:root {
  --base-light: #f0f0f1;
  --base-dark: #19191d;
  --layer1-dark: #29292d;
  --layer2-dark: #39393d;
  --primary-light: #ecfdfe;
  --primary-main: #03a9f4;
}

body {
  background-color: #f0f0f2;
  margin: 0;
  padding: 0;
  text-align: center;
  background: var(--base-light);
}

article {
  text-align: left;
}

a {
  color: inherit;
  text-decoration: none;
}

a:hover {
  color: inherit;
  text-decoration: underline;
}

@media screen and (min-width: 576px) {
  nav {
    max-width: 540px;
    margin: auto;
  }
  
  article {
    max-width: 540px;
    margin: auto;
  }

  footer {
    max-width: 540px;
    margin: auto;
  }
}

@media (prefers-color-scheme: dark) {
  body {
    color: var(--base-light);
    background: var(--base-dark);
  }

  .loader div {
    background: var(--primary-main);
  }

  .card {
    background-color: var(--layer1-dark);
  }

  .list-group-item {
    color: var(--base-light);
    background-color: var(--layer2-dark);
  }
}

/* Loading spinner */

.loader {
  display: inline-block;
  position: relative;
  width: 80px;
  height: 80px;
}
.loader div {
  position: absolute;
  top: 33px;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--primary-main);
  animation-timing-function: cubic-bezier(0, 1, 1, 0);
}
.loader div:nth-child(1) {
  left: 8px;
  animation: loader1 0.6s infinite;
}
.loader div:nth-child(2) {
  left: 8px;
  animation: loader2 0.6s infinite;
}
.loader div:nth-child(3) {
  left: 32px;
  animation: loader2 0.6s infinite;
}
.loader div:nth-child(4) {
  left: 56px;
  animation: loader3 0.6s infinite;
}
@keyframes loader1 {
  0% {
    transform: scale(0);
  }
  100% {
    transform: scale(1);
  }
}
@keyframes loader3 {
  0% {
    transform: scale(1);
  }
  100% {
    transform: scale(0);
  }
}
@keyframes loader2 {
  0% {
    transform: translate(0, 0);
  }
  100% {
    transform: translate(24px, 0);
  }
}