/* =========================================================================
   Sync · 官网样式
   基调：编辑部杂志感 —— 暖白纸底、墨色文字、思源宋体标题 + 思源黑体正文，
         品牌紫仅作克制点缀；大量留白、细发丝分隔线。
   ========================================================================= */

:root {
  /* 纸感底色 */
  --paper: #f7f3ea;
  --paper-deep: #efe8d8;
  --paper-card: #fcfaf5;

  /* 墨色文字 */
  --ink: #1c1a15;
  --ink-soft: #5a564c;
  --ink-faint: #6b665a;

  /* 分隔线 */
  --line: #ded5c1;
  --line-strong: #c8bda6;

  /* 品牌紫（克制使用） */
  --accent: #7365f6;
  --accent-deep: #5b4bd8;
  --accent-soft: #ede9fc;

  /* 字体 */
  --serif: "Noto Serif SC", "Source Han Serif SC", "Songti SC", "SimSun", "STSong", serif;
  --sans: "Noto Sans SC", "Source Han Sans SC", "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", sans-serif;

  /* 布局 */
  --container: 1120px;
  --gutter: clamp(20px, 4vw, 44px);

  /* 字号（1.25 比例） */
  --fs-3xl: clamp(2.1rem, 5.4vw, 3.6rem);
  --fs-2xl: clamp(1.6rem, 3.4vw, 2.3rem);
  --fs-xl: 1.25rem;
  --fs-base: 1rem;
  --fs-sm: 0.875rem;
  --fs-xs: 0.75rem;
}

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

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  font-family: var(--sans);
  font-size: var(--fs-base);
  line-height: 1.75;
  color: var(--ink);
  background-color: var(--paper);
  background-image: radial-gradient(
      1200px 600px at 82% -8%,
      rgba(115, 101, 246, 0.05),
      rgba(115, 101, 246, 0) 60%
    );
  background-repeat: no-repeat;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

a {
  color: var(--ink);
  text-decoration: none;
}

a:hover {
  color: var(--accent-deep);
}

::selection {
  background: var(--accent);
  color: var(--paper);
}

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 2px;
}

.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

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

/* ---------- 顶栏 ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(247, 243, 234, 0.92);
  backdrop-filter: saturate(1.2) blur(6px);
  border-bottom: 1px solid var(--line);
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  height: 68px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--serif);
  font-weight: 700;
  font-size: 1.35rem;
  letter-spacing: 0.04em;
  color: var(--ink);
}

.brand:hover {
  color: var(--ink);
}

.brand__mark {
  width: 30px;
  height: 30px;
  flex: none;
}

.brand__slogan {
  display: none;
  font-family: var(--sans);
  font-size: var(--fs-xs);
  letter-spacing: 0.06em;
  color: var(--ink-faint);
  padding-left: 12px;
  margin-left: 4px;
  border-left: 1px solid var(--line-strong);
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 4px;
}

.site-nav a {
  font-size: var(--fs-sm);
  letter-spacing: 0.04em;
  color: var(--ink-soft);
  padding: 8px 14px;
  border-radius: 4px;
  transition: color 0.18s ease;
}

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

.header-cta {
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.header-cta--mobile {
  display: none;
}

/* 移动端菜单开关 */
.nav-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  border: 1px solid var(--line-strong);
  border-radius: 6px;
  background: transparent;
  cursor: pointer;
  color: var(--ink);
}

.nav-toggle svg {
  width: 22px;
  height: 22px;
}

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 9px;
  min-height: 46px;
  padding: 0 22px;
  font-family: var(--sans);
  font-size: 0.95rem;
  font-weight: 500;
  letter-spacing: 0.02em;
  border-radius: 6px;
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform 0.15s ease, background-color 0.18s ease,
    border-color 0.18s ease, color 0.18s ease;
}

.btn:active {
  transform: translateY(1px);
}

.btn svg {
  width: 18px;
  height: 18px;
}

.btn--primary {
  background: var(--accent);
  color: #fff;
}

.btn--primary:hover {
  background: var(--accent-deep);
  color: #fff;
}

.btn--ink {
  background: var(--ink);
  color: var(--paper);
}

.btn--ink:hover {
  background: #000;
  color: var(--paper);
}

.btn--ghost {
  background: transparent;
  color: var(--ink);
  border-color: var(--line-strong);
}

.btn--ghost:hover {
  border-color: var(--ink);
  color: var(--ink);
}

.btn--sm {
  min-height: 40px;
  padding: 0 16px;
  font-size: 0.875rem;
}

/* ---------- 区块通用 ---------- */
.section {
  padding-block: clamp(72px, 10vw, 128px);
  scroll-margin-top: 76px;
}

.section + .section {
  border-top: 1px solid var(--line);
}

.section-head {
  max-width: 640px;
  margin-bottom: clamp(40px, 6vw, 64px);
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-size: var(--fs-xs);
  letter-spacing: 0.16em;
  color: var(--accent-deep);
  margin: 0 0 18px;
}

.eyebrow::before {
  content: "";
  width: 22px;
  height: 1px;
  background: var(--accent);
}

.section-title {
  font-family: var(--serif);
  font-weight: 700;
  font-size: var(--fs-2xl);
  line-height: 1.3;
  letter-spacing: 0.01em;
  margin: 0 0 16px;
  color: var(--ink);
}

.section-desc {
  font-size: 1.05rem;
  color: var(--ink-soft);
  margin: 0;
}

/* ---------- Hero ---------- */
.hero {
  position: relative;
  overflow: hidden;
  padding-block: clamp(32px, 4vw, 56px);
}

.hero__inner {
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(0, 0.8fr);
  gap: clamp(32px, 5vw, 72px);
  align-items: center;
  position: relative;
}

.hero__label {
  display: inline-block;
  font-size: var(--fs-sm);
  letter-spacing: 0.18em;
  color: var(--accent-deep);
  padding-bottom: 10px;
  margin-bottom: 22px;
  border-bottom: 1px solid var(--line-strong);
}

.hero__title {
  font-family: var(--serif);
  font-weight: 700;
  font-size: var(--fs-3xl);
  line-height: 1.22;
  letter-spacing: 0.01em;
  margin: 0 0 22px;
  color: var(--ink);
}

.hero__title em {
  font-style: normal;
  color: var(--accent-deep);
}

.hero__lead {
  font-size: 1.08rem;
  line-height: 1.9;
  color: var(--ink-soft);
  max-width: 30em;
  margin: 0 0 34px;
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
}

.hero__aside {
  display: flex;
  justify-content: center;
  min-width: 0;
}

.hero__screenshot {
  width: auto;
  height: auto;
  max-width: 100%;
  max-height: min(620px, calc(100svh - 180px));
  border: 1px solid var(--line);
  border-radius: 28px;
  box-shadow: 0 18px 40px -16px rgba(28, 26, 21, 0.22);
}

/* ---------- 三步（产品介绍） ---------- */
.steps {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: clamp(28px, 4vw, 56px);
}

.step {
  position: relative;
  padding-top: 8px;
}

.step + .step::before {
  content: "";
  position: absolute;
  left: -1px;
  top: 0;
  bottom: 0;
  width: 1px;
  background: var(--line);
}

.step__num {
  font-family: var(--serif);
  font-weight: 700;
  font-size: 0.95rem;
  letter-spacing: 0.12em;
  color: var(--accent-deep);
  display: block;
  margin-bottom: 20px;
}

.step__icon {
  width: 44px;
  height: 44px;
  color: var(--ink);
  margin-bottom: 22px;
}

.step__title {
  font-family: var(--serif);
  font-weight: 700;
  font-size: 1.35rem;
  margin: 0 0 12px;
  color: var(--ink);
}

.step__body {
  font-size: 0.98rem;
  color: var(--ink-soft);
  margin: 0;
}

/* ---------- 下载 ---------- */
.download-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: clamp(20px, 3vw, 36px);
}

.dl-card {
  background: var(--paper-card);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: clamp(28px, 4vw, 40px);
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.dl-card__head {
  display: flex;
  align-items: center;
  gap: 16px;
}

.dl-card__icon {
  width: 44px;
  height: 44px;
  flex: none;
  color: var(--ink);
}

.dl-card__title {
  font-family: var(--serif);
  font-weight: 700;
  font-size: 1.3rem;
  margin: 0;
}

.dl-card__sub {
  font-size: var(--fs-sm);
  color: var(--ink-faint);
  margin: 2px 0 0;
}

.dl-card__body {
  font-size: 0.95rem;
  color: var(--ink-soft);
  margin: 0;
}

.dl-card__row {
  display: flex;
  align-items: center;
  gap: 24px;
  flex-wrap: wrap;
  margin-top: auto;
}

.qr-placeholder {
  width: 96px;
  height: 96px;
  flex: none;
  color: var(--ink);
  opacity: 0.75;
}

.dl-note {
  margin-top: 28px;
  font-size: var(--fs-sm);
  color: var(--ink-faint);
}

.dl-note strong {
  color: var(--ink-soft);
  font-weight: 500;
}

/* ---------- FAQ ---------- */
.faq {
  max-width: 780px;
  margin-inline: auto;
}

.faq-item {
  border-top: 1px solid var(--line);
}

.faq-item:last-child {
  border-bottom: 1px solid var(--line);
}

.faq-item summary {
  list-style: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  padding: 22px 4px;
  font-family: var(--serif);
  font-weight: 600;
  font-size: 1.1rem;
  color: var(--ink);
  transition: color 0.18s ease;
}

.faq-item summary::-webkit-details-marker {
  display: none;
}

.faq-item summary:hover {
  color: var(--accent-deep);
}

.faq-item__mark {
  flex: none;
  width: 20px;
  height: 20px;
  color: var(--ink-faint);
  transition: transform 0.22s ease;
}

.faq-item[open] .faq-item__mark {
  transform: rotate(45deg);
  color: var(--accent);
}

.faq-item__answer {
  padding: 0 4px 24px;
  color: var(--ink-soft);
  max-width: 640px;
}

.faq-item__answer p {
  margin: 0 0 12px;
}

.faq-item__answer p:last-child {
  margin-bottom: 0;
}

.faq-item__answer a {
  color: var(--accent-deep);
  text-decoration: underline;
  text-underline-offset: 3px;
}

/* ---------- 关于 / 联系 ---------- */
.about-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.1fr) minmax(0, 0.9fr);
  gap: clamp(32px, 5vw, 72px);
  align-items: start;
}

.about-prose {
  font-size: 1.02rem;
  line-height: 1.95;
  color: var(--ink-soft);
}

.about-prose p {
  margin: 0 0 16px;
}

.about-prose strong {
  color: var(--ink);
  font-weight: 500;
}

.contact-card {
  background: var(--paper-card);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: clamp(28px, 4vw, 36px);
}

.contact-card__title {
  font-family: var(--serif);
  font-weight: 700;
  font-size: 1.25rem;
  margin: 0 0 10px;
}

.contact-card__text {
  font-size: 0.95rem;
  color: var(--ink-soft);
  margin: 0 0 22px;
}

.contact-card__qr {
  width: 128px;
  height: 128px;
  margin-bottom: 20px;
  color: var(--ink);
  opacity: 0.8;
}

/* ---------- 页脚 ---------- */
.site-footer {
  border-top: 1px solid var(--line);
  padding-block: 48px 40px;
  background: var(--paper-deep);
}

.site-footer__inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.site-footer__brand {
  font-family: var(--serif);
  font-weight: 700;
  font-size: 1.15rem;
  color: var(--ink);
}

.site-footer__brand small {
  display: block;
  font-family: var(--sans);
  font-weight: 400;
  font-size: var(--fs-xs);
  letter-spacing: 0.06em;
  color: var(--ink-faint);
  margin-top: 4px;
}

.site-footer__links {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 24px;
  font-size: var(--fs-sm);
}

.site-footer__links a {
  color: var(--ink-soft);
}

.site-footer__links a:hover {
  color: var(--accent-deep);
}

.site-footer__meta {
  flex-basis: 100%;
  padding-top: 20px;
  border-top: 1px solid var(--line-strong);
  font-size: var(--fs-xs);
  color: var(--ink-faint);
  display: flex;
  flex-wrap: wrap;
  gap: 8px 28px;
}

/* ---------- 协议 / 政策页 ---------- */
.legal {
  padding-block: clamp(56px, 8vw, 96px);
}

.legal__head {
  border-bottom: 1px solid var(--line-strong);
  padding-bottom: 28px;
  margin-bottom: 40px;
}

.legal__title {
  font-family: var(--serif);
  font-weight: 700;
  font-size: var(--fs-2xl);
  margin: 0 0 12px;
  color: var(--ink);
}

.legal__meta {
  font-size: var(--fs-sm);
  color: var(--ink-faint);
}

.legal__body {
  max-width: 720px;
}

.legal__body h2 {
  font-family: var(--serif);
  font-weight: 700;
  font-size: 1.3rem;
  margin: 44px 0 14px;
  color: var(--ink);
}

.legal__body p {
  color: var(--ink-soft);
  margin: 0 0 14px;
}

.legal__body ul,
.legal__body ol {
  color: var(--ink-soft);
  margin: 0 0 14px;
  padding-left: 1.4em;
}

.legal__body li {
  margin-bottom: 8px;
}

.legal__notice {
  margin-top: 48px;
  padding: 18px 20px;
  border-left: 3px solid var(--accent);
  background: var(--accent-soft);
  border-radius: 0 6px 6px 0;
  font-size: var(--fs-sm);
  color: var(--ink-soft);
}

/* ---------- 响应式 ---------- */
@media (max-width: 900px) {
  .hero__inner {
    grid-template-columns: 1fr;
  }

  .hero__screenshot {
    width: min(100%, 280px);
    max-height: none;
  }

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

  .step + .step::before {
    display: none;
  }

  .step + .step {
    padding-top: 32px;
    border-top: 1px solid var(--line);
    margin-top: 4px;
  }

  .download-grid,
  .about-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 720px) {
  .brand__slogan {
    display: none;
  }

  .site-nav {
    position: absolute;
    top: 68px;
    left: 0;
    right: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 8px var(--gutter) 20px;
    background: var(--paper);
    border-bottom: 1px solid var(--line);
    transform: translateY(-8px);
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transition: opacity 0.2s ease, transform 0.2s ease, visibility 0.2s;
  }

  .site-nav.is-open {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
  }

  .site-nav a {
    padding: 14px 4px;
    font-size: 1rem;
    border-bottom: 1px solid var(--line);
  }

  .header-cta--mobile {
    display: flex;
    margin-top: 16px;
  }

  .header-cta--mobile .btn {
    width: 100%;
  }

  .nav-toggle {
    display: inline-flex;
  }

  .header-cta--desktop {
    display: none;
  }
}

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

  * {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
  }
}