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

html,
body {
  width: 100%;
  height: 100%;
}

html {
  background-image: url(../img/background.jpg);
  background-repeat: no-repeat;
  background-position: center;
  background-size: cover;
}

body {
  color: #333;
  font-family: 'Lato';
  font-size: 26px;
  display: flex;
  justify-content: center;
  align-items: center;
}

.calculator {
  background-color: rgba(255,255,255,0.9);
  display: grid;
  grid-template-columns: (3 * 1fr);
  grid-template-rows: (6 * 1fr);
}

.calculator__display {
  color: #333;
  font-family: 'Lato';
  font-size: 26px;
  text-align: right;
  border: 1px solid #ccc;
  padding: 0 20px 0 20px;
  outline: none;
  grid-column: 1 / 5;
}

.calculator__button {
  border: 1px solid #ccc;
  display: flex;
  justify-content: center;
  align-items: center;
}

.calculator__button:hover {
  color: #fff;
  background-color: #333;
  border: 1px solid #333;
}

.button__big {
  grid-column: 1 / 5;
}

@media (min-width:750px) {
  .calculator {
    width: 400px;
    height: 600px;
  }
}

@media (max-width: 749px) {
  .calculator,
  .calculator__display,
  .calculator__button {
    width: 100%;
    height: 100%;
  }
}