border-bottom: 2px solid transparent;
  white-space: nowrap;
}

.site-nav a:hover,
.titleblock-quicklinks a:hover {
  color: var(--ink);
}

.site-nav a.active,
.titleblock-quicklinks a.active {
  color: var(--cyan);
  border-bottom-color: var(--cyan);
}

.nav-dropdown {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: 0.15rem;
}

.nav-dropdown-label {
  display: block;
  cursor: pointer;
  color: var(--ink-muted);
  text-decoration: none;
  font-family: var(--font-display);
  font-size: 0.8rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding-bottom: 0.25rem;
  border-bottom: 2px solid transparent;
  white-space: nowrap;
}

.nav-dropdown:hover .nav-dropdown-label,
.nav-dropdown:focus-within .nav-dropdown-label {
  color: var(--ink);
}

.nav-dropdown-label.active {
  color: var(--cyan);
  border-bottom-color: var(--cyan);
}

/* Separate tap target from the label link, so touch users can open the
   submenu without being forced to navigate — see nav.js. */
.nav-dropdown-toggle {
  background: none;
  border: none;
  margin: 0;
  padding: 0 0.15rem 0.25rem;
  cursor: pointer;
  color: var(--ink-muted);
  font-size: 0.65rem;
  line-height: 1;
}

.nav-dropdown-toggle:hover,
.nav-dropdown:hover .nav-dropdown-toggle,
.nav-dropdown:focus-within .nav-dropdown-toggle {
  color: var(--ink);
}

.nav-dropdown.open .nav-dropdown-toggle {
  color: var(--cyan);
}

.nav-dropdown-menu {
  display: none;
  flex-direction: column;
  position: absolute;
  top: 100%;
  left: 0;
  min-width: 160px;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 0.4rem 0;
  z-index: 20;
}

.nav-dropdown:hover .nav-dropdown-menu,
.nav-dropdown:focus-within .nav-dropdown-menu,
.nav-dropdown.open .nav-dropdown-menu {
  display: flex;
}

.nav-dropdown-menu a {
  display: block;
  padding: 0.5rem 1rem;
  color: var(--ink-muted);
  text-decoration: none;
  font-size: 0.8rem;
  letter-spacing: 0.04em;
  text-transform: none;
  border-bottom: none;
  white-space: nowrap;
}

.nav-dropdown-menu a:hover {
  color: var(--ink);
  background: var(--bg-deep);
}

.nav-dropdown-menu a.active {
  color: var(--cyan);
}

main {
  max-width: 960px;
  margin: 0 auto;
  padding: 2rem;
}

/* Skyscraper ad slots, flanking the centered content column. Hidden until
   the viewport is wide enough that they can't possibly overlap main
   content or force horizontal scrolling. */
.ad-slot {
  display: none;
  position: fixed;
  /* Aligned with the top of the first content card on the home page. */
  top: 195px;
  width: 160px;
  height: 600px;
  z-index: 5;
}

.ad-slot-left {
  left: calc(50% - 480px - 184px);
}

.ad-slot-right {
  right: calc(50% - 480px - 184px);
}

@media (min-width: 1400px) {
  .ad-slot {
    display: block;
  }
}

/* In-content ad unit, injected by ads.js on viewports below 1400px (where the
   fixed side rails don't fit). */
.ad-incontent {
  margin: 2.5rem auto;
  min-height: 90px;
  text-align: center;
  overflow: hidden;
}

.ad-incontent::before {
  content: "Advertisement";
  display: block;
  font-family: var(--font-display);
  font-size: 0.6rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--ink-muted);
  opacity: 0.55;
  margin-bottom: 0.45rem;
}

.ad-incontent ins {
  display: block;
}

@media (min-width: 1400px) {
  .ad-incontent {
    display: none;
  }
}

.site-footer {
  max-width: 960px;
  margin: 2rem auto 0;
  padding: 1.5rem 2rem 2.5rem;
  border-top: 1px solid var(--line);
  font-size: 0.78rem;
  color: var(--ink-muted);
}

.site-footer p {
  margin: 0 0 0.5rem;
  max-width: none;
}

.site-footer p:last-child {
  margin-bottom: 0;
}

.site-footer a {
  color: var(--cyan);
}

.hero-note {
  color: var(--ink-muted);
  font-size: 1.05rem;
  max-width: none;
  margin: 0 0 2rem;
}

.marker {
  color: var(--amber);
  font-family: var(--font-display);
}

/* Ask / search panels */
.tools {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.25rem;
  margin-bottom: 2.5rem;
}

@media (max-width: 720px) {
  .tools { grid-template-columns: 1fr; }
}

.panel {
  background: rgba(234, 242, 246, 0.04);
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 1.25rem;
}

.panel-head, .sheet-head {
  display: flex;
  align-items: baseline;
  gap: 0.6rem;
  margin-bottom: 0.9rem;
}

.ref-tag {
  font-family: var(--font-display);
  font-size: 0.7rem;
  color: var(--amber);
  letter-spacing: 0.08em;
}

.panel-head h2, .sheet-head h3 {
  margin: 0;
  font-size: 1rem;
  font-weight: 600;
}

textarea, input[type="search"] {
  width: 100%;
  background: var(--bg-deep);
  border: 1px solid var(--line);
  border-radius: 3px;
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 0.95rem;
  padding: 0.6rem 0.7rem;
  resize: vertical;
}

textarea:focus, input[type="search"]:focus, button:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 1px;
}

button {
  margin-top: 0.6rem;
  background: var(--amber);
  color: var(--bg-deep);
  border: none;
  border-radius: 3px;
  padding: 0.5rem 1.1rem;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 0.85rem;
  letter-spacing: 0.04em;
  cursor: pointer;
}

button:hover { filter: brightness(1.08); }

.status {
  min-height: 1.2em;
  font-size: 0.85rem;
  color: var(--ink-muted);
  font-family: var(--font-display);
}

.status.error {
  color: var(--amber);
}

.answer {
  white-space: pre-wrap;
  font-size: 0.95rem;
  margin-top: 0.5rem;
}

.results {
  list-style: none;
  margin: 0.75rem 0 0;
  padding: 0;
  display: grid;
  gap: 0.75rem;
  max-height: 260px;
  overflow-y: auto;
}

.results li {
  border-left: 2px solid var(--cyan);
  padding-left: 0.75rem;
}

.results li.empty {
  border-left-color: var(--line);
  color: var(--ink-muted);
}

.results .meta {
  display: block;
  font-family: var(--font-display);
  font-size: 0.7rem;
  color: var(--ink-muted);
  margin: 0.15rem 0 0.3rem;
}

.results p {
  margin: 0;
  font-size: 0.9rem;
  color: var(--ink-muted);
}

/* Reference sheets */
.sheets {
  display: grid;
  gap: 1rem;
}

.sheet {
  background: var(--paper);
  color: var(--paper-ink);
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 1.25rem 1.5rem;
  min-width: 0;
}

.sheet .ref-tag { color: var(--amber); }

.placeholder {
  margin: 0;
  font-size: 0.9rem;
  color: var(--paper-muted);
  font-style: italic;
}

.legend {
  text-align: center;
  padding: 2rem;
  font-family: var(--font-display);
  font-size: 0.7rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-muted);
}

/* Fastener picker + spec sheet */
.fastener-controls {
  display: flex;
  gap: 1.25rem;
  flex-wrap: wrap;
  margin-bottom: 1.5rem;
}

.field {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.field label {
  font-family: var(--font-display);
  font-size: 0.7rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-muted);
}

.field select {
  background: var(--bg-deep);
  border: 1px solid var(--line);
  border-radius: 3px;
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 0.95rem;
  padding: 0.55rem 0.7rem;
  min-width: 160px;
}

.field select:focus {
  outline: 2px solid var(--cyan);
  outline-offset: 1px;
}

.fastener-sheet .sheet-head h3 {
  font-family: var(--font-display);
  font-weight: 500;
}

.spec-table {
  width: 100%;
  border-collapse: collapse;
  margin-bottom: 1.25rem;
  font-size: 0.9rem;
}

.spec-table th, .spec-table td {
  text-align: left;
  padding: 0.4rem 0.6rem;
  border-bottom: 1px solid rgba(228, 232, 240, 0.12);
  overflow-wrap: break-word;
  word-break: break-word;
}

.spec-table th {
  font-family: var(--font-display);
  font-size: 0.7rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--paper-muted);
}

.spec-table-narrow {
  table-layout: fixed;
}

.spec-table-narrow th, .spec-table-narrow td {
  padding: 0.4rem 0.4rem;
  text-align: center;
  word-break: break-word;
}

.spec-group {
  margin-bottom: 1.25rem;
}

.spec-group h4 {
  margin: 0 0 0.5rem;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--paper-ink);
}

.group-note {
  font-weight: 400;
  font-size: 0.75rem;
  color: var(--paper-muted);
  text-transform: none;
  letter-spacing: 0;
}

.spec-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 0.75rem;
}

.spec-cell dt {
  font-family: var(--font-display);
  font-size: 0.65rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--paper-muted);
}

.spec-cell dd {
  margin: 0.15rem 0 0;
  font-size: 0.95rem;
}

.spec-cell-wide {
  grid-column: 1 / -1;
}

.calc-flag {
  color: var(--amber);
  font-weight: 700;
  margin-left: 0.15rem;
  cursor: help;
}

.callout {
  font-family: var(--font-display);
  font-size: 0.85rem;
  background: rgba(228, 232, 240, 0.06);
  border-left: 2px solid var(--amber);
  padding: 0.6rem 0.8rem;
  margin: 0 0 0.4rem;
  line-height: 1.6;
}

.data-note {
  font-size: 0.85rem;
  color: var(--ink-muted);
  max-width: none;
  margin: 0 0 1.5rem;
}

.data-note a { color: var(--cyan); }

.page-citation {
  font-style: normal;
  line-height: 1.7;
}

.page-citation em {
  font-style: italic;
}

.section-title {
  font-family: var(--font-display);
  font-size: 1.1rem;
  color: var(--ink);
  margin: 2.5rem 0 1rem;
  padding-bottom: 0.5rem;
  border-bottom: 2px solid var(--cyan);
}

.section-title:first-of-type {
  margin-top: 0.5rem;
}

/* GD&T cards */
.gdt-grid {
  display: grid;
  gap: 1.25rem;
}

.gdt-card {
  background: var(--paper);
  color: var(--paper-ink);
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 1.25rem 1.5rem;
}

.gdt-desc {
  margin: 0 0 0.25rem;
  font-size: 0.92rem;
  color: var(--paper-ink);
  max-width: none;
}

.gdt-visual {
  display: flex;
  gap: 1.5rem;
  flex-wrap: wrap;
  align-items: flex-start;
  margin-top: 1rem;
}

.gdt-diagram {
  flex: 1 1 260px;
  background: var(--bg-deep);
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 0.5rem;
}

.gdt-diagram svg {
  width: 100%;
  height: auto;
  display: block;
}

.gdt-callout {
  flex: 1 1 220px;
  display: flex;
  flex-direction: column;
  gap: 0.85rem;
}

.fcf {
  display: inline-flex;
  align-self: flex-start;
  font-family: var(--font-display);
  font-size: 0.9rem;
  border: 1.5px solid var(--paper-ink);
  background: var(--bg-deep);
  border-radius: 2px;
}

.fcf-cell {
  padding: 0.4rem 0.6rem;
  border-right: 1.5px solid var(--paper-ink);
  display: flex;
  align-items: center;
  color: var(--paper-ink);
}

.fcf-cell:last-child { border-right: none; }

.fcf-symbol {
  font-size: 1.15rem;
  color: var(--cyan);
}

.tol-pills {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.tol-pill {
  border: 1px solid var(--line);
  border-radius: 3px;
  padding: 0.4rem 0.65rem;
  text-align: center;
}

.tol-pill .val {
  font-family: var(--font-display);
  color: var(--cyan);
  font-weight: 600;
  display: block;
  font-size: 0.95rem;
}

.tol-pill .lbl {
  color: var(--paper-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  font-size: 0.65rem;
}

.tol-pill.standard {
  border-color: var(--amber);
}

.tol-pill.standard .val {
  color: var(--amber);
}

.gdt-math {
  margin: 0;
  font-size: 0.8rem;
  color: var(--paper-muted);
}

.chart-embed {
  margin: 2.5rem 0 0;
  padding: 0;
}

.chart-embed img {
  width: 100%;
  border-radius: 4px;
  border: 1px solid var(--line);
  display: block;
}

.chart-embed figcaption {
  font-size: 0.75rem;
  color: var(--ink-muted);
  margin-top: 0.6rem;
  text-align: center;
}

.chart-embed figcaption a { color: var(--cyan); }

/* Alloy filter tool */
.alloy-filters {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(195px, 1fr));
  gap: 0.9rem 1rem;
  margin-bottom: 1.25rem;
}

.alloy-filters .field {
  padding-bottom: 0.85rem;
  border-bottom: 1px solid var(--line);
}

.alloy-filters .field select {
  min-width: 0;
  width: 100%;
}

.alloy-filters .field .or-better {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  font-family: var(--font-body);
  font-size: 0.78rem;
  color: var(--ink-muted);
  text-transform: none;
  letter-spacing: normal;
  cursor: pointer;
}

.alloy-filters .field .or-better input {
  accent-color: var(--cyan);
  cursor: pointer;
}

.alloy-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 1.5rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--line);
}

.alloy-toolbar .status {
  margin: 0;
}

.alloy-toolbar button {
  margin-top: 0;
  background: transparent;
  border: 1px solid var(--line);
  color: var(--ink-muted);
}

.alloy-toolbar button:hover {
  color: var(--ink);
  filter: none;
  border-color: var(--ink-muted);
}

.alloy-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 1rem;
  align-items: start;
}

.alloy-card-head {
  justify-content: space-between;
}

.alloy-type-badge {
  font-family: var(--font-display);
  font-size: 0.65rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  padding: 0.2rem 0.5rem;
  border-radius: 3px;
  border: 1px solid var(--line);
  white-space: nowrap;
}

.alloy-type-badge.ferrous {
  color: var(--cyan);
  border-color: var(--cyan);
}

.alloy-type-badge.nonferrous {
  color: var(--amber);
  border-color: var(--amber);
}

.alloy-category {
  margin: -0.5rem 0 0.9rem;
  font-size: 0.8rem;
  color: var(--paper-muted);
  font-style: italic;
}

.alloy-props {
  margin: 0;
}

.alloy-props .spec-cell dd {
  font-size: 0.85rem;
}

.alloy-uses {
  margin: 1rem 0 0;
  padding-top: 0.75rem;
  border-top: 1px solid rgba(228, 232, 240, 0.12);
  font-size: 0.85rem;
  color: var(--paper-muted);
}

.alloy-uses strong {
  color: var(--paper-ink);
}

/* Calculators landing page */
.calc-search {
  margin: 0 0 2rem;
}

.calc-group {
  margin-bottom: 1rem;
  background: #0e1017;
  border: 1px solid rgba(232, 238, 246, 0.12);
  border-radius: 8px;
  overflow: hidden;
}

.calc-group-title {
  display: flex;
  align-items: center;
  gap: 0.9rem;
  font-family: var(--font-display);
  font-size: 1.15rem;
  color: var(--ink);
  margin: 0;
  padding: 0.85rem 1.25rem;
  cursor: pointer;
  user-select: none;
  list-style: none;
}

.calc-group-title::-webkit-details-marker {
  display: none;
}

.calc-group-label {
  flex: 1;
}

.calc-group-count {
  font-size: 0.8rem;
  font-weight: 400;
  letter-spacing: 0.02em;
  color: var(--ink-muted);
}

.calc-group-toggle {
  font-size: 0.85rem;
  color: var(--ink-muted);
  transition: transform 0.15s ease;
}

.calc-group[open] .calc-group-toggle {
  transform: rotate(180deg);
}

.calc-group[open] .calc-group-title {
  border-bottom: 1px solid var(--line);
}

.calc-group > .calc-categories {
  display: grid;
  gap: 0.85rem;
  padding: 1.1rem 1.25rem 1.25rem;
}

.calc-category {
  position: relative;
  overflow: hidden;
  background: linear-gradient(180deg, rgba(125, 211, 252, 0.05), rgba(18, 20, 29, 0) 60%), #181b26;
  border: 1px solid rgba(232, 238, 246, 0.11);
  border-radius: 5px;
  padding: 0.9rem 1.1rem 1rem;
  transition: border-color 0.16s ease, box-shadow 0.16s ease;
}

.calc-category::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--cyan), rgba(125, 211, 252, 0));
}

.calc-category:hover {
  border-color: rgba(125, 211, 252, 0.35);
  box-shadow: 0 10px 26px -18px rgba(125, 211, 252, 0.3);
}

.calc-category h3 {
  margin: 0 0 0.6rem;
  font-size: 0.9rem;
  font-family: var(--font-display);
  color: var(--paper-ink);
}

.calc-category ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(min(360px, 100%), 1fr));
  gap: 0.5rem 1.25rem;
}

/* Home page */
.section-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 1.1rem;
  margin: 2rem 0 3rem;
}

.section-card {
  position: relative;
  display: flex;
  flex-direction: column;
  background: linear-gradient(180deg, rgba(125, 211, 252, 0.05), rgba(18, 20, 29, 0) 55%), var(--paper);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 1.5rem 1.5rem 1.35rem;
  overflow: hidden;
  transition: transform 0.16s ease, border-color 0.16s ease, box-shadow 0.16s ease;
}

.section-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--cyan), rgba(125, 211, 252, 0));
}

.section-card:hover {
  transform: translateY(-3px);
  border-color: rgba(125, 211, 252, 0.45);
  box-shadow: 0 12px 30px -16px rgba(125, 211, 252, 0.35);
}

.section-card-icon {
  width: 2rem;
  height: 2rem;
  margin-bottom: 0.9rem;
  color: var(--cyan);
}

.section-card-icon svg {
  width: 100%;
  height: 100%;
  display: block;
}

.section-card h3 {
  margin: 0 0 0.5rem;
  font-family: var(--font-display);
  font-size: 1.02rem;
  color: var(--paper-ink);
}

.section-card p {
  margin: 0 0 1.1rem;
  font-size: 0.88rem;
  line-height: 1.55;
  color: var(--paper-muted);
  max-width: 44ch;
}

.section-card a {
  margin-top: auto;
  align-self: flex-start;
  color: var(--cyan);
  font-family: var(--font-display);
  font-size: 0.76rem;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color 0.16s ease;
}

/* Make the whole card a click target while keeping a real link for
   keyboard and assistive tech (the "stretched link" pattern). */
.section-card a::after {
  content: "";
  position: absolute;
  inset: 0;
}

.section-card:hover a {
  border-bottom-color: var(--cyan);
}

.section-card:focus-within {
  border-color: var(--cyan);
  box-shadow: 0 0 0 2px rgba(125, 211, 252, 0.55);
}

.section-card a:focus-visible {
  outline: none;
}

@media (prefers-reduced-motion: reduce) {
  .section-card { transition: none; }
  .section-card:hover { transform: none; }
}

/* Same visual treatment as .calc-category, just side by side in threes. */
.popular-resources {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1rem;
}

.calc-category li {
  font-size: 0.84rem;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.calc-category a {
  color: var(--cyan);
  text-decoration: none;
}

.calc-category a:hover {
  text-decoration: underline;
}

.calc-category .soon {
  color: var(--paper-muted);
  cursor: default;
}

.calc-category .soon-tag {
  font-family: var(--font-display);
  font-size: 0.65rem;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--paper-muted);
  border: 1px solid var(--line);
  border-radius: 3px;
  padding: 0.05rem 0.35rem;
  margin-left: 0.4rem;
}

/* Calculator pages */
.calc-desc {
  color: var(--ink-muted);
  max-width: none;
  margin: 0 0 1.5rem;
}

.calc-diagram {
  background: var(--bg-deep);
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 1rem;
  margin-bottom: 1.5rem;
  max-width: 580px;
}

.calc-diagram svg {
  width: 100%;
  height: auto;
  display: block;
}

.calc-diagram figcaption {
  margin-top: 0.6rem;
  font-size: 0.78rem;
  color: var(--ink-muted);
  text-align: center;
}

.contact-layout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem;
  align-items: start;
  margin: 0 0 1.5rem;
}

.contact-form {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 2rem 2.25rem;
  margin: 0;
}

.contact-form textarea {
  resize: vertical;
  min-height: 220px;
}

.contact-form .calc-actions {
  margin-top: 0.5rem;
}

.contact-aside {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.contact-aside-card {
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 1.5rem 1.75rem;
}

.contact-aside-card h3 {
  margin: 0 0 0.75rem;
  font-family: var(--font-display);
  font-size: 0.95rem;
  color: var(--paper-ink);
}

.contact-aside-card p {
  margin: 0;
  font-size: 0.9rem;
  color: var(--paper-muted);
  line-height: 1.6;
}

.contact-aside-card ul {
  margin: 0;
  padding-left: 1.1rem;
  font-size: 0.88rem;
  color: var(--paper-muted);
  line-height: 1.6;
}

.contact-aside-card li + li {
  margin-top: 0.5rem;
}

.contact-aside-card li strong {
  color: var(--paper-ink);
}

@media (max-width: 720px) {
  .contact-layout {
    grid-template-columns: 1fr;
  }
}

.calc-form {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 1rem;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 1.25rem 1.5rem;
  margin-bottom: 1.5rem;
}

.calc-field {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.calc-field label {
  font-family: var(--font-display);
  font-size: 0.7rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--paper-muted);
}

.calc-field input, .calc-field select {
  background: var(--bg-deep);
  border: 1px solid var(--line);
  border-radius: 3px;
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 0.95rem;
  padding: 0.55rem 0.7rem;
}

.calc-field input:focus, .calc-field select:focus {
  outline: 2px solid var(--cyan);
  outline-offset: 1px;
}

.calc-field-group {
  display: flex;
  gap: 0.4rem;
}

.calc-field-group input {
  flex: 1 1 auto;
  min-width: 0;
}

.calc-field-group .calc-unit-select {
  flex: 0 0 auto;
  width: auto;
  padding-right: 1.6rem;
}

.calc-actions {
  grid-column: 1 / -1;
  display: flex;
  gap: 0.75rem;
  margin-top: 0.25rem;
}

.calc-actions button {
  margin-top: 0;
}

.calc-actions .calc-reset-btn {
  background: transparent;
  border: 1px solid var(--line);
  color: var(--ink-muted);
}

.calc-actions .calc-reset-btn:hover {
  color: var(--ink);
  filter: none;
  border-color: var(--ink-muted);
}

.calc-results {
  background: var(--paper);
  border: 1px solid var(--line);
  border-left: 3px solid var(--cyan);
  border-radius: 4px;
  padding: 1.1rem 1.5rem;
  margin-bottom: 2rem;
  min-height: 3rem;
  color: var(--paper-ink);
}

.calc-results:empty::before {
  content: "Fill in the fields above and press Solve.";
  color: var(--paper-muted);
  font-size: 0.9rem;
  font-style: italic;
}

.calc-results.calc-error {
  border-left-color: var(--amber);
  color: var(--amber);
  font-size: 0.9rem;
}

/* Two-card calculator workspace — left card holds the stacked inputs, right
   card shows the solution. Opt-in per calculator via .calc-workspace +
   .calc-form-stacked (currently only the stress & strain calculator). */
.calc-workspace {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.25rem;
  align-items: start;
  margin-bottom: 2rem;
}

/* Left column: loading type in its own card, then the inputs card. */
.calc-inputs-col {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.calc-loadtype-card {
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 1.25rem 1.5rem;
}

.calc-form-stacked {
  display: flex;
  flex-direction: column;
  gap: 0.9rem;
  margin-bottom: 0;
}

/* Centre the loading diagram above the workspace. */
main:has(.calc-workspace) .calc-diagram {
  margin-left: auto;
  margin-right: auto;
}

/* Uniform column widths: every value input the same, every unit dropdown the
   same, and the two action buttons together spanning that same total width. */
.calc-form-stacked .calc-field-group input {
  flex: 1 1 0;
}

.calc-form-stacked .calc-field-group .calc-unit-select {
  flex: 0 0 7rem;
  width: 7rem;
}

.calc-form-stacked .calc-actions {
  display: flex;
  gap: 0.5rem;
}

.calc-form-stacked .calc-actions button {
  flex: 1 1 0;
  margin: 0;
}

.calc-solution-card {
  background: var(--paper);
  border: 1px solid var(--line);
  border-left: 3px solid var(--cyan);
  border-radius: 4px;
  padding: 1.1rem 1.5rem 1.25rem;
}

.calc-solution-card:has(.calc-error) {
  border-left-color: var(--amber);
}

.calc-solution-title {
  margin: 0 0 0.9rem;
  font-family: var(--font-display);
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--paper-muted);
}

.calc-solution-card .calc-results {
  background: none;
  border: none;
  border-radius: 0;
  padding: 0;
  margin: 0;
  min-height: 2.5rem;
}

.calc-solution-card .calc-results:empty::before {
  content: "Enter values on the left and press Solve.";
}

@media (max-width: 720px) {
  .calc-workspace {
    grid-template-columns: 1fr;
  }
}

.calc-result-list {
  margin: 0;
  display: grid;
  gap: 0.6rem;
}

.calc-result-row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 1rem;
  border-bottom: 1px solid rgba(228, 232, 240, 0.1);
  padding-bottom: 0.5rem;
}

.calc-result-row:last-child {
  border-bottom: none;
  padding-bottom: 0;
}

.calc-result-row dt {
  font-family: var(--font-display);
  font-size: 0.85rem;
  color: var(--paper-muted);
}

.calc-result-row dd {
  margin: 0;
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--cyan);
  text-align: right;
}

.calc-history {
  margin-bottom: 2rem;
}

.calc-history-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0.9rem;
}

.calc-history-head h2 {
  margin: 0;
  font-size: 0.95rem;
}

.calc-history-head button {
  margin-top: 0;
  background: transparent;
  border: 1px solid var(--line);
  color: var(--ink-muted);
  font-size: 0.75rem;
  padding: 0.35rem 0.7rem;
}

.calc-history-head button:hover {
  color: var(--ink);
  filter: none;
  border-color: var(--ink-muted);
}

#calc-history-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0.5rem;
  max-height: 420px;
  overflow-y: auto;
}

.calc-history-item {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 1rem;
  background: var(--paper);
  border: 1px solid var(--line);
  border-left: 2px solid var(--cyan);
  border-radius: 3px;
  padding: 0.55rem 0.9rem;
  cursor: pointer;
  font-size: 0.85rem;
}

.calc-history-item:hover {
  border-left-color: var(--amber);
  background: rgba(228, 232, 240, 0.06);
}

.calc-history-summary {
  color: var(--paper-ink);
  font-family: var(--font-display);
}

.calc-history-time {
  color: var(--paper-muted);
  font-size: 0.75rem;
  white-space: nowrap;
}

#calc-history-list li.empty {
  color: var(--paper-muted);
  font-style: italic;
  font-size: 0.85rem;
  border: none;
  background: none;
  padding: 0;
  cursor: default;
}

/* Fastener combined table + copy buttons */
.fastener-combined-table {
  margin-bottom: 1.5rem;
}

.fastener-combined-table td {
  vertical-align: middle;
}

.fastener-value-cell {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.6rem;
}

.fastener-value-cell-stacked {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 0.3rem;
}

.drill-ref {
  font-family: var(--font-display);
  font-size: 0.8rem;
  color: var(--paper-muted);
  white-space: nowrap;
}

.fastener-callout-text {
  font-family: var(--font-display);
  font-size: 0.95rem;
  color: var(--paper-ink);
  white-space: nowrap;
}

.copy-btn {
  margin-top: 0;
  background: transparent;
  border: 1px solid var(--line);
  color: var(--ink-muted);
  font-size: 0.7rem;
  letter-spacing: 0.04em;
  padding: 0.25rem 0.6rem;
  border-radius: 3px;
  cursor: pointer;
}

.copy-btn:hover {
  color: var(--ink);
  filter: none;
  border-color: var(--ink-muted);
}

.copy-btn.copied {
  color: var(--bg-deep);
  background: var(--cyan);
  border-color: var(--cyan);
}

.copy-btn.copy-failed {
  color: var(--bg-deep);
  background: var(--amber);
  border-color: var(--amber);
}

.fastener-pitch-select {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.fastener-pitch-select label {
  font-family: var(--font-display);
  font-size: 0.7rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--paper-muted);
}

.fastener-pitch-select select {
  background: var(--bg-deep);
  border: 1px solid var(--line);
  border-radius: 3px;
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 0.9rem;
  padding: 0.45rem 0.6rem;
}

.fastener-callout-line {
  margin-bottom: 0.4rem;
}

.fastener-callout-line:last-child {
  margin-bottom: 0;
}

.fastener-group-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  margin-bottom: 0.5rem;
}

.fastener-group-head h4 {
  margin: 0;
}

.fastener-length-select {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  margin: 0.6rem 0;
}

.fastener-length-select label {
  font-family: var(--font-display);
  font-size: 0.7rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--paper-muted);
}

.fastener-length-select select {
  background: var(--bg-deep);
  border: 1px solid var(--line);
  border-radius: 3px;
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 0.85rem;
  padding: 0.4rem 0.55rem;
}

.fastener-fit-select {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.fastener-fit-select label {
  font-family: var(--font-display);
  font-size: 0.7rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--paper-muted);
}

.fastener-fit-select select {
  background: var(--bg-deep);
  border: 1px solid var(--line);
  border-radius: 3px;
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 0.85rem;
  padding: 0.4rem 0.55rem;
}

.fastener-legend {
  font-size: 0.8rem;
  color: var(--ink-muted);
  margin: 0 0 1.5rem;
}

.fastener-legend-row {
  display: flex;
  gap: 0.75rem;
  margin-bottom: 0.2rem;
}

.fastener-legend-row:last-child {
  margin-bottom: 0;
}

.fastener-legend-symbol {
  display: inline-block;
  width: 1.4rem;
  flex-shrink: 0;
  font-family: var(--font-display);
}

.fastener-legend-row .calc-flag {
  margin: 0;
}