To remove the "strike-through" select
YOOtheme > STYLE > Components > Navbar > Nav Item Line > Mode: Disable,

Presumably you are referring to the "Page Border".

Try and set YOOtheme > STYLE > General > Theme > PAGE > Border Width: 0px.

In the Row go to Edit Layout

For the second row to be first on a mobile put:

Column1 - order first / Medium (Tablet Landscape)

Column2 - order first / Always

https://arbcult.ywdw.co.uk/

open the Customizer, go to STYLE > Components > Navbar, pick your colour by setting Border: rgba(190, 175, 130, 1) (for example), set Border Width: 15px, and select Mode: Border.

If this doesn't work add CSS and style for a bottom border

/*header bottom border*/
.uk-navbar-container:not(.uk-navbar-transparent),
.uk-navbar-transparent {
border-bottom: #ff5b00;
border-bottom-style: solid;
border-bottom-width: 12px;
}

For top and bottom border

/*header top and bottom border*/
.uk-navbar-container:not(.uk-navbar-transparent),
.uk-navbar-transparent {
border-bottom: #9E9E9E;
border-bottom-style: solid;
border-bottom-width: 1px;
}

.uk-navbar-container:not(.uk-navbar-transparent),
.uk-navbar-transparent {
border-top: #9E9E9E;
border-top-style: solid;
border-top-width: 1px;
}

Style / NAVBAR 

Dropdown background colour

Text colour

Sub menu drop down font size

 Now the active state colour needs to be set up like this:

In the item settings: Item > Settings > Item > Type > click on dynamic and select, Item

Item > Active click on dyanmic and select, Active - Menu item.

Full Width

Layout / Header / Dropdown / tick the radio button for Enable dropbar

Grid / Settings / Image / Box Shadow and Floating Shadow.

Style / Components / Navbar / Dropdown / Padding,
Scroll down to Dropdown Nav Item / Padding Horizontal and insert the very same value say 20px.

Scroll up to Dropdown Nav / Margin Horizontal and insert the same value, but with a leading negative sign: -20px.

Then if using a mega menu - Menus / Main Menu / Heating (Builder) / Nav / Items / Settings / Active

make sure 'Enable active state' is not checked.

Change the text colour in Nav, not Navbar

Style / Button - right at the bottom of the Button style area

/* To Top Button style */

.uk-totop {

padding: 30px;

color: #ffffff;

background-color: #00000089;

}