Change the Text Color Inside Search Form Widget
This is a Developer Level doc.
If you're unfamiliar with CSS and/or editing files, codes and templates, as well as with resolving possible conflict, please seek help from a professional. Under our Support Policy, we don't provide support for modifications and customization.
If you want to change the color of the text (default text: Search...) inside Search form widgets that are placed in sidebars or footer widget area, use the following CSS snippet:
/* Change Search Form Placeholder Text Color */
input#s::placeholder {
color: #fff;
}
Change the color value per your need.
All CSS snippets should be added via a child theme's style.css file or using the built-in Custom CSS panel.
Useful Link: HTML Color Picker