Ключевые слова: app, application, art, back to school, button, class, color, concept, contour, course, design, e learning, education, equipment, flat, geometry, gradient, icon, illustration, instrument, interface, isolated, learning, line, linear, lineart, logo, mathematics, measure, mobile, modern, orange, outline, pictogram, pixel perfect, purple, rectangle, ruler, school, sign, simple, stationery, study, symbol, tool, ui, user interface, web,