/* 背景渐变效果 */
#background {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -2;
    background: 
        radial-gradient(circle at 20% 30%, rgba(46, 16, 16, 0.3) 0%, transparent 40%),
        radial-gradient(circle at 80% 80%, rgba(20, 20, 46, 0.3) 0%, transparent 40%),
        linear-gradient(to bottom, #0a0a0a, #111122, #0a0a0a);
}

/* 粒子背景画布 */
#particles {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
}