styles.css

:root {
  --font-family-open-sans: "Open Sans", "Helvetica Neue", Helvetica, Roboto, Arial, sans-serif;
  --font-family-martel: "Martel", Georgia, Cambria, "Times New Roman", Times, serif;
  --font-family-hack: "Hack", Consolas, "Liberation Mono", Courier, monospace;
}

html,
body {
  height:100%
}

html {
  box-sizing:border-box
}

*,
*:before,
*:after {
  -webkit-box-sizing:inherit;
  -moz-box-sizing:inherit;
  box-sizing:inherit
}

html, body {
  padding: 0;
  margin: 0;
  font-size: 100%;
}

h1, h2, h3, h4, h5, h6 {
  color: #222;
  font-style: normal;
  font-weight: 800;
  line-height: 1.4;
  margin-bottom: .5rem;
  margin-top: .2rem;
  text-rendering: optimizeLegibility;
}

p {
  font-family: inherit;
  font-size: 1rem;
  font-weight: normal;
  line-height: 1.6;
  margin-bottom: 1.25rem;
  text-rendering: optimizeLegibility;
}

/* Reset */
div, dl, dt, dd, ul, ol, li, h1, h2, h3, h4, h5, h6, pre, form, p, blockquote, th, td {
  margin: 0;
  padding: 0;
}

@media only screen and (min-width: 40.0625em) {
  h1,
  h2,
  h3,
  h4,
  h5,
  h6 {
    line-height:1.4
  }
  h1 {
    font-size:2.75rem
  }
  h2 {
    font-size:2.3125rem
  }
  h3 {
    font-size:1.6875rem
  }
  h4 {
    font-size:1.4375rem
  }
  h5 {
    font-size:1.125rem
  }
  h6 {
    font-size:1rem
  }
}