You can use the selector nth-child(20n)
to apply a style to the rows that are 20 or a multiple of 20. In this case, I understand that by blank space you mean leaving a margin with respect to the rest of the rows.
However, as @MarcosGallardo said, in my original response I modified the display: table-row
of the rows since I assigned them display: block
to be able to modify the margin of the rows since these, by default, can not have margin.
In order not to modify the style of the tr
and it seems that there is a margin for the top and bottom of the row 20 or multiple of 20 what can be done is to assign a height to the writing line by means of the property line-height
.
Subsequently, we can set the white background for that particular row so that there seems to be a margin at the top and bottom of the row.
Example:
tr{
background-color: red;
}
tr:nth-child(20n){
line-height: 50px;
background-color: white;
}
<table>
<tr><td>Hola</td><td>Pepito</td></tr><tr><td>Hola</td><td>Pepito</td></tr>
<tr><td>Hola</td><td>Pepito</td></tr><tr><td>Hola</td><td>Pepito</td></tr>
<tr><td>Hola</td><td>Pepito</td></tr><tr><td>Hola</td><td>Pepito</td></tr>
<tr><td>Hola</td><td>Pepito</td></tr><tr><td>Hola</td><td>Pepito</td></tr>
<tr><td>Hola</td><td>Pepito</td></tr><tr><td>Hola</td><td>Pepito</td></tr>
<tr><td>Hola</td><td>Pepito</td></tr><tr><td>Hola</td><td>Pepito</td></tr>
<tr><td>Hola</td><td>Pepito</td></tr><tr><td>Hola</td><td>Pepito</td></tr>
<tr><td>Hola</td><td>Pepito</td></tr><tr><td>Hola</td><td>Pepito</td></tr>
<tr><td>Hola</td><td>Pepito</td></tr><tr><td>Hola</td><td>Pepito</td></tr>
<tr><td>Hola</td><td>Pepito</td></tr><tr><td>Hola</td><td>Pepito</td></tr>
<tr><td>Hola</td><td>Pepito</td></tr><tr><td>Hola</td><td>Pepito</td></tr>
<tr><td>Hola</td><td>Pepito</td></tr><tr><td>Hola</td><td>Pepito</td></tr>
<tr><td>Hola</td><td>Pepito</td></tr><tr><td>Hola</td><td>Pepito</td></tr>
<tr><td>Hola</td><td>Pepito</td></tr><tr><td>Hola</td><td>Pepito</td></tr>
<tr><td>Hola</td><td>Pepito</td></tr><tr><td>Hola</td><td>Pepito</td></tr>
<tr><td>Hola</td><td>Pepito</td></tr><tr><td>Hola</td><td>Pepito</td></tr>
<tr><td>Hola</td><td>Pepito</td></tr><tr><td>Hola</td><td>Pepito</td></tr>
<tr><td>Hola</td><td>Pepito</td></tr><tr><td>Hola</td><td>Pepito</td></tr>
<tr><td>Hola</td><td>Pepito</td></tr><tr><td>Hola</td><td>Pepito</td></tr>
<tr><td>Hola</td><td>Pepito</td></tr><tr><td>Hola</td><td>Pepito</td></tr>
<tr><td>Hola</td><td>Pepito</td></tr><tr><td>Hola</td><td>Pepito</td></tr>
</table>