style.css

* {
    padding:0;
    margin: 0;
    box-sizing: border-box;
}

body {
    margin: 0 auto;
    background-color: #ebebeb;
    overflow: hidden;
}

:root {
    --color-header:#aee4f3;
    --color-blue:#0057B8;
    --color-yellow:#FFD700;
}

@keyframes text {
    from {
        font-size: 2em;
        margin-top:-200px;
    }
    to {
        font-size: 5em;
        margin-top:250px;
    }
}

@keyframes green {
    from {
        opacity:0;
    }
    to {
        opacity: 1;
        margin-top: 200px;
    }
}

@keyframes sun {
    from {
        margin-top:20vh;
        margin-left: -50vw;
    }
    to {
        margin-top:-25vh;
        margin-left: 0vw;
    }
}

.dropdown_text {
    padding: 15px;
    position: relative;
    font-family: 'Caveat', cursive;
    text-align: center;
    color:var(--color-blue);
    animation-fill-mode: forwards;
    animation-duration: 4s;
    animation-name: text;
}
.sun, 
.green {
    position: absolute;
}

.green {
    width: 100vw;
    height: 100vh;
    z-index: 0;
    background-image: url(./img/popup-icons/backgr2.png);
    background-size:cover;
    animation-fill-mode: forwards;
    animation-duration: 1s;
    animation-name: green;
}

.sun {
    width: 50vw;
    max-width: 600px;
    z-index: 0;
    color: var(--color-yellow);
    animation-fill-mode: forwards;
    animation-duration: 3s;
    animation-name: sun;
}

.header {
    position: relative;
    display: flex;
    height: 5em;
    justify-content: space-between;
    background-color:var(--color-header);
    border-bottom: 8px double var(--color-blue);
    box-shadow: 2px 2px 50px #bebdbd;
    z-index: 10;
    transition: all ease-out 0.3s;
}

.header:hover {
    box-shadow: none;
}

.header_logo img{
    width: 5em;
    padding-left: 1em;
}

.header_nav {
    width: 40%;
}

.menu {
    list-style: none;
    display: flex;    
    justify-content: space-around;
    padding-top: 20px;
    padding-bottom: 20px;
    font-size: 1.1em;
}

.menu_item>a{
    height: 32px;
    text-align: center;
    padding-top: 5px;
}

.menu_item a,
.popup_menu_item {
    display: inline-block;
    text-decoration: none;
    width: 74px;
}

.menu_item a:active,
.popup_menu_item:active {
    color:var(--color-blue);
    background-color: var(--color-yellow);
}

.menu_item a:focus,
.popup_menu_item:focus-within {
    background-color: var(--color-yellow);
    border-radius: 10%;

    box-shadow: 0 1px 4px rgba(0, 0, 0, .3),
    -23px 0 20px -23px rgba(0, 0, 0, .6),
    23px 0 20px -23px rgba(0, 0, 0, .6),
    inset 0 0 40px rgba(0, 0, 0, .1);
}

.menu_item a:hover,
.popup_menu_item:hover {
    box-shadow: 0 1px 4px rgba(0, 0, 0, .3),
    -23px 0 20px -23px rgba(0, 0, 0, .6),
    23px 0 20px -23px rgba(0, 0, 0, .6),
    inset 0 0 40px rgba(0, 0, 0, .1);
}

.menu_img:hover {
    box-shadow: 0 1px 4px rgba(0, 0, 0, .3),
    -23px 0 20px -23px rgba(0, 0, 0, .6),
    23px 0 20px -23px rgba(0, 0, 0, .6),
    inset 0 0 40px rgba(0, 0, 0, .1);
}

.menu_img {
    width: 2.5em;
    height: 2.5em;
    padding: 5px;
    margin-top:-6px;
    border-radius: 50%;
}

.header_menu_label {
    padding-top: 12px;
}

.header_menu_input:focus + * .menu_img {
    background-color: var(--color-yellow);
}

.header_menu_input, 
.popup_menu_more {
    -webkit-appearance: none;
    -moz-appearance: none;
    appearance: none;
}

.popup_menu_more {
    position: absolute;
}

.popup_menu_wrap {
    position: absolute;
    right:5vh;
    top:85px;
    padding: 10px;
    z-index: 10;
    width : 286px;
    max-height: 560px;
    overflow-y:auto;
    overflow-x: hidden;
    background-color:#e0e0e0;
    box-shadow: 0 1px 6px rgb(32 33 36 / 20%);
}

.popup_menu_wrap,
.menu_label_more {
    display: none;

}

.popup_menu_item {
    font-size: 0.8em;
    text-align: center;
    z-index: 100;
}

.header_menu_input:checked ~ .popup_menu_wrap {
    display: flex;
    flex-direction: column;
    align-items:stretch;
}

.popup_menu {
    list-style: none;
    display: grid;
    margin-bottom: 16px;
    width: 250px;
    grid-template-columns: 1fr 1fr 1fr;
    grid-template-rows: auto;
    grid-gap: 15px;
    grid-template-areas: 
        "a c d"
        "e f g"
        "h i j"
        "k l m"
    ;
}

.header_menu_label_more {
    border-width:0 0 2px 0;
    border-style:none none solid none;
    border-color: #e0e0e0;
    text-align: center;
}

.popup_menu_more:checked ~  .menu_label_more {
    list-style: none;
    display: grid;
    margin-top: 20px;
    grid-template-columns: 1fr 1fr 1fr;
    grid-template-rows: auto;
    grid-gap: 15px;
    grid-template-areas: 
        "a c d"
        "e f g"
        "h i j"
    ;
}

.header_menu_label_more_ico {
    display: inline-block;
    width: 25px;
    height: 25px;
    margin-top: 5px;
    border: solid var(--color-blue);
    border-width: 0 8px 8px 0;
    transform: rotate( 45deg);
    transition: all 0.5s;
}

.popup_menu_more:checked + * .header_menu_label_more_ico {
    transform: rotate( 225deg);
}

.popup_menu_more:hover + .header_menu_label_more,
.popup_menu_more:focus + .header_menu_label_more,
.popup_menu_more:active + .header_menu_label_more
{
    border-width:0 0 2px 0;
    border-style:none none solid none;
    border-color: var(--color-yellow);
}

@media screen and (min-width:250px) and (max-width:767px) {
    .popup_menu {
        right: 10px;
    }
}

@media screen and (min-width:1025px) and (max-width:1200px) {
    .header_nav {
        width:40%;
        font-size: 1em;
    }
}

@media screen and (min-width:769px) and (max-width:1024px) {
    .header_nav {
        width:50%;
        font-size: 1em;
    }
}

@media screen and (min-width:481px) and (max-width:768px) {
    .header_nav {
        width:60%;
        font-size: 1em;
    }
    .menu_item>a{
        height: 28px;
        text-align: center;
        padding-top: 3px;
    }
}

@media screen and (max-width:480px) {
    .header_nav {
        width:80%;
        font-size: 1em;
    }
    .menu_item>a{
        height: 22px;
        width: auto;
        text-align: center;
        padding-top: 2px;
    }
}