Flexbox Rule of Thumb

There seems certain rules for me when I write CSS using Flexbox...

Properties always to be added

/* for container (parent) */
.row {
  display: flex;
  flex-flow: row wrap;
}

/* for items (children) */
.item {
  flex: 0 0 25%;
}
/*
shorthand for
flex-grow: 0; (default: 0)
flex-shrink: 0; (default: 1)
flex-basis: 25%;
*/