:root {
  --bg: #F7F8FA;
  --bg-glow: #E8EEF8;
  --text: #12141A;
  --muted: #5A6170;
  --accent: #1A5CFF;
  --accent-soft: rgba(26, 92, 255, 0.08);
  --frame-border: #E2E6EE;
  --white: #FFFFFF;
  --shadow: 0 18px 50px rgba(18, 20, 26, 0.08);
  --radius-img: 4px;
  --radius-btn: 999px;
  --font: "Segoe UI Variable", "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  --max: 1120px;
}

*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
}

body {
  font-family: var(--font);
  color: var(--text);
  background:
    radial-gradient(1200px 600px at 50% -10%, var(--bg-glow), transparent 60%),
    var(--bg);
  line-height: 1.7;
  min-height: 100vh;
}

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

.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;
}

/* —— 首屏：品牌 + 简介同屏 —— */
.top {
  max-width: var(--max);
  margin: 0 auto;
  padding: 3.5rem 1.5rem 1.25rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2rem;
}

.hero {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 0.85rem;
  width: 100%;
}

.hero-brand {
  display: flex;
  align-items: center;
  gap: 0.85rem;
}

.hero-logo {
  width: 64px;
  height: 64px;
  object-fit: contain;
}

.hero-title {
  font-size: clamp(2.6rem, 6.5vw, 4.25rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1;
  color: var(--text);
}

.hero-tagline {
  font-size: clamp(0.98rem, 2vw, 1.15rem);
  color: var(--muted);
  font-weight: 400;
  max-width: 36rem;
}

/* 圆角描边按钮 */
.btn-cta {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  margin-top: 0.35rem;
  padding: 0.72rem 1.85rem;
  min-height: 44px;
  background: transparent;
  color: var(--accent);
  text-decoration: none;
  font-size: 1rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  border: 1.5px solid var(--accent);
  border-radius: var(--radius-btn);
  box-shadow: none;
  transition: background 0.2s ease, color 0.2s ease, border-color 0.2s ease, transform 0.2s ease;
}

.btn-cta:hover {
  background: var(--accent);
  color: var(--white);
  border-color: var(--accent);
  transform: translateY(-1px);
}

.btn-cta:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
}

/* Hero entrance */
.hero-brand,
.hero-tagline,
.btn-cta {
  opacity: 0;
  transform: translateY(14px);
  animation: hero-in 0.6s ease forwards;
}

.hero-tagline { animation-delay: 0.1s; }
.btn-cta { animation-delay: 0.2s; }

@keyframes hero-in {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* —— 简介（首屏可见，无滚动等待） —— */
.about {
  width: 100%;
  max-width: 46rem;
  padding: 0;
  margin: 0 auto;
  text-align: center;
  opacity: 0;
  transform: translateY(14px);
  animation: hero-in 0.65s ease 0.28s forwards;
}

.about .section-title {
  margin-bottom: 0.85rem;
}

.about-text {
  font-size: 1rem;
  color: var(--text);
  max-width: none;
  text-align: left;
  line-height: 1.75;
}

/* —— Sections —— */
.section {
  max-width: var(--max);
  margin: 0 auto;
  padding: 2rem 1.5rem 1rem;
}

.section-title {
  font-size: 0.85rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 1.25rem;
}

.showcase {
  padding-top: 1.5rem;
  padding-bottom: 1.5rem;
}

.showcase-frame {
  background: var(--white);
  border: 1px solid var(--frame-border);
  border-radius: var(--radius-img);
  box-shadow: var(--shadow);
  overflow: hidden;
  padding: 0.5rem;
}

.showcase-img {
  width: 100%;
  border-radius: 2px;
}

/* —— Changelog —— */
.changelog {
  padding-top: 2rem;
  padding-bottom: 2rem;
}

.changelog-root {
  max-width: 46rem;
}

.changelog-status {
  color: var(--muted);
  font-size: 0.95rem;
}

.changelog-list {
  list-style: none;
  margin: 0;
  padding: 0 0 0 1.1rem;
  border-left: 1px solid var(--frame-border);
}

.changelog-item {
  position: relative;
  padding: 0 0 1.6rem 1.25rem;
}

.changelog-item:last-child {
  padding-bottom: 0;
}

.changelog-item::before {
  content: "";
  position: absolute;
  left: -1.15rem;
  top: 0.45rem;
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 3px var(--bg);
}

.changelog-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0.5rem 0.85rem;
  margin-bottom: 0.45rem;
}

.changelog-version {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--text);
  letter-spacing: -0.01em;
}

.changelog-date {
  font-size: 0.9rem;
  color: var(--muted);
}

.changelog-note {
  width: 100%;
  font-size: 0.9rem;
  color: var(--muted);
  margin-top: -0.15rem;
}

.changelog-bullets {
  margin: 0;
  padding-left: 1.15rem;
  color: var(--text);
  font-size: 0.95rem;
}

.changelog-bullets li {
  margin: 0.2rem 0;
}

.changelog-item.is-hidden {
  display: none;
}

.changelog-toggle {
  display: inline-flex;
  align-items: center;
  margin-top: 1.25rem;
  padding: 0;
  border: none;
  background: none;
  color: var(--accent);
  font: inherit;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
}

.changelog-toggle:hover {
  text-decoration: underline;
}

.changelog-toggle:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
}

/* —— Reveal —— */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}

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

/* —— Footer —— */
.footer {
  max-width: var(--max);
  margin: 0 auto;
  padding: 2rem 1.5rem 3.5rem;
  border-top: 1px solid var(--frame-border);
}

.footer-contact {
  color: var(--muted);
  font-size: 0.95rem;
  display: flex;
  flex-direction: row;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem 0.75rem;
}

.footer-sep {
  color: var(--frame-border);
}

/* —— Responsive —— */
@media (max-width: 767px) {
  .top {
    padding: 2.25rem 1.25rem 0.75rem;
    gap: 1.5rem;
  }

  .hero-logo {
    width: 52px;
    height: 52px;
  }

  .hero-brand {
    gap: 0.65rem;
  }

  .btn-cta {
    width: 100%;
    max-width: 18rem;
  }

  .section {
    padding: 1.5rem 1.25rem 0.5rem;
  }

  .about-text {
    font-size: 0.95rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  .hero-brand,
  .hero-tagline,
  .btn-cta,
  .about {
    animation: none;
    opacity: 1;
    transform: none;
  }

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

  .btn-cta {
    transition: none;
  }

  .btn-cta:hover {
    transform: none;
  }
}