/* 基础变量 — 主题色保持不变 */
:root {
  --primary: hsl(351 79% 54%);
  --primary-light: hsl(351 79% 64%);
  --primary-dark: hsl(351 79% 42%);
  --primary-glow: hsl(351 79% 54% / 0.45);
  --primary-soft: hsl(351 80% 96%);
  --foreground: hsl(0 0% 7%);
  --muted: hsl(215 8% 46%);
  --card: hsl(0 0% 100%);
  --dark: hsl(0 0% 7%);
  --radius: 0.75rem;
  --max-w: 80rem;
}

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

html { scroll-behavior: smooth; }

body {
  font-family: 'Noto Sans SC', -apple-system, BlinkMacSystemFont, sans-serif;
  color: var(--foreground);
  line-height: 1.65;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

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

.container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 1.25rem;
}

@media (min-width: 768px) {
  .container { padding: 0 2rem; }
}

/* 滚动入场 — JS 加 .visible */
.reveal {
  opacity: 0;
  transform: translateY(48px);
  transition: opacity 0.85s cubic-bezier(0.22, 1, 0.36, 1),
              transform 0.85s cubic-bezier(0.22, 1, 0.36, 1);
}
.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}
.reveal-left,
.reveal-right,
.reveal-scale {
  opacity: 0;
  transition: opacity 0.85s cubic-bezier(0.22, 1, 0.36, 1),
              transform 0.85s cubic-bezier(0.22, 1, 0.36, 1);
}
.reveal-left { transform: translateX(-60px); }
.reveal-left.visible { opacity: 1; transform: translateX(0); }
.reveal-right { transform: translateX(60px); }
.reveal-right.visible { opacity: 1; transform: translateX(0); }
.reveal-scale { transform: scale(0.88); }
.reveal-scale.visible { opacity: 1; transform: scale(1); }

.stagger > *:nth-child(1) { transition-delay: 0.05s; }
.stagger > *:nth-child(2) { transition-delay: 0.12s; }
.stagger > *:nth-child(3) { transition-delay: 0.19s; }
.stagger > *:nth-child(4) { transition-delay: 0.26s; }
.stagger > *:nth-child(5) { transition-delay: 0.33s; }
.stagger > *:nth-child(6) { transition-delay: 0.4s; }

/* Header */
.site-header {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 200;
  padding: 0.75rem 0;
  transition: background 0.4s, box-shadow 0.4s, padding 0.4s;
}
.site-header.scrolled {
  background: hsl(0 0% 100% / 0.92);
  backdrop-filter: blur(16px);
  box-shadow: 0 4px 30px hsl(0 0% 0% / 0.08);
  padding: 0.5rem 0;
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}
.logo {
  display: flex;
  align-items: center;
  gap: 0.625rem;
  font-weight: 800;
  font-size: 1rem;
  z-index: 2;
}
.logo img { height: 36px; width: auto; }

.nav-toggle {
  display: flex;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  z-index: 2;
}
.nav-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--foreground);
  transition: 0.3s;
  border-radius: 2px;
}
.nav {
  display: none;
  position: fixed;
  inset: 0;
  background: hsl(0 0% 100% / 0.98);
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  z-index: 1;
}
.nav.open { display: flex; }
.nav a {
  font-size: 1.125rem;
  font-weight: 500;
  padding: 0.5rem 1rem;
  border-radius: var(--radius);
  transition: color 0.2s, background 0.2s;
}
.nav a:hover, .nav a.active {
  color: var(--primary);
  background: var(--primary-soft);
}

@media (min-width: 1100px) {
  .nav-toggle { display: none; }
  .nav {
    display: flex;
    position: static;
    flex-direction: row;
    flex-wrap: wrap;
    background: none;
    justify-content: flex-end;
    gap: 0.125rem;
  }
  .nav a { font-size: 0.8125rem; }
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.875rem 2rem;
  font-size: 1rem;
  font-weight: 500;
  line-height: 1.25;
  border-radius: 0.375rem;
  border: none;
  cursor: pointer;
  text-decoration: none;
  position: relative;
  overflow: hidden;
  transition:
    transform 0.25s cubic-bezier(0.22, 1, 0.36, 1),
    box-shadow 0.25s,
    background 0.25s,
    border-color 0.25s;
}
.btn::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(120deg, transparent 30%, hsl(0 0% 100% / 0.22) 50%, transparent 70%);
  transform: translateX(-100%);
  transition: transform 0.55s ease;
  pointer-events: none;
}
.btn:hover::after { transform: translateX(100%); }
.btn:hover { transform: translateY(-2px) scale(1.03); }
.btn:active { transform: scale(0.97); }
.btn svg { flex-shrink: 0; }
.btn .btn-arrow { transition: transform 0.25s; }
.btn:hover .btn-arrow { transform: translateX(4px); }

.btn-primary {
  background: var(--primary);
  color: #fff;
  box-shadow: 0 10px 15px hsl(351 79% 54% / 0.25);
}
.btn-primary:hover {
  box-shadow: 0 10px 25px hsl(351 79% 54% / 0.4);
}

.btn-ghost {
  background: hsl(0 0% 100% / 0.05);
  color: #fff;
  border: 1px solid hsl(0 0% 100% / 0.3);
  backdrop-filter: blur(8px);
}
.btn-ghost:hover {
  background: hsl(0 0% 100% / 0.1);
  border-color: hsl(0 0% 100% / 0.5);
}

.btn-lg {
  padding: 1rem 2.5rem;
}

.section { padding: 5rem 0; position: relative; }
.section-tag {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.25em;
  text-transform: uppercase;
  color: var(--primary);
  margin-bottom: 0.75rem;
}
.section-title {
  font-size: clamp(1.5rem, 3.5vw, 2.25rem);
  font-weight: 700;
  line-height: 1.3;
  margin-bottom: 1rem;
}
.section-title em {
  font-style: normal;
  color: var(--primary);
}
.section-desc {
  color: var(--muted);
  max-width: 36rem;
  font-size: 1.0625rem;
}

/* Overview — 左侧随 overview-item.visible 联动 */
.overview-section {
  padding: 5rem 0;
}

.overview-grid {
  display: grid;
  gap: 3rem;
  grid-template-columns: minmax(220px, 340px) 1fr;
  align-items: start;
}

.overview-aside {
  position: relative;
  align-self: start;
}

.overview-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 1rem;
}

.overview-tag {
  padding: 0.375rem 0.875rem;
  background: var(--primary-soft);
  color: var(--primary);
  border-radius: 999px;
  font-size: 0.8125rem;
  font-weight: 600;
  transition: background 0.35s, color 0.35s, box-shadow 0.35s;
}

.overview-tag.is-active {
  background: var(--primary);
  color: #fff;
  box-shadow: 0 4px 16px hsl(351 79% 54% / 0.22);
}

.overview-content {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.overview-content .overview-item.pain-card {
  margin-bottom: 0;
}

.overview-content .overview-item .overview-item-num {
  color: var(--primary);
  font-weight: 900;
  font-size: 0.875rem;
}

.overview-content .overview-item p {
  margin-top: 0.5rem;
  color: var(--muted);
  font-size: 0.9375rem;
  line-height: 1.75;
}

@media (max-width: 900px) {
  .overview-grid {
    grid-template-columns: 1fr;
  }
}

/* Footer */
.site-footer {
  background: var(--dark);
  color: hsl(0 0% 100% / 0.65);
  padding: 3rem 0 1.5rem;
  font-size: 0.875rem;
}
.footer-grid {
  display: grid;
  gap: 2rem;
  margin-bottom: 2rem;
}
@media (min-width: 768px) {
  .footer-grid { grid-template-columns: 2fr 1fr 1fr; }
}
.footer-brand .name {
  font-size: 1.25rem;
  font-weight: 800;
  color: white;
  margin-bottom: 0.5rem;
}
.footer-col h4 {
  color: white;
  margin-bottom: 0.875rem;
}
.footer-col a {
  display: block;
  padding: 0.25rem 0;
  color: hsl(0 0% 100% / 0.55);
  transition: color 0.2s;
}
.footer-col a:hover { color: var(--primary-light); }
.footer-bottom {
  border-top: 1px solid hsl(0 0% 100% / 0.08);
  padding-top: 1.5rem;
  text-align: center;
  color: hsl(0 0% 100% / 0.4);
}

/* 光标跟随光晕（由 JS 控制） */
@media (max-width: 768px) {
  .overview-grid { grid-template-columns: 1fr !important; }
}

.cursor-glow {
  position: fixed;
  width: 400px;
  height: 400px;
  border-radius: 50%;
  pointer-events: none;
  z-index: 0;
  transform: translate(-50%, -50%);
  opacity: 0;
  transition: opacity 0.4s;
  mix-blend-mode: multiply;
}