 <p>Apply the min-width property.</p> <p>In Your CSS Style Sheet</p> <pre><code>.Textbox { min-width:100%; } </code></pre> <p>In Your *.aspx</p> <pre><code>&lt;asp:TextBox CssClass="TextboxStyle" placeholder="Enter the Title" runat="server" ID="TextBox1"&gt;&lt;/asp:TextBox&gt; </code></pre> <p>This will update your text box</p>