Give the element you want to prevent selection of an id.
Then put this in your CSS:
#id-name {
-webkit-touch-callout: none;
-webkit-user-select: none;
-khtml-user-select: none;
-moz-user-select: none;
-ms-user-select: none;
user-select: none;
}
::-moz-selection {
background: transparent;
}
::selection {
background: transparent;
}