#particleCanvas {
    position: fixed; 
    top: 0;
    left: 0;
    z-index: 0; 
    pointer-events: none;
    width: 100vw; 
    height: 100vh; 
}

/* 页面内容层级要高于画布 */
.content {
    position: relative;
    z-index: 1;
}