Change BackGround color of Active and Inactive AJAX Tab Panel Header in ASP.Net

I have a tabcontainer with three tabpanel. The first tab is always enabled, while the other two get enabled and disabled in the code-behind depending on some conditions. I would like to customize the header style of the second and third tab such that:  - If the tabs are disabled, the header (title of the tab) font color should be gray  - If the tabs are disabled, the header (title of the tab) font color should be blue Currently, I have the following in my style sheet: `a.ajax__tab_tab{ color: blue; }` but this always sets the tab title font color to blue, regardless of whether the tab is enabled or disabled. This piece of code shows the conditions to enable or disable the tabs. Can I control for style here as well?

 protected void HorizonTextBox_TextChanged(object sender, EventArgs e)
        {
            if (HorizonTextBox.Text != "")
            {
                TabPanel2.Enabled = true;
                TabPanel3.Enabled = true;
                WholeUpdatePanel.Update();
            }
            else
            {
                TabPanel2.Enabled = false;
                TabPanel3.Enabled = false;
                WholeUpdatePanel.Update();
            }
        }

Any  help would be appreciate! Thanks!