:root {
  --f-bg: #f8fafc;
  --f-surface: #ffffff;
  --f-ink: #152139;
  --f-muted: #5d6b80;
  --f-accent: #0070f7;
  --f-accent-text: #0064dc;
  --f-deep: #06193a;
  --f-line: #dce4ed;
  --f-soft: #edf6ff;
  --f-section-muted: #f1f4f6;
  --f-backdrop: rgba(6, 25, 58, 0.24);
  --f-shadow: 0 24px 80px rgba(6, 25, 58, 0.12);
  --f-focus: rgba(0, 112, 247, 0.28);
  --f-font: "Helvetica Neue", "PingFang SC", "Microsoft YaHei", sans-serif;
  --f-nav-h: 72px;
  --f-z-nav: 30;
  --f-z-sticky: 5;
  --f-ease: cubic-bezier(0.22, 0.75, 0.25, 1);
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  overflow-x: clip;
  background: var(--f-surface);
  color: var(--f-ink);
  font-family: var(--f-font);
  letter-spacing: 0;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--f-nav-h) + 28px);
}

body {
  font-size: 16px;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
}

button,
a,
input {
  -webkit-tap-highlight-color: transparent;
}

button,
input {
  font: inherit;
}

button,
a {
  touch-action: manipulation;
}

button {
  color: inherit;
}

a {
  color: inherit;
  text-decoration: none;
}

button {
  cursor: pointer;
}

button:disabled {
  cursor: not-allowed;
  opacity: 0.45;
}

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

h1,
h2,
h3,
p,
figure {
  margin: 0;
}

h1,
h2,
h3 {
  min-width: 0;
  overflow-wrap: anywhere;
  font-weight: 400;
}

button:focus-visible,
a:focus-visible,
[tabindex="0"]:focus-visible {
  outline: 2px solid var(--f-accent-text);
  outline-offset: 5px;
}

[hidden] {
  display: none !important;
}

.f-container {
  width: min(1264px, calc(100% - 104px));
  margin-inline: auto;
  min-width: 0;
}

.f-icon {
  width: 20px;
  height: 20px;
  display: block;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.6;
  stroke-linecap: round;
  stroke-linejoin: round;
  flex: none;
}

.f-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
  min-height: 48px;
  padding: 11px 23px;
  border: 1px solid var(--f-accent-text);
  border-radius: 4px;
  background: var(--f-accent-text);
  color: var(--f-surface);
  font-size: 14px;
  font-weight: 500;
  line-height: 24px;
  white-space: nowrap;
  transition:
    background-color 200ms ease,
    border-color 200ms ease,
    transform 300ms var(--f-ease);
}

.f-button:hover {
  background: var(--f-deep);
  border-color: var(--f-deep);
}

.f-button:active {
  transform: translateY(1px);
}

.f-button .f-icon,
.f-text-link .f-icon {
  width: 17px;
  height: 17px;
  transition: transform 300ms var(--f-ease);
}

.f-button:hover .f-icon,
.f-text-link:hover .f-icon {
  transform: translateX(3px);
}

.f-text-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  min-height: 44px;
  padding: 8px 0;
  border: 0;
  border-radius: 0;
  background: transparent;
  color: var(--f-accent-text);
  font-size: 14px;
  font-weight: 500;
  line-height: 24px;
  white-space: nowrap;
}

.f-icon-button {
  position: relative;
  width: 44px;
  height: 44px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 0;
  border-radius: 4px;
  background: transparent;
  color: var(--f-ink);
  flex: none;
}

.f-icon-button:hover {
  background: var(--f-soft);
}

.f-icon-button:active {
  background: var(--f-line);
}

.f-tooltip {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  z-index: var(--f-z-nav);
  width: max-content;
  max-width: 180px;
  padding: 5px 9px;
  border-radius: 4px;
  background: var(--f-deep);
  color: var(--f-surface);
  font-size: 12px;
  font-weight: 400;
  line-height: 1.5;
  pointer-events: none;
  opacity: 0;
  transition: opacity 150ms ease;
}

.f-icon-button:hover .f-tooltip,
.f-icon-button:focus-visible .f-tooltip {
  opacity: 1;
}

.f-brand {
  position: relative;
  display: block;
  width: 150px;
  height: 51px;
  overflow: clip;
  flex: none;
}

.f-brand img {
  width: 187px;
  height: 187px;
  max-width: none;
  transform: translate(-22px, -65px);
}

.f-brand-small {
  width: 119px;
  height: 40px;
}

.f-brand-small img {
  width: 148px;
  height: 148px;
  transform: translate(-18px, -51px);
}

.f-skip {
  position: fixed;
  top: 8px;
  left: 12px;
  z-index: calc(var(--f-z-nav) + 1);
  padding: 8px 16px;
  border-radius: 4px;
  background: var(--f-surface);
  color: var(--f-accent-text);
  transform: translateY(-160%);
}

.f-skip:focus {
  transform: none;
}

.f-header-sentinel {
  position: absolute;
  inset: 0 auto auto 0;
  width: 1px;
  height: 1px;
  pointer-events: none;
}

.f-header {
  position: sticky;
  top: 0;
  z-index: var(--f-z-nav);
  height: var(--f-nav-h);
  background: var(--f-surface);
  border-bottom: 1px solid transparent;
  transition: border-color 200ms ease;
}

.f-header.is-scrolled {
  border-color: var(--f-line);
}

.f-header-inner {
  display: flex;
  align-items: center;
  gap: 28px;
  height: 100%;
}

.f-nav {
  display: flex;
  align-items: center;
  gap: 34px;
  margin-left: auto;
}

.f-nav a,
.f-login-link {
  position: relative;
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  font-size: 13px;
  font-weight: 500;
  white-space: nowrap;
}

.f-nav a::after {
  content: "";
  position: absolute;
  right: 0;
  bottom: 5px;
  left: 0;
  height: 1px;
  background: var(--f-accent-text);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 250ms var(--f-ease);
}

.f-nav a:hover::after,
.f-nav a[aria-current="true"]::after {
  transform: scaleX(1);
}

.f-header-actions {
  display: flex;
  align-items: center;
  gap: 18px;
  margin-left: 28px;
}

.f-login-link {
  padding-inline: 10px;
  color: var(--f-accent-text);
}

.f-tabs {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  border-bottom: 1px solid var(--f-line);
}

.f-tab {
  position: relative;
  min-width: 0;
  height: 66px;
  padding: 16px 12px;
  border: 0;
  background: transparent;
  color: var(--f-muted);
  font-size: 16px;
  font-weight: 400;
  line-height: 28px;
  white-space: nowrap;
}

.f-tab::after {
  content: "";
  position: absolute;
  right: 0;
  bottom: -1px;
  left: 0;
  height: 2px;
  background: var(--f-accent-text);
  transform: scaleX(0);
  transition: transform 300ms var(--f-ease);
}

.f-tab[aria-selected="true"] {
  color: var(--f-accent-text);
}

.f-tab[aria-selected="true"]::after {
  transform: scaleX(1);
}

.f-tab:hover {
  color: var(--f-ink);
}

.f-dialog {
  width: min(680px, calc(100% - 36px));
  max-height: min(80dvh, 820px);
  margin: auto;
  padding: 0;
  border: 1px solid var(--f-line);
  border-radius: 8px;
  background: var(--f-surface);
  color: var(--f-ink);
  box-shadow: var(--f-shadow);
}

.f-dialog::backdrop {
  background: var(--f-backdrop);
}

.f-dialog-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  padding: 20px 24px;
  border-bottom: 1px solid var(--f-line);
}

.f-dialog-header h2 {
  font-size: 20px;
  line-height: 1.5;
  font-weight: 500;
}

.f-dialog-body {
  padding: 30px 32px 36px;
  font-size: 14px;
  line-height: 1.9;
}

.f-dialog-body > p {
  color: var(--f-muted);
}

.f-dialog-body h3 {
  margin-top: 28px;
  margin-bottom: 12px;
  font-size: 15px;
  font-weight: 500;
}

.f-evidence-list {
  padding: 0;
  margin: 0;
  list-style: none;
}

.f-evidence-list li {
  padding: 16px 0;
  border-bottom: 1px solid var(--f-line);
}

.f-evidence-list strong {
  display: block;
  margin-bottom: 4px;
  font-size: 14px;
  font-weight: 500;
}

.f-evidence-list p {
  color: var(--f-muted);
}

.f-static-fallback {
  max-width: 800px;
  padding: 60px 28px;
  margin: auto;
}

.f-static-fallback h1 {
  font-size: 42px;
  margin-top: 42px;
  margin-bottom: 24px;
}

.f-static-fallback section {
  margin-top: 64px;
}

.f-static-fallback h2 {
  margin-bottom: 24px;
  font-size: 28px;
  line-height: 1.6;
}

.f-static-fallback article {
  margin-top: 32px;
}

.f-static-fallback h3 {
  margin-bottom: 12px;
  font-size: 19px;
}

.f-static-photo {
  width: 100%;
  height: auto;
  margin-top: 32px;
}

.f-static-fallback p + p {
  margin-top: 18px;
}

.f-static-fallback a {
  display: inline-block;
  margin-top: 28px;
  color: var(--f-accent-text);
}

@media (max-width: 800px) {
  :root {
    --f-nav-h: 64px;
  }

  .f-container {
    width: calc(100% - 48px);
  }

  .f-header-inner {
    gap: 12px;
  }

  .f-brand {
    width: 126px;
    height: 43px;
  }

  .f-brand img {
    width: 157px;
    height: 157px;
    transform: translate(-19px, -54px);
  }

  .f-nav {
    position: absolute;
    top: var(--f-nav-h);
    right: 0;
    left: 0;
    display: grid;
    gap: 8px;
    margin: 0;
    padding: 18px 24px 24px;
    border-bottom: 1px solid var(--f-line);
    background: var(--f-surface);
  }

  .f-nav a {
    width: fit-content;
    min-height: 44px;
    font-size: 15px;
  }

  .f-header-actions {
    margin-left: auto;
    gap: 6px;
  }

  .f-tab {
    height: 62px;
    padding-inline: 4px;
    font-size: 14px;
  }
}

@media (max-width: 360px) {
  .f-container {
    width: calc(100% - 40px);
  }

  .f-tab {
    font-size: 13px;
    padding-inline: 2px;
  }

  .f-dialog-header {
    padding: 16px;
  }

  .f-dialog-body {
    padding: 24px 20px;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* 2026-10-21 · B5 logo: the artwork is already cropped to the mark, so it simply fits the brand box */
.f-brand img,
.f-brand-small img {
  width: 100%;
  height: 100%;
  object-fit: contain;
  object-position: left center;
  transform: none;
}
@media (max-width: 720px) {
  br.bd { display: none; }
}
/* the work tabs rotate by themselves: a thin line under the open tab fills as its turn runs out */
.f-work-demo .f-tab { position: relative; }
.f-work-demo .f-tab::before {
  content: "";
  position: absolute;
  left: 14px;
  right: 14px;
  bottom: 3px;
  height: 2px;
  border-radius: 2px;
  background: currentColor;
  opacity: 0.45;
  transform-origin: left;
  transform: scaleX(var(--p, 0));
  pointer-events: none;
}
video[data-film]:not([controls]) { cursor: pointer; }

/* long heading lines break between phrases, never inside one */
.ph { display: inline-block; }