.definition {
  border: 3px;
  border-style: solid;
  border-color: #ff0000;
  padding: 1em;
  margin: 1em 0;
  background-color: #ff000012;
}

.definition > p {
  margin: 0;
}

.theorem {
  border: 3px;
  border-style: solid;
  border-color: #007bff;
  padding: 1em;
  margin: 1em 0;
  background-color: #c8ecf4;
}

.theorem > p {
  margin: 0;
}

.proof {
  padding: 1em;
  background: #eef;
  border-top: 10px solid #ddf;
  border-left: 10px solid #ddf;
  border-right: 10px solid #ddf;
  border-bottom: 10px solid #ddf;
  border-bottom-left-radius: 10px;
  -moz-border-radius-bottomleft: 10px;
  border-bottom-right-radius: 10px;
  -moz-border-radius-bottomright: 10px;
}

.proof p {
  margin-bottom: 0px;
}

.btn-proof {
  background-color: #ddf;
  border-color: black;
  font-weight: bold;
}

.collapse_panel {
  width: 100%;
  text-align: left;
  background-color: #999;
  border: #ccc;
  display: block;
  margin: 10px 0;
}