HTML table with vertical scroll inside tbody (source: https://jsfiddle.net/hashem/CrSpu/555/)

fiddle.css

table.scroll {
    /* width: 100%; */ /* Optional */
    /* border-collapse: collapse; */
    border-spacing: 0;
    border: 2px solid black;
}

table.scroll tbody,
table.scroll thead { display: block; }

thead tr th { 
    height: 30px;
    line-height: 30px;
    /* text-align: left; */
}

table.scroll tbody {
    height: 100px;
    overflow-y: auto;
    overflow-x: hidden;
}

tbody { border-top: 2px solid black; }

tbody td, thead th {
    /* width: 20%; */ /* Optional */
    border-right: 1px solid black;
    /* white-space: nowrap; */
}

tbody td:last-child, thead th:last-child {
    border-right: none;
}

fiddle.html

<table class="scroll">
    <thead>
        <tr>
            <th>Head 1</th>
            <th>Head 2</th>
            <th>Head 3</th>
            <th>Head 4</th>
            <th>Head 5</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td>Content 1</td>
            <td>Content 2</td>
            <td>Content 3</td>
            <td>Content 4</td>
            <td>Content 5</td>
        </tr>
        <tr>
            <td>Content 1</td>
            <td>Lorem ipsum dolor sit amet.</td>
            <td>Content 3</td>
            <td>Content 4</td>
            <td>Content 5</td>
        </tr>
        <tr>
            <td>Content 1</td>
            <td>Content 2</td>
            <td>Content 3</td>
            <td>Content 4</td>
            <td>Content 5</td>
        </tr>
        <tr>
            <td>Content 1</td>
            <td>Content 2</td>
            <td>Content 3</td>
            <td>Content 4</td>
            <td>Content 5</td>
        </tr>
        <tr>
            <td>Content 1</td>
            <td>Content 2</td>
            <td>Content 3</td>
            <td>Content 4</td>
            <td>Content 5</td>
        </tr>
        <tr>
            <td>Content 1</td>
            <td>Content 2</td>
            <td>Content 3</td>
            <td>Content 4</td>
            <td>Content 5</td>
        </tr>
        <tr>
            <td>Content 1</td>
            <td>Content 2</td>
            <td>Content 3</td>
            <td>Content 4</td>
            <td>Content 5</td>
        </tr>
    </tbody>
</table>

fiddle.js

// Change the selector if needed
var $table = $('table.scroll'),
    $bodyCells = $table.find('tbody tr:first').children(),
    colWidth;

// Adjust the width of thead cells when window resizes
$(window).resize(function() {
    // Get the tbody columns width array
    colWidth = $bodyCells.map(function() {
        return $(this).width();
    }).get();
    
    // Set the width of thead columns
    $table.find('thead tr').children().each(function(i, v) {
        $(v).width(colWidth[i]);
    });    
}).resize(); // Trigger resize handler