This is due to the behavior table where you cannot decrease its width less than the needed width for its content.
To be able to change this you need to set table-layout
to fixed as by default it's auto and as you can read here:
Automatic table layout algorithm (this is default):
The column width
is set by the widest unbreakable content in the cells Can be slow,
since it needs to read through all the content in the table, before
determining the final layout
and
Fixed table layout algorithm:
The horizontal layout only depends on
the table's width and the width of the columns, not the contents of
the cells Allows a browser to lay out the table faster than the
automatic table layout The browser can begin to display the table once
the first row has been received
main {
position: relative;
width: 80%;
float: right;
height: auto;
}
div.container {
width: 95%;
height: auto;
margin: 0 auto;
}
main div.container>table {
width: 10px;
overflow: hidden;
background-color: red;
}
<main>
<div class="container">
<table>
<thead>
<tr>
<th>Keterangan event</th>
<th>Waktu event</th>
<th>Lokasi event</th>
<th>Lokasi event</th>
<th>Cover</th>
</tr>
</thead>
<tbody>
<tr>
<td>something</td>
<td>something</td>
<td>something</td>
<td>something</td>
<td>something</td>
</tr>
</tbody>
</table>
after adding table-layout:fixed;
<table style="table-layout:fixed;">
<thead>
<tr>
<th>Keterangan event</th>
<th>Waktu event</th>
<th>Lokasi event</th>
<th>Lokasi event</th>
<th>Cover</th>
</tr>
</thead>
<tbody>
<tr>
<td>something</td>
<td>something</td>
<td>something</td>
<td>something</td>
<td>something</td>
</tr>
</tbody>
</table>
</div>
</main>
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…