1.Please try to add this code into the custom.css and remove previously added margins for logo:
@media only screen and (max-width: 992px){
.header-logo img {
max-width: 210px !important;
}}
.navbar{ padding: 15px 0; }
2-4.You may call any custom font from the custom.css specifying “font-face” css value and adjusting it to the single element which is not utilizing main backend fonts.
Theme editor is not related to the theme options and you should check your wordpress configuration.
