Techniques are described herein for, among other things, selecting and/or modifying a portion of online content based on an emotional state of a user. The user's emotional state is determined based on the user's online activity. A portion or portions of online content are selected and/or modified for provision to the user based on the user's emotional state. A portion of online content may be modified in any of a variety of ways. For example, a color that is included in a portion of online content may be replaced with a different color. In another example, a color filter may be applied to the portion of online content. In yet another example, visual attribute(s) of the portion of online content may be modified. Examples of a visual attribute include, but are not limited to, hue, brightness, contrast, and saturation.