/* ═══════════════════════════════════════════
   期许AI Base Styles v2.0
   Reset + Typography + Layout + Utilities
   ═══════════════════════════════════════════ */

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}

body {
  font-family: var(--font-sans);
  background: var(--qixu-bg-base);
  color: var(--qixu-text-primary);
  line-height: 1.7;
  overflow-x: hidden;
  font-variant-numeric: tabular-nums;
  transition: background var(--transition-slow), color var(--transition-slow);
}

a { color: inherit; text-decoration: none; }
button { font-family: inherit; cursor: pointer; border: none; background: none; }
img, svg { display: block; max-width: 100%; }
ul, ol { list-style: none; }
table { border-collapse: collapse; width: 100%; }

::selection {
  background: var(--qixu-primary);
  color: #fff;
}

/* ── 全局深色滚动条（极光风格）── */
html {
  scrollbar-width: thin;
  scrollbar-color: var(--qixu-border) transparent;
}
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb {
  background: var(--qixu-border);
  border-radius: 10px;
  transition: background var(--transition-fast);
}
::-webkit-scrollbar-thumb:hover { background: var(--qixu-primary); }

/* ── Typography Scale ── */
.t-display { font-size: clamp(36px, 5.5vw, 60px); font-weight: 900; letter-spacing: 0; line-height: 1.08; }
.t-h1 { font-size: clamp(28px, 4vw, 44px); font-weight: 900; letter-spacing: 0; line-height: 1.12; }
.t-h2 { font-size: clamp(24px, 3vw, 34px); font-weight: 800; letter-spacing: 0; line-height: 1.18; }
.t-h3 { font-size: clamp(18px, 2vw, 22px); font-weight: 700; letter-spacing: 0; line-height: 1.3; }
.t-h4 { font-size: 17px; font-weight: 600; line-height: 1.35; }
.t-body { font-size: 16px; line-height: 1.75; }
.t-body-sm { font-size: 14px; line-height: 1.65; }
.t-caption { font-size: 13px; line-height: 1.5; color: var(--qixu-text-muted); }
.t-mono { font-family: var(--font-mono); }
.t-gradient { background: var(--qixu-gradient-brand); -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text; }

/* ── Layout Containers ── */
.container {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 var(--space-8);
}

.container-wide {
  max-width: var(--maxw-wide);
  margin: 0 auto;
  padding: 0 var(--space-8);
}

/* ── Section (呼吸感：加大垂直间距) ── */
.section {
  padding: var(--space-32) 0;
}

.section-lg {
  padding: var(--space-28) 0;
}

.section-md {
  padding: var(--space-20) 0;
}

/* ── Section Header ── */
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--qixu-primary-light);
  background: var(--qixu-primary-glow);
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-full);
  margin-bottom: var(--space-6);
}

.section-header {
  margin-bottom: var(--space-16);
}

.section-header.center {
  text-align: center;
}

.section-header.center .eyebrow {
  margin-left: auto;
  margin-right: auto;
}

.section-header.center .section-desc {
  margin-left: auto;
  margin-right: auto;
}

.section-title {
  font-size: clamp(28px, 4vw, 42px);
  font-weight: 900;
  letter-spacing: 0;
  line-height: 1.15;
  margin-bottom: var(--space-6);
}

.section-desc {
  font-size: 17px;
  color: var(--qixu-text-secondary);
  max-width: 640px;
  line-height: 1.75;
}

/* ── Scroll Reveal ── */
.reveal {
  opacity: 0;
  transform: translateY(28px);
  transition: opacity 0.7s var(--ease-out), transform 0.7s var(--ease-out);
}

.reveal.in {
  opacity: 1;
  transform: translateY(0);
}

.reveal[data-delay="1"] { transition-delay: 0.1s; }
.reveal[data-delay="2"] { transition-delay: 0.2s; }
.reveal[data-delay="3"] { transition-delay: 0.3s; }
.reveal[data-delay="4"] { transition-delay: 0.4s; }

/* ── Divider ── */
.divider {
  height: 1px;
  background: var(--qixu-border);
  margin: var(--space-16) 0;
}

/* ── Page wrapper for inner pages ── */
.page-wrapper {
  min-height: 100vh;
  padding-top: var(--nav-h);
}