.blurred-box {
    position: relative;
    width: 250px;
    height: 350px;
    top: calc(50% - 175px);
    left: calc(50% - 125px);
    background: inherit;
    border-radius: 2px;
    overflow: hidden;
}

    .blurred-box:after {
        content: '';
        width: 300px;
        height: 300px;
        background: inherit;
        position: absolute;
        left: -25px;
        left position right: 0;
        top: -25px;
        top position bottom: 0;
        box-shadow: inset 0 0 0 200px rgba(255,255,255,0.05);
        filter: blur(10px);
    }