Feet never come closer than shoulder width (EVER!) whilst standing in front of an opponent - our bodies are all designed to be top-heavy and must be centered between our evenly spread legs - when moving in a boxing ring, practice "sliding & gliding" - to do this, step with your front foot first and lightly drag your back foot next, returning back home - same rule applies when sliding & gliding backwards:  step back with your hind leg first, while lightly dragging the front leg back to HOME.