Whatever the case, it is necessary to create a TrueType font file that, among other things, describes each glyph in the font as an outline in the TrueType format. TrueType fonts can also be obtained by converting fonts from other formats. From design to font fileĪ TrueType font can originate as a new design drawn on paper or created on a computer screen. In the remainder of this chapter, “TrueType font” will be used to mean OpenType fonts that have TrueType glyph outlines. This chapter includes an introduction to TrueType instructions and how they are interpreted. It begins with an overview of the steps involved in taking a design from paper to the creation of a bitmap that can be sent to an output device and follows with a closer look at each of the steps in the process. This chapter introduces the basic concepts needed to create and instruct an OpenType font that contains TrueType outline data. In particular, the TrueType instruction set provides a powerful means of controlling glyph outlines at all or specific sizes and resolutions. When outlines are rasterized, TrueType “hinting” instructions contained in a font can be used to refine the rasterized results. OpenType supports the TrueType glyph outline format, in which a glyph outline is described as second-order Bezier splines. When used with the font-size property, em inherits the font-size from its parent element. In typography, the term em ' was originally a reference to the width of the capital M in the typeface and size being used '. The CSS em unit gets its name from a typographical unit. Here are some common relative length units: em For example, the relative font size of an element may be calculated using the parent element's font size. Relative length units are relative to another element's size or settings. In CSS, 1pc is roughly 16 pixels, or 1/6 of an inch. In CSS, 1pt is roughly 1.3333 pixels, or 1/72th of an inch. In CSS, 1in is roughly 96 pixels, or about 2.54cm. In CSS, 1mm is roughly 3.78 pixels, or 1/10th of a centimeter.

In CSS, 1cm is roughly 37.8 pixels, or about 25.2/64 of an inch. You can read more about the history of the pixel unit and why a CSS inch doesn't always match a physical inch in this article. If you know that your page will be printed on a high quality printer, then you may consider using another unit like cm or mm. Screens on modern devices have much higher resolutions and DPIs, so a line that's 96 pixels long may not measure exactly 1 inch, depending on the device.Įven though sizing in pixels can vary across devices, it's generally considered better to use pixels for screens. All other absolute length units are based on this definition of a pixel.īut when that standard was originally formulated, most monitors had a resolution of 1024 x 768, and a DPI (dots per inch) of 96. In CSS, 1 pixel is formally defined as 1/96 of an inch. Pixels, or px, are one of the most common length units in CSS. Here are some common absolute length units in CSS: px However, depending on your screen size and quality, or settings in your browser or OS, there may be some exceptions. Absolute Length UnitsĪbsolute length units are based on an actual physical unit, and are generally considered to be the same size across devices. There are two general kinds of units used for length and size in CSS: absolute and relative. In CSS, length is a number an a unit with no whitespace. Many CSS properties like width, margin, padding, and font-size take a length, and CSS has many different ways to express length.

4 pt grid type sizes