The first letter of an element is not always trivial to identify:

• Punctuation that precedes or immediately follows the first letter is included in the match. Punctuation includes any Unicode character defined in the open (Ps), close (Pe), initial quote (Pi), final quote (Pf), and other punctuation (Po) classes.
• Some languages have digraphs that are always capitalized together, like the IJ in Dutch. In these cases, both letters of the digraph should be matched by the ::first-letter pseudo-element.
• A combination of the ::before pseudo-element and the content property may inject some text at the beginning of the element. In that case, ::first-letter will match the first letter of this generated content.

Only a small subset of CSS properties can be used with the ::first-letter pseudo-element:

• All font properties: font, font-style, font-feature-settings, font-kerning, font-language-override, font-stretch, font-synthesis, font-variant, font-variant-alternates, font-variant-caps, font-variant-east-asian, font-variant-ligatures, font-variant-numeric, font-variant-position, font-weight, font-size, font-size-adjust, line-height and font-family
• All background properties: background, background-color, background-image, background-clip, background-origin, background-position, background-repeat, background-size, background-attachment, and background-blend-mode
• All margin properties: margin, margin-top, margin-right, margin-bottom, margin-left
• All padding properties: padding, padding-top, padding-right, padding-bottom, padding-left
• All border properties: the shorthands border, border-style, border-color, border-width, border-radius, border-image, and the longhands properties
• The color property
• The text-decoration, text-shadow, text-transform, letter-spacing, word-spacing (when appropriate), line-height, text-decoration-color, text-decoration-line, text-decoration-style, box-shadow, float, vertical-align (only if float is none) CSS properties

In this example we will use the ::first-letter pseudo-element to create a simple drop cap effect on the first letter of the paragraph coming right after the <h2>.

HTML

<h2>My heading</h2>
<p>
  Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy
  eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam
  voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita
  kasd gubergren, no sea takimata sanctus est.
</p>
<p>
  Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie
  consequat.
</p>

CSS

p {
  width: 500px;
  line-height: 1.5;
}

h2 + p::first-letter {
  color: white;
  background-color: black;
  border-radius: 2px;
  box-shadow: 3px 3px 0 red;
  font-size: 250%;
  padding: 6px 3px;
  margin-right: 6px;
  float: left;
}

Result

This example illustrates the effect of ::first-letter on special punctuation and non-Latin characters.

HTML

<p>
  Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie
  consequat.
</p>
<p>-The beginning of a special punctuation mark.</p>
<p>_The beginning of a special punctuation mark.</p>
<p>"The beginning of a special punctuation mark.</p>
<p>'The beginning of a special punctuation mark.</p>
<p>*The beginning of a special punctuation mark.</p>
<p>#The beginning of a special punctuation mark.</p>
<p>「特殊的汉字标点符号开头。</p>
<p>《特殊的汉字标点符号开头。</p>
<p>"特殊的汉字标点符号开头。</p>

CSS

p::first-letter {
  color: red;
  font-size: 150%;
}

Result

• ::first-line