An arched window covering having shade mount with a base, at least a spacer, and two rails wherein a shade is mounted on the shade mount and the width of the spacer is adjustable and positioned on the base such that the rails movably engage the base and a length of the shade mount is changeable by changing the width of the spacer to thereby adapt to a differing size of a shade mounted on the shade mount by adjusting the spacer rather than cutting the rail to fit the windows with different sizes.