CSS Grid and Flexbox are both powerful layout systems, but they're designed for different types of layouts.

1. Flexbox: Flexbox is a one-dimensional layout model, and it is a great choice for laying out items in a single row or a single column. It's perfect for components of an application or small-scale layouts where you want to align items in a particular direction. For example, you might use Flexbox for a navigation bar, a sidebar, or for aligning a group of items in a header.
   

   .container {
     display: flex;
     justify-content: space-between;
   }

   
   
2. Grid: CSS Grid is a two-dimensional layout model, and it's a great choice for larger scale layouts that need both rows and columns. It's perfect for designing the overall layout of a page or for building more complex components that need to align items in two dimensions. For example, you might use Grid for a photo gallery, a card grid, or for the overall layout of a webpage.
   

   .container {
     display: grid;
     grid-template-columns: repeat(3, 1fr);
     grid-gap: 10px;
   }
   

   
   

In many cases, Grid and Flexbox can be used together. For example, you might use Grid for the overall layout of a page, and then use Flexbox for the layout of individual components or sections of the page. The choice between Grid and Flexbox ultimately depends on the specific needs of your layout.

What about flex: 1 1 auto? Mostly we see flex: 1, which means occupy or fill the available gap.

The flex property in CSS is a shorthand for three properties: flex-grow, flex-shrink, and flex-basis. The flex: 1 1 auto declaration can be broken down as follows:

1. flex-grow: 1: This means that the item will grow to take up any extra space in the container if necessary. The 1 value means that each flex item will receive the same amount of extra space.

2. flex-shrink: 1: This means that the item can shrink if the container is too small. Items shrink to the size of their content, but not further. The 1 value again means that each flex item will shrink at the same rate.

3. flex-basis: auto: This sets the initial main size of the item. auto means that the browser will look at the width or height property (depending on the flex-direction) of the item. If the item has no size specified, it will base the size on its content.

So, flex: 1 1 auto means the item is allowed to grow and shrink from its initial size (based on its width/height or its content if not specified) to fill the container. This is a common setting for flex items because it allows them to adapt to the available space.

flex: 1 1 200px

The flex-basis value of 200px ensures that the flex item has a minimum size of 200px, but it can grow or shrink from that initial size based on the available space in the flex container and the values of flex-grow and flex-shrink.