convert base font-size: 10px; rem to base font-size: 16px; rem

base-rem-converter.js

code = `` // put your code here

index = 0

while (index > -1) {
    regex = /(\d+|\d*\.\d+)rem/g
    result = regex.exec(code.slice(index))

    if (result == null) {
        index = -1
    } else {
        index = result.index + code.slice(0, index).length
        codeBefore = code.slice(0, index)
        codeAfter = code.slice(index + result[0].length)
        number = parseFloat(result[1])
        number = number * 10 / 16 // rem -> base 10px -> base 16px
        code = codeBefore + number + 'rem' + codeAfter
        index += number.toString().length + 3
    }
}

console.log(code) // copy from browser console