style.css

body {
  margin: 0;
  padding: 0;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  flex-direction: column;
}
.container {
  width: 350px;
  height: 400px;
  box-shadow: 0px 1px 2px 1px hsl(0, 0%, 70%);
  border-top-left-radius: 20px;
  border-bottom-right-radius: 20px;
}
.container h3 {
  font-family: Cambria Math;
  text-align: center;
  /* text-shadow: 3px 3px 3px maroon;*/
  padding-top: 12px;
}
.container #enter {
  padding-left: 12px;
  padding-top: 12px;
  font-family: Segoe UI Symbol;
}
.inputs {
  display: flex;
  flex-wrap: wrap;
  width: 100%;
  justify-content: center;
}
.inputs .pr {
  margin: 11px;
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
}
.inputs .pr input {
  margin: 5px;
  width: 80px;
  height: 30px;
  padding-left: 6px;
  border: none;
  outline: none;
  box-shadow: 0px 1px 2px 1px hsl(0, 0%, 70%);
  border-radius: 5px;
}
.resul {
  margin-top: 12px;
  width: 100%;
  display: flex;
  justify-content: center;
}
.resul input {
  width: 130px;
  padding-left: 8px;
  height: 20px;
  border: none;
  outline: none;
  box-shadow: 0px 1px 2px 1px hsl(0, 0%, 70%);
}
#firs {
  border-top-left-radius: 19px;
  border-bottom-left-radius: 19px;
}
#sec {
  border-top-right-radius: 19px;
  border-bottom-right-radius: 19px;
}
.re {
  width: 100%;
  display: flex;
  justify-content: space-around;
}
.buttons {
  margin-top: 90px;
  display: flex;
  width: 1005;
  justify-content: center;
}
.buttons div {
  padding-left: 6px;
}
.buttons button {
  height: 40px;
  width: 70px;
  border: none;
  border-radius: 5px;
  font-family: consolas;
  box-shadow: 0px 1px 2px 1px hsl(0, 0%, 70%);
}
.second_bu button {
  background-color: hsla(0, 90%, 30%, 1);
  color: white;
  font-weight: bold;
}
.second_bu button:active {
  background-color: hsla(0, 90%, 10%, 1);
}
.inputs #A,
#B,
#C {
  font-family: mangia;
  color: hsl(0, 80%, 30%);
}