@mumumat:
Hi Muriel:
For this purpose, the theme as a built-in feature Custom CSS. You can add your desired style in here. So if you just want to customize styles, you do not need to create a child theme or edit style.css file. Go to Dashboard=> Appearance=> Customize=> Theme Options=> Custom CSS box and add the following CSS:
#search-toggle {
display: none;
}
By menu color, do you mean menu background color? If so add the following CSS:
.nav-primary {
background-color: #00FF00;
}
Note: Please use you desired color hex.
Regards,
Mahesh