This gist is used for a medium article

style.css

* {
  padding: 0;
  margin: 0;
  box-sizing: border-box;
}

html {
  background-color: #fff;
  color: #000;
  font-family: sans-serif;
  line-height: 1.4;
}

/* This is going to act as a parent class for all of your children classes that you will be changing the colors of */
.dark-theme {
  background-color: #000;
  color: #fff;
}

.dark-theme .button {
  background-color: #fff;
  color: #000;
}

.dark-theme .nav-link {
  color: #ccc;
}

.container {
  margin: 0 auto;
  max-width: 900px;
}

.navbar {
  padding: 0.75rem;
}

.nav {
  display: flex;
  align-items: center;
  list-style-type: none;
}

.nav-item {
  margin: 0.5rem 1rem;
}

.nav-link {
  color: #777;
  text-decoration: none;
}

.pull-right {
  margin-left: auto;
}

.button {
  background-color: #000;
  color: #fff;
  padding: 0.5rem 1rem;
  border: none;
  outline: none;
  cursor: pointer;
  border-radius: 20px;
}

.card {
  margin: 1rem;
  padding: 0.5rem;
}