essential dimensions

dimens.xml

<resources>
    <dimen name="fab_margin">16dp</dimen>
    <!-- Default screen margins, per the Android Design guidelines. -->
    <dimen name="activity_horizontal_margin">16dp</dimen>
    <dimen name="activity_vertical_margin">16dp</dimen>
    <dimen name="nav_header_vertical_spacing">8dp</dimen>
    <dimen name="nav_header_height">176dp</dimen>
    <dimen name="two_dp">2dp</dimen>
    <dimen name="four_dp">4dp</dimen>
    <dimen name="six_dp">6dp</dimen>
    <dimen name="eight_dp">8dp</dimen>
    <dimen name="twelve_dp">12dp</dimen>
    <dimen name="sixteen_dp">16dp</dimen>
</resources>