CSS selectors

group selector ','
h1, h2, h3 {...}

contextual selector ' '
p em {...}

child selector '>'
p > span {css ...} : only the 'span' which is child of 'p' will apply the embraced css

universal selector '*'
p * span {css ...} : the 'span' under all kids of 'p' will apply the embraced css but the 'span' which is the kid of 'p' will not!

adjacent limb selector '+'