Tags <b:skin> and <b:template-skin> are elements used only the header of the Blogger theme XML file, whose content is hold a series of CSS code and variable declarations used along with CSS and can be interacting with the Theme Designer tool .
<b:skin> is responsible for CSS used for the current blog look, while the <b:template-skin> is responsible for the display template in the Layout Editor.
The Syntax
B: SKIN
<b:skin>
<![CDATA[
]]>
</b:skin>B: TEMPLATE-SKIN
<b:template-skin>
<![CDATA[
]]>
</b:template-skin>- CDATA must be nested in the tags.
- The tag <b:skin> is required in all themes.
- Tags <b:skin> and <b:template-skin> are separated tags and can not be nested. They must be positioned in the header of the XML file between <head> and </head>.
- <b:template-skin> can't be used in b:layoutsVersion 1.
Official themes distributed by Blogger has own Group of variable, this determine variable to be used in Layout > Theme Designer.