How to draw circle on webform() ?

See more:

C#

ASP.NET

CSS

Hi,
Iam trying to draw a circle on center of page. I can't understand my mistake. Because there is no output. And I am using Windows-10 EDGE.

My Codes

str_solution.Append(@"<style type='text/css'>
                 .brown-circle {
                 display: block;
                 height: 20px;
                 width: 20px;
                 background-color: #B0641C;
                -moz-border-radius: 10px;
                -webkit-border-radius: 10px;
                -khtml-border-radius: 10px;
                 border-radius: 10px;
               position:relative;
                 float:left;
                margin:0 5px 10px 0;
                 } 
                .yellow-circle {
                 display: block;
                 height: 20px;
                 width: 20px;
                 background-color: #f7c639;
                -moz-border-radius: 10px;
                -webkit-border-radius: 10px;
                -khtml-border-radius: 10px;
                 border-radius: 10px;
               position:relative;
                 float:left;
                margin:-8px 5px 10px 0;
                 } 
            
                 </style>");

        for (int i = 0; i < 10; i++)
        {
            str_solution.Append("<span class=brown-circle></span>");
        }
        str_solution.Append("<br/><br/>");

        for (int i = 0; i < 10; i++)
        {
            str_solution.Append("<span class=yellow-circle></span>");
        }
        lbl_circle.Text = str_solution.ToString();

Thanks

What I have tried:

I try to Draw Circle on WebForm. But Not Displaying, May be Browser-Edge?