1. A method comprising: at an electronic device with a display and one or more input devices; displaying on the display of the electronic device, a first text string with a first type style and a second text string with a second type style, wherein the first type style is different than the second type style; the first text string is displayed proximate to the second text string on the display with a first spatial arrangement that is determined based at least in part on the first type style and the second type style; after displaying the first text string and the second text string on the display, receiving, via the one or more input devices, input that changes a font size of the first text string and changes the respective font size of the second text string; in response to receiving the input, dynamically adjusting, by the electronic device, one or more font metrics that determine the spatial arrangement of text in accordance with text layout rules based on the first type style and the second type style; and displaying, on the display of the electronic device, the first text string and the second text string with the respective font size changed and with a second spatial arrangement that is determined based on the first type style, the second type style and the dynamically adjusted one or more font metrics.