Default styles with responsive typography

style.css

@charset "UTF-8";
html{
  font-family:"PT Serif", Georgia, serif;
  font-size:100%;
  line-height:1.6;
  background:#fff;
  color:#000;
  -webkit-overflow-scrolling:touch; }

body{
  margin:1em;
  font-size:1rem; }
  @media (min-width: 20rem){
    body{
      font-size:calc(1rem + 0.0125 * (100vw - 20rem)); } }
  @media (min-width: 40rem){
    body{
      font-size:1.25rem; } }
  body header,
  body main,
  body footer,
  body article{
    position:relative;
    max-width:40rem;
    margin:0 auto; }
  body > header{
    margin-bottom:3.5em; }
    body > header h1{
      margin:0;
      font-size:1.5em; }
    body > header p{
      margin:0;
      font-size:.85em; }
  body > footer{
    margin-top:4.5em;
    padding-bottom:1.5em;
    text-align:center;
    font-size:.8rem;
    color:#aaa; }

nav{
  margin:1em 0; }
  nav ul{
    list-style:none;
    margin:0;
    padding:0; }
  nav li{
    display:inline-block;
    margin-right:1em;
    margin-bottom:.25em; }
  nav a:visited{
    color:#0064c1; }
  nav a:hover{
    color:#3000c1; }

ul, ol{
  margin-top:0;
  padding-top:0;
  padding-left:2.5em; }

p{
  margin:1em 0;
  -webkit-hyphens:auto;
      -ms-hyphens:auto;
          hyphens:auto; }
  p:first-child{
    margin-top:0; }
  p:last-child{
    margin-bottom:0; }
  p + ul, p + ol{
    margin-top:-.75em; }
  p img, p picture{
    float:right;
    margin-bottom:.5em;
    margin-left:.5em; }
  p picture img{
    float:none;
    margin:0; }

dd{
  margin-bottom:1em;
  margin-left:0;
  padding-left:2.5em; }

dt{
  font-weight:700; }

blockquote{
  margin:0;
  padding-left:2.5em; }

aside{
  margin:.5em 0;
  font-style:italic;
  color:#aaa; }
  @media (min-width: 65rem){
    aside{
      position:absolute;
      right:-12.5rem;
      width:9.375rem;
      max-width:9.375rem;
      margin:0;
      padding-left:.5em;
      font-size:.8em;
      border-left:1px solid #f2f2f2; } }
  aside:first-child{
    margin-top:0; }
  aside:last-child{
    margin-bottom:0; }

section + section{
  margin-top:2em; }

h1, h2, h3, h4, h5, h6{
  margin:1.25em 0 0;
  line-height:1.2; }
  h1:hover > a[href^='#'][id], h1:focus > a[href^='#'][id], h2:hover > a[href^='#'][id], h2:focus > a[href^='#'][id], h3:hover > a[href^='#'][id], h3:focus > a[href^='#'][id], h4:hover > a[href^='#'][id], h4:focus > a[href^='#'][id], h5:hover > a[href^='#'][id], h5:focus > a[href^='#'][id], h6:hover > a[href^='#'][id], h6:focus > a[href^='#'][id]{
    opacity:1;
    transition:opacity 0s, color 300ms ease-out; }
  h1 + p, h1 + details, h2 + p, h2 + details, h3 + p, h3 + details, h4 + p, h4 + details, h5 + p, h5 + details, h6 + p, h6 + details{
    margin-top:.5em; }
  h1 > a[href^='#'][id], h2 > a[href^='#'][id], h3 > a[href^='#'][id], h4 > a[href^='#'][id], h5 > a[href^='#'][id], h6 > a[href^='#'][id]{
    position:absolute;
    left:-.5em;
    opacity:0;
    background:none;
    color:rgba(0, 0, 0, 0.5);
    transition:opacity 300ms ease-out; }
    h1 > a[href^='#'][id]:target, h1 > a[href^='#'][id]:hover, h1 > a[href^='#'][id]:focus, h2 > a[href^='#'][id]:target, h2 > a[href^='#'][id]:hover, h2 > a[href^='#'][id]:focus, h3 > a[href^='#'][id]:target, h3 > a[href^='#'][id]:hover, h3 > a[href^='#'][id]:focus, h4 > a[href^='#'][id]:target, h4 > a[href^='#'][id]:hover, h4 > a[href^='#'][id]:focus, h5 > a[href^='#'][id]:target, h5 > a[href^='#'][id]:hover, h5 > a[href^='#'][id]:focus, h6 > a[href^='#'][id]:target, h6 > a[href^='#'][id]:hover, h6 > a[href^='#'][id]:focus{
      opacity:1;
      box-shadow:none;
      color:#000;
      transition:opacity 0s, color 0s; }
    h1 > a[href^='#'][id]:target:focus, h2 > a[href^='#'][id]:target:focus, h3 > a[href^='#'][id]:target:focus, h4 > a[href^='#'][id]:target:focus, h5 > a[href^='#'][id]:target:focus, h6 > a[href^='#'][id]:target:focus{
      outline:none; }
    h1 > a[href^='#'][id]::before, h2 > a[href^='#'][id]::before, h3 > a[href^='#'][id]::before, h4 > a[href^='#'][id]::before, h5 > a[href^='#'][id]::before, h6 > a[href^='#'][id]::before{
      content:'•'; }

h1{
  font-size:2em; }

h2{
  font-size:1.75em; }

h3{
  font-size:1.25em; }

h4{
  font-size:1.15em; }

h5{
  font-size:1em; }

h6{
  margin-top:1em;
  font-size:1em;
  color:#aaa; }

article + article{
  margin-top:5em; }

article header p{
  font-family:system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, Cantarell, "Fira Sans", "Droid Sans", "Helvetica Neue", Helvetica, Arial, sans-serif;
  font-size:.6em;
  color:#aaa; }
  article header p + h1, article header p + h2{
    margin-top:-.25em; }

article header h1 + p, article header h2 + p{
  margin-top:.25em; }

article header h1 a, article header h2 a{
  color:#000;
  background:url('data:image/svg+xml;charset=utf8,%3Csvg xmlns="http://www.w3.org/2000/svg" width="1" height="1"%3E%3Crect x="0" y="0.5" width="1" height="0.5" fill="rgba(0, 0, 0, 0.35)"/%3E%3C/svg%3E') left bottom repeat-x; }
  @media screen and (-ms-high-contrast: active), (-ms-high-contrast: none){
    article header h1 a, article header h2 a{
      background:url('data:image/svg+xml;charset=utf8,%3Csvg xmlns="http://www.w3.org/2000/svg" width="1" height="2"%3E%3Crect x="0" y="1" width="1" height="1" fill="rgba(0, 0, 0, 0.35)"/%3E%3C/svg%3E') left bottom repeat-x; } }
  article header h1 a:visited, article header h2 a:visited{
    color:#aaa;
    background:url('data:image/svg+xml;charset=utf8,%3Csvg xmlns="http://www.w3.org/2000/svg" width="1" height="1"%3E%3Crect x="0" y="0.5" width="1" height="0.5" fill="rgba(170, 170, 170, 0.35)"/%3E%3C/svg%3E') left bottom repeat-x; }
    @media screen and (-ms-high-contrast: active), (-ms-high-contrast: none){
      article header h1 a:visited, article header h2 a:visited{
        background:url('data:image/svg+xml;charset=utf8,%3Csvg xmlns="http://www.w3.org/2000/svg" width="1" height="2"%3E%3Crect x="0" y="1" width="1" height="1" fill="rgba(170, 170, 170, 0.35)"/%3E%3C/svg%3E') left bottom repeat-x; } }
    article header h1 a:visited:hover, article header h2 a:visited:hover{
      color:#3000c1; }

article > footer{
  margin-top:1.5em;
  font-size:.85em; }

a{
  text-decoration:none;
  color:#0064c1;
  transition:color 300ms ease-out, box-shadow 300ms ease-out;
  background:url('data:image/svg+xml;charset=utf8,%3Csvg xmlns="http://www.w3.org/2000/svg" width="1" height="1"%3E%3Crect x="0" y="0.5" width="1" height="0.5" fill="rgba(0, 100, 193, 0.35)"/%3E%3C/svg%3E') left bottom repeat-x; }
  @media screen and (-ms-high-contrast: active), (-ms-high-contrast: none){
    a{
      background:url('data:image/svg+xml;charset=utf8,%3Csvg xmlns="http://www.w3.org/2000/svg" width="1" height="2"%3E%3Crect x="0" y="1" width="1" height="1" fill="rgba(0, 100, 193, 0.35)"/%3E%3C/svg%3E') left bottom repeat-x; } }
  a:visited{
    color:#80b2e0; }
  a:hover, a:active{
    outline-width:0; }
  a:hover{
    box-shadow:inset 0px -1px #3000c1;
    color:#3000c1;
    transition:color 0s, box-shadow 0s; }

abbr{
  margin-right:-.075em;
  -webkit-hyphens:none;
      -ms-hyphens:none;
          hyphens:none;
  letter-spacing:.075em;
  font-size:.9em; }

img, picture{
  display:block;
  max-width:100%;
  margin:0 auto; }

audio, video{
  width:100%;
  max-width:100%; }

video{
  -o-object-position:0 -1px;
     object-position:0 -1px; }

figure{
  margin:1em 0 .5em;
  padding:0; }
  figure + p{
    margin-top:.5em; }
  figure figcaption{
    opacity:.65;
    font-size:.85em; }

table{
  display:inline-block;
  border-spacing:0;
  border-collapse:collapse;
  overflow-x:auto;
  max-width:100%;
  text-align:left;
  vertical-align:top;
  background:linear-gradient(rgba(0, 0, 0, 0.15) 0%, rgba(0, 0, 0, 0.15) 100%) 0 0, linear-gradient(rgba(0, 0, 0, 0.15) 0%, rgba(0, 0, 0, 0.15) 100%) 100% 0;
  background-attachment:scroll, scroll;
  background-size:1px 100%, 1px 100%;
  background-repeat:no-repeat, no-repeat; }
  table caption{
    font-size:.9em;
    background:#fff; }
  table td, table th{
    padding:.35em .75em;
    vertical-align:top;
    font-size:.9em;
    border:1px solid #f2f2f2;
    border-top:0;
    border-left:0; }
    table td:first-child, table th:first-child{
      padding-left:0;
      background-image:linear-gradient(to right, white 50%, rgba(255, 255, 255, 0) 100%);
      background-size:2px 100%;
      background-repeat:no-repeat; }
    table td:last-child, table th:last-child{
      padding-right:0;
      border-right:0;
      background-image:linear-gradient(to left, white 50%, rgba(255, 255, 255, 0) 100%);
      background-position:100% 0;
      background-size:2px 100%;
      background-repeat:no-repeat; }
    table td:only-child, table th:only-child{
      background-image:linear-gradient(to right, white 50%, rgba(255, 255, 255, 0) 100%), linear-gradient(to left, white 50%, rgba(255, 255, 255, 0) 100%);
      background-position:0 0, 100% 0;
      background-size:2px 100%, 2px 100%;
      background-repeat:no-repeat, no-repeat; }
  table th{
    line-height:1.2; }

code, kbd, var, samp{
  font-family:Consolas, "Lucida Console", Monaco, monospace;
  font-style:normal; }

pre{
  overflow-x:auto;
  font-size:.8em;
  background:linear-gradient(rgba(0, 0, 0, 0.15) 0%, rgba(0, 0, 0, 0.15) 100%) 0 0, linear-gradient(rgba(0, 0, 0, 0.15) 0%, rgba(0, 0, 0, 0.15) 100%) 100% 0;
  background-attachment:scroll, scroll;
  background-size:1px 100%, 1px 100%;
  background-repeat:no-repeat, no-repeat; }
  pre > code{
    display:inline-block;
    overflow-x:visible;
    box-sizing:border-box;
    min-width:100%;
    border-right:3px solid #fff;
    border-left:1px solid #fff; }

hr{
  height:1px;
  margin:2em 0;
  border:0;
  background:#f2f2f2; }

details{
  margin:1em 0; }
  details[open]{
    padding-bottom:.5em;
    border-bottom:1px solid #f2f2f2; }

summary{
  display:inline-block;
  font-weight:700;
  border-bottom:1px dashed;
  cursor:pointer; }
  summary::-webkit-details-marker{
    display:none; }

noscript{
  color:#d00000; }

::-moz-selection{
  background:rgba(0, 100, 193, 0.15); }

::selection{
  background:rgba(0, 100, 193, 0.15); }

Fluid typography https://www.smashingmagazine.com/2017/05/fluid-responsive-typography-css-poly-fluid-sizing/

About font loading https://www.zachleat.com/web/comprehensive-webfonts/

More about typography https://matejlatin.co.uk/

https://github.com/kennethwang14/TypographyHandbook