:root {
  --ink: #142033;
  --muted: #62748b;
  --soft: #eef7ff;
  --paper: #ffffff;
  --line: #d8e6f3;
  --blue: #1f65b7;
  --blue-dark: #174a88;
  --green: #3b7f67;
  --amber: #c27829;
  --shadow: 0 22px 70px rgba(31, 101, 183, 0.18);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  background: #f7fbff;
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Text", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  letter-spacing: 0;
}

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

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 68px;
  padding: 0 clamp(20px, 5vw, 72px);
  background: rgba(247, 251, 255, 0.9);
  border-bottom: 1px solid rgba(216, 230, 243, 0.8);
  backdrop-filter: blur(18px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-size: 20px;
  font-weight: 800;
}

.brand img {
  border-radius: 8px;
}

nav {
  display: flex;
  align-items: center;
  gap: 24px;
  color: var(--muted);
  font-size: 14px;
  font-weight: 700;
}

nav a:hover {
  color: var(--blue);
}

.hero {
  position: relative;
  min-height: 84vh;
  display: flex;
  align-items: center;
  overflow: hidden;
  padding: 92px clamp(22px, 7vw, 96px) 86px;
  background: var(--soft);
}

.hero-visual {
  position: absolute;
  inset: 72px 0 auto 33%;
  height: min(560px, 70vh);
  opacity: 0.82;
}

.app-window {
  width: min(920px, 72vw);
  height: 100%;
  border: 1px solid rgba(134, 171, 205, 0.45);
  border-radius: 18px;
  background: var(--paper);
  box-shadow: var(--shadow);
  overflow: hidden;
  transform: rotate(-1.5deg);
}

.window-top {
  height: 48px;
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 0 16px;
  background: #dfefff;
  border-bottom: 1px solid var(--line);
}

.window-top span {
  width: 11px;
  height: 11px;
  border-radius: 50%;
  background: #9ab4cd;
}

.window-top span:nth-child(1) { background: #f36d5f; }
.window-top span:nth-child(2) { background: #f4bf4f; }
.window-top span:nth-child(3) { background: #5ec46b; }

.tab {
  height: 30px;
  display: flex;
  align-items: center;
  padding: 0 16px;
  border-radius: 8px;
  color: #587087;
  background: rgba(255, 255, 255, 0.52);
  font-size: 13px;
  font-weight: 700;
}

.tab.active {
  color: var(--ink);
  background: #ffffff;
}

.window-body {
  display: grid;
  grid-template-columns: 230px 1fr;
  min-height: calc(100% - 48px);
}

.window-body aside {
  padding: 26px 18px;
  background: #e7f4ff;
  border-right: 1px solid var(--line);
}

.window-body aside b {
  display: block;
  margin-bottom: 18px;
  font-size: 18px;
}

.window-body aside p {
  margin: 0 0 18px;
  padding: 10px 12px;
  border-radius: 8px;
  color: #7d90a3;
  background: rgba(255, 255, 255, 0.65);
  font-size: 13px;
}

.file {
  margin-top: 10px;
  padding: 12px;
  border-radius: 10px;
  color: #4e657d;
  font-size: 13px;
  font-weight: 700;
}

.file.active {
  color: var(--ink);
  background: #cfe4fb;
}

.window-body article {
  padding: 56px 72px;
  background: #fbfdff;
}

.window-body article h2 {
  max-width: 520px;
  margin: 0 0 18px;
  font-size: 34px;
}

.window-body article h3 {
  margin: 44px 0 14px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--line);
  font-size: 22px;
}

.window-body article p,
.window-body article li {
  max-width: 580px;
  color: #4f6176;
  font-size: 17px;
  line-height: 1.8;
}

.hero-content {
  position: relative;
  z-index: 2;
  width: min(620px, 100%);
}

.eyebrow,
.section-kicker {
  margin: 0 0 12px;
  color: var(--blue);
  font-size: 13px;
  font-weight: 850;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

h1,
h2,
h3,
p {
  letter-spacing: 0;
}

h1 {
  margin: 0;
  font-size: clamp(72px, 11vw, 148px);
  line-height: 0.9;
  font-weight: 900;
}

.lead {
  max-width: 540px;
  margin: 28px 0 0;
  color: #40566e;
  font-size: clamp(22px, 3vw, 34px);
  line-height: 1.45;
  font-weight: 800;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-top: 34px;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 46px;
  padding: 0 22px;
  border-radius: 8px;
  font-size: 15px;
  font-weight: 850;
}

.button.primary {
  color: #ffffff;
  background: var(--blue);
  box-shadow: 0 12px 24px rgba(31, 101, 183, 0.22);
}

.button.primary:hover {
  background: var(--blue-dark);
}

.button.secondary {
  color: var(--blue);
  border: 1px solid rgba(31, 101, 183, 0.25);
  background: rgba(255, 255, 255, 0.74);
}

.note {
  max-width: 520px;
  margin-top: 18px;
  color: var(--muted);
  font-size: 13px;
  line-height: 1.7;
}

.intro,
.features,
.download-section,
.contact-section {
  padding: 86px clamp(22px, 7vw, 96px);
}

.intro {
  display: grid;
  grid-template-columns: minmax(260px, 0.9fr) minmax(320px, 1.1fr);
  gap: 64px;
  background: #ffffff;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.intro h2,
.section-heading h2,
.download-section h2,
.contact-section h2 {
  margin: 0;
  font-size: clamp(34px, 5vw, 58px);
  line-height: 1.12;
}

.intro p:last-child,
.download-section p {
  margin: 0;
  color: #4f6176;
  font-size: 20px;
  line-height: 1.9;
}

.section-heading {
  max-width: 780px;
  margin-bottom: 42px;
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 16px;
}

.feature-grid article,
.download-panel,
.contact-list {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #ffffff;
  box-shadow: 0 14px 40px rgba(20, 32, 51, 0.06);
}

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

.feature-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  margin-bottom: 22px;
  border-radius: 50%;
  color: var(--blue);
  background: #e6f2ff;
  font-size: 13px;
  font-weight: 900;
}

.feature-grid h3 {
  margin: 0 0 10px;
  font-size: 22px;
}

.feature-grid p {
  margin: 0;
  color: #53667b;
  font-size: 16px;
  line-height: 1.8;
}

.feature-grid article:nth-child(2) .feature-icon,
.feature-grid article:nth-child(5) .feature-icon {
  color: var(--green);
  background: #e7f5ef;
}

.feature-grid article:nth-child(3) .feature-icon,
.feature-grid article:nth-child(6) .feature-icon {
  color: var(--amber);
  background: #fff2df;
}

.download-section {
  display: grid;
  grid-template-columns: minmax(320px, 1fr) 360px;
  gap: 56px;
  align-items: center;
  background: #eaf5ff;
}

.download-section p {
  margin-top: 20px;
}

.download-panel {
  padding: 30px;
}

.download-panel img {
  border-radius: 16px;
}

.download-panel h3 {
  margin: 20px 0 12px;
  font-size: 28px;
}

.download-panel p {
  margin: 0 0 24px;
  font-size: 15px;
  line-height: 1.8;
}

.contact-section {
  display: grid;
  grid-template-columns: minmax(300px, 0.9fr) minmax(340px, 1.1fr);
  gap: 56px;
  background: #ffffff;
}

.contact-list {
  overflow: hidden;
}

.contact-list div {
  display: grid;
  grid-template-columns: 120px 1fr;
  gap: 18px;
  padding: 20px 24px;
  border-bottom: 1px solid var(--line);
}

.contact-list div:last-child {
  border-bottom: 0;
}

.contact-list span {
  color: var(--muted);
  font-weight: 750;
}

.contact-list strong {
  font-size: 20px;
}

footer {
  display: flex;
  justify-content: space-between;
  gap: 18px;
  padding: 28px clamp(22px, 7vw, 96px);
  color: var(--muted);
  background: #f7fbff;
  border-top: 1px solid var(--line);
  font-size: 14px;
}

footer span:first-child {
  color: var(--ink);
  font-weight: 850;
}

@media (max-width: 900px) {
  .site-header {
    position: static;
  }

  nav {
    gap: 14px;
  }

  .hero {
    min-height: auto;
    padding-top: 70px;
  }

  .hero-visual {
    position: relative;
    inset: auto;
    order: 2;
    width: 100%;
    height: 360px;
    margin-top: 42px;
  }

  .hero {
    display: block;
  }

  .app-window {
    width: 100%;
    transform: none;
  }

  .window-body {
    grid-template-columns: 150px 1fr;
  }

  .window-body article {
    padding: 34px 28px;
  }

  .window-body article h2 {
    font-size: 25px;
  }

  .intro,
  .download-section,
  .contact-section {
    grid-template-columns: 1fr;
  }

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

@media (max-width: 640px) {
  .site-header {
    height: auto;
    align-items: flex-start;
    gap: 16px;
    flex-direction: column;
    padding-top: 18px;
    padding-bottom: 18px;
  }

  nav {
    flex-wrap: wrap;
  }

  h1 {
    font-size: 76px;
  }

  .lead {
    font-size: 22px;
  }

  .window-body {
    grid-template-columns: 1fr;
  }

  .window-body aside {
    display: none;
  }

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

  .contact-list div {
    grid-template-columns: 1fr;
    gap: 6px;
  }

  footer {
    flex-direction: column;
  }
}