Hi 
Can you give a little more detail on how you are pasting? What theme you are using? Your Obsidian version, etc?
When I create a CSS code block in an Obsidian note and paste in some css using the default theme, it wraps:
```css
.workspace-leaf-content[data-type=recent-files] .view-content .nav-file-title-content {
font-size: 13px;
padding-bottom: 6px;
color: var(--nav-item-color);
}
```
See the forum code fomatting tips if want to post the code here on the forum.