Hello,
1/ Use the next custom CSS code:
.et-menu-list .subitem-title-holder a {
position: relative;
display: inline-block;
}
.et-menu-list .subitem-title-holder a:before {
content: '';
height: 2px;
width: 0;
right: 0;
position: absolute;
transition: width .2s ease-in-out;
bottom: 5px;
background: var(--et_active-color, currentColor);
}
.et-menu-list .subitem-title-holder a:hover:before {
width: 100%;
right: auto;
left: 0;
}
, change padding for menu items and columns, for example – https://gyazo.com/fbcc0ec7e4a9b6c95f249751f3bf77f7 https://gyazo.com/40fbe514fc3e5a7a2ca04eb6dca7dbab
2/ Theme Options > Header builder > Main menu > Mega Menu Dropdown Full-Width
Regards