The placeholder text should always be there, but it depends on your browser, as placeholders are browser-specific.
To add a button, this should help: https://generatepress.com/forums/topic/change-the-search-bar-style-in-split-template/#post-961560
To style the input, try this:
.navigation-search input[type="search"], .navigation-search input[type="search"]:active {
background: #3b6caa;
opacity: 1;
}
::-webkit-input-placeholder { /* Chrome/Opera/Safari */
color: #fff;
}
::-moz-placeholder { /* Firefox 19+ */
color: #fff;
}
:-ms-input-placeholder { /* IE 10+ */
color: #fff;
}
:-moz-placeholder { /* Firefox 18- */
color: #fff;
}
Let me know 🙂