:root {
  --color-brown: #71441E;
  --color-blue: #0D0D51;
  --color-gray: #AAAAAA;
  --color-green: #58B058;

  --size-bee: 0.2rem;
  --size-mouse: 0.5rem;
  --size-cat: 0.75rem;
  --size-dog: 1rem;
  --size-lion: 1.25rem;
  --size-bear: 1.5rem;
  --size-horse: 2rem;
  --size-camel: 2.625rem;
  --size-rhino: 3.375rem;
  --size-elephant: 4.25rem;
  --size-mammoth: 5.25rem;
}

@media screen and (max-width: 500px) {
  html { font-size: 14px; }
}

@media screen and (min-width: 500px) and (max-width: 900px) {
  html { font-size: 18px; }
}

@media screen and (min-width: 900px) {
  html { font-size: 20px; }
}

body {
  max-width: 800px;
  margin: 0 auto;
  padding: var(--size-dog);
}

header {
  font-size: var(--size-horse);
  font-weight: bold;
  color: var(--color-brown);
  margin: 0 auto var(--size-horse);
  padding: var(--size-dog) 0;
  max-width: 800px;
  border-bottom: var(--size-bee) solid #884433;
  text-align: center;
}

h1, h2, h3 {
  color: var(--color-brown);
  margin-bottom: var(--size-bear);
}

h1 {
  font-size: var(--size-bear);
}

h2 {
  font-size: var(--size-dog);
}

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

a:hover {
  text-decoration: underline;
}

ul, ol {
  padding-left: var(--size-dog);
  list-style-type: none;
  margin-bottom: var(--size-horse);
  margin: var(--size-cat) 0 var(--size-dog);
}

ol {
  counter-reset: ol;
  position: relative;
}

ol > li, ul > li {
  padding: var(--size-mouse) 0;
}

ol > li {
  padding-left: var(--size-horse);
  position: relative;
  text-align: justify;
  transition: color 0.1s ease-in;
}

ol > li::before {
  display: inline;
  position: absolute;
  top: var(--size-mouse);
  left: 0;
  counter-increment: ol;
  content: counter(ol) ".";
  color: var(--color-brown);
  font-weight: bold;
  transition: color 0.1s ease-in;
}

ol > li:hover {
  cursor: pointer;
}

ol > li.completed {
  color: var(--color-gray);
}

ol > li.completed::before {
  color: var(--color-green);
}

input {
  background-color: transparent;
  font-size: inherit;
  border: 1px solid var(--color-gray);
  border-radius: var(--size-bee);
  padding: var(--size-bee);
  text-align: center;
  width: var(--size-rhino);
  margin-right: var(--size-bee);
}