/* 几何 — 站点入口首页
   设计语言：Apple 浅色（白 / #f5f5f7 两调、#1d1d1f 墨色、#0071e3 蓝、980px 胶囊）
   动效：仅一段编排好的入场序列 + 一层极淡呼吸光晕 */

:root {
  --paper: #ffffff;
  --paper-alt: #f5f5f7;
  --ink: #1d1d1f;
  --ink-2: #6e6e73;
  /* 苹果官网版权行用 #86868b，但它在 #f5f5f7 上只有 3.33:1，不过 WCAG AA；
     这里收深到 #6e6e73（4.66:1）以保住对比度基线。 */
  --ink-3: #6e6e73;
  --blue: #0071e3;
  --blue-hover: #0077ed;
  --hairline: #d2d2d7;
  --green: #30d158;
  --pill: 980px;
  --ease: cubic-bezier(.16, 1, .3, 1);
  --font: -apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Text",
          "Helvetica Neue", "PingFang SC", "Microsoft YaHei", sans-serif;
}

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

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

body.home {
  min-height: 100svh;
  margin: 0;
  overflow-x: hidden;
  background: linear-gradient(to bottom, var(--paper) 58%, var(--paper-alt) 100%);
  color: var(--ink);
  font-family: var(--font);
  font-size: 17px;
  line-height: 1.47;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* 唯一的环境动效：标题背后一层几乎看不见的蓝色光晕 */
.home__glow {
  position: fixed;
  z-index: 0;
  inset: 0;
  pointer-events: none;
  background: radial-gradient(58% 46% at 50% 40%, rgba(0, 113, 227, .07), transparent 72%);
  animation: glowBreathe 14s ease-in-out infinite;
}

.home__shell {
  position: relative;
  z-index: 1;
  min-height: 100svh;
  display: grid;
  grid-template-rows: auto 1fr auto;
}

/* ---------- 顶栏 ---------- */

.topbar {
  position: sticky;
  top: 0;
  z-index: 10;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  width: 100%;
  padding: 0 max(22px, calc((100% - 980px) / 2));
  border-bottom: 1px solid var(--hairline);
  background: rgba(255, 255, 255, .72);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  backdrop-filter: saturate(180%) blur(20px);
  opacity: 0;
  animation: fade .6s .05s var(--ease) forwards;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  color: var(--ink);
  text-decoration: none;
}

.brand__mark { width: 24px; height: 24px; display: block; object-fit: contain; }

.brand__name {
  font-size: 15px;
  font-weight: 600;
  letter-spacing: -.01em;
}

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

.topbar__link {
  color: var(--ink);
  font-size: 12px;
  text-decoration: none;
  transition: color .2s ease;
}

.topbar__link:hover { color: var(--blue); }

.topbar__state {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  color: var(--ink-2);
  font-size: 12px;
  white-space: nowrap;
}

.topbar__state i,
.dot {
  width: 6px;
  height: 6px;
  flex: 0 0 auto;
  border-radius: 50%;
  background: var(--green);
}

/* ---------- 主视觉 ---------- */

.hero {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  width: min(980px, calc(100% - 44px));
  margin: 0 auto;
  padding: 6vh 0 7vh;
  text-align: center;
}

.hero__title {
  margin: 0;
  font-size: clamp(40px, 6.4vw, 80px);
  font-weight: 600;
  letter-spacing: -.022em;
  line-height: 1.08;
}

/* 签名元素：标题逐行从遮罩后升起 */
.hero__line {
  display: block;
  overflow: hidden;
  padding-bottom: .14em;
  margin-bottom: -.14em;
}

.hero__line > span {
  display: block;
  transform: translateY(115%);
  animation: lineRise .95s var(--ease) forwards;
}

.hero__line:nth-child(1) > span { animation-delay: .16s; }
.hero__line:nth-child(2) > span { animation-delay: .27s; }
.hero__line--accent > span { color: var(--blue); }

.hero__lead {
  max-width: 34ch;
  margin: 20px 0 0;
  color: var(--ink-2);
  font-size: clamp(17px, 1.6vw, 21px);
  font-weight: 400;
  letter-spacing: .011em;
  line-height: 1.52;
  text-wrap: balance;
  opacity: 0;
  animation: rise .7s .46s var(--ease) forwards;
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 14px 30px;
  margin-top: 32px;
  opacity: 0;
  animation: rise .7s .58s var(--ease) forwards;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  font-size: 17px;
  line-height: 1.23;
  text-decoration: none;
  white-space: nowrap;
}

.btn--primary {
  padding: 11px 25px;
  border-radius: var(--pill);
  background: var(--blue);
  color: #fff;
  transition: background .2s ease;
}

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

.btn--link { gap: 3px; color: var(--blue); }

.btn--link b {
  font-size: 20px;
  font-weight: 400;
  line-height: 1;
  transition: transform .2s var(--ease);
}

.btn--link:hover { text-decoration: underline; text-underline-offset: 3px; }
.btn--link:hover b { transform: translateX(3px); }

/* ---------- 底栏 ---------- */

.footbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px 24px;
  width: min(980px, calc(100% - 44px));
  margin: 0 auto;
  padding: 17px 0 20px;
  border-top: 1px solid var(--hairline);
  color: var(--ink-2);
  font-size: 12px;
  opacity: 0;
  animation: fade .7s .72s var(--ease) forwards;
}

.footbar__status { display: flex; align-items: center; gap: 10px; }

.footbar__status time {
  font-variant-numeric: tabular-nums;
  letter-spacing: .02em;
}

.footbar__sep { width: 1px; height: 11px; background: var(--hairline); }

.footbar__copy { color: var(--ink-3); font-size: 12px; }

/* ---------- 焦点可见 ---------- */

a:focus-visible {
  outline: 2px solid var(--blue);
  outline-offset: 3px;
  border-radius: 6px;
}

.btn--primary:focus-visible { border-radius: var(--pill); outline-offset: 4px; }

/* ---------- 关键帧 ---------- */

@keyframes lineRise { to { transform: translateY(0); } }
@keyframes fade { to { opacity: 1; } }
@keyframes rise { from { opacity: 0; transform: translateY(16px); } to { opacity: 1; transform: none; } }
@keyframes glowBreathe {
  0%, 100% { opacity: .82; transform: scale(1); }
  50%      { opacity: 1;   transform: scale(1.05); }
}

/* ---------- 响应式（沿用 Apple 的 734px 断点） ---------- */

@media (max-width: 734px) {
  body.home { font-size: 16px; }

  .topbar { padding: 0 18px; }
  .topbar__nav { gap: 15px; }
  .topbar__state { display: none; }

  .hero { width: calc(100% - 36px); padding: 4vh 0 6vh; }
  .hero__title { font-size: clamp(34px, 9.2vw, 46px); letter-spacing: -.016em; }
  .hero__lead { max-width: 26ch; margin-top: 15px; font-size: 16px; line-height: 1.5; }
  .hero__actions { gap: 12px; margin-top: 26px; }
  .btn { width: 100%; }
  .btn--primary { padding: 12px 24px; }

  .footbar {
    flex-direction: column;
    gap: 9px;
    width: calc(100% - 36px);
    padding: 15px 0 18px;
    text-align: center;
  }
}

@media (max-height: 620px) {
  .hero { padding: 3vh 0 4vh; }
  .hero__lead { margin-top: 12px; }
  .hero__actions { margin-top: 20px; }
}

/* ---------- 降级动效 ---------- */

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: .001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .001ms !important;
  }

  .home__glow { opacity: .9; transform: none; }
  .topbar, .hero__lead, .hero__actions, .footbar { opacity: 1; }
  .hero__line > span { transform: none; }
}