Lite CSS is described as 'simple but also unique web framework. The term 'Lite' expresses the simplicity but also how light the project is!' and is a CSS Framework in the Development category. There are more than 50 alternatives to Lite CSS, not only websites but also apps for a variety of platforms, including Self-Hosted solutions, Mac, Windows and Linux. The best alternative is Bootstrap, which is both free and Open Source. Other great sites and apps similar to Lite CSS are Bulma (Free, Open Source), Materialize (Free, Open Source), UIkit (Free, Open Source) and Semantic UI (Free, Open Source).
Structure is a declarative, Flexbox based grid framework. Structure defines layout using non-standard attributes on elements. (If you have used frameworks like AngularJS, you have already gotten some exposure to declarative syntax and non-standard attributes.)