:root {
    --BG: linear-gradient(to top left, #ff00bf 0%, transparent 100%); 
    --FG: linear-gradient(to bottom, #002fff 75%, transparent 100%);
} 

.winder {
    position: absolute;
    z-index: 1;
    background: 
        linear-gradient(aliceblue 0 0) padding-box, /*this is your grey background*/
        linear-gradient(to top left, #ff00bf, white) border-box;
    border: 5px solid transparent;
    border-image-slice: 1;
    border-radius: 5px;
    box-shadow: 0 0 10px black;
}

.winderheader {
    padding-bottom: 5px;
    padding-left: 5px;
    cursor: move;
    z-index: 2;
    background: var(--FG);
    color: #fdfdff;
    height: 50px;
    font-family: barcodetext;
    font-size: 40px;
}

.windercontent {
    padding-left: 5px;
    padding-right: 5px;
    border-radius: 5px;
    font-size: 20px;
}