I tried to enable customer support but it's not happening... How do i raise a case??

Hi, I'm new to SF...while I'm practicing on playground i came across a doubt that when i try to apply CSS props for id it won't work...it only work for classes? I need to know about it.
<p id="demo"> Hello </p>
<p class="abc"> world </p>

i wanna apply Css props for Hello now.. How do i do it?

I tried to enable customer support but it's not happening... How do i raise a case??

I tried to enable customer support but it's not happening... How do i raise a case??

Hi, I'm new to SF...while I'm practicing on playground i came across a doubt that when i try to apply CSS props for id it won't work...it only work for classes? I need to know about it.
<p id="demo"> Hello </p>
<p class="abc"> world </p>

i wanna apply Css props for Hello now.. How do i do it?