kahuna/public/js/upload/prompt/prompt.css

file-prompt {
    display: block;
    background: #444;
    padding: 10px;
}

file-prompt file-uploader {
    display: inline-block;
    padding: 0 5px;
}

file-prompt file-uploader .file-uploader__select-files {
    margin-top: 0;
}

file-prompt .message {
    text-align: center;
}

file-prompt .preset-labels {
    display: flex;
    justify-content: center;
    align-items: baseline;
    padding-top: 10px;
}

file-prompt .preset-labels__heading {
    color: #999;
    font-size: 0.8em;
}