:root {
  --page-bg: #111214;
  --panel: #1a1b1f;
  --panel-soft: #202126;
  --panel-light: #27282e;
  --line: rgba(255, 255, 255, 0.1);
  --line-strong: rgba(255, 25, 31, 0.48);
  --text: #ffffff;
  --muted: #a8a9b2;
  --muted-dark: #747681;
  --red: #f20d13;
  --red-dark: #cc080d;
  --shell: 1180px;
  --header-height: 76px;
  --radius-large: 24px;
  --radius-medium: 16px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-width: 320px;
  color: var(--text);
  background:
    radial-gradient(circle at 72% 8%, rgba(85, 88, 102, 0.12), transparent 32%),
    var(--page-bg);
  font-family:
    Inter,
    "PingFang SC",
    "Microsoft YaHei",
    Arial,
    sans-serif;
  -webkit-font-smoothing: antialiased;
}

body,
button,
a {
  font: inherit;
}

img {
  display: block;
  max-width: 100%;
  transform: none !important;
}

a {
  color: inherit;
}

button {
  color: inherit;
}

.page-shell {
  width: min(var(--shell), calc(100% - 40px));
  margin: 0 auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  min-height: var(--header-height);
  background: rgba(8, 9, 11, 0.94);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(18px);
}

.header-inner {
  width: min(1400px, calc(100% - 48px));
  min-height: var(--header-height);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 28px;
}

.brand {
  display: inline-flex;
  align-items: center;
  min-width: 145px;
  text-decoration: none;
}

.brand img {
  width: auto;
  max-width: 185px;
  max-height: 44px;
  object-fit: contain;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 22px;
}

.header-note {
  color: var(--muted);
  font-size: 13px;
}

.button {
  min-height: 48px;
  padding: 0 24px;
  border: 1px solid transparent;
  border-radius: 999px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  font-weight: 800;
  text-decoration: none;
  transition:
    transform 180ms ease,
    background 180ms ease,
    border-color 180ms ease;
}

.button:hover {
  transform: translateY(-2px);
}

.button svg {
  width: 19px;
  height: 19px;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.8;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.button-primary {
  color: #fff;
  background: var(--red);
  border-color: var(--red);
}

.button-primary:hover {
  background: var(--red-dark);
  border-color: var(--red-dark);
}

.button-secondary {
  color: #fff;
  background: transparent;
  border-color: rgba(255, 255, 255, 0.22);
}

.button-secondary:hover {
  background: rgba(255, 255, 255, 0.06);
  border-color: rgba(255, 255, 255, 0.36);
}

.button-small {
  min-height: 42px;
  padding: 0 21px;
}

.button-compact {
  min-height: 42px;
  padding: 0 20px;
  font-size: 14px;
}

/* Hero */

.download-hero {
  position: relative;
  overflow: hidden;
  padding: 86px 0 58px;
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.018), transparent 48%),
    #151618;
}

.hero-decoration {
  position: absolute;
  pointer-events: none;
  border: 1px solid rgba(255, 255, 255, 0.11);
  border-radius: 50%;
}

.hero-decoration-one {
  width: 900px;
  height: 380px;
  right: -380px;
  top: -230px;
  transform: rotate(-22deg);
}

.hero-decoration-two {
  width: 760px;
  height: 460px;
  left: -420px;
  bottom: -330px;
  transform: rotate(16deg);
}

.hero-grid {
  position: relative;
  z-index: 2;
  display: grid;
  grid-template-columns: minmax(0, 0.95fr) minmax(440px, 1.05fr);
  gap: clamp(54px, 7vw, 100px);
  align-items: center;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  margin-bottom: 18px;
  color: var(--red);
  font-size: 12px;
  font-weight: 900;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

.hero-content h1 {
  max-width: 650px;
  margin: 0;
  font-size: clamp(48px, 5.2vw, 76px);
  line-height: 1.04;
  letter-spacing: -0.055em;
}

.hero-content h1 strong {
  display: block;
  color: #fff;
  font-weight: inherit;
}

.hero-intro {
  max-width: 610px;
  margin: 24px 0 0;
  color: var(--muted);
  font-size: 17px;
  line-height: 1.85;
}

.hero-buttons {
  margin-top: 32px;
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
}

.download-steps {
  max-width: 620px;
  margin: 52px 0 0;
  padding: 0;
  list-style: none;
}

.download-steps li {
  min-height: 82px;
  display: flex;
  align-items: center;
  gap: 18px;
  border-bottom: 1px solid var(--line);
}

.download-steps li:last-child {
  border-bottom: 0;
}

.step-icon {
  width: 52px;
  height: 52px;
  flex: 0 0 52px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  color: #d8d8dc;
  background: #242529;
  border-radius: 10px;
}

.step-icon svg {
  width: 24px;
  height: 24px;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.65;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.download-steps small {
  display: block;
  margin-bottom: 5px;
  color: var(--muted);
  font-weight: 700;
}

.download-steps strong {
  color: #fff;
  font-size: 18px;
}

.download-steps .is-active strong {
  color: var(--red);
}

/* Signup card */

.signup-panel {
  position: relative;
  min-height: 540px;
  padding: 38px 38px 0;
  overflow: hidden;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius-large);
  background:
    radial-gradient(circle at 70% 70%, rgba(255, 20, 26, 0.07), transparent 30%),
    var(--panel);
}

.signup-panel::before,
.signup-panel::after {
  content: "";
  position: absolute;
  pointer-events: none;
  border: 1px solid rgba(255, 255, 255, 0.09);
  border-radius: 50%;
}

.signup-panel::before {
  width: 520px;
  height: 240px;
  right: -280px;
  top: 110px;
  transform: rotate(-22deg);
}

.signup-panel::after {
  width: 460px;
  height: 220px;
  left: -250px;
  bottom: -110px;
  transform: rotate(18deg);
}

.signup-panel-header {
  position: relative;
  z-index: 2;
  display: flex;
  align-items: center;
  gap: 16px;
}

.signup-mark {
  width: 52px;
  height: 52px;
  flex: 0 0 52px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  color: #d5d5da;
  background: #28292e;
  border-radius: 10px;
}

.signup-mark svg {
  width: 25px;
  height: 25px;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.55;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.signup-panel-header span {
  color: var(--muted);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.signup-panel h2 {
  margin: 5px 0 0;
  color: var(--red);
  font-size: clamp(24px, 2.4vw, 34px);
  line-height: 1.2;
}

.signup-panel > p {
  position: relative;
  z-index: 2;
  max-width: 480px;
  margin: 25px 0 0 68px;
  color: #d1d2d7;
  line-height: 1.75;
}

.signup-button {
  position: relative;
  z-index: 3;
  width: calc(100% - 68px);
  min-height: 46px;
  margin: 28px 0 0 68px;
  padding: 0 20px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  color: var(--red);
  border: 1px solid var(--red);
  border-radius: 999px;
  font-weight: 900;
  text-decoration: none;
  transition: background 180ms ease, color 180ms ease;
}

.signup-button:hover {
  color: #fff;
  background: var(--red);
}

.device-visual {
  position: absolute;
  z-index: 2;
  left: 50%;
  bottom: 8px;
  width: min(88%, 560px);
  margin: 0;
  transform: translateX(-50%);
}

.device-visual img {
  width: 100%;
  height: auto;
  max-height: 255px;
  object-fit: contain;
  object-position: center bottom;
}

/* Platform section */

.platform-section {
  padding: 72px 0 88px;
  background: #101113;
}

.section-heading {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 36px;
  margin-bottom: 30px;
}

.section-heading h2 {
  margin: 0;
  font-size: clamp(32px, 4vw, 48px);
  letter-spacing: -0.045em;
}

.section-heading p {
  max-width: 490px;
  margin: 0;
  color: var(--muted);
  line-height: 1.75;
}

.platform-selector {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.platform-button {
  position: relative;
  min-height: 94px;
  padding: 20px;
  color: var(--muted);
  text-align: left;
  background: transparent;
  border: 0;
  border-right: 1px solid var(--line);
  cursor: pointer;
}

.platform-button:last-child {
  border-right: 0;
}

.platform-button::before {
  content: "";
  position: absolute;
  left: 20px;
  right: 20px;
  top: -1px;
  height: 3px;
  background: transparent;
}

.platform-button.is-active {
  color: #fff;
  background: rgba(255, 255, 255, 0.025);
}

.platform-button.is-active::before {
  background: var(--red);
}

.platform-name {
  display: block;
  margin-bottom: 6px;
  font-size: 19px;
  font-weight: 900;
}

.platform-button small {
  color: var(--muted-dark);
}

.specification-panel {
  margin-top: 32px;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: var(--radius-large);
  background: var(--panel);
}

.specification-header {
  min-height: 118px;
  padding: 28px 32px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  border-bottom: 1px solid var(--line);
}

.specification-header span {
  display: block;
  margin-bottom: 7px;
  color: var(--muted);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.specification-header h2 {
  margin: 0;
  font-size: 27px;
}

.specification-content {
  display: grid;
  grid-template-columns: minmax(0, 1.6fr) minmax(300px, 0.8fr);
}

.specification-main {
  padding: 34px 36px;
}

.specification-item {
  display: grid;
  grid-template-columns: 70px minmax(0, 1fr);
  gap: 24px;
  align-items: start;
}

.spec-number {
  color: var(--red);
  font-size: 42px;
  font-weight: 900;
  line-height: 1;
}

.specification-item h3 {
  margin: 0 0 17px;
  font-size: 26px;
}

.specification-item ul,
.download-note ul {
  margin: 0;
  padding-left: 20px;
  color: var(--muted);
  line-height: 1.8;
}

.download-note {
  padding: 34px;
  background: var(--panel-soft);
  border-left: 1px solid var(--line);
}

.note-label {
  display: inline-flex;
  margin-bottom: 17px;
  color: var(--red);
  font-size: 12px;
  font-weight: 900;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.download-note h3 {
  margin: 0;
  font-size: 23px;
}

.download-note p {
  margin: 16px 0 20px;
  color: var(--muted);
  line-height: 1.75;
}

/* Final CTA */

.final-download {
  padding: 64px 0;
  background:
    radial-gradient(circle at 82% 50%, rgba(242, 13, 19, 0.12), transparent 28%),
    #18191c;
  border-top: 1px solid var(--line);
}

.final-download-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 50px;
}

.final-download h2 {
  max-width: 690px;
  margin: 0;
  font-size: clamp(32px, 4vw, 48px);
  letter-spacing: -0.045em;
}

.final-download p {
  max-width: 650px;
  margin: 17px 0 0;
  color: var(--muted);
  line-height: 1.75;
}

.final-actions {
  flex: 0 0 auto;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

/* Footer */

.site-footer {
  padding: 34px 0;
  background: #090a0c;
  border-top: 1px solid var(--line);
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 36px;
}

.footer-inner img {
  width: auto;
  max-width: 145px;
  max-height: 35px;
  object-fit: contain;
}

.footer-inner p {
  max-width: 680px;
  margin: 0;
  color: #777985;
  font-size: 13px;
  line-height: 1.7;
  text-align: right;
}

[hidden] {
  display: none !important;
}

/* Responsive */

@media (max-width: 980px) {
  .hero-grid {
    grid-template-columns: 1fr;
  }

  .signup-panel {
    min-height: 510px;
  }

  .section-heading,
  .final-download-inner {
    align-items: flex-start;
    flex-direction: column;
  }

  .specification-content {
    grid-template-columns: 1fr;
  }

  .download-note {
    border-top: 1px solid var(--line);
    border-left: 0;
  }

  .final-actions {
    width: 100%;
    flex-direction: row;
    flex-wrap: wrap;
  }
}

@media (max-width: 760px) {
  :root {
    --header-height: 66px;
  }

  .page-shell {
    width: min(100% - 28px, var(--shell));
  }

  .header-inner {
    width: min(100% - 28px, 1400px);
  }

  .header-note {
    display: none;
  }

  .brand img {
    max-width: 145px;
    max-height: 36px;
  }

  .download-hero {
    padding: 58px 0 38px;
  }

  .hero-content h1 {
    font-size: clamp(42px, 13vw, 60px);
  }

  .hero-intro {
    font-size: 16px;
  }

  .hero-buttons,
  .final-actions {
    flex-direction: column;
  }

  .hero-buttons .button,
  .final-actions .button {
    width: 100%;
  }

  .download-steps {
    margin-top: 38px;
  }

  .signup-panel {
    min-height: 500px;
    padding: 28px 22px 0;
  }

  .signup-panel > p {
    margin-left: 0;
  }

  .signup-button {
    width: 100%;
    margin-left: 0;
  }

  .device-visual {
    width: 96%;
  }

  .platform-section {
    padding: 54px 0 66px;
  }

  .platform-selector {
    grid-template-columns: repeat(2, 1fr);
  }

  .platform-button:nth-child(2) {
    border-right: 0;
  }

  .platform-button:nth-child(-n + 2) {
    border-bottom: 1px solid var(--line);
  }

  .specification-header {
    align-items: flex-start;
    flex-direction: column;
  }

  .specification-main,
  .download-note {
    padding: 26px 22px;
  }

  .specification-item {
    grid-template-columns: 1fr;
    gap: 14px;
  }

  .spec-number {
    font-size: 32px;
  }

  .footer-inner {
    align-items: flex-start;
    flex-direction: column;
  }

  .footer-inner p {
    text-align: left;
  }
}

@media (max-width: 440px) {
  .header-actions .button {
    min-height: 40px;
    padding: 0 16px;
    font-size: 13px;
  }

  .signup-panel {
    min-height: 480px;
  }

  .signup-panel-header {
    align-items: flex-start;
  }

  .device-visual {
    bottom: 12px;
  }

  .platform-button {
    min-height: 82px;
    padding: 16px;
  }
}