... and you can always just print the three parts seperately:
echo '<link rel="stylesheet" href="';
echo $Local_PathToHomeDir;
echo 'styles/main.css" type="text/css" /> ";
But my favourite, is concatenation, because that doesn't mess up your syntax-highlighting and is a lot more readable than the other methods:
echo '<link rel="stylesheet" href="'.$Local_PathToHomeDir.'styles/main.css" type="text/css">';