Hi,

Try to add the following code snippet to the Custom CSS area in Theme Settings.

Shop sidebar burger menu:

body .woodmart-show-sidebar-btn .woodmart-side-bar-icon {
    display:none;
}

.woodmart-show-sidebar-btn:before {
    content: "\f1de";
    font-size:20px;
    font-weight:400;
    color:rgba(0,0,0,.3);
    margin-right:10px;
    font-family: "FontAwesome";
}

Sidebar close button:

body .widget-heading .close-side-widget {
	padding-right: 0;
}

body .widget-heading .close-side-widget:after {
	  content: "\f00d";
    font-size:20px;
    font-weight:400;
    margin-right:10px;
    font-family: "FontAwesome";
		position: relative;
		top: 1px;
		width: auto;
		height: auto;
		background-color: transparent;
		margin: 0;
		margin-left: 7px;
		transform: none !important;
}

body .widget-heading .close-side-widget:before {
	display: none;
}

We can’t control the thickness of the close font awesome icon via CSS.

Regards