I want to use different stylesheets for different screen
<link rel="stylesheet" href='media700.css' media="screen and (max-device-width:700px)">
<link rel="stylesheet" href='media1366.css' media="screen and (min-device-width:701px)">
width of your device is larger than
is not true and
is true, therefore the behavior you experience is actually expected.
The two rules cannot override each-other, as they are mutually exclusive.