I suggest you follow the step-by-step guide for creating storage cabinets under the bathroom sink. Take proper measurements - Measure the available available space in height, width and height. Cut Plywood to size - With a circular saw and framing square, cut all the required pieces out. You can use a sliding compound saw as an alternative. Attach the base and sides - Start assembling the sink cabinets by placing the bottom piece of plywood sheet on a flat surface. Attach the back and top boards - Place the plywood sheet for the top part of the cabinet and attach wood screws to connect it to both the sides. Turn the back faces of the cabinet upwards. Keep the back piece over the structure and fix it into place with wood screws. Attach shelves - Place the cabinet in an upright position to install the shelves. Slide a shelf into the structure so it is flush against the back. Attach door - Keep both hinges of the door on the same side of the plywood sheet. Drill them using wood screws into place. Now keep the door over the cabinet structure, extend the hinges to one of the side panels and fix them to make them secure. Fix a hasp closure on the other side of the door, placing it in the center of the hinges.

I love dark shades but from my experience oil stains on a dark shaded cabinets in kitchen specifically are more prominent.

that's what I meant. The cabinets below and above the counter can be finished with a light toned wood grained laminate. if you feel that is too plain, another option would be to go with light wood grain below and plain off white above. Maybe add a couple of wood grained shutters above also to break the monotony

One Follow-up question.. Is there any strength issue with 20mm Granite slab over 40mm Granite.. Are the 20mm granite slab prone to chipping or crack on normal usage.. Usage would be like, chopping vegetables, keeping hot vessels,.. The normal usage what happens in normal indian kitchen.. I just want to be sure that I decide based on experts judgement (like you), as people are just throwing their opinion based on their guess...