simple.css

/* Global variables. */
:root {
  /* Set sans-serif & mono fonts */
  --sans-font: -apple-system, BlinkMacSystemFont, "Avenir Next", Avenir,
    "Nimbus Sans L", Roboto, Noto, "Segoe UI", Arial, Helvetica,
    "Helvetica Neue", sans-serif;
  --mono-font: Consolas, Menlo, Monaco, "Andale Mono", "Ubuntu Mono", monospace;

  /* Default (light) theme */
  --bg: #fff;
  --accent-bg: #f5f7ff;
  --text: #212121;
  --text-light: #585858;
  --border: #d8dae1;
  --accent: #0d47a1;
  --code: #d81b60;
  --preformatted: #444;
  --marked: #ffdd33;
  --disabled: #efefef;
}

/* Dark theme */
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #212121;
    --accent-bg: #2b2b2b;
    --text: #dcdcdc;
    --text-light: #ababab;
    --border: #666;
    --accent: #ffb300;
    --code: #f06292;
    --preformatted: #ccc;
    --disabled: #111;
  }
  /* Add a bit of transparancy so light media isn't so glaring in dark mode */
  img,
  video {
    opacity: 0.8;
  }
}

html {
  /* Set the font globally */
  font-family: var(--sans-font);
  scroll-behavior: smooth;
}

/* Make the body a nice central block */
body {
  color: var(--text);
  background: var(--bg);
  font-size: 1.15rem;
  line-height: 1.5;
  display: grid;
  grid-template-columns:
    1fr min(45rem, 90%) 1fr;
  margin: 0;
}

body>* {
  grid-column: 2;
}

/* Make the header bg full width, but the content inline with body */
body > header {
  background: var(--accent-bg);
  border-bottom: 1px solid var(--border);
  text-align: center;
  padding: 0 0.5rem 2rem 0.5rem;
  grid-column: 1 / -1;
  box-sizing: border-box;
}

body > header h1 {
  max-width: 1200px;
  margin: 1rem auto;
}

body > header p {
  max-width: 40rem;
  margin: 1rem auto;
}

/* Add a little padding to ensure spacing is correct between content and nav */
main {
  padding-top: 1.5rem;
}

body > footer {
  margin-top: 4rem;
  padding: 2rem 1rem 1.5rem 1rem;
  color: var(--text-light);
  font-size: 0.9rem;
  text-align: center;
  border-top: 1px solid var(--border);
}

/* Format headers */
h1 {
  font-size: 3rem;
}

h2 {
  font-size: 2.6rem;
  margin-top: 3rem;
}

h3 {
  font-size: 2rem;
  margin-top: 3rem;
}

h4 {
  font-size: 1.44rem;
}

h5 {
  font-size: 1.15rem;
}

h6 {
  font-size: 0.96rem;
}

/* Fix line height when title wraps */
h1,
h2,
h3 {
  line-height: 1.1;
}

/* Reduce header size on mobile */
@media only screen and (max-width: 720px) {
  h1 {
    font-size: 2.5rem;
  }

  h2 {
    font-size: 2.1rem;
  }

  h3 {
    font-size: 1.75rem;
  }

  h4 {
    font-size: 1.25rem;
  }
}

/* Format links & buttons */
a,
a:visited {
  color: var(--accent);
}

a:hover {
  text-decoration: none;
}

button,
[role="button"],
input[type="submit"],
input[type="reset"],
input[type="button"] {
  border: none;
  border-radius: 5px;
  background: var(--accent);
  font-size: 1rem;
  color: var(--bg);
  padding: 0.7rem 0.9rem;
  margin: 0.5rem 0;
}

button[disabled],
[role="button"][aria-disabled="true"],
input[type="submit"][disabled],
input[type="reset"][disabled],
input[type="button"][disabled],
input[type="checkbox"][disabled],
input[type="radio"][disabled],
select[disabled] {
  cursor: default;
  opacity: 0.5;
  cursor: not-allowed;
}

input:disabled,
textarea:disabled,
select:disabled {
  cursor: not-allowed;
  background-color: var(--disabled);
}

input[type="range"] {
  padding: 0;
}

/* Set the cursor to '?' while hovering over an abbreviation */
abbr {
  cursor: help;
}

button:focus,
button:enabled:hover,
[role="button"]:focus,
[role="button"]:not([aria-disabled="true"]):hover,
input[type="submit"]:focus,
input[type="submit"]:enabled:hover,
input[type="reset"]:focus,
input[type="reset"]:enabled:hover,
input[type="button"]:focus,
input[type="button"]:enabled:hover {
  filter: brightness(1.4);
  cursor: pointer;
}

/* Format navigation */
nav {
  font-size: 1rem;
  line-height: 2;
  padding: 1rem 0;
}

nav a,
nav a:visited {
  margin: 0 1rem 0 0;
  border: 1px solid var(--border);
  border-radius: 5px;
  color: var(--text);
  display: inline-block;
  padding: 0.1rem 1rem;
  text-decoration: none;
}

nav a:hover {
  color: var(--accent);
  border-color: var(--accent);
}

/* Reduce nav side on mobile */
@media only screen and (max-width: 750px) {
  nav a {
    border: none;
    padding: 0;
    color: var(--accent);
    text-decoration: underline;
    line-height: 1;
  }
}

/* Format the expanding box */
details {
  background: var(--accent-bg);
  border: 1px solid var(--border);
  border-radius: 5px;
  margin-bottom: 1rem;
}

summary {
  cursor: pointer;
  font-weight: bold;
  padding: 0.6rem 1rem;
}

details[open] {
  padding: 0.6rem 1rem 0.75rem 1rem;
}

details[open] summary + * {
  margin-top: 0;
}

details[open] summary {
  margin-bottom: 0.5rem;
  padding: 0;
}

details[open] > *:last-child {
  margin-bottom: 0;
}

/* Format tables */
table {
  border-collapse: collapse;
  width: 100%;
  margin: 1.5rem 0;
}

td,
th {
  border: 1px solid var(--border);
  text-align: left;
  padding: 0.5rem;
}

th {
  background: var(--accent-bg);
  font-weight: bold;
}

tr:nth-child(even) {
  /* Set every other cell slightly darker. Improves readability. */
  background: var(--accent-bg);
}

table caption {
  font-weight: bold;
  margin-bottom: 0.5rem;
}

/* Format forms */
textarea,
select,
input {
  font-size: inherit;
  font-family: inherit;
  padding: 0.5rem;
  margin-bottom: 0.5rem;
  color: var(--text);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 5px;
  box-shadow: none;
  box-sizing: border-box;
  width: 60%;
  -moz-appearance: none;
  -webkit-appearance: none;
  appearance: none;
}

/* Add arrow to drop-down */
select {
  background-image: linear-gradient(45deg, transparent 49%, var(--text) 51%),
    linear-gradient(135deg, var(--text) 51%, transparent 49%);
  background-position: calc(100% - 20px), calc(100% - 15px);
  background-size: 5px 5px, 5px 5px;
  background-repeat: no-repeat;
}

select[multiple] {
  background-image: none !important;
}

/* checkbox and radio button style */
input[type="checkbox"],
input[type="radio"] {
  vertical-align: bottom;
  position: relative;
}

input[type="radio"] {
  border-radius: 100%;
}

input[type="checkbox"]:checked,
input[type="radio"]:checked {
  background: var(--accent);
}

input[type="checkbox"]:checked::after {
  /* Creates a rectangle with colored right and bottom borders which is rotated to look like a check mark */
  content: " ";
  width: 0.1em;
  height: 0.25em;
  border-radius: 0;
  position: absolute;
  top: 0.05em;
  left: 0.18em;
  background: transparent;
  border-right: solid var(--bg) 0.08em;
  border-bottom: solid var(--bg) 0.08em;
  font-size: 1.8em;
  transform: rotate(45deg);
}
input[type="radio"]:checked::after {
  /* creates a colored circle for the checked radio button  */
  content: " ";
  width: 0.25em;
  height: 0.25em;
  border-radius: 100%;
  position: absolute;
  top: 0.125em;
  background: var(--bg);
  left: 0.125em;
  font-size: 32px;
}

/* Make the textarea wider than other inputs */
textarea {
  width: 80%;
}

/* Makes input fields wider on smaller screens */
@media only screen and (max-width: 720px) {
  textarea,
  select,
  input {
    width: 100%;
  }
}

/* Ensures the checkbox and radio inputs do not have a set width like other input fields */
input[type="checkbox"],
input[type="radio"] {
  width: auto;
}

/* do not show border around file selector button */
input[type="file"] {
  border: 0;
}

/* Misc body elements */
hr {
  color: var(--border);
  border-top: 1px;
  margin: 1rem auto;
}

mark {
  padding: 2px 5px;
  border-radius: 4px;
  background: var(--marked);
}

main img,
main video {
  max-width: 100%;
  height: auto;
  border-radius: 5px;
}

figure {
  margin: 0;
  text-align: center;
}

figcaption {
  font-size: 0.9rem;
  color: var(--text-light);
  margin-bottom: 1rem;
}

blockquote {
  margin: 2rem 0 2rem 2rem;
  padding: 0.4rem 0.8rem;
  border-left: 0.35rem solid var(--accent);
  color: var(--text-light);
  font-style: italic;
}

cite {
  font-size: 0.9rem;
  color: var(--text-light);
  font-style: normal;
}

/* Use mono font for code elements */
code,
pre,
pre span,
kbd,
samp {
  font-size: 1.075rem;
  font-family: var(--mono-font);
  color: var(--code);
}

kbd {
  color: var(--preformatted);
  border: 1px solid var(--preformatted);
  border-bottom: 3px solid var(--preformatted);
  border-radius: 5px;
  padding: 0.1rem;
}

pre {
  padding: 1rem 1.4rem;
  max-width: 100%;
  overflow: auto;
  overflow-x: auto;
  color: var(--preformatted);
  background: var(--accent-bg);
  border: 1px solid var(--border);
  border-radius: 5px;
}

/* Fix embedded code within pre */
pre code {
  color: var(--preformatted);
  background: none;
  margin: 0;
  padding: 0;
}