Module:Flex columns/styles.css explained

/* */.flex-columns-container

.flex-columns-container > .flex-columns-column

@media screen and (max-width: 393px)

.flex-columns-container > .flex-columns-column:first-child

.flex-columns-container > .flex-columns-column:last-child

@media screen and (max-width: 720px)

.flex-columns-container > .flex-columns-column > div

.flex-columns-container > .flex-columns-column > div.flex-columns-noflex