body {
  --text-color: #333;
  --bkg-color: white;
  --anchor-color: blue;
  --code-bkg-color: aliceblue;
  --blockquote-bkg-color: linear-gradient(180deg, rgba(209,239,255,1) 0%, rgba(255,255,255,1) 65%, rgba(151,211,244,1) 100%);
  --visited-anchor-color: dodgerblue;
  --nice-list-bkg: linear-gradient(180deg, rgba(209,239,255,1) 0%, rgba(255,255,255,1) 65%, rgba(151,211,244,1) 100%);
}

body.dark-theme {
  --text-color: #eee;
  --bkg-color: #333;
  --anchor-color: #809fff;
  --code-bkg-color: #444;
  --blockquote-bkg-color: linear-gradient(180deg, rgba(34,34,34,1) 0%, rgba(9,9,121,1) 68%, rgba(34,34,34,1) 100%);
  --visited-anchor-color: dodgerblue;
  --nice-list-bkg: linear-gradient(180deg, rgba(34,34,34,1) 0%, rgba(9,9,121,1) 68%, rgba(0,212,255,1) 100%);
}

body {
  margin: 0;
  font-size: 18px;
  color: var(--text-color);
  background: var(--bkg-color);
  font-family: Helvetica, sans-serif;
}

main {
  margin: auto;
  width: 85%;
  max-width: 55em;
  line-height: 1.6;
  padding: 10px;
}

header h3 { font-size: 1.75em; }

h1 { font-size: 2.5em; }
h2 { font-size: 2em; }
main h3 { font-size: 1.75em; border-bottom: solid 1px lightgray; }
main h4 { font-size: 1.5em; border-bottom: solid 1px lightgray; }
main h5 { font-size: 1.3em; font-style: italic; border-bottom: solid 1px lightgray; }
main h6 { font-size: 1.1em; font-style: italic; border-bottom: solid 1px lightgray; }

.header {
  background: rgb(27,158,245);
  background: linear-gradient(90deg, rgba(27,158,245,1) 0%, rgba(180,134,204,1) 100%);
  padding: 1em;
  color: white;
}

.header .description {
  font-style: italic;
  color: #eee;
}

.header .navigation {
  float: right;
  margin: -10px;
}

.header .top-menu .section-link {
  padding: 0 0.1em 0 0.1em;
  text-decoration: none;
}

.header .top-menu .section-link.selected {
  border-bottom: solid 4px blueviolet;
  font-weight: bold;
}

#toggle-theme {
  background: none;
  position: absolute;
  top: 0;
  right: 0;
}

#toggle-theme:hover {
  background: rgb(0,0,255,0.1);
}

footer {
  display: flex;
  justify-content: space-around;
  background-color: rgba(27,158,245,1);
  padding: 2em 1em 2em 1em;
  color: white;
  margin-top: 4em;
}

nav a, nav a:visited {
  color: blue;
}

a {
  color: var(--anchor-color);
}

a:visited {
  color: var(--visited-anchor-color);
}

footer a {
  color: blue;
}

footer a:visited {
  color: lightblue;
}

.colorful-title {
  color: gray;
  font-weight: bold;
  font-size: 1.5em;
  mix-blend-mode: difference;
}

/* https://cssgradient.io/ */
.colorful-background {
  padding: 0em 1em 0.4em 1em;
  margin: 0.7em 0 0.7em 0;
  border: solid 1px var(--code-bkg-color);
  background: rgb(49,183,255);
  background: linear-gradient(180deg, rgba(49,183,255,1) 0%, rgba(255,255,255,1) 50%, rgba(151,211,244,1) 100%);
}

body.dark-theme .colorful-background {
  padding: 0em 1em 0.4em 1em;
  margin: 0.7em 0 0.7em 0;
  border: solid 1px #eee;
  background: rgb(34,34,34);
  background: linear-gradient(180deg, rgba(34,34,34,1) 0%, rgba(9,9,121,1) 68%, rgba(0,212,255,1) 100%);
}

.labels {
  padding-top: 0.5em;
}

.label {
  padding: 0.24em;
  background: purple;
  border-radius: 0.2em;
  color: white;
  margin: 0.2em;
  font-size: 0.8em;
}

.category {
  background: blue;
}

.spacer {
  flex-grow: 1;
}

.date {
  font-style: italic;
  font-size: 1.0em;
  color: #c0c0c0;
}

pre {
  padding: 0 1em 0;
  margin: 3em 0 2em 0;
  background: var(--code-bkg-color);
  overflow: auto;
}

code {
  background: var(--code-bkg-color);
  padding: 0.25em;
}

pre > code {
  background: unset;
}

blockquote {
  font-style: italic;
  background: rgb(209,239,255);
  background: var(--blockquote-bkg-color);
  padding: 1em;
  margin: 1em 0 1em 0;
  border: solid 1px var(--code-bkg-color);
}

summary {
  font-size: 1.4em;
  cursor: pointer;
}

summary > span {
  font-size: 0.8em;
  font-style: italic;
}

hr {
  margin: 2em 0 4em 0;
}

details {
  background: var(--code-bkg-color);
  padding: 0.6em;
}

img {
  margin: 2em 0px 0px 2em;
  max-width: 80%;
}

figure > img {
  margin: 0;
}

figcaption {
  margin: 0 auto 2em auto;
  width: 80%;
  font-size: 0.8em;
}

img.icon-logo {
  padding: 0;
  margin: 0;
  position: relative;
  top: 3.1em;
  left: 90%;
}

small.img-description {
  margin: 0px 0px 0px 2em;
}

.small {
  font-size: 0.75em;
}

.nice-list li {
  background: rgb(209,239,255);
  background: var(--nice-list-bkg);
  padding: 0.5em;
  list-style: none;
  margin: 0 0 0.25em 0;
}

table {
  border-collapse: collapse;
}

table thead th {
  min-width: 10em;
}

table, th, td {
  border: solid black 1px;
}

iframe.spaced {
  padding: 0.2em;
}

button {
  background-color: rgba(27,158,245,1);
  padding: 10px;
  border: none;
  font-size: 1.4em;
  min-width: 4em;
  cursor: pointer;
  color: white;
}

button:hover {
  background-color: rgba(27,158,245,0.8);
}

.center-container {
  display: flex;
  justify-content: center;
}

.quote {
  margin: 2em;
  font-style: italic;
}