* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
html, body {
    height: auto;
    font-family: Arial, sans-serif;
    line-height: 1.5;
    overflow: hidden;
}
body {
    user-select: none;
    -webkit-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    width: 100%;
    height: 100vh;
}

.bg {
    width: 100vw;
    height: 100vh;
    background-image: url(./thumbnail.jpg);
    background-size: cover;
    background-position: center;
}

h1 ,h3 {
    position: absolute;
    font-weight: bold;
    display: flex;
    justify-content: center;
    text-align: center;
    width: 100%;
}
h3 {
    top: 35%;
    font-size: 30px;
}
h1 {
    top: 20%;
    font-size: 80px;
}
@media (max-width: 768px) {
    h1 {
        font-size: 40px;
        top: 30%;
    }
    h3 {
        font-size: 15px;
        top: 40%;
    }
}

.version {
    position: absolute;
    top: 50%;
    width: 100vw;
    display: flex;
    justify-content: center;
    align-items: center;
    text-align: center;
    gap: 150px;
}
.ver {
    position: relative;
}
@media (max-width: 768px) {
    .version {
        flex-direction: column;
        gap: 50px;
    }
}

.btn {
    z-index: 999;
    width: 200px;
    height: 80px;
    color: #fff;
    background-color: #333;
    display: flex;
    justify-content: center;
    align-items: center;
    border-radius: 3px;
    font-size: 20px;
    font-weight: bold;
    text-decoration: none;
    transition: 0.3s all ease-in-out 0s;
}
.btn:hover {
    color: #333;
}
.btn::before {
    content: "";
    position: absolute;
    width: 100%;
    height: 100%;
    top: 0; left: 0;
    z-index: -1;
    background-color: #fff;
    transition: 0.4s all ease-in-out 0s;
    border-radius: 3px;
}
.btn::before {
    left: unset;
    right: 0; width: 0;
}
.btn:hover::before {
    right: unset;
    width: 100%;
    left: 0;
}
@media (max-width: 768px) {
    .btn {
        width: 160px;
        height: 60px;
        font-size: 15px;
    }
}