I just updated this for clarity.
So I have some buttons I have created which consist of a circle and a font-awesome icon. Each of these buttons are to link to social media. I now want to put these buttons inside a table row, where each will be horizontally and vertically aligned to the center of each table cell. How do I horizontally align them?
Here is my html:
<!DOCTYPE html>
    <html lang="en">
    <head>
    <script src="https://use.fontawesome.com/604215ea7e.js"></script>
        <style>
         .social_icon
        {  
            width: 40px;
            height: 40px;
            border-radius: 50%;
            background-color: #ccc;
            text-align: center;
            display: table-cell;
            vertical-align: middle;
        }
        .social_icon:hover
        {   
            background-color: #999;
            cursor: pointer;
        }
        #footer_social_icons
        {       
            width: 20%;
            height: 80px;
            background-color: #636363;
            text-align: center;
        }
        #footer_social_icons table
        {   
            width: 100%;
            height: 80px;
        }
        #footer_social_icons td
        {
            vertical-align: middle;
            border: 1px solid #fff; /* to show not centred */
        }
        </style>
    </head>
    <body>
    <div id="footer_social_icons">
        <table>
            <tr>
                <td>
                    <div class="social_icon">
                        <i class="fa fa-google-plus" aria-hidden="true"></i>
                    </div>
                </td>
                <td>
                    <div class="social_icon">
                        <i class="fa fa-facebook" aria-hidden="true"></i>
                    </div>
                </td>
                <td>
                    <div class="social_icon">
                        <i class="fa fa-twitter" aria-hidden="true"></i>
                    </div>
                </td>
                <td>
                    <div class="social_icon">
                        <i class="fa fa-envelope" aria-hidden="true"></i>
                    </div>
                </td>
            </tr>
        </table>
    </div>
    </body>
    </html>
 
     
     
    