Contact Form 7

Useful CSS

Input color, background-color and border-color:

input[type="text"],
input[type="password"],
input[type="color"],
input[type="date"],
input[type="datetime"],
input[type="datetime-local"],
input[type="email"],
input[type="number"],
input[type="range"],
input[type="search"],
input[type="tel"],
input[type="time"],
input[type="url"],
input[type="month"],
input[type="week"],
textarea {
    border: 1px solid #dfe5e8 !important;
    background-color: #f5f7f6 !important; 
    color: #3c3950 !important; 
}

Submit button color and background-color:

.wpcf7 input[type='submit'] {
        background-color: #3c3950;
        color: #ffffff;
}

Submit button  hover colors:

.wpcf7 input[type='submit']:hover {
        background-color: #3c3950;
        color: #ffffff;
}

You can modify this css and insert it in Theme Options -> Custom CSS to apply on all contact forms:

To apply this custom CSS on a single content element only, use the "Extra class name" field in this element in WPBakery:

The example of the css selector for the "custom-contact-form" class name in this case:

.custom-contact-form .wpcf7 input[type='submit'] {
        background-color: #3c3950;
        color: #ffffff;
}