@import url('https://fonts.googleapis.com/css?family=Open+Sans:400,700&display=swap');

* {
  box-sizing: border-box;
  outline: 0;
}

body {
  margin: 0;
  padding: 0;
  background-image: url(../img/backiee-130807.jpg);
  background-size: cover;
  font-family: 'Open sans', sans-serif;
  font-size: 1.3em;
  line-height: 1.5em;
}

.container {
  max-width: 640px;
  margin: 50px auto;
  background-color: rgb(44, 40, 40);
  padding: 20px;
  border-radius: 10px;
  border: solid 5px black;
}

.calculadora {
  width: 400px;
  margin: auto;
}

h1 {
  color: white;
  text-align: center;
  text-shadow: 2px 2px black;
}

.display {
  font-size: 2em;
  width: 100%;
  text-align: right;
  border-radius: 4px;
  margin-bottom: 20px;
}

.btn {
  width: 65%;
  height: 30px;
  font-size: 1em;
  border: solid 2px black;
  background-color: rgb(195, 195, 195);
  border-radius: 4px;
  cursor: pointer;
}

.btn-num:hover,
.btn-del:hover {
  background-color: gray;
  transition: 0.3s;
}

.btn-eq {
  background-color: lime;
}

.btn-eq:hover {
  background-color: green;
  transition: .3s;
}

.btn-clear:hover {
  background-color: rgb(181, 3, 3);
  transition: .3s;
}

.btn-clear {
  background-color: rgb(255, 0, 0);
}