Border
if You want to add Border on outside of main container, so follow these easy steps on blogger account.
Steps
>> Open Your Blogspot Account.
>> Select Theme
>> Select Customize
>> Then Select Advance
>> Select ADD CSS
then Paste This Code for inside Boder
.main-inner {
border: 5px solid purple;
border-radius: 25px;
margin-top:1px;
margin-bottom:1px;
}
>> Click on SAVE THEME Button.
Border For Outside on Main Page in Blogger / Blogspot Theme
Steps
>> Open Your Blogspot Account.
>> Select Theme
>> Select Customize
>> Then Select Advance
>> Select ADD CSS
then Paste This Code for outside Border
.main-outer {
border: 5px solid purple;
border-radius: 25px;
margin-top:1px;
margin-bottom:1px;
}
>> Click on SAVE THEME