font-family: 'Segoe UI', Tahoma, sans-serif;

The browser will attempt to apply the font face “Segoe UI” to the characters within the elements targeted by the above property. If this font is not available, or the font does not contain a glyph for the required character, the browser will fall back to Tahoma, and, if necessary, any sans-serif font on the user’s computer. Note that any font names with more than one word such as “Segoe UI” need to have single or double quotes around them.

font-family: Consolas, 'Courier New', monospace;

The browser will attempt to apply the font face “Consolas” to the characters within the elements targeted by the above property. If this font is not available, or the font does not contain a glyph for the required character, the browser will fall back to “Courier New,” and, if necessary, any monospace font on the user’s computer.