@property --mask-start{syntax:"<length-percentage>";inherits:false;initial-value:100%}@property --mask-stop{syntax:"<length-percentage>";inherits:false;initial-value:100%}.gradient-mask{-webkit-mask-image:linear-gradient(to bottom,black var(--mask-start),transparent var(--mask-stop),transparent);-webkit-mask-image:linear-gradient(to bottom,black var(--mask-start),transparent var(--mask-stop),transparent);mask-image:linear-gradient(to bottom,black var(--mask-start),transparent var(--mask-stop),transparent);transition:--mask-start .45s,--mask-stop .45s}