Do you know that you can use CSS to define the font-weight for Google Fonts ?
These values will allow you to set the font-weight inside your HTML
The above will give you the light version of your Google Font, Robot for example ( you need to add required code in your HTML page as well)
Apart from the above values, you can use values between 100 - 900 ( counts of 100 ) to specify the font weight.
400 = regular , 700 = bold , 100 = lighter