JSFiddle - React, Tailwind, and code Playground

HTML

<form action="http://do.convertapi.com/web2pdf">
    <div id="main_form">
        <h3> Convert web page and return PDF file as stream</h3>
        <label for="curl">Api Key:</label>
        <input type="text" name="ApiKey" value="" style="width:300px;"/>
        <label for="curl">Enter Url for converting.</label>
        <input type="text" name="curl" value="https://diy-tickets.com/includes/makepdf.php?tid=1393963381" style="width:400px;"/>
        <input type="submit" value="Convert" />
        <input type="button" onclick="javascript:document.getElementById('option_form').style.display = 'inline-block';document.getElementById('main_form').style.display = 'none';"  value="Options"/><br />
    </div>
    <div id="option_form" style="margin: auto">
        <div id="leftContainer" class="optionPanel">
            <div>
                <label>Security</label>
                <span title="HTTP authentication username, used if conversion web page is protected with HTTP authentication.">
                    <span style="width:95px">user name:</span><input type="text" name="AuthUsername" />
                </span><br />
                <span title="HTTP Authentication password, used if conversion web page is protected with HTTP authentication.">
                    <span style="width:95px">user password:</span><input type="password" name="AuthPassword" />
                </span>
            </div>
            <div>
                <label>Page</label>
                <span title=" PDF page orientation">
                    orietation:
                        <input type="radio" name="PageOrientation" title="Portrait page orientation" value="portrait" checked="checked" />portrait
                        <input type="radio" name="PageOrientation" title="Landscape page orientation" value="landscape" />landscape
                </span><br />

                <span title=" PDF page paper sizes">
                    size:
                    <select name="PageSize">
          ...

CSS

p{margin:2px; font-weight:bold;}
span{vertical-align:middle;display:inline-block; margin-top:5px;}
label {font-size:18px; color:#3D668F; display:block; font-weight:bold; margin-top:12px;}
input[type="text"], input[type="password"], select, textarea {
border: 1px solid #E4E4E4;
width: 150px;
height: 22px;
line-height: 22px;
-moz-border-radius: 3px;
border-radius: 3px;
margin: 2px 5px;
padding-left: 0;
padding-right: 0;
}
input[type="button"], input[type="submit"] {
-moz-border-radius: 5px;
cursor: pointer;
color: white;
border-radius: 5px;
border: 1px #747472 solid;
background-color: #3D668F;
height: 28px;
text-decoration: none;
text-shadow: 0 1px 1px #253E5C;
font-weight: bold;
margin-top:5px;
}
input.mini{width:50px;}
#option_form{display:none;}
.optionPanel {float:left;margin: 2px 5px;}