/* =========================================================================
   Reno Calculators — main stylesheet
   Modern "technical / engineering" theme. Mobile-first.
   No external dependencies: system UI + system monospace fonts only,
   blueprint patterns are pure CSS gradients (zero extra requests).
   ========================================================================= */

:root {
  /* Neutral ink/slate scale — cool, precise, engineering feel */
  --color-bg: #ffffff;
  --color-surface: #f4f7f6;
  --color-surface-2: #eaeff0;
  --color-border: #d6dedb;
  --color-border-strong: #b9c4c0;
  --color-text: #14201c;
  --color-muted: #56635e;

  /* Brand */
  --color-primary: #0f7a64;
  --color-primary-dark: #0a5746;
  --color-primary-tint: #e2f0ec;

  /* Technical accents (decorative grid lines, blueprint marks) */
  --color-ink: #0c1714;
  --color-grid: rgba(15, 122, 100, 0.07);
  --color-grid-strong: rgba(15, 122, 100, 0.16);

  --color-accent: #c2620a; /* warnings / decorative marks only */
  --color-error: #92400e; /* ≥4.5:1 on white */
  --color-focus: #0f7a64;

  --font-sans: system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial,
    "Apple Color Emoji", "Segoe UI Emoji", sans-serif;
  --font-mono: ui-monospace, "SF Mono", "Cascadia Code", "Cascadia Mono",
    "Segoe UI Mono", "Roboto Mono", "JetBrains Mono", Menlo, Consolas,
    "Liberation Mono", monospace;

  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 1rem;
  --space-4: 1.5rem;
  --space-5: 2.5rem;
  --space-6: 4rem;

  /* Tighter radii read as more "engineered" than soft/round */
  --radius: 8px;
  --radius-sm: 5px;
  --shadow-sm: 0 1px 2px rgba(12, 23, 20, 0.05);
  --shadow: 0 1px 2px rgba(12, 23, 20, 0.04), 0 6px 20px rgba(12, 23, 20, 0.07);
  --shadow-lg: 0 2px 4px rgba(12, 23, 20, 0.05), 0 14px 40px rgba(12, 23, 20, 0.12);
  --maxw: 72rem;
  --maxw-prose: 44rem;

  --ease: cubic-bezier(0.2, 0.6, 0.2, 1);
}

@media (prefers-color-scheme: dark) {
  :root {
    --color-bg: #0c1411;
    --color-surface: #121c18;
    --color-surface-2: #18241f;
    --color-border: #26332e;
    --color-border-strong: #36473f;
    --color-text: #e9efec;
    --color-muted: #9fafa8;

    --color-primary: #4fc4a6;
    --color-primary-dark: #6fd3ba;
    --color-primary-tint: #15271f;

    --color-ink: #050a08;
    --color-grid: rgba(79, 196, 166, 0.07);
    --color-grid-strong: rgba(79, 196, 166, 0.16);

    --color-accent: #e0922f;
    --color-error: #fbbf24;
    --color-focus: #4fc4a6;

    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.4);
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.4), 0 6px 22px rgba(0, 0, 0, 0.45);
    --shadow-lg: 0 2px 4px rgba(0, 0, 0, 0.5), 0 16px 44px rgba(0, 0, 0, 0.6);
  }
}

/* ---- Reset / base ------------------------------------------------------ */
*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  font-size: 100%;
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 1rem;
  line-height: 1.65;
  color: var(--color-text);
  background: var(--color-bg);
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

main {
  flex: 1 0 auto;
}

h1,
h2,
h3,
h4 {
  line-height: 1.18;
  margin: 0 0 var(--space-3);
  font-weight: 700;
  letter-spacing: -0.015em;
}

h1 {
  font-size: clamp(1.9rem, 1.2rem + 3vw, 3rem);
  letter-spacing: -0.025em;
}
h2 {
  font-size: clamp(1.4rem, 1.1rem + 1.3vw, 1.95rem);
  letter-spacing: -0.02em;
}
h3 {
  font-size: 1.2rem;
}

p {
  margin: 0 0 var(--space-3);
}

a {
  color: var(--color-primary);
  text-decoration-thickness: 1px;
  text-underline-offset: 2px;
  transition: color 0.15s var(--ease);
}
a:hover {
  color: var(--color-primary-dark);
}

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

:focus-visible {
  outline: 3px solid var(--color-focus);
  outline-offset: 2px;
  border-radius: 2px;
}

/* Tabular figures everywhere numbers carry meaning */
input,
.result-main,
.example-steps,
.formula-block,
.result-formula,
.field-unit {
  font-variant-numeric: tabular-nums;
}

/* ---- Utilities --------------------------------------------------------- */
.container {
  width: 100%;
  max-width: var(--maxw);
  margin-inline: auto;
  padding-inline: var(--space-4);
}

.prose {
  max-width: var(--maxw-prose);
}
.prose ul,
.prose ol {
  padding-left: 1.25rem;
}
.prose li {
  margin-bottom: var(--space-2);
}

.lead {
  font-size: clamp(1.05rem, 1rem + 0.4vw, 1.2rem);
  color: var(--color-muted);
  line-height: 1.55;
}

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

.skip-link {
  position: absolute;
  left: var(--space-3);
  top: -3rem;
  background: var(--color-primary);
  color: #fff;
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-sm);
  z-index: 100;
  transition: top 0.15s var(--ease);
}
.skip-link:focus {
  top: var(--space-2);
}

/* "Eyebrow" technical label — monospace, uppercase, with a leading tick. */
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--color-primary-dark);
  margin: 0 0 var(--space-3);
}
.eyebrow::before {
  content: "";
  width: 1.6rem;
  height: 2px;
  background: var(--color-primary);
}

/* ---- Buttons ----------------------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  font: inherit;
  font-weight: 600;
  letter-spacing: -0.01em;
  text-decoration: none;
  cursor: pointer;
  padding: 0.7rem 1.4rem;
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  text-align: center;
  transition: background 0.15s var(--ease), color 0.15s var(--ease),
    border-color 0.15s var(--ease), box-shadow 0.15s var(--ease),
    transform 0.1s var(--ease);
}
.btn:active {
  transform: translateY(1px);
}
.btn-primary {
  background: var(--color-primary);
  color: #fff;
  box-shadow: var(--shadow-sm), inset 0 1px 0 rgba(255, 255, 255, 0.15);
}
.btn-primary:hover {
  background: var(--color-primary-dark);
  color: #fff;
  box-shadow: var(--shadow);
}
.btn-ghost {
  background: var(--color-bg);
  color: var(--color-primary-dark);
  border-color: var(--color-border-strong);
}
.btn-ghost:hover {
  border-color: var(--color-primary);
  color: var(--color-primary-dark);
  background: var(--color-primary-tint);
}
@media (prefers-color-scheme: dark) {
  .btn-primary {
    color: #04110d;
  }
}

/* ---- Header ------------------------------------------------------------ */
.site-header {
  border-bottom: 1px solid var(--color-border);
  background: color-mix(in srgb, var(--color-bg) 82%, transparent);
  -webkit-backdrop-filter: saturate(1.4) blur(10px);
  backdrop-filter: saturate(1.4) blur(10px);
  position: sticky;
  top: 0;
  z-index: 50;
}
.header-inner {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  min-height: 4rem;
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  font-weight: 700;
  font-size: 1.1rem;
  letter-spacing: -0.02em;
  text-decoration: none;
  color: var(--color-text);
  white-space: nowrap;
}
.header-end {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  margin-left: auto;
}
.brand-mark {
  display: grid;
  place-items: center;
  width: 2.1rem;
  height: 2.1rem;
  border-radius: var(--radius-sm);
  background: linear-gradient(150deg, var(--color-primary), var(--color-primary-dark));
  color: #fff;
  font-weight: 800;
  box-shadow: var(--shadow-sm), inset 0 1px 0 rgba(255, 255, 255, 0.25);
}
@media (prefers-color-scheme: dark) {
  .brand-mark {
    color: #04110d;
  }
}
.nav-toggle {
  display: inline-flex;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 2.75rem;
  height: 2.75rem;
  padding: 0;
  background: var(--color-bg);
  border: 1px solid var(--color-border-strong);
  border-radius: var(--radius-sm);
  cursor: pointer;
}
.nav-toggle-bar,
.nav-toggle-bar::before,
.nav-toggle-bar::after {
  content: "";
  display: block;
  width: 1.25rem;
  height: 2px;
  margin-inline: auto;
  background: var(--color-text);
  position: relative;
  border-radius: 2px;
}
.nav-toggle-bar::before {
  position: absolute;
  top: -6px;
}
.nav-toggle-bar::after {
  position: absolute;
  top: 6px;
}
.primary-nav {
  display: none;
}
.primary-nav.is-open {
  display: block;
  position: absolute;
  left: 0;
  right: 0;
  top: 100%;
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  box-shadow: var(--shadow);
}
.primary-nav > ul {
  list-style: none;
  margin: 0;
  padding: var(--space-2) var(--space-3);
  display: flex;
  flex-direction: column;
}
.primary-nav > ul li a {
  display: block;
  padding: var(--space-2) 0;
  color: var(--color-text);
  text-decoration: none;
  font-weight: 600;
}
.primary-nav > ul li a[aria-current="page"] {
  color: var(--color-primary);
}

/* Header calculator search */
.nav-search {
  position: relative;
  margin: 0 var(--space-3) var(--space-3);
}
.nav-search-input {
  font: inherit;
  width: 100%;
  min-height: 44px;
  padding: 0.5rem 0.85rem 0.5rem 2.2rem;
  border: 1px solid var(--color-border-strong);
  border-radius: var(--radius-sm);
  background: var(--color-surface)
    url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 24 24' fill='none' stroke='%2356635e' stroke-width='2' stroke-linecap='round'%3E%3Ccircle cx='11' cy='11' r='7'/%3E%3Cpath d='m21 21-4.3-4.3'/%3E%3C/svg%3E")
    no-repeat 0.7rem center;
  color: var(--color-text);
  transition: border-color 0.15s var(--ease), box-shadow 0.15s var(--ease);
}
.nav-search-input:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px var(--color-primary-tint);
  outline: none;
}
.nav-search-results {
  list-style: none;
  margin: 0;
  padding: var(--space-1);
  position: absolute;
  left: 0;
  right: 0;
  top: calc(100% + 4px);
  z-index: 60;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-lg);
  max-height: 60vh;
  overflow: auto;
}
.nav-search-results li a {
  display: block;
  padding: 0.5rem 0.6rem;
  border-radius: var(--radius-sm);
  color: var(--color-text);
  text-decoration: none;
  font-weight: 600;
  font-size: 0.95rem;
}
.nav-search-results li a:hover,
.nav-search-results li.is-active a {
  background: var(--color-primary-tint);
  color: var(--color-primary-dark);
}
.nav-search-results li a strong {
  color: var(--color-primary-dark);
  font-weight: 800;
}
.nav-search-results .no-result {
  padding: 0.5rem 0.6rem;
  color: var(--color-muted);
  font-size: 0.9rem;
}

/* Language switcher */
.lang-switcher {
  position: relative;
}
.lang-switcher > summary {
  list-style: none;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  min-height: 44px;
  padding: 0.35rem 0.65rem;
  border: 1px solid var(--color-border-strong);
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: 0.9rem;
  color: var(--color-text);
  transition: border-color 0.15s var(--ease);
}
.lang-switcher > summary::-webkit-details-marker {
  display: none;
}
.lang-switcher > summary:hover,
.lang-switcher[open] > summary {
  border-color: var(--color-primary);
}
.lang-globe {
  flex: none;
  color: var(--color-muted);
}
.lang-menu {
  position: absolute;
  right: 0;
  top: calc(100% + 6px);
  z-index: 60;
  min-width: 220px;
  list-style: none;
  margin: 0;
  padding: var(--space-1);
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-lg);
  max-height: 70vh;
  overflow: auto;
}
.lang-menu li a {
  display: block;
  padding: 0.5rem 0.6rem;
  border-radius: var(--radius-sm);
  color: var(--color-text);
  text-decoration: none;
  font-weight: 600;
  font-size: 0.92rem;
}
.lang-menu li a:hover {
  background: var(--color-primary-tint);
  color: var(--color-primary-dark);
}
.lang-menu li a.is-current {
  color: var(--color-primary);
}

@media (min-width: 48rem) {
  .nav-toggle {
    display: none;
  }
  .primary-nav,
  .primary-nav.is-open {
    display: flex;
    align-items: center;
    gap: var(--space-4);
    position: static;
    border: 0;
    box-shadow: none;
    flex: 1;
    background: transparent;
  }
  .primary-nav > ul {
    flex-direction: row;
    gap: var(--space-4);
    padding: 0;
  }
  .primary-nav > ul li a {
    padding: 0;
    position: relative;
  }
  /* Underline grows from the left on hover — subtle technical cue */
  .primary-nav > ul li a::after {
    content: "";
    position: absolute;
    left: 0;
    bottom: -0.4rem;
    height: 2px;
    width: 100%;
    background: var(--color-primary);
    transform: scaleX(0);
    transform-origin: left;
    transition: transform 0.18s var(--ease);
  }
  .primary-nav > ul li a:hover::after,
  .primary-nav > ul li a[aria-current="page"]::after {
    transform: scaleX(1);
  }
  .nav-search {
    margin: 0 0 0 auto;
    width: 260px;
  }
}

/* ---- Footer ------------------------------------------------------------ */
.site-footer {
  margin-top: var(--space-6);
  background: var(--color-surface);
  border-top: 1px solid var(--color-border);
  /* thin technical accent rule on top of the footer */
  box-shadow: inset 0 2px 0 var(--color-primary);
  padding-block: var(--space-5) var(--space-4);
  font-size: 0.95rem;
}
.footer-inner {
  display: grid;
  gap: var(--space-4);
}
.footer-name {
  font-weight: 700;
  letter-spacing: -0.01em;
  margin-bottom: var(--space-1);
}
.footer-tagline {
  color: var(--color-muted);
  margin: 0;
}
.footer-nav ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3) var(--space-4);
}
.footer-nav a {
  color: var(--color-text);
  text-decoration: none;
}
.footer-nav a:hover {
  color: var(--color-primary-dark);
  text-decoration: underline;
}
.footer-legal {
  margin-top: var(--space-4);
  padding-top: var(--space-3);
  border-top: 1px dashed var(--color-border);
  color: var(--color-muted);
  font-size: 0.85rem;
}
@media (min-width: 48rem) {
  .footer-inner {
    grid-template-columns: 1fr auto;
    align-items: center;
  }
}

/* ---- Hero / sections --------------------------------------------------- */
/* Blueprint-grid hero: layered CSS gradients only, no images. */
.hero {
  position: relative;
  isolation: isolate;
  padding-block: clamp(var(--space-5), 6vw, var(--space-6));
  border-bottom: 1px solid var(--color-border);
  background:
    radial-gradient(120% 80% at 85% -10%, var(--color-primary-tint), transparent 60%),
    var(--color-bg);
  overflow: hidden;
}
.hero::before {
  /* fine + coarse grid lines = engineering drawing paper */
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  background-image:
    linear-gradient(var(--color-grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--color-grid) 1px, transparent 1px),
    linear-gradient(var(--color-grid-strong) 1px, transparent 1px),
    linear-gradient(90deg, var(--color-grid-strong) 1px, transparent 1px);
  background-size: 28px 28px, 28px 28px, 140px 140px, 140px 140px;
  -webkit-mask-image: linear-gradient(180deg, #000 0%, transparent 92%);
  mask-image: linear-gradient(180deg, #000 0%, transparent 92%);
}
.hero h1 {
  max-width: 20ch;
}
.hero .lead {
  max-width: 56ch;
}
.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
  margin-top: var(--space-4);
}

.section {
  padding-block: clamp(var(--space-5), 5vw, var(--space-6));
}
.section-intro {
  max-width: var(--maxw-prose);
  margin-bottom: var(--space-5);
}

/* ---- Cards ------------------------------------------------------------- */
.card-grid {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: var(--space-3);
  grid-template-columns: 1fr;
}
@media (min-width: 36rem) {
  .card-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}
@media (min-width: 60rem) {
  .card-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}
.card {
  position: relative;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-bg);
  box-shadow: var(--shadow-sm);
  transition: transform 0.18s var(--ease), border-color 0.18s var(--ease),
    box-shadow 0.18s var(--ease);
  overflow: hidden;
}
/* Accent rail that wipes in along the top edge on hover */
.card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-primary-dark));
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.22s var(--ease);
}
.card:hover {
  transform: translateY(-3px);
  border-color: var(--color-border-strong);
  box-shadow: var(--shadow-lg);
}
.card:hover::before,
.card:focus-within::before {
  transform: scaleX(1);
}
.card-link {
  /* icon + title share row 1; description spans the full width on row 2 */
  display: grid;
  grid-template-columns: auto 1fr;
  align-items: center;
  align-content: start;
  column-gap: var(--space-3);
  padding: var(--space-4);
  text-decoration: none;
  color: inherit;
  height: 100%;
}
/* Group icon badge on each card (replaces the old numeric counter) */
.card-icon {
  display: inline-grid;
  place-items: center;
  width: 2.75rem;
  height: 2.75rem;
  border-radius: var(--radius-sm);
  background: var(--color-primary-tint);
  color: var(--color-primary-dark);
  border: 1px solid var(--color-border);
  transition: background 0.18s var(--ease), color 0.18s var(--ease),
    border-color 0.18s var(--ease);
}
.card-icon svg {
  width: 1.55rem;
  height: 1.55rem;
}
.card:hover .card-icon,
.card:focus-within .card-icon {
  background: var(--color-primary);
  color: #fff;
  border-color: var(--color-primary);
}
@media (prefers-color-scheme: dark) {
  .card:hover .card-icon,
  .card:focus-within .card-icon {
    color: #04110d;
  }
}
.card-title {
  margin: 0;
  color: var(--color-text);
  font-size: 1.12rem;
}
.card:hover .card-title {
  color: var(--color-primary-dark);
}
.card-text {
  grid-column: 1 / -1;
  margin: var(--space-3) 0 0;
  color: var(--color-muted);
  font-size: 0.95rem;
}

/* ---- Calculator group sections ---------------------------------------- */
.calc-group {
  margin-bottom: var(--space-5);
}
.calc-group-head {
  margin-bottom: var(--space-4);
  padding-bottom: var(--space-2);
  border-bottom: 1px solid var(--color-border);
}
.calc-group-head h2 {
  margin-bottom: var(--space-1);
}
.calc-group-head p {
  color: var(--color-muted);
  margin: 0;
}

/* ---- Breadcrumb -------------------------------------------------------- */
.breadcrumb {
  padding-top: var(--space-4);
  font-size: 0.85rem;
  font-family: var(--font-mono);
}
.breadcrumb ol {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  margin: 0;
  padding: 0;
}
.breadcrumb a {
  text-decoration: none;
}
.breadcrumb a:hover {
  text-decoration: underline;
}
.breadcrumb li:not(:last-child)::after {
  content: "/";
  margin-left: var(--space-2);
  color: var(--color-border-strong);
}
.breadcrumb [aria-current="page"] {
  color: var(--color-muted);
}

/* ---- Page header ------------------------------------------------------- */
.page-header {
  padding-block: var(--space-4) var(--space-3);
}

/* ---- Calculator tool --------------------------------------------------- */
.calculator-tool {
  margin-top: var(--space-3);
}
/* The form reads like an instrument panel: surface card with a header rule */
.calc-form {
  display: grid;
  gap: var(--space-4);
  padding: var(--space-4);
  border: 1px solid var(--color-border-strong);
  border-radius: var(--radius);
  background: var(--color-surface);
  box-shadow: var(--shadow-sm);
}
@media (min-width: 40rem) {
  .calc-form {
    padding: var(--space-5);
  }
}
.field-grid {
  display: grid;
  gap: var(--space-4) var(--space-3);
}
@media (min-width: 40rem) {
  .field-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* Unit system toggle — segmented control look */
.unit-toggle {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-2) var(--space-3);
  margin: 0;
  padding: var(--space-2) var(--space-3);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-bg);
}
.unit-toggle legend {
  float: left;
  padding: 0;
  margin-right: var(--space-2);
  font-weight: 600;
  font-size: 0.82rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-muted);
}
.unit-toggle .radio {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-weight: 600;
  cursor: pointer;
}
.unit-toggle .radio input {
  accent-color: var(--color-primary);
}

.field {
  display: grid;
  gap: var(--space-1);
  align-content: start;
}
.field label {
  font-weight: 600;
  font-size: 0.95rem;
}
.field-unit {
  font-weight: 500;
  font-family: var(--font-mono);
  font-size: 0.82rem;
  color: var(--color-muted);
}
.field input,
.field select {
  font: inherit;
  padding: 0.6rem 0.7rem;
  border: 1px solid var(--color-border-strong);
  border-radius: var(--radius-sm);
  background: var(--color-bg);
  color: var(--color-text);
  width: 100%;
  transition: border-color 0.15s var(--ease), box-shadow 0.15s var(--ease);
}
.field input:focus,
.field select:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px var(--color-primary-tint);
  outline: none;
}
.field input[aria-invalid="true"] {
  border-color: var(--color-accent);
  background: rgba(194, 98, 10, 0.06);
}
.field input[aria-invalid="true"]:focus {
  box-shadow: 0 0 0 3px rgba(194, 98, 10, 0.18);
}
.field-help {
  margin: 0;
  font-size: 0.85rem;
  color: var(--color-muted);
}
.field-error {
  margin: 0;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--color-error);
}
.form-actions {
  display: flex;
  gap: var(--space-3);
  flex-wrap: wrap;
  align-items: center;
}

/* Structured result output — a "readout" panel */
.calc-output {
  display: block;
  position: relative;
  margin-top: var(--space-4);
  padding: var(--space-4);
  border: 1px solid var(--color-primary);
  border-left-width: 4px;
  border-radius: var(--radius);
  background:
    radial-gradient(120% 100% at 100% 0%, var(--color-primary-tint), transparent 70%),
    var(--color-bg);
  box-shadow: var(--shadow);
  scroll-margin-top: 5rem;
}
@media (min-width: 40rem) {
  .calc-output {
    padding: var(--space-5);
  }
}
.result-save {
  margin-top: var(--space-3);
}
.result-main {
  font-size: clamp(1.4rem, 1.1rem + 1.4vw, 1.9rem);
  font-weight: 800;
  line-height: 1.2;
  letter-spacing: -0.02em;
  color: var(--color-primary-dark);
  margin-bottom: var(--space-3);
}
.result-warning {
  margin: 0 0 var(--space-3);
  padding: var(--space-2) var(--space-3);
  border-left: 4px solid var(--color-accent);
  background: rgba(194, 98, 10, 0.08);
  border-radius: var(--radius-sm);
  font-size: 0.95rem;
}
.result-block {
  margin-top: var(--space-4);
}
.result-block h3 {
  font-family: var(--font-mono);
  font-size: 0.74rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--color-muted);
  margin-bottom: var(--space-2);
}
.result-block ul {
  margin: 0;
  padding-left: 1.1rem;
}
.result-block li {
  margin-bottom: var(--space-1);
}
.result-formula {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 0.92rem;
  line-height: 1.6;
}
.result-suggestion {
  padding: var(--space-3);
  border-radius: var(--radius-sm);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
}
.result-suggestion p {
  margin: 0;
}
.result-disclaimer {
  margin: var(--space-4) 0 0;
  padding-top: var(--space-3);
  border-top: 1px dashed var(--color-border);
  font-size: 0.85rem;
  color: var(--color-muted);
}
.calc-error {
  margin-top: var(--space-3);
  padding: var(--space-3);
  border: 1px solid var(--color-accent);
  border-left-width: 4px;
  border-radius: var(--radius-sm);
  background: rgba(194, 98, 10, 0.08);
  color: var(--color-error);
  font-weight: 500;
}

.calculator-content {
  margin-top: var(--space-5);
}

.disclaimer {
  font-size: 0.9rem;
  color: var(--color-muted);
}

/* ---- FAQ --------------------------------------------------------------- */
.faq {
  margin-top: var(--space-5);
}
.faq-item {
  border-bottom: 1px solid var(--color-border);
  padding: var(--space-2) 0;
}
.faq-item summary {
  cursor: pointer;
  font-weight: 600;
  padding: var(--space-2) 0;
  list-style: none;
  display: flex;
  align-items: flex-start;
  gap: 0.6rem;
}
.faq-item summary::-webkit-details-marker {
  display: none;
}
/* Custom +/− marker so the disclosure reads as a control */
.faq-item summary::before {
  content: "+";
  font-family: var(--font-mono);
  font-weight: 700;
  color: var(--color-primary);
  line-height: 1.4;
  flex: none;
  transition: transform 0.18s var(--ease);
}
.faq-item[open] summary::before {
  content: "\2212"; /* minus */
}
.faq-item p {
  margin: var(--space-2) 0 var(--space-2);
  padding-left: 1.2rem;
  color: var(--color-muted);
}

/* ---- Related ----------------------------------------------------------- */
.related {
  margin-top: var(--space-5);
}

/* ---- Calculator supporting content ------------------------------------- */
.tool-trust {
  margin: var(--space-3) 0 0;
  font-size: 0.85rem;
  color: var(--color-muted);
  display: flex;
  align-items: baseline;
  gap: 0.45rem;
}
.tool-trust::before {
  content: "//";
  font-family: var(--font-mono);
  color: var(--color-primary);
  font-weight: 700;
}
.calculator-content > section {
  margin-top: var(--space-5);
}
.calculator-content > section:first-child {
  margin-top: var(--space-4);
}
.calculator-content h2 {
  font-size: 1.35rem;
}
.steps {
  margin: 0;
  padding-left: 1.25rem;
}
.steps li {
  margin-bottom: var(--space-2);
}
.formula-block {
  margin: 0;
  padding: var(--space-3) var(--space-4);
  border: 1px solid var(--color-border);
  border-left: 4px solid var(--color-primary);
  background: var(--color-surface);
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: 0.92rem;
  line-height: 1.6;
  overflow-x: auto;
}
.example-box {
  padding: var(--space-4);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-surface);
}
.example-box > p:first-child {
  margin-top: 0;
}
.example-steps {
  margin: var(--space-2) 0;
  padding-left: 1.1rem;
  font-family: var(--font-mono);
  font-size: 0.9rem;
}
.example-steps li {
  margin-bottom: var(--space-1);
}
.example-result {
  margin: var(--space-3) 0 0;
  padding-top: var(--space-3);
  border-top: 1px dashed var(--color-border-strong);
}
.tick-list,
.cross-list {
  list-style: none;
  margin: 0;
  padding: 0;
}
.tick-list li,
.cross-list li {
  position: relative;
  padding-left: 1.85rem;
  margin-bottom: var(--space-2);
}
.tick-list li::before {
  content: "✓";
  position: absolute;
  left: 0;
  top: 0.05em;
  font-weight: 700;
  color: var(--color-primary);
}
.cross-list li::before {
  content: "✕";
  position: absolute;
  left: 0;
  top: 0.05em;
  font-weight: 700;
  color: var(--color-error);
}
.last-updated {
  margin-top: var(--space-5);
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--color-muted);
}

/* ---- Category filter (/calculators/) ----------------------------------- */
.calc-filter {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-2) var(--space-3);
  margin-top: var(--space-4);
}
.calc-filter-label {
  font-weight: 600;
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-muted);
}
.calc-filter-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
}
.filter-btn {
  font: inherit;
  font-size: 0.9rem;
  font-weight: 600;
  min-height: 40px;
  padding: 0.4rem 0.95rem;
  border: 1px solid var(--color-border-strong);
  border-radius: 999px;
  background: var(--color-bg);
  color: var(--color-text);
  cursor: pointer;
  transition: border-color 0.15s var(--ease), background 0.15s var(--ease),
    color 0.15s var(--ease);
}
.filter-btn:hover {
  border-color: var(--color-primary);
  color: var(--color-primary-dark);
}
.filter-btn.is-active {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: #fff;
  box-shadow: var(--shadow-sm);
}
@media (prefers-color-scheme: dark) {
  .filter-btn.is-active {
    color: #04110d;
  }
}

/* ---- Touch targets ----------------------------------------------------- */
.field input,
.field select {
  min-height: 44px;
}

/* ---- Motion ------------------------------------------------------------ */
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.001ms !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
}