JSFiddle - React, Tailwind, and code Playground

HTML

<link href='http://fonts.googleapis.com/css?family=Share:400,400italic,700,700italic' rel='stylesheet' type='text/css'>
<body>
    <div id="header">
        <div id="header_logo" align="left">
            <img src="http://futurized.t15.org/fut_logo.png" style="height: 12px;" />
        </div>
        <div id="menubuttons" style="float: right;">
            <ul>
                <li class='active'><a href='index.html'><span>Home</span></a>

                </li>
                <li><a href='#'><span>Info</span></a>

                </li>
                <li><a href='#'><span>Spenden</span></a>

                </li>
                <li class='last'><a href='#'><span>Kontakt & Impressum</span></a>

                </li>
            </ul>
        </div>
    </div>
    <div id="theme">
        <!-- Anfang Theme // monatliches Thema -->
        <img src="http://wallpapers.funmunch.com/wallpaper_space-wallpaper-015-1680x1050.jpeg?w=1680&h=1050&f=space-wallpaper-015.jpg" alt="Space" style="width: 100%; height: 400px" />
    </div>
    <!-- Ende Theme -->
    <div class="contentLine">
        <!-- main container which contains all columns -->
        <div class="column">Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet.</div>
        <div class="column">Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo...

CSS

body {
    margin: 0 auto;
    padding: 0;
    font-family:'Share', cursive;
}
#header {
    width: 100%;
    vertical-align: middle;
}
#header_logo {
    width:;
    float: left;
    margin: 11px 20px 20px 20px;
    background-color:;
}
#menubuttons {
    margin-right: 0;
    margin-top: 0;
    height: 2.5em;
    line-height: 2.5em;
    display: inline-block;
    background-color: red;
}
#menubuttons ul {
    list-style-type: none;
    margin:0;
    padding:0;
}
#menubuttons li {
    float: left;
    margin-right: 20px;
}
a {
    font-family:'Share', cursive;
}
a:link {
    text-decoration:none;
}
a:visited {
    text-decoration:none;
}
a:hover {
    text-decoration:underline;
}
a:active {
    text-decoration:underline;
}
#theme {
    width: 100%;
    height: 400px;
    background-color: green;
    margin-top: 0;
    float: left;
}
.contentLine {
    margin: 0 auto;
    margin-top: 20px;
    width: 96%;
}
.contentLine .column {
    float: left;
    margin: 0;
    width: 30%;
    margin-right: 1%;
    padding: 1%;
    position: inherit;
    /* shadow for seeing div boundaries */
    box-shadow: 0 0 1px black inset;
}
.contentLine #last {
    margin-right: 0;
}