unwrapping

Making Stylesheet (CSS) Tweaks to your Tumblr Theme: 
To change the styles for your theme — without editing the theme HTML — go to Customize and follow these steps. Some theme developers offer CSS (Cascading Style Sheet) snippets to make specific customizations.

For example, if you use Tumblr’s default theme (Optica), be sure to see Optica Tips. Optica theme users can find CSS snippets to…

Jan. 22, 2015 Update:
The Optica theme stylesheet changed. To reinstate the dates for posts on index pages, add this CSS:

.date-notes .post-date.post-date {
     display:block;
}