* {
    box-sizing: border-box;
}

body {
    margin: 0;
    padding: 0;
}

header {
    --header-color: #225;
    --nav-color: #55a;

    height: 100px;
    display: flex;
    flex-direction: column;
    background-color: var(--header-color);
}

header .title {
    font-size: 20px;
    color: #fff;
    height: 50px;
}

header nav {
    background-color: var(--nav-color);
    height: 50px;
}

main {
    font-size: 20px;
}

.drawer-menu-toggle {
    display: flex;
    justify-content: center;
    align-items: center;
    flex-flow: column;
    width: 50px;
    height: 100%;
    cursor: pointer;
}

.drawer-menu-toggle .hamburger {
    height: 2px;
    width: 30px;
    background-color: #000;
    margin-bottom: 7.5px;
}

.drawer-menu-toggle .hamburger:last-child {
    margin-bottom: 0;
}

.drawer-menu {
    --drawer-menu-width: 300px;
    --drawer-menu-header-height: 50px;
    --i: 1;
}

.drawer-menu input#check {
    display: none;
}

.drawer-menu .drawer-menu-contents .drawer-menu-toggle::before {
    font-size: 30px;
    content: "×";
}

.drawer-menu .drawer-menu-contents {
    position: fixed;
    display: flex;
    flex-flow: column;
    top: 0;
    left: calc(-1 * var(--drawer-menu-width));
    width: var(--drawer-menu-width);
    height: 100dvh;
    background-color: #ddd;
    transition: left 0.5s;
}

.drawer-menu .drawer-menu-contents .drawer-menu-header {
    width: var(--drawer-menu-width);
    height: var(--drawer-menu-header-height);
}

.drawer-menu input#check:checked ~ .drawer-menu-contents {
    left: 0;
}

.drawer-menu .drawer-menu-contents .drawer-menu-header {
    height: var(--drawer-menu-header-height);
    background-color: var(--nav-color);
    display: flex;
    justify-content: flex-end;
}

.drawer-menu .drawer-menu-contents .drawer-menu-body {
    display: flex;
    flex-flow: column;
}

.drawer-menu .drawer-menu-contents .drawer-menu-body .drawer-menu-item {
    font-size: 15px;
    color: #000;
    text-decoration: none;
    display: flex;
    justify-content: flex-end;
}

.drawer-menu .drawer-menu-contents .drawer-menu-body .drawer-menu-item::after {
    content: "";
    display: block;
    width:  var(--drawer-menu-width);
    background-color: #555;
}

.drawer-menu .drawer-menu-contents .drawer-menu-body .drawer-menu-item span {
    padding: 15px;
    margin-left: calc(-1 * var(--drawer-menu-width));
    width: var(--drawer-menu-width);
}

.drawer-menu input#check:checked ~ .drawer-menu-contents .drawer-menu-body .drawer-menu-item::after {
    width: 0px;
    transition: width 0.5s calc(0.25s * var(--i));
}

.drawer-menu .drawer-menu-contents .drawer-menu-item:hover {
    background-color: #999;
}

.drawer-menu input#check:checked ~ .backdrop {
    content: "";
    display: block;
    background-color: rgba(0, 0, 0, 0.5);
    position: fixed;
    width: 100vw;
    height: 100dvh;
    top: 0;
    left: 0;
}

.item-1 {
    --i: 1;
}

.item-2 {
    --i: 2;
}

.item-3 {
    --i: 3;
}