.siren {
     position: absolute;
     top: 0;
     left: 0;
     width: 100%;
     height: 100%;
     z-index: 1;
     filter: blur(20px);
     /* 增加模糊感 */
     pointer-events: none;
 }

 /* 红色警灯层 */
 .red {
     background: radial-gradient(circle at 20% 30%, rgba(255, 0, 50, 0.8) 0%, rgba(255, 0, 50, 0) 60%);
     animation: policeFlashRed 5s infinite;
 }

 /* 蓝色警灯层 */
 .blue {
     background: radial-gradient(circle at 80% 70%, rgba(0, 50, 255, 0.8) 0%, rgba(0, 50, 255, 0) 60%);
     animation: policeFlashBlue 5s infinite;
 }

 /* 动画：交替闪烁 */
 @keyframes policeFlashRed {
     0% {
         opacity: 1;
     }

     50% {
         opacity: 0.05;
     }

     100% {
         opacity: 1;
     }
 }

 @keyframes policeFlashBlue {
     0% {
         opacity: 0.05;
     }

     50% {
         opacity: 1;
     }

     100% {
         opacity: 0.05
     }
 }