The following provides info about the base font and heading sizes used on NYC.gov and the agency templates.
Base font is 16px / 20px Helvetica Neue. Text color is dark gray, hex #333333 or rgb(51,51,51).
font-family: "Helvetica Neue", Helvetica,
Arial, sans-serif;
font-size: 16px;
line-height: 20px;
color: #333333;
The following heading styles are listed with font size in pixels followed by line height in pixels.
font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
font-weight: bold;
color: #333333 /rgb(51,51,51);
letter-spacing: -.025em