:root {
  --circle-diameter: 2em;
  --focus-color: #68c;
  --page-background: #fdfefa;
  --item-background: #fefffc;
  --summary-background: #eee;
  --summary-open-background: #f6f6f6;
  --summary-latest-background: #eef6ff;
  --border-color: #ccc;
  --page-margin: 1em;
  --text-color: #333;
}

html, body: {
  margin: 0;
  padding: 0;
}
body {
  font-family: Verdana, sans-serif;
  line-height: 1.4em;
  margin: auto;
  padding: 0;
  max-width: 40em;
  color: var(--text-color);
  font-variant-numeric: oldstyle-nums;
  -webkit-font-feature-settings: "onum";
  font-feature-settings: "onum";
  background-color: var(--page-background);
}
ol {
  list-style: none;
  padding: 0 0 0 4em;
  margin: 0 auto;
}
li {
  margin: 1em 0;
  position: relative;
}
h1 {
  font-family: Georgia, serif;
  font-weight: bold;
  letter-spacing: 0.03em;
  margin: 3rem 1rem;
  line-height: 1em;
}
h1 > a {
  text-decoration: none;
}
a, a:visited {
  color: var(--focus-color);
}
p {
  margin: 1rem;
}
details {
  border: solid 2px var(--border-color);
  border-radius: 0.5em;
  position: relative;
  transition: opacity 0.15s ease-in-out;
  background-color: var(--item-background);
  line-height: 1.5em;
}
summary {
  cursor: pointer;
  padding: 0 0.5em;
  border-radius: calc(0.5em - 2px);
  line-height: var(--circle-diameter);
}
summary,
summary > .number {
  transition: background-color 0.15s ease-in-out;
}
summary::marker {
  margin-right: 5em;
  display: inline-block;
  padding-right: 2em;
}
summary:hover,
details[open] > summary {
  background: var(--summary-background);
}
a:target {
  margin: -1px 0 0 0;
  border: solid 2px var(--text-color);
}
details.target {
  border-color: #666;
}
details.latest {
  border-color: var(--focus-color);
}
details.latest > summary:not(:hover) {
  background-color: var(--summary-latest-background);
}
details.latest > summary {
  background-color: var(--summary-latest-background);
}
details[open] > summary:not(:hover) {
  background: var(--summary-open-background);
}
details[open] > summary {
  border-bottom-left-radius: 0;
  border-bottom-right-radius: 0;
}
.number,
.number:visited {
  position: absolute;
  left: calc(var(--circle-diameter) - 5em - 2px);
  top: -2px;
  width: var(--circle-diameter);
  background: var(--focus-color);
  border-radius: 100px;
  border: solid 2px transparent;
  height: var(--circle-diameter);
  line-height: var(--circle-diameter);
  text-align: center;
  color: white;
  user-select: none;
  text-decoration: none;
  font-weight: bold;
}
summary:hover > .number {
  background: #9ce;
}
details:target .number {
  border-color: var(--text-color);
}
details > p,
details > :is(h1, h2, h3, h4, h5, h6) {
  margin: 1rem;
}
.future > details:not(:hover):not([open]):not(.target) {
  opacity: 0.7;
}

li:not(.future) + .future {
  
}
li:not(.future) + .future::before {
  content: '☃';
  font-size: 3em;
  display: block;
  text-align: center;
  position: relative;
  width: 100%;
  height: 3rem;
  top: -0.5rem;
  line-height: 3rem;
  color: #ccc;
  padding: 0.5rem 0;
}


@media only screen and (max-width: 42em) {
  :root {
    --page-margin: 0.2em;
  }
  body {
    max-width: none;
  }
  details {
    border-style: none;
    margin-bottom: -2px;
  }
  details,
  summary {
    border-radius: 0;
  }
  ol {
    padding: 0;
  }
  li {
    margin: 0;
  }
  li:last-child > details {
    border-style: none;
  }
  summary,
  details > p {
    padding-left: calc(var(--circle-diameter) + 2em);
  }
  details > p {
    margin-left: 0;
    margin-right: 0;
    padding-right: 1em;
  }
  .number {
    left: 1em;
    top: 0.5em;
  }
  summary {
    padding-top: 0.5em;
    padding-bottom: 0.5em;
  }

  li:not(.future) + .future::before {
    top: 0;
  }
}

@media (prefers-color-scheme: dark) {
  :root {
    --page-background: #111;
    --summary-background: rgba(255, 255, 255, 0.05);
    --summary-open-background: rgba(255, 255, 255, 0.1);
    --summary-latest-background: rgba(238, 246, 255, 0.2);
    --item-background: #393939;
    --text-color: #eee;
    --focus-color: #8ae;
  }
}