Ключевые слова: alternative, art, bio, black, button, circle, color, colorful, concept, contour, design, eco, ecological, ecology, electric, electrical, electricity, energy, environment, environmental, global, graphic, green, icon, idea, illustration, isolated, leaf, line, linear, lineart, modern, natural, nature, outline, plant, plug, power, recycle, renewable, save, saving, sign, symbol, technology,