/* 精聊Chat — 青绿海蓝配色 + 设计令牌 */
:root {
  --brand-magenta: #99f6e4;
  --brand-purple: #14b8a6;
  --brand-cyan: #0369a1;
  --brand-primary: #0f766e;
  --brand-primary-hover: #115e59;

  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #64748b;
  --surface: #ffffff;
  --surface-elevated: #f8fafc;
  --border-subtle: rgba(15, 118, 110, 0.14);

  --radius-sm: 10px;
  --radius-md: 14px;
  --radius-lg: 18px;
  --shadow-card: 0 2px 8px rgba(15, 23, 42, 0.05);
  --shadow-float: 0 12px 40px -16px rgba(15, 23, 42, 0.12), 0 8px 24px -8px rgba(13, 148, 136, 0.14);
  --ease-out: cubic-bezier(0.22, 1, 0.36, 1);
  --section-pad-y: clamp(2.75rem, 6vw, 4.25rem);
  --content-max: 1120px;
}

@media (prefers-reduced-motion: reduce) {
  .banner__bd {
    animation: none;
  }

  .chat-features__card {
    transition: none;
  }

  .chat-features__card:hover {
    transform: none;
  }

  .banner__download-item {
    transition: background-color 0.15s ease;
  }

  .banner__download-item:hover {
    transform: none;
  }
}

@keyframes banner-in {
  from {
    opacity: 0;
    transform: translateY(50px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  scroll-behavior: smooth;
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
}

body {
  margin: 0;
  min-height: 100%;
  background: var(--surface-elevated);
  color: var(--text-primary);
  font-size: 17px;
  font-family:
    "PingFang SC",
    "Microsoft YaHei",
    -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    Roboto,
    "Helvetica Neue",
    Arial,
    sans-serif;
  line-height: 1.6;
}

::selection {
  background: rgba(20, 184, 166, 0.28);
  color: var(--text-primary);
}

.skip-link {
  position: absolute;
  left: 12px;
  top: -100px;
  z-index: 9999;
  padding: 10px 18px;
  border-radius: var(--radius-sm);
  background: var(--brand-primary);
  color: #fff;
  font-size: 14px;
  font-weight: 500;
  text-decoration: none;
  box-shadow: var(--shadow-float);
  transition: top 0.2s var(--ease-out);
}

.skip-link:focus {
  top: 12px;
}

body:has(#android-modal:checked) {
  overflow: hidden;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.wrap {
  position: relative;
  min-height: 100vh;
  overflow-x: hidden;
}

.main-content {
  position: relative;
}

/* —— 顶部绿弧 Banner —— */
.banner {
  position: relative;
  color: rgba(255, 255, 255, 0.9);
  padding: 152px 24px 112px;
  text-align: center;
}

.banner__inner {
  position: absolute;
  z-index: 0;
  left: 50%;
  bottom: 0;
  width: 150%;
  min-width: 1440px;
  height: 100%;
  transform: translateX(-50%);
  background: linear-gradient(
    155deg,
    var(--brand-magenta) 0%,
    var(--brand-purple) 42%,
    var(--brand-cyan) 100%
  );
  border-radius: 0 0 50% 50%;
  overflow: hidden;
  box-shadow: 0 40px 80px -40px rgba(3, 105, 161, 0.45);
}

.banner__bd {
  position: relative;
  z-index: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  animation: banner-in 1.3s both;
}

.banner__logo {
  display: block;
  width: min(320px, 88vw);
  height: auto;
  max-height: 88px;
  object-fit: contain;
  margin: 0 auto 28px;
  filter: drop-shadow(0 8px 24px rgba(0, 0, 0, 0.12));
}

.banner__desc_wrap {
  margin: 0 0 44px;
}

.banner__desc {
  margin: 0;
  font-size: 1.0625rem;
  letter-spacing: 0.04em;
  line-height: 1.65;
  text-align: center;
  text-shadow: 0 1px 18px rgba(0, 0, 0, 0.08);
}

.banner__desc--lead {
  font-size: clamp(1.125rem, 2.8vw, 1.3125rem);
  font-weight: 600;
  letter-spacing: 0.08em;
}

.banner__desc + .banner__desc {
  margin-top: 0.45rem;
  font-weight: 400;
  opacity: 0.94;
  letter-spacing: 0.06em;
}

.banner__download {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  align-items: center;
  justify-items: center;
  column-gap: 24px;
  width: 100%;
  max-width: 640px;
}

.banner__download-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: flex-start;
  width: 120px;
  height: 120px;
  padding-top: 26px;
  border-radius: 50%;
  background-color: rgba(255, 255, 255, 0.09);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid rgba(255, 255, 255, 0.14);
  color: inherit;
  text-decoration: none;
  font-size: 14px;
  font-weight: 500;
  line-height: 1.4;
  cursor: pointer;
  transition:
    background-color 0.25s var(--ease-out),
    transform 0.25s var(--ease-out),
    box-shadow 0.25s var(--ease-out);
}

.banner__download-item:hover {
  background-color: rgba(255, 255, 255, 0.2);
  transform: translateY(-3px);
  box-shadow: 0 12px 28px rgba(0, 0, 0, 0.15);
}

.banner__download-item--btn {
  border: none;
  margin: 0;
  font: inherit;
}

.banner__download-item:focus-visible {
  outline: 2px solid #fff;
  outline-offset: 3px;
}

.icon-svg {
  display: block;
  flex-shrink: 0;
  margin-bottom: 4px;
}

.banner__download-item span {
  margin: 0 10px;
  text-align: center;
}

/* 右上角语言区 */
.lang_change {
  position: absolute;
  top: 32px;
  right: 32px;
  z-index: 2;
  display: flex;
  align-items: center;
  gap: 0;
  font-size: 16px;
  line-height: 1;
}

.lang-switcher__brand {
  color: rgba(255, 255, 255, 0.6);
  text-decoration: none;
  padding: 0 8px;
  transition: color 0.3s ease;
}

.lang-switcher__brand:focus-visible {
  outline: 2px solid rgba(255, 255, 255, 0.85);
  outline-offset: 4px;
  border-radius: 4px;
}

.lang-switcher__sep {
  width: 1px;
  height: 14px;
  background: hsla(0, 0%, 100%, 0.3);
  margin: 0 4px;
}

.lang-switcher__current {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 0 8px;
  color: rgba(255, 255, 255, 0.6);
}

/* —— 介绍图区域 —— */
.intro-showcase {
  position: relative;
  z-index: 1;
  padding: var(--section-pad-y) 24px calc(var(--section-pad-y) + 0.5rem);
  background: linear-gradient(180deg, var(--surface-elevated) 0%, var(--surface) 32%, var(--surface) 100%);
}

.intro-showcase__inner {
  max-width: var(--content-max);
  margin: 0 auto;
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(280px, 1.15fr);
  gap: 40px 56px;
  align-items: center;
}

.intro-showcase__eyebrow {
  margin: 0 0 10px;
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--brand-primary);
}

.intro-showcase__title {
  margin: 0 0 16px;
  font-size: clamp(1.5rem, 2.5vw, 2rem);
  font-weight: 600;
  line-height: 1.35;
  letter-spacing: -0.02em;
  color: var(--text-primary);
}

.intro-showcase__lead {
  margin: 0 0 20px;
  font-size: 16px;
  line-height: 1.75;
  color: var(--text-secondary);
}

.intro-showcase__bullets {
  margin: 0;
  padding: 0;
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.intro-showcase__bullets li {
  position: relative;
  padding-left: 22px;
  font-size: 15px;
  line-height: 1.6;
  color: var(--text-secondary);
}

.intro-showcase__bullets li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.55em;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--brand-magenta), var(--brand-purple));
}

.intro-showcase__figure {
  margin: 0;
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-float);
  border: 1px solid var(--border-subtle);
  background: var(--surface);
}

.intro-showcase__img {
  display: block;
  width: 100%;
  height: auto;
  vertical-align: middle;
}

@media (max-width: 900px) {
  .intro-showcase__inner {
    grid-template-columns: 1fr;
    gap: 28px;
  }

  .intro-showcase__figure {
    order: -1;
    max-width: 560px;
    margin: 0 auto;
    width: 100%;
  }
}

@media (max-width: 600px) {
  .intro-showcase {
    padding: 40px 16px 48px;
  }
}

/* —— 聊天功能介绍网格 —— */
.section-eyebrow {
  margin: 0 0 10px;
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.08em;
  color: var(--brand-primary);
}

.chat-features {
  padding: var(--section-pad-y) 24px calc(var(--section-pad-y) + 0.75rem);
  background: var(--surface-elevated);
  border-top: 1px solid rgba(148, 163, 184, 0.2);
}

.chat-features__inner {
  max-width: var(--content-max);
  margin: 0 auto;
}

.chat-features__header {
  text-align: center;
  max-width: 680px;
  margin: 0 auto 40px;
}

.chat-features__heading {
  margin: 0 0 14px;
  font-size: clamp(1.35rem, 2.4vw, 1.85rem);
  font-weight: 600;
  line-height: 1.35;
  letter-spacing: -0.02em;
  color: var(--text-primary);
}

.chat-features__subtitle {
  margin: 0;
  font-size: 16px;
  line-height: 1.75;
  color: var(--text-secondary);
}

.chat-features__subtitle strong {
  color: var(--text-primary);
  font-weight: 600;
}

.chat-features__grid {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.chat-features__card {
  margin: 0;
  padding: 26px 22px 24px;
  background: var(--surface);
  border-radius: var(--radius-md);
  border: 1px solid var(--border-subtle);
  box-shadow: var(--shadow-card);
  transition:
    transform 0.3s var(--ease-out),
    box-shadow 0.3s var(--ease-out),
    border-color 0.25s ease;
}

.chat-features__card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-float);
  border-color: rgba(20, 184, 166, 0.35);
}

.chat-features__icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  margin-bottom: 16px;
  border-radius: 12px;
  background: linear-gradient(145deg, rgba(45, 212, 191, 0.2), rgba(13, 148, 136, 0.12));
}

.chat-features__icon svg {
  display: block;
}

.chat-features__title {
  margin: 0 0 10px;
  font-size: 17px;
  font-weight: 600;
  color: var(--text-primary);
}

.chat-features__desc {
  margin: 0;
  font-size: 14px;
  line-height: 1.68;
  color: var(--text-muted);
}

.chat-features__desc strong {
  color: var(--text-secondary);
  font-weight: 600;
}

.intro-showcase__lead strong {
  color: #0e7490;
  font-weight: 600;
}

@media (max-width: 900px) {
  .chat-features__grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 560px) {
  .chat-features {
    padding: 36px 16px 44px;
  }

  .chat-features__grid {
    grid-template-columns: 1fr;
  }

  .chat-features__card {
    padding: 20px 18px;
  }
}

/* —— Android 下载弹层（checkbox 控制，无 JS）—— */
.download__dialog-wrp {
  position: fixed;
  inset: 0;
  z-index: 200;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
  visibility: hidden;
  opacity: 0;
  pointer-events: none;
  transition:
    opacity 0.3s ease,
    visibility 0.3s ease;
}

.modal-check:checked ~ .download__dialog-wrp {
  visibility: visible;
  opacity: 1;
  pointer-events: auto;
}

.modal-check:checked ~ .download__dialog-wrp .download__dialog {
  transform: scale(1);
}

.download__dialog-mask {
  position: absolute;
  inset: 0;
  background: rgba(0, 0, 0, 0.5);
  cursor: pointer;
}

.download__dialog {
  position: relative;
  z-index: 1;
  width: min(480px, 100%);
  padding: 24px;
  background: #fff;
  border-radius: 12px;
  box-sizing: border-box;
  transform: scale(0.98);
  transition: transform 0.25s ease;
}

.download__dialog-close {
  position: absolute;
  top: 24px;
  right: 24px;
  width: 24px;
  height: 24px;
  cursor: pointer;
  background: rgba(0, 0, 0, 0.55);
  mask: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='24' height='24' viewBox='0 0 24 24'%3E%3Cpath fill='%23000' fill-rule='evenodd' d='M12.25 10.693L6.057 4.5 5 5.557l6.193 6.193L5 17.943 6.057 19l6.193-6.193L18.443 19l1.057-1.057-6.193-6.193L19.5 5.557 18.443 4.5z'/%3E%3C/svg%3E")
    center / contain no-repeat;
  -webkit-mask: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='24' height='24' viewBox='0 0 24 24'%3E%3Cpath fill='%23000' fill-rule='evenodd' d='M12.25 10.693L6.057 4.5 5 5.557l6.193 6.193L5 17.943 6.057 19l6.193-6.193L18.443 19l1.057-1.057-6.193-6.193L19.5 5.557 18.443 4.5z'/%3E%3C/svg%3E")
    center / contain no-repeat;
}

.download__dialog-hd {
  font-size: 24px;
  font-weight: 500;
  line-height: 29px;
  margin-bottom: 40px;
  padding-top: 48px;
  text-align: center;
  color: rgba(0, 0, 0, 0.9);
}

.download__btn {
  position: relative;
  display: flex;
  align-items: center;
  width: 256px;
  max-width: 100%;
  margin: 0 auto 32px;
  padding-left: 24px;
  height: 70px;
  border-radius: 6px;
  background: rgba(0, 0, 0, 0.05);
  color: rgba(0, 0, 0, 0.9);
  text-decoration: none;
  overflow: hidden;
  box-sizing: border-box;
}

.download__btn:hover::after {
  content: "";
  position: absolute;
  inset: 0;
  background: rgba(0, 0, 0, 0.05);
}

.download__btn_primary {
  background: linear-gradient(90deg, #2dd4bf, var(--brand-primary));
  color: #fff;
}

.download__btn_primary:hover::after {
  background: rgba(255, 255, 255, 0.08);
}

.icon-btn-svg {
  flex-shrink: 0;
  width: 32px;
  height: 32px;
  margin-right: 8px;
}

.download__btn-title {
  font-size: 15px;
  line-height: 18px;
  white-space: nowrap;
}

/* —— 页脚 —— */
.footer-wrp {
  position: relative;
  width: 100%;
  background: var(--surface);
}

.footer-wrp::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(
    90deg,
    var(--brand-magenta),
    var(--brand-purple),
    var(--brand-cyan)
  );
}

.footer {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  box-sizing: border-box;
  width: 100%;
  padding: 48px 24px 40px;
  text-align: center;
}

.footer__bd {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.footer__links {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  margin-bottom: 12px;
  font-size: 13px;
  line-height: 20px;
}

.footer__links a {
  color: var(--text-secondary);
  text-decoration: none;
  white-space: nowrap;
  border-radius: 4px;
}

.footer__links a:hover {
  text-decoration: underline;
  color: var(--brand-primary-hover);
}

.footer__links a:focus-visible {
  outline: 2px solid var(--brand-primary);
  outline-offset: 3px;
}

.footer__divider {
  display: inline-block;
  margin: 0 8px;
  color: var(--text-muted);
  opacity: 0.55;
  vertical-align: middle;
}

.footer__copyright {
  margin-bottom: 12px;
  font-size: 12px;
  line-height: 20px;
  color: var(--text-muted);
}

.footer__social {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
}

.footer__social-link {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 24px;
  height: 24px;
  transition: opacity 0.2s ease;
}

.footer__social-link:hover {
  opacity: 0.7;
}

.footer__social-link svg {
  display: block;
}

@media (min-width: 1440px) {
  .banner__desc {
    font-size: 20px;
  }

  .banner__download {
    column-gap: 32px;
  }
}

@media (max-width: 760px) {
  body {
    font-size: 15px;
  }

  .banner__desc {
    font-size: 16px;
  }

  .download__dialog-close {
    top: 16px;
    right: 16px;
  }

  .download__dialog {
    width: 310px;
  }

  .download__dialog-hd {
    font-size: 22px;
    line-height: 26px;
    padding-top: 34px;
  }

  .download__btn {
    width: 214px;
  }
}

@media (max-width: 600px) {
  .lang_change {
    top: 24px;
    right: 16px;
  }

  .banner__desc {
    font-size: 15px;
  }

  .banner__download {
    grid-template-columns: repeat(2, 1fr);
    row-gap: 24px;
    column-gap: 40px;
    max-width: 320px;
  }

  .footer {
    padding: 32px 16px 24px;
  }
}

@media (max-width: 414px) {
  .banner__download-item {
    width: 100px;
    height: 100px;
    font-size: 13px;
    padding-top: 20px;
  }

  .icon-svg {
    width: 32px;
    height: 32px;
  }
}

@media (max-width: 342px) {
  .download__dialog {
    width: auto;
    max-width: calc(100vw - 32px);
  }
}