Change layout for the share options on mobile (#1645)

* Change layout for the share options on mobile

Before, it was impossible to click on links to share on small screens.
Now, all dropdowns are opened at the bottom of the screen and stays there.

Linked to #1506

* Change rule for border-radius

p/themes/base-theme/template.css

@@ -835,6 +835,15 @@ input:checked + .slide-container .properties {
 	.no-mobile {
 		display: none;
 	}
+	.dropdown .dropdown-menu {
+		border-radius: 0;
+		bottom: 0;
+		position: fixed;
+		width: 100%;
+	}
+	.dropdown-menu::after {
+		display: none;
+	}
 	.aside .toggle_aside,
 	.nav-login {
 		display: block;