/* Shared chrome for BF Labs Skills prototypes.
   Tokens and components come from github.com/Sunnyender-org/bflabs-ui.
   Layout chrome follows bflabs.cn header / language / orbit / footer. */

@import url("https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600&family=Noto+Sans+SC:wght@400;500;600&family=Space+Grotesk:wght@400;500;600;700&display=swap");

html,
body {
  margin: 0;
  min-height: 100%;
  background: var(--bf-background);
}

.sk-header {
  position: sticky;
  z-index: 40;
  top: 0;
  height: 5.5rem;
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  padding: 0 clamp(1.5rem, 3.2vw, 3.5rem);
  background: color-mix(in srgb, var(--bf-background) 90%, transparent);
  backdrop-filter: blur(18px);
}

.sk-header .bf-brand-mark {
  width: 2.875rem;
}

.sk-header .bf-brand-lockup__name {
  letter-spacing: 0.17em;
}

.sk-nav {
  display: flex;
  gap: clamp(1.5rem, 2.6vw, 2.75rem);
  font-family: var(--bf-font-display);
  font-size: 0.875rem;
  font-weight: 500;
}

.sk-nav a {
  position: relative;
  padding-block: 0.5rem;
  color: var(--bf-foreground);
  transition:
    color var(--bf-duration-fast) var(--bf-ease-standard),
    opacity var(--bf-duration-fast) var(--bf-ease-standard),
    transform var(--bf-duration-fast) var(--bf-ease-forward);
}

.sk-nav:hover a {
  color: var(--bf-foreground-muted);
  opacity: 0.4;
}

.sk-nav a:hover,
.sk-nav a:focus-visible,
.sk-nav a[aria-current="page"] {
  color: var(--bf-color-orange);
  opacity: 1;
  transform: translateY(-2px);
}

.sk-nav a::after {
  content: "";
  position: absolute;
  inset: auto 0 2px;
  height: 1px;
  background: var(--bf-color-orange);
  transform: scaleX(0);
  transform-origin: 100%;
  transition: transform var(--bf-duration-fast) var(--bf-ease-standard);
}

.sk-nav a:hover::after,
.sk-nav a[aria-current="page"]::after {
  transform: scaleX(1);
  transform-origin: 0;
}

.sk-tools {
  justify-self: end;
  display: flex;
  align-items: center;
  gap: 1.25rem;
}

.sk-lang {
  display: inline-flex;
  align-items: center;
  min-height: 2.5rem;
  color: var(--bf-foreground-muted);
  font-family: var(--bf-font-display);
  font-size: 0.6875rem;
  font-weight: 600;
  letter-spacing: 0.12em;
}

.sk-lang button {
  min-width: 2.5rem;
  min-height: 2.5rem;
  padding: 0 0.5rem;
  border: 0;
  background: transparent;
  color: inherit;
  cursor: pointer;
  transition:
    color var(--bf-duration-fast) var(--bf-ease-standard),
    background-color var(--bf-duration-fast) var(--bf-ease-standard),
    transform 160ms var(--bf-ease-forward);
}

.sk-lang button:hover,
.sk-lang button[aria-pressed="true"] {
  background: var(--bf-color-charcoal);
  color: var(--bf-color-warm-white);
}

.sk-lang button:active {
  transform: scale(0.96);
}

.sk-lang span {
  color: var(--bf-foreground-subtle);
}

.sk-exit {
  color: var(--bf-foreground-muted);
  font-family: var(--bf-font-display);
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: 0.06em;
  transition:
    color var(--bf-duration-fast) var(--bf-ease-standard),
    transform var(--bf-duration-fast) var(--bf-ease-forward);
}

.sk-exit:hover,
.sk-exit:focus-visible {
  color: var(--bf-color-orange);
  transform: translateY(-2px);
}

.sk-host {
  color: var(--bf-foreground-subtle);
  font-family: var(--bf-font-display);
  font-size: 0.625rem;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: lowercase;
}

.sk-orbit {
  --geometry-opacity: 0.14;
  position: fixed;
  top: 52%;
  right: clamp(-26rem, -19vw, -11rem);
  z-index: 0;
  width: clamp(51rem, 74vw, 82rem);
  color: var(--bf-color-charcoal);
  opacity: var(--geometry-opacity);
  pointer-events: none;
  transform: translate3d(0, calc(-50% + 0px), 0) rotate(-7deg);
}

.sk-orbit svg {
  width: 100%;
  height: auto;
  overflow: visible;
}

.sk-orbit__shell {
  transform-origin: 50% 50%;
  animation: 18s ease-in-out infinite sk-orbit-breathe;
}

.sk-orbit__ring {
  fill: none;
  stroke: currentColor;
  stroke-width: 1.2px;
  opacity: var(--ring-opacity, 0.55);
  vector-effect: non-scaling-stroke;
  animation: sk-orbit-travel var(--ring-duration, 28s) linear var(--ring-delay, 0s) infinite;
}

.sk-orbit__ring.is-accent {
  stroke: var(--bf-color-orange);
  opacity: 0.7;
}

.sk-footer {
  position: relative;
  z-index: 1;
  background: var(--bf-color-charcoal);
  color: var(--bf-color-warm-white);
}

.sk-footer__contact {
  display: grid;
  grid-template-columns: minmax(0, 1.15fr) minmax(20rem, 0.85fr);
  gap: clamp(3rem, 8vw, 8rem);
  align-items: end;
  padding: clamp(5rem, 9vw, 8rem) clamp(1.5rem, 3.2vw, 3.5rem);
  border-bottom: 1px solid color-mix(in srgb, var(--bf-color-warm-white) 16%, transparent);
}

.sk-footer__contact h2 {
  margin: 0;
  max-width: 18ch;
  font-family: var(--bf-font-display);
  font-size: clamp(2.75rem, 5.4vw, 5.75rem);
  font-weight: 500;
  letter-spacing: -0.06em;
  line-height: 0.96;
}

.sk-footer__mail {
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: center;
  gap: 0.75rem 1.5rem;
  min-height: 7rem;
  padding: 1.5rem 0;
  border-top: 1px solid color-mix(in srgb, var(--bf-color-warm-white) 16%, transparent);
  border-bottom: 1px solid color-mix(in srgb, var(--bf-color-warm-white) 16%, transparent);
  transition:
    color var(--bf-duration-fast) var(--bf-ease-standard),
    transform var(--bf-duration-fast) var(--bf-ease-forward);
}

.sk-footer__mail span {
  color: var(--bf-color-silver);
  font-family: var(--bf-font-display);
  font-size: 0.625rem;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.sk-footer__mail strong {
  grid-column: 1;
  font-family: var(--bf-font-display);
  font-size: clamp(1.4rem, 2.2vw, 2.4rem);
  font-weight: 500;
  letter-spacing: -0.03em;
}

.sk-footer__mail svg {
  grid-area: 1 / 2 / 3;
  width: 1.75rem;
  height: 1.75rem;
  stroke: var(--bf-color-orange);
  fill: none;
  transition: transform var(--bf-duration-fast) var(--bf-ease-forward);
}

.sk-footer__mail:hover {
  color: var(--bf-color-orange);
  transform: translateY(-3px);
}

.sk-footer__mail:hover svg {
  transform: translateX(6px);
}

.sk-footer__bar {
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: center;
  gap: 2rem;
  padding: clamp(2rem, 4vw, 3.5rem) clamp(1.5rem, 3.2vw, 3.5rem);
}

.sk-footer__bar .bf-brand-mark {
  width: 4.75rem;
  filter: brightness(0) invert(1);
}

.sk-footer__meta {
  display: flex;
  flex-wrap: wrap;
  gap: clamp(1.25rem, 3vw, 2.75rem);
  color: var(--bf-color-silver);
  font-family: var(--bf-font-display);
  font-size: 0.75rem;
  font-weight: 500;
}

.sk-footer__meta a:hover {
  color: var(--bf-color-orange);
}

.sk-footer__legal {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 1.5rem;
  padding: 1.1rem clamp(1.5rem, 3.2vw, 3.5rem) 1.5rem;
  border-top: 1px solid color-mix(in srgb, var(--bf-color-warm-white) 16%, transparent);
  color: var(--bf-color-silver);
  font-family: var(--bf-font-display);
  font-size: 0.5625rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.sk-footer__legal span:nth-child(2) {
  justify-self: center;
}

.sk-footer__legal span:last-child {
  justify-self: end;
}

.sk-arrow {
  width: 1.25rem;
  height: 1.25rem;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.5;
  stroke-linecap: square;
  stroke-linejoin: miter;
}

@keyframes sk-orbit-travel {
  to {
    stroke-dashoffset: -2000px;
  }
}

@keyframes sk-orbit-breathe {
  0%,
  100% {
    transform: translateY(-5px) scaleX(0.985);
  }
  50% {
    transform: translateY(7px) scaleX(1.015);
  }
}

@media (max-width: 860px) {
  .sk-header {
    height: 4.75rem;
    grid-template-columns: 1fr auto;
  }

  .sk-nav {
    display: none;
  }

  .sk-footer__contact,
  .sk-footer__legal {
    grid-template-columns: 1fr;
  }

  .sk-footer__legal span:nth-child(2),
  .sk-footer__legal span:last-child {
    justify-self: start;
  }
}

@media (prefers-reduced-motion: reduce) {
  .sk-orbit,
  .sk-orbit__shell,
  .sk-orbit__ring {
    animation: none !important;
  }
}