style.css

@import url('https://fonts.googleapis.com/css?family=Roboto:300,400,700');

:root {
  --bg-color: #333;
  --def-color: #d3e6f1;
  --def-accent-color: #abc;
  --link-color: #08c;
}

/************Reset**************/
* {
  box-sizing: border-box;
}

html,
body,
div,
object,
iframe,
fieldset {
  margin: 0;
  padding: 0;
  border: 0;
}

ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

table {
  border-collapse: collapse;
  border-spacing: 0;
}

header,
article,
figure {
  display: block;
}

svg:not(:root) {
  overflow: hidden;
}

/************End Reset**************/

body {
  font-family: "Roboto", "Helvetica Neue", "Arial", sans-serif;
  font-size: 105%;
  color: #333;
  line-height: 1.5;
  overflow-x: hidden;
}

article {
  padding: 10px;
  margin: 0 auto;
  max-width: 605px;
}

/* nav {
  margin: 0;
  max-width: 100%;
  position: fixed;
  left: 10px;
}


@media screen and (max-width: 900px) {
  nav {
    display: none;
  }
} */

h1,
h2,
h3 {
  font-weight: 400;
}

button {
  font-family: "Roboto", "Helvetica Neue", "Arial", sans-serif;
  font-size: 1em;
  margin: 0.3em;
}

input {
  font-family: Monaco, monospace;
  font-size: 90%;
  border: 10px;
  margin: 0.2em;
  width: 80px;
}

input[type="number"] {
  background-color: #eee;
}

input[type="text"] {
  background-color: #eee;
}

input:focus {
  outline: 0;
}

input[type="range"] {
  height: 12px;
}

input[type=range]::-moz-focus-outer {
  border: 0;
}

a {
  text-decoration: none;
  color: var(--link-color);
}

a:hover {
  text-decoration: underline;
  /* color: #000; */
}

summary {
  cursor: pointer;
  outline: none;
}

hr {
  border: 0;
  border-bottom: 1px solid #aaa;
}

::selection {
  color: white;
  background-color: var(--link-color);
}

pre {
  overflow-x: auto;
  background-color: #eee;
}

table {
  margin: 5px auto;
  border-collapse: collapse;
  border: 1px solid #eee;
  width: 100%;
}

tr:hover {
  background-color: #f4f4f4;
}

th,
td {
  text-align: center;
  border: 1px solid #eee;
  padding: 0.25rem;
  border-collapse: collapse;
}

th {
  background-color: #444;
  color: #fff;
}

canvas,
.SVG-shadow {
  margin: 0px;
  box-shadow: 2px 2px 8px #aaa;
  border-radius: 5px;
  user-select: none;
}

.no-shadow {
  box-shadow: none;
  border-radius: 0px;
}

.book-cover {
  box-shadow: 3px 3px 10px #666;
  margin: 20px auto;
  display: block;
  border-radius: 3px;
}

.underlined {
  /* text-transform: uppercase; */
  color: #000;
  margin-top: 6em;
  margin-bottom: 0em;
  border-bottom: 1px solid #aaa;
  font-weight: 300;
  font-size: 1.75em;
  word-spacing: 2px;
}

.underlined-small {
  color: #000;
  margin-top: 2.5em;
  margin-bottom: 0em;
  border-bottom: 1px solid #aaa;
  font-weight: 300;
  font-size: 1.3em;
}

.center {
  text-align: center;
  padding: 0;
  margin: auto;
  display: block;
}

.on-edge {
  margin-left: -1em;
  margin-right: -1em;
}

.definition {
  color: #000;
  background-color: var(--def-color);
  padding: 1em;
  margin: 1em 0em 1em 0em;
  border-radius: 1em;
  line-height: 1.6;
  font-size: 110%;
}

.definition em {
  color: #888;
  font-weight: 300;
}

.derive {
  color: #111;
  background-color: #eee;
  padding: 1em;
  border-radius: 1em;
}

.example {
  margin: 8em 0em 8em 0em;
}

.example-small {
  margin: 3em 0em 3em 0em;
}

.details {
  margin: 0;
  padding: 1em;
  background-color: #eee;
  border-radius: 15px;
}

.katex {
  font-size: 1.5em;
}

/* Grid with auto placement ______________________________________*/
.listing {
  list-style: none;
  display: grid;
  grid-gap: 20px;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
}

.listing li {
  display: flex;
  flex-direction: column;
}


@media screen and (max-width: 500px) {
  .listing {
    grid-column-gap: 15px;
    grid-row-gap: 15px;
    grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
    /* font-size: 90%; */
  }
}


/* flex grid thirds _________________________________*/

.flex-grid-thirds {
  display: flex;
}

.col {
  flex: 1;
}

@media (max-width: 500px) {
  .flex-grid-thirds {
    display: block;
  }
}

/* Header setup_________________________________*/
header {
  background-color: var(--bg-color);
  padding: 5px 0px;
  text-align: center;
  width: 100%;
  margin: 0 auto;
  /* max-width: 585px; */
  /* border-bottom: 2px solid #000; */
}

header h1 {
  font-size: 50px;
  font-weight: 300;
  letter-spacing: 1px;
  margin: 0;
  color: #fff;
  /* font-family: "Times New Roman", Times, serif; */
}

header h1 a {
  color: #fff;
  text-decoration: none;
}

header h1 a:hover,
.back a:hover {
  color: #ccc;
  text-decoration: none;
}

header p {
  color: #fff;
}

/* footer setup_________________________________*/
footer {
  margin-top: 4em;
  padding: 1.3em;
  text-align: center;
  background-color: #333;
  font-size: 25px;
}

footer a {
  color: #fff;
}

.back {
  text-align: center;
  padding: 1em;
  margin: 6em 0em 0em 0em;
  width: 100%;
  background-color: var(--bg-color);
}

.back a {
  /* background-color: #222; */
  font-size: 1.3em;
  color: #fff;
  padding: 0.3em 1em;
  border-radius: 1em;
}

@media screen and (min-width: 650px) {
  .col-group {
    overflow: hidden;
  }

  .col-group>div {
    float: left;
    width: 50%;
  }
}

.show-on-mobile {
  display: none;
}

/* responsive media rules for mobile________________________________ */
@media screen and (max-width: 650px) {

  .col-group>div {
    padding-bottom: 20px;
  }

  header h1 {
    font-size: 38px;
    margin: 0px 10px;
    letter-spacing: 1px;
  }

  .definition {
    padding: 10px;
    font-size: 100%;
  }

  .on-edge {
    margin-left: -10px;
    margin-right: -10px;
  }

  .katex {
    font-size: 1.3em;
  }

  canvas {
    max-width: 100%;
    height: auto;
  }

  .hide-on-mobile {
    display: none;
  }

  .show-on-mobile {
    display: block;
  }
}