ar-demo/miniprogram/pages/camera2/camera.wxss

/* pages/camera/camera.wxss */
.camera{
    width: 100vw;
    height: 100vh;
    position: relative;
}
.opt{
    width: 100vw;
    height: 100vh;
    position: absolute;
    z-index: 1000;
    top:0;
    left:0;
    display: flex;
    justify-content: center;
    align-items: center;
}