When I add a logo through Theme-> Customize, the site title is getting written over the logo. If I remove the site title, the logo's size also reduces. How do I add a custom logo without using the site title option.
You have said that you are using Dokan theme but you are using a personalized theme- http://i.imgur.com/djbDqou.png. You are using Dokan plugin but the issue is not related with the plugin. The header logo or banner is not coming from the plugin.