style.css

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Roboto', sans-serif;
}

.container {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background: white;
    overflow: hidden;
    transition: 1s;
}

.inputBox {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    position: relative;
    width: 450px;
}

.inputBox h2 {
    font-size: 30px;
    color: black;
    font-weight: bolder;
    text-align: center;
    user-select: none;
}

.inputBox input {
    position: relative;
    width: 100%;
    font-size: 24px;
    height: 60px;
    border: none;
    padding: 0 20px;
    margin: 15px 0 20px;
    background: transparent;
    outline: none;
    letter-spacing: 4px;
    border-radius: 8px;
    color: black;
    box-shadow: 
    -4px -4px 10px rgba(255,255,255,1),
    inset 4px 4px 10px rgba(0,0,0,0.5),
    inset -4px -4px 10px rgba(255,255,255,1),
    -4px -4px 10px rgba(0,0,0,0.5);
}

.inputBox input::placeholder {
    color: black;
    letter-spacing: 0px;
}

.inputBox #btn {
    position: relative;
    cursor: pointer;
    color: white;
    background: black;
    font-size: 24px;
    display: inline-block;
    padding: 10px 15px;
    border-radius: 8px;
    transition: 0.5s;
    letter-spacing: 4px;
    user-select: none;
}

.inputBox #btn:hover {
    background: #dc21fd;
    color: black;
}

.inputBox #btn:active {
    background: #9c27b0;
}

.copy {
    cursor: pointer;
    position: absolute;
    top: 64px;
    right: 15px;
    width: 32px;
    opacity: 0.5;
    transition: 0.1s;
    user-select: none;
}

.copy:hover {
    opacity: 1;
}

.alertBox {
    user-select: text;
    position: fixed;
    display: flex;
    justify-content: center;
    align-items: center;
    bottom: 50px;
    right: 50px;
    height: calc(100vh - 100px);
    width: calc(100% - 100px);
    background: purple;
    color: white;
    text-align: center;
    font-size: 64px;
    border-radius: 15px 15px 50% 15px;
    transform: translate(-100%, -100%);
    visibility: hidden;
    opacity: 0;
    transition: 1s;
}

.alertBox.active {
    visibility: visible;
    opacity: 1;
    transform: translate(0,0);
    border-radius: 15px;
    background: #9c27b0;
}

@media screen and (min-width: 300px) and (max-width: 800px) {
    .copy {
        top: 50%;
        right: 0;
    }

    .alertBox {
        font-size: 25px;
        font-weight: bold;
    }
}