Answers for "flex cs"

make the first item at the very top of the screen

.fixedElement {
    position:fixed;
    top:0;
    width:100%;
    z-index:100;
}

css flexbox syntax

Display: flex 
Flex-direction: row | row-reverse | column | column-reverse
align-self: flex-start | flex-end | center | baseline | stretch
justify-content: start |  center | space-between | space-around | space-evenly

flexbox css

.container {
  justify-content: flex-start | flex-end | center | space-between | space-around | space-evenly | start | end | left | right ... + safe | unsafe;
}

css all flex properties

.item {
  flex-grow: 4; /* default 0 */
}