:root {
  color-scheme: light;
  --ink: #202124;
  --muted: #5f6368;
  --line: #dadce0;
  --paper: #ffffff;
  --soft: #f8fafd;
  --accent: #2563eb;
  --accent-strong: #1d4ed8;
  --accent-soft: #dbeafe;
  --teal: #0f9f8f;
  font-family:
    Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
    "PingFang SC", "Microsoft YaHei", sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  letter-spacing: 0;
  text-rendering: optimizeLegibility;
}

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

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

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 64px;
  padding: 0 40px;
  background: rgba(255, 255, 255, 0.88);
  border-bottom: 1px solid rgba(218, 220, 224, 0);
  backdrop-filter: blur(18px);
  transition: border-color 180ms ease, box-shadow 180ms ease;
}

.site-header.is-compact {
  border-color: var(--line);
  box-shadow: 0 1px 2px rgba(60, 64, 67, 0.08);
}

.brand,
.site-header nav,
.hero-actions {
  display: flex;
  align-items: center;
}

.brand {
  gap: 10px;
  font-size: 15px;
  font-weight: 600;
  transition: transform 180ms ease;
}

.brand img {
  width: 32px;
  height: 32px;
  border-radius: 8px;
  transition: transform 180ms ease, box-shadow 180ms ease;
}

.brand:hover {
  transform: translateY(-1px);
}

.brand:hover img {
  transform: rotate(-4deg) scale(1.04);
  box-shadow: 0 8px 18px rgba(60, 64, 67, 0.12);
}

.site-header nav {
  gap: 28px;
  color: var(--muted);
  font-size: 14px;
}

.site-header nav a:hover {
  color: var(--ink);
}

.site-header nav a {
  position: relative;
  padding: 6px 0;
}

.site-header nav a::after {
  position: absolute;
  right: 0;
  bottom: 0;
  left: 0;
  height: 2px;
  content: "";
  border-radius: 999px;
  background: var(--accent);
  transform: scaleX(0);
  transform-origin: right;
  transition: transform 180ms ease;
}

.site-header nav a:hover::after {
  transform: scaleX(1);
  transform-origin: left;
}

.hero {
  position: relative;
  display: grid;
  justify-items: center;
  min-height: calc(100svh - 64px);
  padding: 96px 24px 84px;
  overflow: hidden;
  text-align: center;
  --hero-tilt-x: 0deg;
  --hero-tilt-y: 0deg;
  --hero-shift: 0px;
}

.hero::before {
  position: absolute;
  inset: 0;
  pointer-events: none;
  content: "";
  background:
    linear-gradient(115deg, transparent 0 38%, rgba(37, 99, 235, 0.08) 46%, transparent 56%),
    linear-gradient(180deg, rgba(248, 250, 253, 0.95), rgba(255, 255, 255, 0));
  background-size: 220% 100%, 100% 100%;
  transform: translateX(var(--hero-shift));
  transition: transform 220ms ease;
  animation: heroSweep 7s ease-in-out infinite;
}

.app-icon {
  position: relative;
  width: 96px;
  height: 96px;
  margin-bottom: 28px;
  border-radius: 22px;
  box-shadow: 0 8px 24px rgba(60, 64, 67, 0.12);
  transform: perspective(720px) rotateX(var(--hero-tilt-y)) rotateY(var(--hero-tilt-x));
  transition: transform 180ms ease;
  animation:
    iconRise 520ms ease both,
    iconFloat 5.4s ease-in-out 900ms infinite,
    iconGlow 4.8s ease-in-out 900ms infinite;
}

.eyebrow {
  position: relative;
  margin: 0 0 16px;
  color: var(--accent);
  font-size: 14px;
  font-weight: 600;
}

.hero h1,
.section h2,
.preview-copy h2 {
  position: relative;
  margin: 0;
  color: var(--ink);
  font-weight: 500;
  letter-spacing: 0;
}

.hero h1 {
  font-size: clamp(54px, 9vw, 112px);
  line-height: 1;
  animation: rise 560ms ease 80ms both;
}

.hero-copy {
  position: relative;
  width: min(680px, 100%);
  margin: 28px 0 0;
  color: var(--muted);
  font-size: clamp(20px, 2.3vw, 30px);
  line-height: 1.45;
  animation: rise 560ms ease 140ms both;
}

.hero-actions {
  position: relative;
  justify-content: center;
  gap: 18px;
  flex-wrap: wrap;
  margin-top: 34px;
  animation: rise 560ms ease 200ms both;
}

.soon-button,
.download-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 52px;
  border-radius: 999px;
  font-size: 15px;
  font-weight: 600;
  line-height: 1;
  transition:
    transform 180ms ease,
    box-shadow 180ms ease,
    background 180ms ease,
    border-color 180ms ease,
    color 180ms ease;
}

.soon-button,
.download-button-primary {
  padding: 0 28px;
  color: #fff;
  background: var(--accent);
  box-shadow: 0 10px 24px rgba(37, 99, 235, 0.22);
  animation: buttonPulse 3.6s ease-in-out 800ms infinite;
}

.soon-button:hover,
.download-button-primary:hover {
  transform: translateY(-2px);
  background: var(--accent-strong);
  box-shadow: 0 18px 38px rgba(37, 99, 235, 0.3);
}

.download-button {
  min-width: 174px;
}

.download-button-secondary {
  padding: 0 26px;
  color: var(--accent);
  border: 1px solid rgba(37, 99, 235, 0.2);
  background: rgba(255, 255, 255, 0.76);
  box-shadow: 0 8px 20px rgba(60, 64, 67, 0.08);
  backdrop-filter: blur(12px);
}

.download-button-secondary:hover {
  transform: translateY(-2px);
  color: var(--accent-strong);
  border-color: rgba(37, 99, 235, 0.34);
  background: #fff;
  box-shadow:
    0 16px 32px rgba(37, 99, 235, 0.14),
    0 8px 20px rgba(60, 64, 67, 0.08);
}

.platforms {
  position: relative;
  margin: 20px 0 0;
  color: var(--muted);
  font-size: 14px;
}

.rhythm-track {
  position: relative;
  display: grid;
  grid-template-columns: 1fr repeat(3, 18px);
  align-items: center;
  gap: 16px;
  width: min(440px, 76vw);
  height: 28px;
  margin-top: 42px;
  opacity: 0.95;
  animation: rise 560ms ease 260ms both;
}

.rhythm-line {
  position: relative;
  height: 2px;
  overflow: hidden;
  border-radius: 999px;
  background: #e8eaed;
}

.rhythm-line::after {
  position: absolute;
  inset: 0 auto 0 0;
  width: 42%;
  content: "";
  border-radius: inherit;
  background: linear-gradient(90deg, var(--accent), var(--teal));
  animation: rhythmFlow 2.9s ease-in-out infinite;
}

.rhythm-dot {
  width: 9px;
  height: 9px;
  border: 1px solid #cbd5e1;
  border-radius: 50%;
  background: #fff;
  box-shadow: 0 0 0 0 rgba(37, 99, 235, 0);
  animation: dotPulse 2.9s ease-in-out infinite;
}

.rhythm-dot:nth-child(3) {
  animation-delay: 180ms;
}

.rhythm-dot:nth-child(4) {
  animation-delay: 360ms;
}

.rhythm-dot.is-active {
  border-color: var(--accent);
  background: var(--accent);
}

.section {
  padding: 100px 7vw;
  background: var(--soft);
}

.section h2 {
  width: min(820px, 100%);
  margin: 0 auto 56px;
  text-align: center;
  font-size: clamp(36px, 5vw, 64px);
  line-height: 1.12;
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 24px;
  width: min(1040px, 100%);
  margin: 0 auto;
}

.feature-grid article {
  position: relative;
  overflow: hidden;
  min-height: 220px;
  padding: 30px;
  border: 1px solid var(--line);
  border-radius: 24px;
  background: #fff;
  animation: rise 620ms ease both;
  transition: transform 220ms ease, box-shadow 220ms ease, border-color 220ms ease;
}

.feature-grid article::before {
  position: absolute;
  inset: 0;
  pointer-events: none;
  content: "";
  background: linear-gradient(120deg, transparent 0 24%, rgba(37, 99, 235, 0.09) 44%, transparent 64%);
  transform: translateX(-115%);
  transition: opacity 180ms ease, transform 520ms ease;
  opacity: 0;
}

.feature-grid article > * {
  position: relative;
}

.feature-grid article:nth-child(2) {
  animation-delay: 80ms;
}

.feature-grid article:nth-child(3) {
  animation-delay: 160ms;
}

.feature-grid article:hover {
  transform: translateY(-6px);
  border-color: rgba(37, 99, 235, 0.24);
  box-shadow: 0 18px 44px rgba(60, 64, 67, 0.12);
}

.feature-grid article:hover::before {
  transform: translateX(115%);
  opacity: 1;
}

.feature-grid span {
  color: var(--accent);
  font-size: 13px;
  font-weight: 700;
}

.feature-grid h3 {
  margin: 44px 0 12px;
  font-size: 28px;
  line-height: 1.2;
  font-weight: 500;
}

.feature-grid p,
.preview-copy p,
.capability-card span,
.panel-detail {
  margin: 0;
  color: var(--muted);
  font-size: 17px;
  line-height: 1.65;
}

.capability-block {
  width: min(1040px, 100%);
  margin: 92px auto 0;
  scroll-margin-top: 96px;
}

.capability-heading {
  width: min(840px, 100%);
  margin: 0 auto 38px;
  text-align: center;
}

.capability-heading h2 {
  margin: 0;
  color: var(--ink);
  font-size: clamp(34px, 4.1vw, 54px);
  line-height: 1.12;
  font-weight: 500;
  letter-spacing: 0;
}

.heading-chunk {
  display: inline-block;
  white-space: nowrap;
}

.capability-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 18px;
}

.capability-card {
  position: relative;
  display: grid;
  align-content: start;
  min-height: 218px;
  padding: 26px;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 24px;
  color: inherit;
  background: #fff;
  font: inherit;
  text-align: left;
  cursor: pointer;
  transition:
    transform 220ms ease,
    box-shadow 220ms ease,
    border-color 220ms ease,
    background 220ms ease;
}

.capability-card::after {
  position: absolute;
  right: -52px;
  bottom: -64px;
  width: 140px;
  height: 140px;
  content: "";
  border-radius: 50%;
  background: rgba(37, 99, 235, 0.08);
  transform: scale(0.8);
  transition: transform 240ms ease, opacity 240ms ease;
  opacity: 0;
}

.capability-card:hover,
.capability-card:focus-visible,
.capability-card.is-active {
  transform: translateY(-5px);
  border-color: rgba(37, 99, 235, 0.28);
  outline: none;
  box-shadow: 0 18px 42px rgba(60, 64, 67, 0.12);
}

.capability-card:hover::after,
.capability-card:focus-visible::after,
.capability-card.is-active::after {
  transform: scale(1);
  opacity: 1;
}

.capability-card strong {
  position: relative;
  margin: 24px 0 10px;
  color: var(--ink);
  font-size: 22px;
  line-height: 1.22;
  font-weight: 600;
}

.capability-card span:not(.capability-icon) {
  position: relative;
  font-size: 15px;
}

.capability-icon {
  position: relative;
  display: block;
  width: 54px;
  height: 54px;
  border-radius: 18px;
  background: var(--accent-soft);
  box-shadow: inset 0 0 0 1px rgba(37, 99, 235, 0.06);
  transition: transform 220ms ease;
}

.capability-card:hover .capability-icon,
.capability-card:focus-visible .capability-icon,
.capability-card.is-active .capability-icon {
  transform: scale(1.08) rotate(-3deg);
}

.capability-icon::before,
.capability-icon::after {
  position: absolute;
  content: "";
}

.icon-exam::before {
  inset: 15px 12px;
  border: 3px solid var(--accent);
  border-radius: 8px;
}

.icon-bilingual {
  background: #e6faf6;
}

.icon-bilingual::before,
.icon-bilingual::after {
  left: 14px;
  right: 14px;
  height: 3px;
  border-radius: 999px;
  background: var(--teal);
}

.icon-bilingual::before {
  top: 19px;
}

.icon-bilingual::after {
  top: 31px;
}

.icon-explain {
  background: #fff7d6;
}

.icon-explain::before {
  left: 17px;
  top: 12px;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: #f4c430;
}

.icon-explain::after {
  left: 21px;
  top: 34px;
  width: 12px;
  height: 5px;
  border-radius: 999px;
  background: #d9a80f;
}

.icon-review {
  background: #feecec;
}

.icon-review::before {
  left: 13px;
  top: 13px;
  width: 28px;
  height: 28px;
  border: 3px solid #ef4444;
  border-radius: 50%;
}

.icon-review::after {
  left: 25px;
  top: 25px;
  width: 18px;
  height: 3px;
  border-radius: 999px;
  background: #ef4444;
  transform: rotate(-45deg);
}

.icon-words {
  background: #f1ecff;
}

.icon-words::before {
  left: 17px;
  top: 11px;
  width: 20px;
  height: 30px;
  border: 3px solid #7c3aed;
  border-radius: 8px;
}

.icon-words::after {
  left: 24px;
  top: 19px;
  width: 6px;
  height: 16px;
  border-radius: 999px;
  background: #7c3aed;
}

.icon-writing {
  background: #eef6ff;
}

.icon-writing::before {
  left: 18px;
  top: 13px;
  width: 18px;
  height: 28px;
  border-radius: 8px 8px 4px 4px;
  background: var(--accent);
  transform: rotate(42deg);
}

.preview {
  display: grid;
  grid-template-columns: minmax(320px, 0.95fr) minmax(320px, 1.05fr);
  gap: 8vw;
  align-items: center;
  padding: 118px 7vw;
}

.preview-visual {
  position: relative;
  min-height: 360px;
}

.preview-panel {
  position: absolute;
  left: 50%;
  top: 50%;
  width: min(360px, 82%);
  padding: 28px;
  border: 1px solid var(--line);
  border-radius: 28px;
  background: rgba(255, 255, 255, 0.92);
  box-shadow: 0 18px 46px rgba(60, 64, 67, 0.16);
  transform: translate(-50%, -50%);
  animation: panelBreath 5.4s ease-in-out infinite;
  transition: transform 200ms ease, border-color 200ms ease, box-shadow 200ms ease;
}

.preview-panel::before {
  position: absolute;
  inset: 0 26px auto;
  height: 3px;
  content: "";
  border-radius: 999px;
  background: linear-gradient(90deg, transparent, var(--accent), transparent);
  animation: panelScan 3.8s ease-in-out infinite;
}

.preview-panel:hover,
.preview-panel:focus-within {
  transform: translate(-50%, calc(-50% - 4px));
  border-color: rgba(37, 99, 235, 0.22);
  box-shadow: 0 24px 58px rgba(37, 99, 235, 0.13), 0 18px 46px rgba(60, 64, 67, 0.12);
}

.panel-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  color: var(--muted);
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
}

.panel-head strong {
  color: var(--teal);
  font-size: 12px;
}

.panel-stage {
  margin-top: 28px;
  color: var(--ink);
  font-size: 28px;
  line-height: 1.15;
  font-weight: 500;
  transition: opacity 160ms ease, transform 160ms ease;
}

.panel-detail {
  min-height: 48px;
  margin-top: 12px;
  font-size: 15px;
  transition: opacity 160ms ease, transform 160ms ease;
}

.preview-panel.is-switching .panel-stage,
.preview-panel.is-switching .panel-detail {
  opacity: 0;
  transform: translateY(6px);
}

.panel-line {
  width: 64%;
  height: 14px;
  margin-top: 16px;
  border-radius: 999px;
  background: #e8eaed;
  animation: lineBreathe 3.2s ease-in-out infinite;
}

.panel-line.wide {
  width: 100%;
  margin-top: 0;
}

.panel-row {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
  margin-top: 28px;
}

.panel-tab {
  min-height: 52px;
  padding: 0 10px;
  border: 1px solid transparent;
  border-radius: 16px;
  color: var(--muted);
  background: #f1f3f4;
  font: inherit;
  font-size: 14px;
  font-weight: 700;
  cursor: pointer;
  transition: transform 180ms ease, color 180ms ease, background 180ms ease, border-color 180ms ease;
}

.panel-tab:hover,
.panel-tab:focus-visible,
.panel-tab.is-active {
  color: var(--accent);
  border-color: rgba(37, 99, 235, 0.18);
  background: var(--accent-soft);
  outline: none;
}

.panel-tab:hover,
.panel-tab:focus-visible {
  transform: translateY(-3px);
}

.panel-meter {
  height: 5px;
  margin-top: 24px;
  overflow: hidden;
  border-radius: 999px;
  background: #edf2f7;
}

.panel-meter span {
  display: block;
  width: 38%;
  height: 100%;
  border-radius: inherit;
  background: linear-gradient(90deg, var(--accent), var(--teal));
  transition: width 240ms ease;
}

.preview-copy h2 {
  max-width: 620px;
  font-size: clamp(38px, 5vw, 68px);
  line-height: 1.12;
}

.preview-copy p {
  margin-top: 24px;
  font-size: 19px;
}

.site-footer {
  display: flex;
  justify-content: space-between;
  gap: 18px;
  padding: 28px 7vw;
  color: var(--muted);
  border-top: 1px solid var(--line);
  font-size: 14px;
}

.site-footer a {
  color: var(--accent);
  font-weight: 600;
}

.js .reveal {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 560ms ease, transform 560ms ease;
}

.js .reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

@keyframes rise {
  from {
    opacity: 0;
    transform: translateY(16px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes heroSweep {
  0%,
  100% {
    background-position: -30% 50%, 0 0;
  }

  50% {
    background-position: 130% 50%, 0 0;
  }
}

@keyframes iconRise {
  from {
    opacity: 0;
    translate: 0 16px;
  }

  to {
    opacity: 1;
    translate: 0 0;
  }
}

@keyframes iconFloat {
  0%,
  100% {
    translate: 0 0;
  }

  50% {
    translate: 0 -8px;
  }
}

@keyframes iconGlow {
  0%,
  100% {
    box-shadow: 0 8px 24px rgba(60, 64, 67, 0.12);
  }

  50% {
    box-shadow: 0 18px 44px rgba(37, 99, 235, 0.16);
  }
}

@keyframes buttonPulse {
  0%,
  100% {
    box-shadow: 0 10px 24px rgba(37, 99, 235, 0.22);
  }

  50% {
    box-shadow: 0 14px 36px rgba(37, 99, 235, 0.34);
  }
}

@keyframes rhythmFlow {
  0%,
  100% {
    width: 34%;
    transform: translateX(0);
  }

  50% {
    width: 58%;
    transform: translateX(86%);
  }
}

@keyframes dotPulse {
  0%,
  100% {
    box-shadow: 0 0 0 0 rgba(37, 99, 235, 0);
  }

  45% {
    box-shadow: 0 0 0 8px rgba(37, 99, 235, 0.08);
  }
}

@keyframes panelBreath {
  0%,
  100% {
    box-shadow: 0 18px 46px rgba(60, 64, 67, 0.16);
  }

  50% {
    box-shadow: 0 22px 54px rgba(37, 99, 235, 0.12), 0 18px 46px rgba(60, 64, 67, 0.1);
  }
}

@keyframes panelScan {
  0%,
  100% {
    transform: translateX(-42%);
    opacity: 0.45;
  }

  50% {
    transform: translateX(42%);
    opacity: 1;
  }
}

@keyframes lineBreathe {
  0%,
  100% {
    opacity: 0.72;
  }

  50% {
    opacity: 1;
  }
}

@media (max-width: 860px) {
  .site-header {
    padding: 0 20px;
  }

  .site-header nav {
    gap: 18px;
  }

  .hero {
    padding-top: 78px;
  }

  .feature-grid,
  .capability-grid,
  .preview {
    grid-template-columns: 1fr;
  }

  .feature-grid article {
    min-height: auto;
  }
}

@media (max-width: 560px) {
  .site-header nav a:first-child {
    display: none;
  }

  .hero {
    min-height: calc(100svh - 64px);
    padding: 74px 20px 64px;
  }

  .app-icon {
    width: 84px;
    height: 84px;
  }

  .hero-actions {
    flex-direction: column;
    width: 100%;
  }

  .soon-button,
  .download-button {
    width: 100%;
  }

  .section,
  .preview {
    padding: 76px 20px;
  }

  .capability-block {
    margin-top: 70px;
  }

  .capability-heading {
    text-align: center;
  }

  .capability-card {
    min-height: auto;
    padding: 24px;
  }

  .feature-grid article {
    padding: 26px;
    border-radius: 20px;
  }

  .preview-visual {
    min-height: 300px;
  }

  .site-footer {
    flex-direction: column;
    padding: 24px 20px;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition: none !important;
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
  }

  .js .reveal {
    opacity: 1;
    transform: none;
  }
}