gtk2/demos/gtk-demo/markup.txt

Text sizes: <span size="xx-small">tiny</span> <span size="x-small">very small</span> <span size="small">small</span> <span size="medium">normal</span> <span size="large">large</span> <span size="x-large">very large</span> <span size="xx-large">huge</span>

Text <span color="gray">c<span color="green">o</span>l<span color="tomato">o</span>rs</span> and <span background="pink">backgrounds</span>

Colorful <span underline="low" underline-color="blue"><span underline="double" underline-color="red">under</span>lines</span> and <span background="pink"><span underline="error">mo</span><span underline="error" underline-color="green">re</span></span>

Colorful <span strikethrough="true" strikethrough-color="magenta">strikethroughs</span>

Superscripts and subscripts: 𝜀<span rise="-6000" size="x-small" font_desc="italic">0</span> = 𝜔<span rise="8000" size="smaller">𝜔<span rise="14000" size="smaller">𝜔<span rise="20000">.<span rise="23000">.<span rise="26000">.</span></span></span></span></span>

<span letter_spacing="3000">Letterspacing</span>

OpenType font features: <span font_desc="sans regular" font_features="dlig=0">feast</span> versus <span font_desc="sans regular" font_features="dlig=1">feast</span>

Shortcuts: <tt>Monospace</tt> – <b>Bold</b> – <i>Italic</i> – <big>Big</big> – <small>Small</small> – <u>Underlined</u> – <s>Strikethrough</s> – Super<sup>script</sup> – Sub<sub>script</sub>