style1.css

@import url('https://fonts.googleapis.com/css2?family=Baloo+2:wght@700&family=MuseoModerno:wght@500&display=swap');

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Baloo 2', cursive;

}

main {
    display: flex;
    justify-content: center;
    align-items: center;
    width: 100%;
    height: 100vh;
    background-color: hsl(217, 54%, 11%);
    
}

.mainbx {
    height: 55vh;
    width: 35%;
    background-color: hsl(216, 50%, 16%);
    padding: 1rem 1rem  1rem  1rem;
    border-radius: 8px;
}

.mainbx h2 {
    color: white;
    font-size: 1.6rem;
    text-align: center;
    padding: 7px;
    font-family: 'MuseoModerno', cursive;
}

.mainbx #number {
    width: 100%;
    height: 7vh;
    font-size: 1.4rem;
    outline: none;
    border-radius: 8px;
    margin-top: 1vh;
    padding-left: 3px;
}
.generate #copy{
    display: none;
   background-color: white;
   color: black;
   width: 13%;
   cursor: pointer;
   height: 4vh;
   border-radius: 2px;
   position: relative;
   top: -22vh;
   right: -28.5vw;
   text-align: center;
}
.mainbx h3 {
    text-align: center;
    color: white;
    width: 100%;
    height: 24vh;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 2rem;
}

.mainbx button {
    outline: none;
    width: 100%;
    height: 9vh;
    font-size: 1.2rem;
    cursor: pointer;
    border-radius: 6px;
    border: none;
    transition: all 0.3s ease-in-out;
    
}
.mainbx button:hover {
    background-color: hsl(217, 54%, 11%) ;
    color: white;
}

@media only screen and (max-width: 600px) {
    body {
      background-color: lightblue;
    }
    .mainbx {
    
        width: 70%;
        height: 60vh;
       
    }
    .mainbx h3 {
       
        height: 29vh;
        
    }
    .generate #copy{
       
       width: 100%;
       
       top: -0.1vh;
       right: -0.5vw; 
       
       margin-bottom: 13px;
    }
    
  }