style.css

* {
    margin: 0;
    padding: 0;
    user-select: none;
    box-sizing: border-box;
    font-family: 'Oswald', sans-serif;
}

.box {
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
    width: 100%;
    height: 100vh;
    background: linear-gradient(145deg, rgb(6, 42, 247) 7%, rgb(13, 6, 77) 100%);
    overflow: hidden;
}

.wrap {
    display: flex;
    flex-direction: row;
    width: 625px;
    height: 605px;
    box-shadow: 5px 5px 30px rgb(0 0 0 / 20%);
    background: rgba(255,255,255,0.05);
    border-top: 1px solid rgba(255,255,255,0.2);
    border-left: 1px solid rgba(255,255,255,0.2);
    border-radius: 35px;
}

.sheetbutton {
    cursor: pointer;
    outline: none;
    font-weight: bolder;
    border: none;
    border-radius: 50px;
    text-align: center;
    letter-spacing: 2px;
    font-size: 35px;
    margin-top: 20px;
    width: 302px;
    height: 75px;
    background: linear-gradient(3deg, rgb(14, 46, 106) 24%, rgb(0, 72, 255) 53%);
    color: whitesmoke;
    transition: 0.5s;
}

.sheetbutton:hover {
    background: rgb(0, 0, 255);
}

.sheetbutton:active {
    background: rgb(33, 33, 105);
}

.bubble {
    cursor: pointer;
    visibility: visible;   
    box-shadow: inset 5px 5px 10px #a4c5d4, inset -5px -5px 10px #8e8f96;
    width: 50px;
    height: 50px;
    margin-top: 5px;
    border-radius: 100%;
}

.bubble.active {
    visibility: hidden;
    cursor: none;
}

.line {
    margin: 15px 1px;
    display: flex;
    flex-direction: column;
}

@media screen and (min-width: 300px) and (max-width: 800px) {
    .box {
        height: 100vh;
        overflow: hidden;
    }

    .wrap {
        width: 335px;
        overflow: hidden;
    }

    .bubble {
        width: 46px;
        height: 46px;
    }
}