/* ========================================================================
   宸擎科技官网 - 基础样式（reset + 排版 + 通用）
   ======================================================================== */

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

html {
  -webkit-text-size-adjust: 100%;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  scroll-behavior: smooth;
  scroll-padding-top: 80px;
}

body {
  font-family: var(--font-sans);
  font-size: var(--text-body);
  line-height: var(--leading-relaxed);
  color: var(--color-text);
  background: var(--color-bg);
  font-weight: var(--weight-regular);
  min-height: 100vh;
  overflow-x: hidden;
}

img, svg, video, canvas { display: block; max-width: 100%; height: auto; }
img { -webkit-user-drag: none; }

input, button, textarea, select { font: inherit; color: inherit; }
button { background: none; border: none; cursor: pointer; }

a { color: inherit; text-decoration: none; transition: color var(--duration-fast) var(--ease-out); }
a:hover { color: var(--color-accent); }

ul, ol { list-style: none; }

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

/* ========== 排版 ========== */
h1, h2, h3, h4, h5, h6 {
  font-weight: var(--weight-semibold);
  line-height: var(--leading-snug);
  letter-spacing: var(--tracking-tight);
  color: var(--color-text);
}

h1 { font-size: var(--text-h1); line-height: var(--leading-tight); }
h2 { font-size: var(--text-h2); }
h3 { font-size: var(--text-h3); }
h4 { font-size: var(--text-h4); }

p { line-height: var(--leading-relaxed); }

strong, b { font-weight: var(--weight-semibold); }

.kicker {
  display: inline-block;
  font-size: var(--text-kicker);
  font-weight: var(--weight-semibold);
  letter-spacing: var(--tracking-wider);
  text-transform: uppercase;
  color: var(--color-text-tertiary);
  margin-bottom: var(--space-4);
}

.lead { font-size: var(--text-lead); color: var(--color-text-secondary); line-height: var(--leading-relaxed); }

.text-secondary { color: var(--color-text-secondary); }
.text-tertiary  { color: var(--color-text-tertiary); }
.text-accent    { color: var(--color-accent); }
.text-brand     { color: var(--color-brand); }

.text-center { text-align: center; }
.text-left   { text-align: left; }
.text-right  { text-align: right; }

/* 数字等宽 */
.tabular { font-variant-numeric: tabular-nums; }

/* ========== 布局容器 ========== */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--container-pad);
}

.section {
  padding: var(--section-py) 0;
}
.section-sm { padding: var(--section-py-sm) 0; }

.section-subtle { background: var(--color-bg-subtle); }
.section-dark {
  background: var(--color-bg-dark);
  color: var(--color-text-inverse);
}
.section-dark h1, .section-dark h2, .section-dark h3, .section-dark h4 { color: var(--color-text-inverse); }
.section-dark p { color: var(--color-text-inverse-sub); }

/* ========== 网格 ========== */
.grid { display: grid; gap: var(--space-6); }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }

@media (max-width: 1024px) {
  .grid-3, .grid-4 { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 640px) {
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
}

.gap-sm { gap: var(--space-4); }
.gap-md { gap: var(--space-6); }
.gap-lg { gap: var(--space-8); }
.gap-xl { gap: var(--space-12); }

/* ========== 通用工具 ========== */
.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.items-start { align-items: flex-start; }
.items-end { align-items: flex-end; }
.justify-center { justify-content: center; }
.justify-between { justify-content: space-between; }
.flex-wrap { flex-wrap: wrap; }

.mt-2 { margin-top: var(--space-2); }
.mt-4 { margin-top: var(--space-4); }
.mt-6 { margin-top: var(--space-6); }
.mt-8 { margin-top: var(--space-8); }
.mt-12 { margin-top: var(--space-12); }
.mb-2 { margin-bottom: var(--space-2); }
.mb-4 { margin-bottom: var(--space-4); }
.mb-6 { margin-bottom: var(--space-6); }
.mb-8 { margin-bottom: var(--space-8); }
.mb-12 { margin-bottom: var(--space-12); }

.hidden { display: none !important; }

/* 响应式：mobile 隐藏 */
@media (max-width: 768px) {
  .hidden-mobile { display: none !important; }
}
/* 响应式：desktop 隐藏 */
@media (min-width: 769px) {
  .hidden-desktop { display: none !important; }
}

/* ========== 滚动入场动画（与 scroll.js 配合） ========== */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity var(--duration-slow) var(--ease-out),
              transform var(--duration-slow) var(--ease-out);
  will-change: opacity, transform;
}
.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

/* stagger 延迟（同级子元素依次入场） */
.stagger > * { transition-delay: 0ms; }
.stagger.is-visible > *:nth-child(1) { transition-delay: 80ms; }
.stagger.is-visible > *:nth-child(2) { transition-delay: 160ms; }
.stagger.is-visible > *:nth-child(3) { transition-delay: 240ms; }
.stagger.is-visible > *:nth-child(4) { transition-delay: 320ms; }
.stagger.is-visible > *:nth-child(5) { transition-delay: 400ms; }
.stagger.is-visible > *:nth-child(6) { transition-delay: 480ms; }
.stagger.is-visible > *:nth-child(7) { transition-delay: 560ms; }
.stagger.is-visible > *:nth-child(8) { transition-delay: 640ms; }

@media (prefers-reduced-motion: reduce) {
  .reveal, .stagger > * { opacity: 1; transform: none; transition: none; }
  html { scroll-behavior: auto; }
}

/* ========== 焦点可见（可访问性） ========== */
:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}