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/AVvXsEhkf5PDX0mj-4RMRkSQiCFg_zxQ6q0dEKgRucD6XEhg60VrYzZHbW5jI7St9CZH8sM9wT9i89T7mwi6Nz4cQmJWNAGgbez8Bz3L7g8okOwoiNvYL_JhmXnDSgyPgcX63oidpau4aMh0owi0/+1+small.jpg" alt="#" /></a>
   
<a href="#"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh2gZ7QVUQ3-NPba1WNBxgDlrNCZhciVDHIbDuODrOmEoWEBOtKUMrJzzCZSTYCvx4E7rbxg3T3ngxxi7x0SFK-y0wCWLGIp3l18pmS3Sa7B8fif6aLTyIFZKEm4RXjX16ocv-N5HojmdKd/+2+small.jpg" alt="#" /></a>
   
<a href="#"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgv9FDORod0jIse-VOw7qmUnJqqUF1pDRdiuFlcwSAT2v0_GqGIOROiJVIAmqgxWBnBbuktbCxmc_yiOy2MD_5xg8Jm2u7QINYiLcGINhT4i6aM832WgG1iO15LjJjdUCKbdC5R4jiTS-ao/+3+small.jpg" alt="#" /></a>     
  
</div>

You are done.

Demo