style.css

BODY {
  font: 16px/1.4 "Trebuchet MS", Arial, sans-serif;
  color: #000;
}

A {
  color: steelblue;
}

H1 {
  font: 2em/1.4 Georgia, serif;
  text-align: center;
  }

H4 {
  margin: 0;
  margin-bottom: .15em;
  font: 1.3em/1.4 Georgia, serif;
  }

P {
  margin: 1.2rem 0;
  }

TEXTAREA {
  width: 100%;
  height: 150px;
  margin: 0;
  border: 1px solid #CCC;
  border-radius: 10px;
  font-size: 13px;
  font-family: monospace;
  }

CODE {
  padding: 0 3px;
  background: #EEE;
  border-radius: 5px;
  text-shadow: 1px 1px 0 white;
  font: 14px/1.4 monospace;
  color: #333;
  }

CODE I {
  font-style: italic;
  color: black;
  }

DL , DD, DT{
  margin: 0;
  }
  DL {
    text-align: right;
    }
  DT {
    border-bottom: 1px dashed;
    display: inline-block;
    line-height: 1;
    color: steelblue;
    cursor: pointer;
    }
    DT:after {
      content: "";
      display: inline-block;
      border: 0 solid transparent;
      border-width: 8px 4px 0;
      border-top-color: currentColor;
      border-bottom-color: currentColor;
      margin-left: 5px;
      }
      .opened:after {
        border-width: 0 4px 8px ;
        }
  DD {
    text-align: left;
    }

.hidden {
  display: none;
  }

.visuallyhidden {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  border: 0;
  padding: 0;
  white-space: nowrap;
  clip-path: inset(100%);
  clip: rect(0 0 0 0);
  overflow: hidden;
}

.wrapper {
  width: 650px;
  margin: 1.5rem auto 4rem;
  }

.header {
  position: relative;
  margin-bottom: 2rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid #CCC;
}
  .header:before {
    content: "";
    display: table;
    width: 100%;
    clear: both;
  }

.langs {
  position: absolute;
  top: 0;
  right: 0;
  margin: auto;
  list-style-type: none;
}
  .langs__item {
    display: inline-block;
  }
  .langs__link--current {
    color: #000;
  }

.footer {
  position: relative;
  display: flex;
  justify-content: space-between;
  margin-top: 3rem;
  padding-top: 2rem;
  border-top: 1px solid #CCC;
}

.panel {
  position: relative;
  z-index: 1;
  margin-bottom: 2.5rem;
  display: flex;
  justify-content: space-between;
}

.options {
  position: relative;
}

.options__middle-word {
  vertical-align: middle;
  color: #AAA
}

.options__text {
  display: inline-block;
  border-bottom: 1px dashed;
  color: steelblue;
  cursor: pointer;
}
.options__input:checked + .options__text {
  border: 0;
  color: inherit;
  cursor: default;
}

.expander {
  position: relative;
  z-index: 2;
}

.expanded {
  position: absolute;
  top: -15px;
  right: -15px;
  left: -15px;
  padding: 2rem 1.5rem 1rem;
  background: #FFF;
  border: 1px solid #CCC;
  border-radius: 5px;
  box-shadow: 0 0 0 5px rgba(0,0,0,.1);
}

.button-example,
.copy-button {
  padding: 0;
  border: 0;
  border-bottom: 1px dashed;
  line-height: 1;
  align-self: center;
  font: inherit;
  font-size: 14px;
  color: steelblue;
  cursor: pointer;
}

.containers {
  margin-bottom: 32px;
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  }

.container {
  position: relative;
  width: 48%;
  margin-bottom: 1em;
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  }

.demo-wrapper {
  width: 100%;
  border: 1px dashed rgba(0,0,0,.25);
  }
  .demo {
    height: 150px;
    background-repeat: no-repeat;
    }

.contrast-buttons {
  display: flex;
  align-items: center;
  margin-bottom: .4em;
  }
  .contrast-button {
    display: block;
    width: 2em;
    height: 2em;
    margin-left: 5px;
    padding: 0;
    border-radius: 50%;
    border: 1px solid rgba(0,0,0,.25);
    outline: none;
    cursor: pointer;
    }

  .contrast-button--current {
    box-shadow: 0 0 0 3px steelblue;
    }
  .contrast-button:active {
    box-shadow: 0 0 0 3px rgba(0,0,0,.25);
    }

  .contrast-button--white {
    background: white;
    }
  .contrast-button--silver {
    background: silver;
    }
  .contrast-button--black {
    background: black;
    }