Horse hides the title bar by default, that’s why the window looks taller than other browsers. The sidebar still works as a drag handle, so most people don’t notice. If you’d rather have the familiar bar back, here’s how.
Enabling the title bar
Menu > Settings, or ⌘+,.
Scroll to Titlebar and turn it on.
Quit and reopen Horse for the change to take effect: right-click the dock icon and Quit, or Menu > Horse > Quit Horse, or ⌘+Q.
Hiding it again
Same Settings panel, toggle off, quit and reopen.