Possible Ways to Style a View (Block)
The possible ways are:

1) using a CSS file, ex: style.css (located in your /sites/all/themes/YOURTHEME/css folder)

.block { border: solid red; }


2) using jQuery, ex: style.js (located in your /sites/all/themes/YOURTHEME/js folder)

$('.block').css({"border":"solid red"});


3) using a template file, ex: block.tpl.php or view.tpl.php (located in your theme's /sites/all/themes/YOURTHEME/template folder)

&lt;style&gt;
.block { border: solid red; }
&lt;/style&gt;


4) Inside the view, if they add a header or footer of text area or unfiltered text and then put inside the header/footer:

&lt;style&gt;
.block { border: solid red; }
&lt;/style&gt;


or 

&lt;script src="myScript.js"&gt;&lt;/script&gt;


5) Using the CSS Injector module

6) Using the JS Injector module