font-display

font-display : auto | block | swap | fallback | optional;

• auto - The font display strategy is defined by the user agent.
• block - Gives the font face a short block period and an infinite swap period.
• swap - Gives the font face an extremely small block period and an infinite swap period.
• fallback - Gives the font face an extremely small block period and a short swap period.
• optional - Gives the font face an extremely small block period and no swap period.

The font display timeline

• Block period - If the font face is not loaded, any element attempting to use it must render an invisible fallback font face. If the font face successfully loads during this period, it is used normally.
• Swap period - If the font face is not loaded, any element attempting to use it must render a fallback font face. If the font face successfully loads during this period, it is used normally.
• Failure period - If the font face is not loaded, the user agent treats it as a failed load causing normal font fallback.