Override field CSS style in Custom Code


I want to override the field style by using custom code in the page’s header.
I want to override the color of the text by referring to the field using id or mappedTo, but it does not show any changes:

<style> div[data-mappedto="Process Name"] { color: blue; } </style>

Is it even possible to override style of fields in the list using custom code?
Thank you!