Mehr als zwei Tabellen auf einer Seite führt zur Formatierungsproblemen

<!doctype html>
<html>
  <head>
    <meta charset = "utf-8">
    <title> </title>
    <style> 
		table {
			font-family: 'Open Sans', 'Neue Helvetica', Helvetica, Arial, sans-serif;
			font-size: 90%;
			text-align: left;
			border-collapse: collapse;
			width:100%;
		}
		td, th {
			padding: 1em;
			vertical-align: top;
		}
		thead th {
			background-color: #6d6e71;
			color: #ffffff;
			text-align: left;
		}
		tbody th {
			font-weight: normal;
			text-align: left;
		}
		td {
			/* text-align: left; */
			width: 20%;
		}
		td:nth-child(2) {
			width: 50%;
		}
	        td:nth-child(3) {
			width: 30%;
		}
		tr {
			background-color: rgba(109,110,113,0.2);
			color: #000000;
		}
		tr:nth-child(odd) {
			background-color: rgba(109,110,113,0.1);
			color: #000000;
		}
	</style>
    </head>
    <body>
    <table>
        <thead>
			<tr>
            <th>Uhrzeit</th>
			<th>Thema</th>
			<th>Referent</th>
			</tr>
		</thead>
        <tbody>
            <tr>
                <td>10:00 - 10:10 Uhr</td>
                <td>Begrüßung</td>
                <td>xyz</td>
            </tr>
            <tr>
                <td>10:10 - 12:10 Uhr</td>
                <td>Das Thema (Teil 1)</td>
                <td>Herr Referent</td>
            </tr>
            <tr>
                <td>12:10 - 13:00 Uhr</td>
                <td>Mittagsbuffet</td>
                <td></td>
            </tr>
            <tr>
                <td>13:00 - 15:00 Uhr</td>
                <td>Das Thema (Teil 2)</td>
                <td>Herr Referent</td>
            </tr>
            <tr>
                <td>15:00 - 15:20 Uhr</td>
                <td>Kaffeepause</td>
                <td></td>
            </tr>
            <tr>
                <td>15:20 - 16:00 Uhr</td>
                <td>Ergänzendes Thema</td>
                <td>xyz</td>
            </tr>
        </tbody>
    </table>
    </body>
</html>