Your style.css file has the text color set for the whole site to a color close to white.   On line 60 you have:
body {
    font-family: 'Orbitron',sans-serif;
    font-size: 13px;
    line-height: 24px;
    color: #fefefe;
    font-weight: 400;
    letter-spacing: 0.06em;
    background-color: #000;
    overflow-y: scroll;
    overflow-x: hidden!important;
    -webkit-font-smoothing: antialiased;
}
You could add a class to override that setting for input form elements below it like:
input {
  color: black;
}
 















