This was one of my first projects when I started to learn web development. Gustavo Neitzke's tutorial "Como Criar uma SIMPLES CALCULADORA com HTML, CSS e Javascript" helped me a lot.
Today (2023) I would change the colors, fonts and maybe try to do something minimalist.
Github Page: Javascript Calculator
Calculadora Javascript feita a partir do tutorial "Como Criar uma SIMPLES CALCULADORA com HTML, CSS e JAVASCRIPT" de Gustavo Neitzke.