This is h1 header as you can see its different to usual

Text between paragraph tags is odd too

as are h2 headers

Defined terms look different too

but when emphaised go red

Lets explain each tag seperately

the h1 tag has been set as shown
h1 {color: aqua; font-style: italic; text-align: centre}

This means for all h1 headers the text is coloured aqua, the letters are in italics and the alignment is centre like below

Not like normal

for h2 headers they are defined thus

h2 {color: #0000FF; background: khaki; font-family: serif, sans-serif;}

This sets their font colour to #0000FF(better known as blue) whilst they have a background set to khaki in colour. The font should appear as serif (or san serif ) if available

Like it is here.

Moving on to general text. Text seperated by <p> tags (like this) are defined by

p {font-style: bold; font-family: comic sans ms, arial;}

This makes the text bold and in the comic sans ms font if available (alt. is arial)

Things get more tricky with defined terms. Usually they are defined thus

dt {color: aqua;}

Which simply makes defined terms text aqua as this is

But the second style tag

dt em {color: red;}

mean that if you use <em> (emphasis) tags the text will appear red as here