Disallow duplicate properties

Rule from css under compatibility category

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A block in a stylesheet may have zero or more declarations. While syntactically correct, duplicate declarations add unnecessary size to a stylesheet and can increase interpretation time. Instances can occur where duplicate declarations are needed, for instance when supporting multiple browsers with varying levels of support for a given property.

.an .element {

    /* this is not valid */
    color: red;
    background-color: crimson;
    color: blue;

    /* this is valid */
    color: rgb(255, 255, 255);
    color: rgba(255, 255, 255, 1);

How do I fix this ?

Check all stylesheets for the presence of two or more identical properties in any selector block and remove the one that is unneeded or erroneous.


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