styles.css

*, *::before, *::after {
  box-sizing: border-box;
  font-family: Gotham Rounded, sans-serif;
  font-weight: normal;
}

:root {
  --gradient1 : linear-gradient(to right, #1078ab, #f6cd7e);
  --gradient2 : linear-gradient(109.6deg,  rgba(245,56,56,1) 11.2%, rgba(234,192,117,1) 78% );
}



.title h1 {
  padding :0%;
  margin: 0;
  border: 1px solid transparent;
  color: transparent;
  font-family: 'Lilita One', cursive;
  font-weight: bolder;
  font-size: 5rem;
  background-color: #aeaeae;
  display: flex;
  justify-content: center;
  align-content: center;
  background: var(--gradient2) ;
  background-size: 300%;
  -webkit-background-clip: text;
  background-clip: text;
  filter: drop-shadow( 3px 3px 3px black);
  animation: animasibg infinite alternate 5s;

}

body {
  padding: 0;
  margin:auto;
  background: var(--gradient1);
  background-size: 200%;
  background-position: left;
  animation:  animasibg infinite alternate 25s;

} 

@keyframes animasibg {
  from {
    background-position: left;
  }

  to {
    background-position: right;
  }
}

.calculator-grid {
  display: grid;
  justify-content: center;
  align-content: center;
  min-height: 100vh;
  grid-template-columns: repeat(4, 100px);
  grid-template-rows: minmax(120px, auto) repeat(5, 100px);
}

.calculator-grid > button {
  cursor: pointer;
  font-size: 2rem;
  border: 1px solid white;
  outline: none;
  background-color: #f9e5b3;
}

.calculator-grid > button:hover {
  background-color: antiquewhite;
}

.span-two {
  grid-column: span 2;
}

.output {
  grid-column: 1 / -1;
  background-color: #f9e5b33a;
  display: flex;
  align-items: flex-end;
  justify-content: space-around;
  flex-direction: column;
  padding: 10px;
  word-wrap: break-word;
  word-break: break-all;
}

.output .previous-operand {
  color: rgba(255, 255, 255, .75);
  font-size: 1.5rem;
}

.output .current-operand {
  color: white;
  font-size: 2.5rem;
}