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

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-h) + 16px);
  -webkit-text-size-adjust: 100%;
}

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

body {
  margin: 0;
  min-height: 100vh;
  background-color: var(--bg);
  background-image:
    radial-gradient(900px 520px at 12% -8%, rgba(110, 231, 255, 0.10), transparent 60%),
    radial-gradient(760px 480px at 88% 4%, rgba(167, 139, 250, 0.11), transparent 62%),
    radial-gradient(700px 600px at 50% 108%, rgba(52, 211, 153, 0.07), transparent 60%);
  background-attachment: fixed;
  color: var(--text);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.65;
  letter-spacing: 0.01em;
  overflow-x: hidden;
}

body::after {
  /* 细颗粒噪点，提升深色质感 */
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 3;
  opacity: 0.035;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='140' height='140'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='3'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
}

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

a { color: inherit; text-decoration: none; }

h1, h2, h3, h4 {
  margin: 0;
  line-height: 1.15;
  letter-spacing: -0.02em;
  font-weight: 700;
}

p { margin: 0; }

button {
  font: inherit;
  color: inherit;
  background: none;
  border: 0;
  cursor: pointer;
}

::selection { background: var(--accent-soft); color: #fff; }

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 4px;
}

.skip-link {
  position: fixed;
  top: -60px;
  left: 16px;
  z-index: 60;
  padding: 10px 16px;
  border-radius: var(--radius-sm);
  background: var(--accent);
  color: #04141a;
  font-weight: 600;
  transition: top var(--t-fast) var(--ease-out);
}
.skip-link:focus { top: 12px; }

/* 滚动进度条 */
.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  height: 2px;
  width: 0%;
  z-index: 55;
  background: var(--grad-accent);
  box-shadow: 0 0 14px rgba(110, 231, 255, 0.6);
  transition: width 90ms linear;
}

/* 指针光晕 */
.cursor-glow {
  position: fixed;
  top: 0;
  left: 0;
  width: 420px;
  height: 420px;
  margin: -210px 0 0 -210px;
  border-radius: 50%;
  pointer-events: none;
  z-index: 1;
  opacity: 0;
  background: radial-gradient(circle, rgba(110, 231, 255, 0.13), transparent 62%);
  transition: opacity var(--t-base) var(--ease-out);
  will-change: transform;
}
.cursor-glow.is-on { opacity: 1; }

@media (hover: none) {
  .cursor-glow { display: none; }
}

/* 通用文本与按钮 */
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--accent);
}
.eyebrow::before {
  content: "";
  width: 22px;
  height: 1px;
  background: currentColor;
  opacity: 0.7;
}

.gradient-text {
  background: var(--grad-accent);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.lede { color: var(--text-dim); font-size: 1.05rem; max-width: 62ch; }

.btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 13px 24px;
  border-radius: 999px;
  font-weight: 600;
  font-size: 0.95rem;
  border: 1px solid var(--line-strong);
  transition: transform var(--t-fast) var(--ease-spring),
    border-color var(--t-base) var(--ease-out),
    box-shadow var(--t-base) var(--ease-out),
    background-color var(--t-base) var(--ease-out);
}
.btn:hover { transform: translateY(-2px); }
.btn:active { transform: translateY(0); }
.btn--primary {
  border-color: transparent;
  color: #04141a;
  background: var(--grad-accent);
  box-shadow: 0 14px 34px -16px rgba(110, 231, 255, 0.8);
}
.btn--primary:hover { box-shadow: 0 20px 44px -16px rgba(110, 231, 255, 0.95); }
.btn--ghost { background: var(--bg-card); color: var(--text); }
.btn--ghost:hover { border-color: var(--accent); color: var(--accent); }

.tag {
  display: inline-block;
  padding: 5px 12px;
  border-radius: 999px;
  border: 1px solid var(--line);
  background: var(--bg-card);
  font-size: 0.8rem;
  color: var(--text-dim);
  transition: border-color var(--t-base) var(--ease-out), color var(--t-base) var(--ease-out);
}
.tag:hover { border-color: var(--accent); color: var(--accent); }