i have created a css file & a html file

if i am using the css from the root directory as the html page its displayed properly
<link href="styles.css" rel="stylesheet" type="text/css" />

but if i put the css file in a folder
<link href="CSS/styles.css" rel="stylesheet" type="text/css" />
few of the style are not applied to the page

i need to use the same css with the same layout as of HTML page in .aspx page VS2008
but when i use it
<link href="styles.css" rel="stylesheet" type="text/css" />
the whole contents are messed out
the arrangenment of the elemnts are lost

how do i rectify