<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <style> body, ul, li, select { margin: 0; padding: 0; box-sizing: border-box; } ul, li { list-style: none; } .calculator { max-width: 300px; margin: 20px auto; border: 1px solid #eee; border-radius: 3px; } ....
