/* Critical CSS - 首屏渲染优化 */
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html{font-family:system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,'Helvetica Neue',Arial,sans-serif;line-height:1.5;-webkit-text-size-adjust:100%;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale}
body{min-height:100vh;background-color:#f8fafc;color:#0f172a}
#root{min-height:100vh}
a{color:inherit;text-decoration:none}
button,input,select,textarea{font-family:inherit;font-size:inherit}
.container{max-width:1280px;margin:0 auto;padding:0 1rem}
.flex{display:flex}
.items-center{align-items:center}
.justify-center{justify-content:center}
.h-16{height:4rem}
.nav{position:sticky;top:0;z-index:40;background:rgba(255,255,255,0.8);backdrop-filter:blur(12px)}
.btn{display:inline-flex;align-items:center;justify-content:center;padding:0.5rem 1rem;border-radius:0.5rem;font-weight:500;cursor:pointer;border:none;transition:opacity 0.2s}
.btn-primary{background-color:#4f46e5;color:white}
.btn-primary:hover{opacity:0.9}
.card{background:white;border-radius:0.75rem;box-shadow:0 1px 3px rgba(0,0,0,0.1)}
.loading-spinner{width:2rem;height:2rem;border:2px solid #e2e8f0;border-top-color:#4f46e5;border-radius:50%;animation:spin 0.8s linear infinite}
@keyframes spin{to{transform:rotate(360deg)}}