style.css

body {
    background-image: url(pic/base.png);
    background-repeat: no-repeat;
    background-size: cover;
    min-height: 100vh;
    background-position: center;
    background-color: #3b8d99;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Tourney', cursive;    
}
.navigation {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100vh;
    background: #111;
    transition: 0.2s;
    display: flex;
    visibility: hidden;
    opacity: 0;;
}
.navigation.active {
    visibility: visible;
    opacity: 1;
}


.navigation .navArea {
    position: relative;
    width: 50%;
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
}
.navigation .navArea ul li {
    list-style: none;    
}

.navigation .navArea ul li::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: #412017;
    z-index: -1;
    opacity: 0;
    transition: 0.5s;
}
.navigation .navArea ul li:nth-child(1)::before {
    background: #f1c596;
}
.navigation .navArea ul li:nth-child(2)::before {
    background: #FF9234;
}
.navigation .navArea ul li:nth-child(3)::before {
    background: #D92027;
}
.navigation .navArea ul li:nth-child(4)::before {
    background: #005792;
}
.navigation .navArea ul li:nth-child(5)::before {
    background: #548514;
}


.navigation .navArea ul li:hover::before {
    opacity: 1;
}

.navigation .navArea ul li a {
    font-size: 3em;
    font-weight: 600;
    text-decoration: none;
    /* color: rgba(255, 255, 255, 0.5); */
    background: linear-gradient(to left, #3b8d99, #aa4b6b, #3b8d99);
    -webkit-text-fill-color: transparent;
    -webkit-background-clip: text;
}
.navigation .navArea ul li:hover a {
    /* color: rgba(255, 255, 255, 1); */
    background: linear-gradient(to left, yellow, #aa664b, yellow);
    -webkit-text-fill-color: transparent;
    -webkit-background-clip: text;
}
.imgArea {
    position: relative;
    width: 50%;
    height: 100vh;
    background: #f00;
}
.imgArea img {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
}
.menuToggle {
    position: absolute;
    top: 40px;
    right: 40px;
    width: 40px;
    height: 40px;
    background: url(pic/menu.png);
    z-index: 1000;
    background-size: 40px;
    background-repeat: no-repeat;
    background-position: center;
    cursor: pointer;
}
.menuToggle.active {
    background: #3b8c9944 url(pic/close.png);
    z-index: 1000;
    background-size: 42px;
    background-repeat: no-repeat;
    background-position: center;
    cursor: pointer;
    filter: invert(1);
}

.top {
    display: flex;
    justify-content: center;
    align-self: center;
    margin-top: 100px;
}
h1 {
    font-size: 60px;
    background: linear-gradient(to left, #03272c, #80052e, #02282e);
    -webkit-text-fill-color: transparent;
    -webkit-background-clip: text;
}


@media (max-width: 800px) {
    .navigation .navArea {
        position: absolute;
        width: 100%;
        height: 100%;
        display: flex;
        justify-content: center;
        align-items: center;
        z-index: 10;
    }
    .navigation .navArea ul {
        display: flex;
        justify-content: center;
        align-items: center;
        flex-direction: column;
    }

    .navigation .navArea ul li {
        color: #fff;
        margin: 5px 10px;
        padding: 5px 10px;
        font-size: 2em;
        font-weight: bolder;
    }
    .navigation .navArea ul li:hover {
        background: #3b8c9944;
    }

    .navigation .navArea ul li a {
        background: linear-gradient(to left, #fff, #a6f7aa, #fff);
    -webkit-text-fill-color: transparent;
    -webkit-background-clip: text;
        font-size: 2em;
        font-weight: bolder;
        letter-spacing: 1px;        
    }
    
    .imgArea {
        position: relative;
        width: 100%;
        height: 100vh;
        background: #3b8c99ca;
    }
    .navigation .navArea ul li:hover::before {
        opacity: 0;
    }
    .imgArea {
        position: absolute;
        width: 100%;
        height: 100vh;
        background: #3b8c99ca;
        opacity: 0.7;
    }
    .top {
        margin-top: 90px;
    }
}
@media (max-width: 600px) {
    .navigation .navArea ul li {        
        font-size: 1.5em;
        font-weight: bolder;
    }
    .navigation .navArea ul li a {
        font-weight: bolder;
        font-size: 1.5em;
        letter-spacing: 0px;        
    }
    h1 {
        font-size: 35px;        
    }
    .top {
        margin-top: 100px;
    }
}

@media (max-width: 390px) {
    .navigation .navArea ul li {        
        font-size: 27px;
        font-weight: bolder;
    }
    .navigation .navArea ul li a {
        font-weight: bolder;
        font-size: 27px;
        letter-spacing: 0px;        
    }
    h1 {
        font-size: 28px;
        
    }
    .top {
        margin-top: 100px;
    }
}