Changing SharePoint 2010 default font size

By default, SharePoint 2010 font size is Verdana 8pt and how do I change the font size?  What if I want to change the font size to something like Arial 13?

How do I make it Arial as a default font in SharePoint 2010 content editor web part so that every time user edit contents, it default not to Verdana?

Here are the steps to change default font size in SharePoint 2010

1. I am using the CSS from Serve’s Blog Copy this CSS and create a new CSS file in SharePoint Designer or download from below

.ms-bodyareacell td, .ms-bodyareacell p, .ms-bodyareacell div, .ms-bodyareacell span,
.ms-bodyareacell p, .ms-bodyareacell a,.ms-bodyareacell a:active, .ms-bodyareacell a:hover,
.ms-bodyareacell a:link, .ms-bodyareacell a:visited,.ms-bodyareacell td,.ms-bodyareacell div,
.ms-bodyareacell font

{
font-size:13px;
font-family:Trebuchet MS,Verdana, Arial;
letter-spacing: normal;
color:black;
}

.ms-bodyareacell h3 a, .ms-bodyareacell h3 span, .ms-bodyareacell h3 div,.ms-bodyareacell h3 p,
.ms-bodyareacell h3 font
{
font-size:15px;
color:black;
}

.ms-wpheader
{
background-color:#e9e9e9;
}

2. Save your CSS file. In this case, I am calling as custom2.css and saving this file in style library

3. Open your master page and add a reference to your new custom2.css file

4. Now go back to your SharePoint page and edit. You will see your default font is changed to what every you specified in your CSS

This is how you can change SharePoint 2010 default font to something you like.