How To Add Outer Borders to Images

1.Login to your blogger dashboard--> layout- -> Edit HTML

2.Scroll down to where you see </head> tag .

3.Copy below code and paste it just before the </head> tag.

<style type='text/css'>
 
#outer-borders a img, #outer-borders a  { border: none; float: left; }
#outer-borders a { margin: 3px; }
#outer-borders a:hover { outline: 3px solid #0000ff; }
 
</style>

Note:You can change border color,outline size,margin,... But both outline size and margin must have a same numerical value.

4.Now add your images as below.

<div id="outer-borders">
   
<a href="#"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh1hyiswEL0YM-bQVUvxLJs7Od2tRNxudjMERheWuAtMZF1Bk09v7ELhPIXg80XyH-PBytqzUzpOzo4UTc3SAgeeflUcj99D53zPDFRuqy69Zjyg9KMgdT5ohiWH3q4Wk9w0RLWBbmK3v1F/+1+small.jpg" alt="#" /></a>
   
<a href="#"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEht2FjhKL2VXDEU_5Uzx2ruFJVKWG4OuXJP81qJ6SALBhf3rj3P8_7MNhzNQudUU0OaOlbnufhOXZgn9_p8oIbc25VCXVTeOPyPiz7G-2jVESHzl8NElvHaaS_WvE9FfNp_-qQvIOjf_RnV/+2+small.jpg" alt="#" /></a>
   
<a href="#"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjptKUCBvq9FpYNvel5NNExpy25E2036EgFqnRaFGY_zQAuYCDtCO9bhb22gqG39q21zwR3fNH23ZJbJ_eiQQWgq5F3K39U6ch-lxpEvfEAnD0bzuB4jrwjnPyjHel0PGBmyZAGPHZsSpWD/+3+small.jpg" alt="#" /></a>     
  
</div>

You are done.

Demo