/* PureFibe™ — site stylesheet
   Layout: left-aligned editorial pages on a cool white ground; the copper of the
   filter media is the only accent, used for the particle scale, buttons and marks. */

:root {
  --ink: #1c2230;
  --ink-2: #4a5262;
  --ink-3: #7a8290;
  --paper: #ffffff;
  --mist: #eef0f3;
  --mist-2: #e2e5ea;
  --line: #d5d9e0;
  --copper: #b5664b;
  --copper-deep: #8c4a34;
  --copper-tint: #f6e7e0;
  --copper-tint-2: #ebcbbd;
  --font-display: "Montserrat", "Helvetica Neue", Arial, sans-serif;
  --font-body: "Source Sans 3", "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --measure: 62ch;
  --gutter-l: max(16px, env(safe-area-inset-left, 0px));
  --gutter-r: max(16px, env(safe-area-inset-right, 0px));
  color-scheme: light;
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 1.125rem;
  line-height: 1.6;
  font-variant-numeric: tabular-nums;
}

img, svg { max-width: 100%; height: auto; display: block; }
a { color: var(--copper-deep); text-decoration-thickness: 1px; text-underline-offset: 3px; }
a:hover { color: var(--copper); }
:focus-visible { outline: 3px solid var(--copper); outline-offset: 3px; border-radius: 2px; }
[hidden] { display: none !important; }

h1, h2, h3, h4 {
  font-family: var(--font-display);
  color: var(--ink);
  line-height: 1.12;
  letter-spacing: -0.012em;
  text-wrap: balance;
  margin: 0;
}
h1 { font-size: clamp(2.1rem, 4.6vw, 3.4rem); font-weight: 700; overflow-wrap: anywhere; hyphens: auto; }
h2 { font-size: clamp(1.6rem, 2.8vw, 2.2rem); font-weight: 600; }
h3 { font-size: 1.25rem; font-weight: 600; letter-spacing: 0; }
p { margin: 0; max-width: var(--measure); }
p + p { margin-top: 1em; }
.lede { font-size: 1.3rem; line-height: 1.5; color: var(--ink-2); }
small, .small { font-size: 0.95rem; }
.muted { color: var(--ink-2); }
ul, ol { margin: 0; padding-left: 1.3em; max-width: var(--measure); }
li + li { margin-top: 0.5em; }
hr { border: 0; border-top: 1px solid var(--line); margin: 0; }

/* Page frame */
.wrap {
  width: 100%;
  max-width: 1160px;
  margin-inline: auto;
  padding-left: var(--gutter-l);
  padding-right: var(--gutter-r);
}
.band { padding-block: clamp(3.5rem, 7vw, 6rem); }
.band--mist { background: var(--mist); }
.band--tint { background: var(--copper-tint); }
.band--tight { padding-block: clamp(2.5rem, 5vw, 4rem); }
.stack > * + * { margin-top: 1.25rem; }
.stack-lg > * + * { margin-top: 2.5rem; }

/* Header */
.site-header {
  position: sticky;
  top: env(safe-area-inset-top, 0px);
  z-index: 20;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: saturate(140%) blur(8px);
  border-bottom: 1px solid var(--line);
}
body::before {
  content: "";
  position: fixed;
  inset: 0 0 auto;
  height: env(safe-area-inset-top, 0px);
  z-index: 30;
  background: var(--paper);
}
.site-header .wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
  min-height: 68px;
}
.wordmark {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.4rem;
  letter-spacing: -0.02em;
  color: var(--ink);
  text-decoration: none;
}
.wordmark:hover { color: var(--ink); }
.wordmark sup { font-size: 0.5em; font-weight: 600; letter-spacing: 0; margin-inline-start: 0.1em; color: var(--ink-3); }
.wordmark svg { width: 26px; height: 26px; flex: none; }
.wordmark { flex: none; }
.nav { display: flex; align-items: center; gap: 1.8rem; }
.nav a {
  font-family: var(--font-display);
  font-size: 0.92rem;
  font-weight: 600;
  color: var(--ink-2);
  text-decoration: none;
  padding-block: 0.4rem;
  border-bottom: 2px solid transparent;
}
.nav a:hover { color: var(--ink); }
.nav a[aria-current="page"] { color: var(--ink); border-bottom-color: var(--copper); }
.nav-toggle {
  display: none;
  appearance: none;
  border: 1px solid var(--line);
  background: var(--paper);
  color: var(--ink);
  border-radius: 6px;
  padding: 0.45rem 0.7rem;
  font: 600 0.9rem var(--font-display);
  cursor: pointer;
}
@media (max-width: 760px) {
  .nav-toggle { display: inline-block; }
  .nav {
    display: none;
    position: absolute;
    left: 0; right: 0; top: 100%;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    background: var(--paper);
    border-bottom: 1px solid var(--line);
    padding: 0.5rem var(--gutter-r) 0.75rem var(--gutter-l);
  }
  .nav.is-open { display: flex; }
  .nav a { padding: 0.8rem 0; border-bottom: 1px solid var(--mist-2); }
  .nav a[aria-current="page"] { border-bottom-color: var(--mist-2); color: var(--copper-deep); }
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 0.98rem;
  line-height: 1;
  padding: 0.95rem 1.4rem;
  border-radius: 6px;
  border: 1px solid var(--copper);
  background: var(--copper);
  color: #fff;
  text-decoration: none;
  cursor: pointer;
  transition: background-color 0.15s ease, border-color 0.15s ease;
}
.btn:hover { background: var(--copper-deep); border-color: var(--copper-deep); color: #fff; }
.btn--ghost { background: transparent; color: var(--ink); border-color: var(--line); }
.btn--ghost:hover { background: var(--mist); border-color: var(--ink-3); color: var(--ink); }
.actions { display: flex; flex-wrap: wrap; gap: 0.8rem; align-items: center; }

/* Hero */
.hero { padding-block: clamp(2.5rem, 6vw, 5rem) clamp(2.5rem, 5vw, 4rem); }
.hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
  gap: clamp(2rem, 5vw, 4.5rem);
  align-items: center;
}
.hero-copy { display: grid; gap: 1.5rem; }
.hero-figure { margin: 0; }
.hero-figure img { border-radius: 14px; background: var(--mist); }
@media (max-width: 820px) {
  .hero-grid { grid-template-columns: 1fr; }
  .hero-figure { order: -1; max-width: 520px; }
}

/* Fact row (datasheet-style) */
.facts {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  margin: 0;
}
.facts > div { padding-block: 1.4rem; padding-inline: 0 1.6rem; min-width: 0; }
.facts > div + div { border-inline-start: 1px solid var(--line); padding-inline-start: 1.6rem; }
.facts dt {
  font-family: var(--font-display);
  font-size: clamp(1.5rem, 2.6vw, 2rem);
  font-weight: 600;
  color: var(--copper-deep);
  letter-spacing: -0.01em;
  line-height: 1.1;
}
.facts dd { margin: 0.45rem 0 0; color: var(--ink-2); font-size: 1.02rem; line-height: 1.45; }
@media (max-width: 720px) {
  .facts { grid-template-columns: 1fr; }
  .facts > div { padding: 1.1rem 0; }
  .facts > div + div { border-inline-start: 0; border-top: 1px solid var(--line); padding-inline-start: 0; }
}

/* Two-column text/figure sections */
.split {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: clamp(2rem, 5vw, 4.5rem);
  align-items: center;
}
.split--text-first .split-figure { order: 2; }
.split-figure { margin: 0; }
.split-figure img { border-radius: 12px; }
.split-figure figcaption { margin-top: 0.7rem; color: var(--ink-3); font-size: 0.95rem; }
@media (max-width: 820px) {
  .split { grid-template-columns: 1fr; }
  .split--text-first .split-figure { order: 0; }
}

.section-head { display: grid; gap: 1rem; margin-bottom: clamp(2rem, 4vw, 3rem); }
.section-head p { max-width: var(--measure); }

/* Particle scale */
.scale-wrap { overflow-x: auto; -webkit-overflow-scrolling: touch; padding-bottom: 0.5rem; }
.scale { min-width: 760px; width: 100%; }
.scale text { font-family: var(--font-body); fill: var(--ink-2); font-size: 15px; }
.scale .tick { fill: var(--ink-3); font-size: 14px; }
.scale .axis { stroke: var(--ink-3); stroke-width: 1.5; }
.scale .tickline { stroke: var(--line); stroke-width: 1; }
.scale .mark { fill: var(--copper); }
.scale .mark-label { fill: var(--ink); font-weight: 600; }
.scale .band-focus { fill: var(--copper-tint-2); }
.scale .band-visible { fill: var(--mist-2); }
.scale .band-label { fill: var(--copper-deep); font-weight: 600; font-family: var(--font-display); font-size: 14px; }
.scale .band-label--grey { fill: var(--ink-2); }
.scale-notes {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.5rem 2.5rem;
  margin-top: 2rem;
  font-size: 1rem;
  color: var(--ink-2);
}
.scale-notes p { margin-top: 0; }
.scale-notes strong { color: var(--ink); font-weight: 600; }
.scale-hint { display: none; color: var(--ink-3); font-size: 0.9rem; margin-top: 0.4rem; }
@media (max-width: 800px) { .scale-hint { display: block; } }

/* Dust types */
.dust-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 2rem 2rem;
}
.dust-grid figure { margin: 0; display: grid; gap: 0.9rem; justify-items: start; }
.dust-grid img { width: min(100%, 200px); aspect-ratio: 1; border-radius: 50%; box-shadow: 0 10px 30px rgba(181, 102, 75, 0.18); }
.dust-grid figcaption { font-size: 1rem; color: var(--ink-2); max-width: 30ch; }
.dust-grid figcaption b { display: block; font-family: var(--font-display); font-weight: 600; color: var(--ink); font-size: 1.02rem; margin-bottom: 0.2rem; }
@media (max-width: 900px) { .dust-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
@media (max-width: 600px) {
  .dust-grid { grid-template-columns: 1fr; gap: 1.5rem; }
  .dust-grid figure { grid-template-columns: 110px 1fr; align-items: center; gap: 1.2rem; }
  .dust-grid img { width: 110px; }
}

/* Run-in labels in lists and captions */
.checklist b, .format figcaption b { display: block; margin-bottom: 0.2rem; }

/* Steps (real sequence: path of the air) */
.steps { list-style: none; padding: 0; margin: 0; max-width: var(--measure); counter-reset: step; display: grid; gap: 1.4rem; }
.steps li { position: relative; padding-inline-start: 3.4rem; counter-increment: step; }
.steps li::before {
  content: counter(step);
  position: absolute;
  inset-inline-start: 0; top: 0.05em;
  width: 2.3rem; height: 2.3rem;
  border-radius: 50%;
  background: var(--copper-tint);
  color: var(--copper-deep);
  font: 600 1rem var(--font-display);
  display: grid; place-items: center;
}
.steps b { font-family: var(--font-display); font-weight: 600; display: block; margin-bottom: 0.2rem; }

/* Product tiles (two filter formats) */
.formats { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 2rem; }
.format {
  display: grid;
  gap: 1rem;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 1.4rem;
}
.format img { border-radius: 10px; background: var(--mist); }
.format h3 { font-size: 1.25rem; }
.format dl { display: grid; grid-template-columns: minmax(0, auto) 1fr; text-align: start; gap: 0.35rem 1.2rem; margin: 0; font-size: 1rem; }
.format dt { color: var(--ink-3); }
.format dd { margin: 0; color: var(--ink); }
@media (max-width: 720px) { .formats { grid-template-columns: 1fr; } }

/* Spec table (datasheet convention) */
.spec { width: 100%; border-collapse: collapse; max-width: 820px; font-size: 1.02rem; table-layout: fixed; }
.spec th, .spec td { text-align: start; vertical-align: top; padding-block: 0.85rem; padding-inline: 0 1rem; border-bottom: 1px solid var(--line); overflow-wrap: anywhere; hyphens: auto; }
.spec th { width: 34%; font-family: var(--font-display); font-weight: 600; font-size: 0.95rem; color: var(--ink-2); }
.spec tr:first-child th, .spec tr:first-child td { border-top: 2px solid var(--ink); }
.spec-note { margin-top: 1rem; color: var(--ink-3); font-size: 0.95rem; max-width: 820px; }

/* Layer diagram */
.layers { width: 100%; max-width: 100%; }
.layers text { font-family: var(--font-body); font-size: 15px; fill: var(--ink-2); }
.layers .lbl { fill: var(--ink); font-weight: 600; }
.layers .mesh { fill: #d9dde3; stroke: #aab1bb; }
.layers .media { fill: var(--copper-tint-2); stroke: var(--copper); }
.layers .support { fill: #f1f2f4; stroke: #b9c0c9; }
.layers .flow { stroke: var(--copper-deep); stroke-width: 2; fill: none; }
.layers .flowhead { fill: var(--copper-deep); }

/* Pleat band (CTA) */
.pleat-band {
  background:
    repeating-linear-gradient(104deg, rgba(181, 102, 75, 0.10) 0 6px, transparent 6px 22px),
    var(--copper-tint);
}
.cta {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 1.5rem 3rem;
  align-items: center;
}
@media (max-width: 720px) { .cta { grid-template-columns: 1fr; } }

/* Article pages */
.article { max-width: 760px; }
.article h2 { margin-top: 3rem; margin-bottom: 1rem; font-size: 1.55rem; }
.article h2:first-of-type { margin-top: 0; }
.article p + p { margin-top: 1.1em; }
.article ul, .article ol { margin-block: 1rem; }
.article figure { margin: 2rem 0; }
.article figure img { border-radius: 12px; }
.article figcaption { margin-top: 0.6rem; font-size: 0.95rem; color: var(--ink-3); }
.sources { font-size: 0.98rem; color: var(--ink-2); }
.sources li { margin-top: 0.6em; }
.checklist { list-style: none; padding: 0; display: grid; gap: 1rem; }
.checklist li { position: relative; padding-inline-start: 2.2rem; }
.checklist li::before {
  content: "";
  position: absolute; inset-inline-start: 0; top: 0.3em;
  width: 1.25rem; height: 1.25rem;
  border-radius: 4px;
  border: 2px solid var(--copper);
  background: var(--copper-tint);
}
.checklist li::after {
  content: "";
  position: absolute; inset-inline-start: 0.43rem; top: 0.42em;
  width: 0.32rem; height: 0.62rem;
  border-right: 2.5px solid var(--copper-deep);
  border-bottom: 2.5px solid var(--copper-deep);
  transform: rotate(42deg);
}
.checklist b { font-family: var(--font-display); font-weight: 600; }

/* Form */
.form { display: grid; gap: 1.2rem; max-width: 640px; }
.form-row { display: grid; gap: 0.4rem; }
.form-row label { font-family: var(--font-display); font-weight: 600; font-size: 0.95rem; }
.form-row .hint { color: var(--ink-3); font-size: 0.9rem; }
.form input, .form select, .form textarea {
  width: 100%;
  font: inherit;
  color: var(--ink);
  background: var(--paper);
  border: 1px solid var(--ink-3);
  border-radius: 6px;
  padding: 0.75rem 0.9rem;
}
.form textarea { min-height: 150px; resize: vertical; }
.form input:focus, .form select:focus, .form textarea:focus { border-color: var(--copper); outline: 3px solid var(--copper-tint-2); outline-offset: 0; }
.form-two { display: grid; grid-template-columns: 1fr 1fr; gap: 1.2rem; }
@media (max-width: 560px) { .form-two { grid-template-columns: 1fr; } }
.notice { border-inline-start: 3px solid var(--copper); background: var(--copper-tint); padding: 0.9rem 1.1rem; border-radius: 8px; font-size: 1rem; }

/* Footer */
.site-footer { border-top: 1px solid var(--line); padding-block: 2.5rem 3rem; color: var(--ink-2); font-size: 0.98rem; }
.site-footer .wrap { display: grid; grid-template-columns: minmax(0, 1.2fr) minmax(0, 1fr); gap: 2rem 4rem; }
.site-footer nav { display: flex; flex-wrap: wrap; gap: 0.5rem 1.4rem; }
.site-footer nav a { color: var(--ink-2); text-decoration: none; font-family: var(--font-display); font-weight: 600; font-size: 0.9rem; }
.site-footer nav a:hover { color: var(--ink); }
.site-footer .legal { margin-top: 1.5rem; font-size: 0.9rem; color: var(--ink-3); max-width: 60ch; }
@media (max-width: 720px) { .site-footer .wrap { grid-template-columns: 1fr; } }

/* Header tools: language switcher + menu button */
.header-tools { display: flex; align-items: center; gap: 0.8rem; order: 3; }
.nav { order: 2; margin-inline-start: auto; margin-inline-end: 1.6rem; }
.lang { position: relative; }
.lang-btn {
  display: inline-flex; align-items: center; gap: 0.5rem;
  font: 600 0.9rem var(--font-display); color: var(--ink-2);
  background: var(--paper); border: 1px solid var(--line); border-radius: 6px;
  padding: 0.42rem 0.6rem; cursor: pointer; max-width: 12rem;
}
.lang-btn:hover { border-color: var(--ink-3); color: var(--ink); }
.lang-btn span { white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.lang-btn .chev { width: 10px; height: 6px; flex: none; color: var(--ink-3); }
.flag { width: 22px; height: 15px; border-radius: 2px; box-shadow: 0 0 0 1px rgba(28, 34, 48, 0.12); flex: none; }
.lang-menu {
  position: absolute; inset-inline-end: 0; top: calc(100% + 6px); z-index: 30;
  width: min(20rem, calc(100vw - 2 * 16px));
  background: var(--paper); border: 1px solid var(--line); border-radius: 10px;
  box-shadow: 0 16px 40px rgba(28, 34, 48, 0.14);
  padding: 0.6rem;
}
.lang-search {
  width: 100%; font: inherit; font-size: 0.95rem; color: var(--ink);
  border: 1px solid var(--ink-3); border-radius: 6px; padding: 0.55rem 0.7rem; margin-bottom: 0.5rem;
}
.lang-search:focus { border-color: var(--copper); outline: 3px solid var(--copper-tint-2); outline-offset: 0; }
.lang-list { list-style: none; margin: 0; padding: 0; max-width: none; max-height: min(22rem, 55vh); overflow-y: auto; }
.lang-list li + li { margin-top: 0; }
.lang-list a {
  display: flex; align-items: center; gap: 0.6rem;
  padding: 0.45rem 0.5rem; border-radius: 6px; text-decoration: none; color: var(--ink);
  font-size: 0.98rem;
}
.lang-list a:hover, .lang-list a:focus-visible { background: var(--mist); color: var(--ink); outline: none; }
.lang-list li[aria-selected="true"] a { background: var(--copper-tint); }
.lang-name { font-weight: 600; }
.lang-en { color: var(--ink-3); font-size: 0.85rem; margin-inline-start: auto; }
.lang-none { padding: 0.5rem; color: var(--ink-3); font-size: 0.95rem; }
.footer-langs { display: flex; flex-wrap: wrap; gap: 0.3rem 0.9rem; margin-top: 1.5rem; grid-column: 1 / -1; }
.footer-langs a { color: var(--ink-3); text-decoration: none; font-size: 0.85rem; }
.footer-langs a:hover, .footer-langs a[aria-current="true"] { color: var(--ink); }
@media (max-width: 760px) {
  .site-header .wrap { gap: 0.6rem; }
  .nav { margin: 0; }
  .header-tools { margin-inline-start: auto; gap: 0.5rem; }
  .lang-btn { max-width: 7.5rem; font-size: 0.85rem; padding: 0.4rem 0.5rem; }
  .lang-btn .flag, .flag { width: 18px; height: 12px; }
  .nav-toggle { padding: 0.4rem 0.55rem; }
  .lang { position: static; }
  .lang-menu { position: fixed; inset-inline: max(16px, env(safe-area-inset-left, 0px)) max(16px, env(safe-area-inset-right, 0px)); top: calc(env(safe-area-inset-top, 0px) + 74px); width: auto; }
}

@media (max-width: 380px) { .lang-btn span { display: none; } .lang-btn { gap: 0.35rem; } }

/* Right-to-left languages */
[dir="rtl"] .scale, [dir="rtl"] .layers { direction: ltr; }
[dir="rtl"] .scale-wrap { direction: ltr; }
[dir="rtl"] h1, [dir="rtl"] h2, [dir="rtl"] h3 { letter-spacing: 0; }
[dir="rtl"] .wordmark { direction: ltr; }
html[dir="rtl"] svg text, html[dir="rtl"] svg tspan { unicode-bidi: plaintext; }