Our pages are currently mobile responsive, not fluid responsive.
Unbounce is built with the flexibility of allowing you to drag-and-drop elements wherever you want -- unfortunately, this prevents us from offering a fluid grid layout.
When Unbounce built our mobile responsive feature, our main concern was ensuring the Desktop and the Mobile views were fully functional and completely customizable across as many devices as possible with minimal work on the part of our customers.
To achieve this, the Mobile Responsive feature offers 2 viewports: Mobile and Desktop.
Our responsive technology uses a single break point of 600px, meaning any device with a viewport width wider than 600px will see the Desktop version of your landing page, and any device with a width smaller than 600px will see the Mobile page.
What about Tablet?
When viewing the page on a tablet, the desktop view is loaded but it is scaled to fit the tablet screen. So while this isn't 100% fluid responsive, it is still functional and will ensure the vast majority of your traffic is served a version that they can see and use without issue.