/* ==========================================================================
   base.css — reset、排版基线、容器、按钮、区块头、reveal 动画
   ========================================================================== */

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

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

body {
  background: var(--bg-deep);
  color: var(--text-main);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

/* 全站底部氛围光（静态，不参与动画） */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background:
    radial-gradient(60% 40% at 15% 0%, var(--c-cyan-faint), transparent 70%),
    radial-gradient(50% 38% at 85% 18%, var(--c-purple-faint), transparent 70%);
}

main,
footer {
  position: relative;
  z-index: 1;
}

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

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

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

ul,
ol {
  list-style: none;
}

::selection {
  background: color-mix(in srgb, var(--c-cyan) 35%, transparent);
  color: #fff;
}

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

/* ---- 容器 ---- */
.container {
  width: min(var(--container), calc(100% - 48px));
  margin-inline: auto;
}

section {
  position: relative;
  scroll-margin-top: calc(var(--nav-h) + 16px);
  padding-block: var(--space-96);
}

/* ---- 区块头（eyebrow + H2 + 副标题）---- */
.sec-head {
  max-width: 760px;
  margin-bottom: var(--space-64);
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--c-cyan);
  margin-bottom: var(--space-16);
}

.eyebrow::before {
  content: "";
  width: 28px;
  height: 1px;
  background: var(--grad-brand);
}

h2 {
  font-size: clamp(1.75rem, 3.2vw, 2.5rem);
  font-weight: 700;
  letter-spacing: 0.02em;
  line-height: 1.3;
  background: linear-gradient(180deg, #fff 55%, color-mix(in srgb, var(--c-cyan) 45%, var(--text-main)));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  color: transparent;
}

.sec-sub {
  margin-top: var(--space-16);
  color: var(--text-sub);
  font-size: 1.02rem;
}

/* ---- 按钮 ---- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  min-height: 48px;
  padding: 0 28px;
  border-radius: 999px;
  font-weight: 600;
  letter-spacing: 0.04em;
  transition: transform 0.25s var(--ease-out), opacity 0.25s var(--ease-out);
  will-change: transform;
}

.btn:hover {
  transform: translateY(-2px);
}

.btn:active {
  transform: translateY(0);
}

.btn-primary {
  position: relative;
  color: #041018;
  background: var(--grad-brand);
  box-shadow: var(--glow-cyan-md), var(--glow-purple-sm);
}

.btn-primary::after {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: inherit;
  background: linear-gradient(120deg, #fff, transparent 40%);
  opacity: 0;
  transition: opacity 0.25s;
}

.btn-primary:hover::after {
  opacity: 0.25;
}

.btn-ghost {
  color: var(--text-main);
  border: 1px solid var(--glass-border);
  background: var(--glass-bg);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
}

.btn-ghost:hover {
  border-color: color-mix(in srgb, var(--c-cyan) 45%, var(--glass-border));
  box-shadow: var(--glow-cyan-sm);
}

/* ---- 滚动进入动画（opacity/transform 纪律）---- */
.reveal {
  opacity: 0;
  transform: translateY(28px);
  transition:
    opacity 0.8s var(--ease-out),
    transform 0.8s var(--ease-out);
  transition-delay: calc(var(--i, 0) * 0.12s);
}

.reveal-left {
  transform: translateX(-32px);
}

.reveal-right {
  transform: translateX(32px);
}

.reveal.in-view {
  opacity: 1;
  transform: none;
}

/* ---- 降级：尊重系统减弱动效设置 ---- */
@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
  *,
  *::before,
  *::after {
    animation: none !important;
    transition: none !important;
  }
  .reveal {
    opacity: 1;
    transform: none;
  }
}