If your fields are in a table, which it looks like you've done, you can use the following css to make it wider:

.cf-form{overflow-x:scroll;}
#q1 .cf-table {width: 2000px;}

#q1 is whatever #q your table is, the width you'll have to play with until you get what you want. 

There is no native concept of Portrait or Landscape in web pages. HTML by default dynamically resizes to fit the width of the screen your are displaying unless something on that page says "I need to be bigger than your available space" which is what you are setting above by changing the width. so if you make something Xpx amount of space and X is larger than your browser window is currently you'll be presented with scroll bars.

The height works sort of the same way, except that it normally is set to make pages scroll automatically by adding more height. That's why if you make a web browser window smaller the page will get longer and longer as each paragraph of text wraps a little shorter.

CSS can override all of this, which is why on Laserfiche forms you can't normally make the width any smaller than 800px without getting a horizontal scrollbar too.