/*
 * VeloPhi — product page on top of /account-assets/wl-ui.css tokens (html[data-site="velophi"]).
 * Motif from the app icon: an orbit seen edge-on, an axis through it and a warm "sun".
 * Glass is used for the navigation bar, the lab window and small floating chips only.
 */
:root {
  --vp-amber: #e7a20f;
  --vp-amber-soft: rgba(245, 179, 36, 0.16);
  --vp-ink: #1b1650;
  --vp-orbit: rgba(81, 70, 216, 0.55);
  --vp-orbit-faint: rgba(81, 70, 216, 0.14);
  --vp-curve: #4f46e5;
  --vp-grid: rgba(27, 22, 80, 0.08);
  --vp-canvas-text: rgba(27, 22, 80, 0.62);
  --vp-body: #ffffff;
  --vp-window-bg: rgba(255, 255, 255, 0.72);
  --vp-stage-bg: linear-gradient(160deg, #f6f6ff 0%, #eceafe 100%);
}
:root[data-theme="dark"] {
  --vp-amber: #fbbf24;
  --vp-amber-soft: rgba(251, 191, 36, 0.16);
  --vp-orbit: rgba(186, 180, 255, 0.6);
  --vp-orbit-faint: rgba(186, 180, 255, 0.12);
  --vp-curve: #a5a0ff;
  --vp-grid: rgba(255, 255, 255, 0.07);
  --vp-canvas-text: rgba(230, 228, 255, 0.62);
  --vp-body: #eef0ff;
  --vp-window-bg: rgba(22, 20, 52, 0.62);
  --vp-stage-bg: linear-gradient(160deg, #1b1846 0%, #110f2e 100%);
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 96px;
}
body {
  min-height: 100vh;
}
main {
  overflow-x: clip;
}
a {
  color: inherit;
}

/* Brand mark ------------------------------------------------------------------ */
.vp-mark {
  display: block;
  flex: none;
  width: 32px;
  height: 32px;
  border-radius: 9px;
}
.site-header .wl-navbar__actions {
  margin-left: 6px;
}
.theme-button svg {
  width: 20px;
  height: 20px;
}

/* Shared type ------------------------------------------------------------------ */
.kicker {
  margin: 0 0 10px;
  color: var(--wl-tint);
  font-size: var(--wl-fs-footnote);
  font-weight: var(--wl-weight-semibold);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}
:lang(zh) .kicker {
  letter-spacing: 0.04em;
}

/* Hero ------------------------------------------------------------------------- */
.hero {
  position: relative;
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1.05fr);
  align-items: center;
  gap: clamp(28px, 5vw, 72px);
  min-height: min(760px, calc(100svh - 80px));
  padding-block: clamp(40px, 7vw, 96px) clamp(48px, 7vw, 88px);
}
.hero-orbits {
  position: absolute;
  top: 50%;
  left: 50%;
  z-index: -1;
  width: 150%;
  max-width: none;
  height: auto;
  translate: -50% -50%;
  fill: none;
  stroke: var(--vp-orbit);
  stroke-width: 1.2;
  opacity: 0.45;
  pointer-events: none;
}
.hero-orbits line {
  stroke-dasharray: 4 10;
}
.hero-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin: 0 0 18px;
  color: var(--wl-tint);
  font-size: var(--wl-fs-footnote);
  font-weight: var(--wl-weight-semibold);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}
.hero-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--vp-amber);
  box-shadow: 0 0 0 5px var(--vp-amber-soft);
}
.hero h1 {
  margin: 0;
  font-family: var(--wl-font-display);
  font-size: clamp(2.6rem, 1.3rem + 3.4vw, 4.1rem);
  font-weight: var(--wl-weight-bold);
  line-height: 1;
  letter-spacing: var(--wl-tracking-display);
}
.hero h1 > span {
  display: block;
}
.hero-accent {
  background: linear-gradient(100deg, var(--wl-tint) 0%, #7c5cf0 55%, #a26bf5 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  padding-bottom: 0.08em;
}
:lang(zh) .hero h1 {
  letter-spacing: -0.01em;
  line-height: 1.12;
}
.hero-lede {
  max-width: 34ch;
  margin: 22px 0 0;
  color: var(--wl-text-2);
  font-size: var(--wl-fs-body-lg);
  line-height: var(--wl-lh-body);
}
.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 30px;
}
.hero-status {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin: 22px 0 0;
  color: var(--wl-text-3);
  font-size: var(--wl-fs-footnote);
}
.pulse {
  position: relative;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--wl-success);
}
.pulse::after {
  content: "";
  position: absolute;
  inset: -4px;
  border-radius: 50%;
  border: 2px solid var(--wl-success);
  opacity: 0;
  animation: vp-ping 2.4s var(--wl-ease-out) infinite;
}
@keyframes vp-ping {
  from {
    opacity: 0.7;
    transform: scale(0.6);
  }
  to {
    opacity: 0;
    transform: scale(1.8);
  }
}

/* Orbit lab (hero visual) --------------------------------------------------------- */
.orbit-lab {
  position: relative;
  margin: 0;
  isolation: isolate;
}
.lab-window {
  overflow: hidden;
  border-radius: var(--wl-radius-2xl);
  background: var(--vp-window-bg);
  box-shadow: var(--wl-shadow-3);
}
.lab-titlebar {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 16px;
  border-bottom: 1px solid var(--wl-separator);
}
.lab-dots {
  display: inline-flex;
  gap: 6px;
}
.lab-dots i {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--wl-fill-2);
}
.lab-dots i:first-child {
  background: var(--vp-amber);
}
.lab-title {
  overflow: hidden;
  color: var(--wl-text-2);
  font-size: var(--wl-fs-footnote);
  font-weight: var(--wl-weight-semibold);
  text-overflow: ellipsis;
  white-space: nowrap;
}
.orbit-canvas {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 9;
  background: var(--vp-stage-bg);
}
.orbit-readouts {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  border-top: 1px solid var(--wl-separator);
}
.readout {
  display: grid;
  gap: 2px;
  padding: 12px 16px;
}
.readout + .readout {
  border-left: 1px solid var(--wl-separator);
}
.readout-label {
  overflow: hidden;
  color: var(--wl-text-3);
  font-size: var(--wl-fs-caption);
  font-weight: var(--wl-weight-semibold);
  text-overflow: ellipsis;
  white-space: nowrap;
}
.readout-value {
  font-family: var(--wl-font-mono);
  font-size: var(--wl-fs-subhead);
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}
.readout:first-child .readout-value {
  color: var(--vp-amber);
}
:root:not([data-theme="dark"]) .readout:first-child .readout-value {
  color: #a86f00;
}
.orbit-controls {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  padding: 10px 12px 12px;
  border-top: 1px solid var(--wl-separator);
}
.orbit-toggle {
  gap: 8px;
  min-width: 108px;
}
.orbit-toggle svg {
  width: 16px;
  height: 16px;
  fill: currentColor;
}
.orbit-toggle .icon-play,
.orbit-toggle[data-paused="true"] .icon-pause {
  display: none;
}
.orbit-toggle[data-paused="true"] .icon-play {
  display: inline;
}
.orbit-rate > button {
  min-height: 36px;
  font-variant-numeric: tabular-nums;
}
.orbit-caption {
  margin: 14px 6px 0;
  color: var(--wl-text-3);
  font-size: var(--wl-fs-footnote);
  text-align: center;
}
.formula-chip {
  position: absolute;
  z-index: 2;
  display: inline-flex;
  padding: 0;
  border-radius: var(--wl-radius-pill);
  box-shadow: var(--wl-shadow-2);
  font-family: var(--wl-font-mono);
  font-size: var(--wl-fs-footnote);
  white-space: nowrap;
}
.formula-chip > span {
  display: block;
  padding: 8px 14px;
}
.chip-a {
  top: -18px;
  right: 28px;
}
.chip-b {
  top: 46%;
  left: -78px;
}
@media (max-width: 1240px) {
  .chip-b {
    display: none;
  }
}

/* Sections ----------------------------------------------------------------------- */
.section {
  padding-block: clamp(56px, 9vw, 112px);
}
.section-head {
  max-width: 760px;
  margin-bottom: clamp(26px, 4vw, 44px);
}
.section-head h2,
.online-copy h2 {
  margin: 0;
  font-family: var(--wl-font-display);
  font-size: clamp(2.1rem, 1.4rem + 2.8vw, 3.5rem);
  font-weight: var(--wl-weight-bold);
  line-height: 1.04;
  letter-spacing: -0.04em;
}
:lang(zh) .section-head h2,
:lang(zh) .online-copy h2 {
  letter-spacing: -0.01em;
}
.section-head > p:last-child {
  max-width: 56ch;
  margin: 14px 0 0;
  color: var(--wl-text-2);
  font-size: var(--wl-fs-body-lg);
}

/* Mini lab ------------------------------------------------------------------------- */
.lab-grid {
  display: grid;
  grid-template-columns: minmax(260px, 340px) minmax(0, 1fr);
  gap: 18px;
  align-items: stretch;
}
.lab-controls {
  display: grid;
  align-content: start;
  gap: 22px;
  padding: 24px;
}
.lab-field {
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: center;
  gap: 6px 12px;
}
.lab-field label,
.lab-label {
  font-weight: var(--wl-weight-semibold);
}
.lab-field output {
  font-family: var(--wl-font-mono);
  font-variant-numeric: tabular-nums;
  color: var(--wl-tint);
}
.lab-field input[type="range"] {
  grid-column: 1 / -1;
  width: 100%;
  height: 32px;
  margin: 0;
  accent-color: var(--wl-tint);
}
.lab-field--gravity {
  grid-template-columns: 1fr;
}
.lab-field--gravity .wl-segmented {
  display: flex;
}
.lab-field--gravity .wl-segmented > button {
  flex: 1;
  padding: 0 8px;
}
.lab-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}
.lab-tip {
  margin: 0;
  padding: 12px 14px;
  border-radius: var(--wl-radius-md);
  background: var(--vp-amber-soft);
  color: var(--wl-text-2);
  font-size: var(--wl-fs-footnote);
}
.lab-stage {
  display: grid;
  align-self: start;
  overflow: hidden;
  padding: 0;
}
.lab-canvas {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 2 / 1;
  background: var(--vp-stage-bg);
}
.lab-results {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  margin: 0;
  border-top: 1px solid var(--wl-separator);
}
.lab-results > div {
  padding: 14px 18px;
}
.lab-results > div + div {
  border-left: 1px solid var(--wl-separator);
}
.lab-results dt {
  color: var(--wl-text-3);
  font-size: var(--wl-fs-caption);
  font-weight: var(--wl-weight-semibold);
}
.lab-results dd {
  margin: 2px 0 0;
  font-family: var(--wl-font-mono);
  font-size: var(--wl-fs-title-3);
  font-variant-numeric: tabular-nums;
}
.lab-results dd.formula {
  color: var(--wl-text-3);
  font-size: var(--wl-fs-caption);
}
.lab-note {
  margin: 0;
  padding: 0 18px 14px;
  color: var(--wl-text-3);
  font-size: var(--wl-fs-caption);
}

/* Teaching -------------------------------------------------------------------------- */
.teach-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 16px;
}
.teach-card {
  padding: 22px 22px 24px;
}
.teach-card h3 {
  margin: 18px 0 6px;
  font-size: var(--wl-fs-title-3);
  letter-spacing: -0.02em;
}
.teach-card p {
  margin: 0;
  color: var(--wl-text-2);
}
.teach-art {
  display: block;
  width: 100%;
  max-width: 180px;
  height: auto;
  border-radius: var(--wl-radius-md);
  background: var(--vp-stage-bg);
}
.teach-art * {
  fill: none;
  stroke-linecap: round;
  stroke-linejoin: round;
}
.art-ground {
  fill: var(--vp-orbit) !important;
}
.art-body {
  fill: var(--vp-body) !important;
  stroke: var(--vp-orbit);
  stroke-width: 2;
}
.art-box,
.art-panel {
  fill: var(--wl-surface) !important;
  stroke: var(--vp-orbit);
  stroke-width: 2;
}
.art-panel--back {
  fill: var(--wl-surface-2) !important;
}
.art-trail,
.art-dash {
  stroke: var(--vp-orbit);
  stroke-width: 2;
  stroke-dasharray: 3 5;
}
.art-arrow,
.art-line {
  stroke: var(--wl-tint);
  stroke-width: 3;
}
.art-play {
  fill: var(--wl-tint) !important;
}
.art-pause {
  fill: var(--vp-orbit) !important;
}
.art-sun {
  fill: var(--vp-amber) !important;
}

/* Online launcher ----------------------------------------------------------------------- */
.online-card {
  position: relative;
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  align-items: center;
  gap: clamp(24px, 5vw, 64px);
  padding: clamp(28px, 5vw, 56px);
  border-radius: var(--wl-radius-2xl);
  background:
    radial-gradient(120% 120% at 0% 0%, var(--vp-amber-soft), transparent 45%),
    linear-gradient(150deg, var(--wl-tint-soft), transparent 60%), var(--wl-surface);
  box-shadow:
    var(--wl-shadow-2),
    0 0 0 1px var(--wl-separator);
}
.online-art {
  position: relative;
  display: grid;
  place-items: center;
  width: clamp(150px, 20vw, 220px);
  aspect-ratio: 1;
}
.online-art img {
  position: relative;
  z-index: 1;
  width: 58%;
  height: auto;
  filter: drop-shadow(0 14px 26px rgba(40, 30, 140, 0.35));
}
.online-ring {
  position: absolute;
  inset: 0;
  border: 1.5px dashed var(--vp-orbit);
  border-radius: 50%;
  transform: rotateX(64deg);
  animation: vp-spin 18s linear infinite;
}
.online-ring.ring-2 {
  inset: 12%;
  border-style: solid;
  border-color: var(--vp-orbit-faint);
  animation-duration: 28s;
  animation-direction: reverse;
}
.online-ring::after {
  content: "";
  position: absolute;
  top: -6px;
  left: calc(50% - 6px);
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--vp-amber);
  box-shadow: 0 0 14px var(--vp-amber);
}
.online-ring.ring-2::after {
  display: none;
}
@keyframes vp-spin {
  to {
    transform: rotateX(64deg) rotateZ(360deg);
  }
}
.online-copy > p {
  margin: 12px 0 0;
  color: var(--wl-text-2);
  font-size: var(--wl-fs-body-lg);
}
.online-copy > .kicker {
  margin: 0 0 10px;
  color: var(--wl-tint);
  font-size: var(--wl-fs-footnote);
}
.online-copy > .online-status {
  display: inline-flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin-top: 20px;
  padding: 6px 12px;
  border-radius: var(--wl-radius-pill);
  background: var(--wl-fill);
  color: var(--wl-text);
  font-size: var(--wl-fs-footnote);
  font-weight: var(--wl-weight-semibold);
}
.status-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--wl-text-3);
}
[data-online-state="ready"] .status-dot {
  background: var(--wl-success);
}
[data-online-state="soon"] .status-dot {
  background: var(--vp-amber);
}
[data-online-state="checking"] .status-dot {
  animation: vp-blink 1.2s ease-in-out infinite;
}
@keyframes vp-blink {
  50% {
    opacity: 0.3;
  }
}
.online-version {
  color: var(--wl-text-3);
  font-weight: var(--wl-weight-medium);
}
.online-caps {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin-top: 16px;
}
.online-caps[hidden],
.online-version[hidden],
.online-soon[hidden],
.online-open[hidden] {
  display: none;
}
.caps-label {
  color: var(--wl-text-3);
  font-size: var(--wl-fs-caption);
  font-weight: var(--wl-weight-semibold);
}
.online-caps ul {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin: 0;
  padding: 0;
  list-style: none;
}
.online-caps li {
  padding: 4px 10px;
  border-radius: var(--wl-radius-pill);
  background: var(--wl-tint-soft);
  color: var(--wl-tint);
  font-size: var(--wl-fs-caption);
  font-weight: var(--wl-weight-semibold);
}
.online-copy > .online-soon {
  font-size: var(--wl-fs-body);
}
.online-open {
  margin-top: 24px;
}
.online-notes {
  display: grid;
  gap: 6px;
  margin: 24px 0 0;
  padding: 0;
  color: var(--wl-text-3);
  font-size: var(--wl-fs-footnote);
  list-style: none;
}
.online-notes li {
  position: relative;
  padding-left: 18px;
}
.online-notes li::before {
  content: "";
  position: absolute;
  top: 0.55em;
  left: 2px;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--vp-orbit);
}

/* Footer ----------------------------------------------------------------------------- */
.footer {
  padding: 28px 0 calc(40px + env(safe-area-inset-bottom));
  border-top: 1px solid var(--wl-separator);
  color: var(--wl-text-3);
  font-size: var(--wl-fs-subhead);
}
.footer-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px 24px;
}
.footer-brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
}
.footer-brand .vp-mark {
  width: 28px;
  height: 28px;
  border-radius: 8px;
}
.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 4px 18px;
}
.footer-links a {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  color: var(--wl-text-2);
  text-decoration: none;
}
.footer-links a:hover {
  color: var(--wl-tint);
}

/* Responsive ---------------------------------------------------------------------------- */
@media (max-width: 1080px) {
  .teach-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}
@media (max-width: 980px) {
  .hero {
    grid-template-columns: 1fr;
    min-height: 0;
  }
  .hero-lede {
    max-width: 46ch;
  }
  .orbit-lab {
    max-width: 680px;
  }
}
@media (max-width: 860px) {
  .lab-grid {
    grid-template-columns: 1fr;
  }
  .lab-canvas {
    aspect-ratio: 16 / 10;
  }
}
@media (max-width: 760px) {
  .wl-navbar__links {
    display: none;
  }
  .wl-navbar__actions {
    margin-left: auto;
  }
  .online-card {
    grid-template-columns: 1fr;
    justify-items: start;
  }
  .online-art {
    width: 140px;
  }
}
@media (max-width: 560px) {
  .teach-grid {
    grid-template-columns: 1fr;
  }
  .chip-a {
    right: 12px;
  }
  .readout {
    padding: 10px 10px;
  }
  .readout-value {
    font-size: var(--wl-fs-footnote);
  }
  .lab-results > div {
    padding: 12px 10px;
  }
  .lab-results dd {
    font-size: var(--wl-fs-body);
  }
  .lab-results dd.formula {
    display: none;
  }
}
@media (max-width: 380px) {
  .orbit-controls {
    justify-content: center;
  }
  .hero-actions .wl-btn {
    width: 100%;
  }
}

/* Motion, transparency and contrast preferences ---------------------------------------------- */
@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
  .pulse::after,
  .online-ring,
  [data-online-state="checking"] .status-dot {
    animation: none;
  }
}
:root[data-motion="reduce"] .pulse::after,
:root[data-motion="reduce"] .online-ring,
:root[data-motion="reduce"] [data-online-state="checking"] .status-dot {
  animation: none;
}
:root[data-motion="reduce"] {
  scroll-behavior: auto;
}
@media (prefers-reduced-transparency: reduce) {
  .lab-window,
  .formula-chip {
    background: var(--wl-surface);
    -webkit-backdrop-filter: none;
    backdrop-filter: none;
  }
}
:root[data-transparency="reduce"] .lab-window,
:root[data-transparency="reduce"] .formula-chip {
  background: var(--wl-surface);
  -webkit-backdrop-filter: none;
  backdrop-filter: none;
}
@media (forced-colors: active) {
  .hero-accent {
    background: none;
    color: CanvasText;
  }
  .orbit-canvas,
  .lab-canvas {
    border: 1px solid CanvasText;
  }
}
@media print {
  .orbit-controls,
  .formula-chip,
  .hero-orbits,
  .lab-buttons {
    display: none;
  }
}