CSS background не хочет уходить на задний план

/*Кнопка меню*/ 
/*	@media screen and (min-width: 614px) { 
		.btn_menu { 
		   display: none; 
	   } 
	}	*/ 
html, body, div, span, applet, object, iframe, h1, h2, h3, h4, h5, h6, p, blockquote, pre, a, abbr, acronym, address, big, cite, code, del, dfn, em, img, ins, kbd, q, s, samp, small, strike, strong, sub, sup, tt, var, b, u, i, center, dl, dt, dd, ol, ul, li, fieldset, form, label, legend, table, caption, tbody, tfoot, thead, tr, th, td, article, aside, canvas, details, embed, figure, figcaption, footer, header, hgroup, menu, nav, output, ruby, section, summary, time, mark, audio, video { 
    margin: 0; 
    padding: 0; 
    border: 0; 
    font-size: 100%; 
    font: inherit; 
    vertical-align: baseline; 
} 
 
html { overflow-x: hidden; } 
 
@media (min-width: 768px) { 
.nav_menu { 
    width: 75px; 
    height: 100%; 
	} 
} 
 
.nav_menu {	 
	width: 100%; 
    height: 70px; 
	top: 0; 
    background-color: #FFF; 
    position: relative; 
    z-index: 99999; 
    box-shadow: 0 2px 30px 0 rgba(0, 0, 0, 0.1); 
} 
 
.btn_menu * { 
    transition: all 0.3s; 
    -webkit-transition: all 0.3s; 
    box-sizing: border-box; 
	cursor: pointer; 
} 
 
.btn_menu { 
    position: absolute; 
	top: 20px; 
	left: 25px; 
    height: 35px; 
    width: 50px; 
} 
 
.btn_menu input[type=checkbox] { 
    display: none; 
} 
 
.btn_menu label { 
    cursor: pointer; 
    position: absolute; 
    z-index: 99; 
    height: 100%; 
    width: 100%; 
} 
 
.btn_menu .btn_menu_img { 
    position: absolute; 
    height: 5px; 
    width: 100%; 
    background-color: #333; 
    box-shadow: 0 3px 0 rgba(0, 0, 0, 0.1); 
	border-radius: 10px; 
} 
 
.btn_menu .diagonal.part-1 { 
    position: relative; 
    float: left; 
} 
 
.btn_menu .horizontal { 
    position: relative; 
    float: left; 
    margin-top: 6px; 
} 
 
.btn_menu .diagonal.part-2 { 
    position: relative; 
    float: left; 
    margin-top: 6px; 
} 
 
.btn_menu input[type=checkbox]:checked ~ .btn_menu_img_on > .horizontal { 
    transform: translate(-100px, 0px); 
    opacity: 0; 
} 
 
.btn_menu input[type=checkbox]:checked ~ .btn_menu_img_on > .diagonal.part-1 { 
    transform: rotate(-135deg); 
    margin-top: 10px; 
} 
 
.btn_menu input[type=checkbox]:checked ~ .btn_menu_img_on > .diagonal.part-2 { 
    transform: rotate(135deg); 
    -webkit-transform: rotate(135deg); 
    margin-top: -16px; 
} 
 
.btn_menu input[type=checkbox]:checked ~ .btn_menu_img_on > .box_menu { 
	transition: all .4s cubic-bezier(0.4, -0.4, 0.2, 0.2); 
	width: 100vw; 
	height: 100vh; 
	display: block; 
	background-color: black; 
	position: absolute; 
	top: 50px; 
	left: -25px; 
	border-radius: 0; 
} 
 
.box_menu { 
	transition: ease .4s; 
	transition-delay: 1.4s; 
	border-radius: 0; 
	cursor: default; 
	position: absolute; 
	top: 50px; 
	left: -25px; 
	width: 0; 
	height: 0; 
	 
} 
 
.btn_menu_img_on > .box_menu > li { 
	cursor: default; 
	list-style-type: none; 
	text-align: center; 
	margin: 20px; 
	transition: ease 0.6s; 
	font-size: 0; 
} 
 
.btn_menu_img_on > .box_menu > li > a { 
	color: #9e8989; 
	text-decoration: none; 
	z-index: 1000; 
} 
 
.btn_menu input[type=checkbox]:checked ~ .btn_menu_img_on > .box_menu > li > a { 
	color: #9e8989; 
	text-decoration: none; 
	z-index: 1000; 
} 
 
.btn_menu input[type=checkbox]:checked ~ .btn_menu_img_on > .box_menu > li > a:hover { 
	color: #fff; 
	z-index: 1000; 
} 
 
.btn_menu input[type=checkbox]:checked ~ .btn_menu_img_on > .box_menu > li:nth-child(1) { 
	font-size: 36px; 
	transition: .6s; 
	color: #ffffff; 
} 
 
.btn_menu_img_on > .box_menu > li:nth-child(1) { 
	font-size: 0px; 
	transition: 1s; 
} 
 
body > div > div > label > ul > li > div { 
	z-index: 0; 
	opacity: 0; 
	transition: .5s; 
} 
 
body > div > div > label > ul > li > a { 
	z-index: 1000; 
  position: relative; 
} 
 
body > div > div > label > ul > li:nth-child(1) > a:hover ~ div { 
	position: absolute; 
	top: 0; 
	left: 0; 
	width: 100vw; 
	height: 100vh; 
	background: url(https://www.canvaspop.com/v2/images/2016/office/fuel-space-large.jpg) 100% 100% no-repeat; 
	background-size: contain; 
	z-index: 1; 
	opacity: 0.2; 
	transition: .5s; 
	background-color: transparent; 
} 
 
.btn_menu input[type=checkbox]:checked ~ .btn_menu_img_on > .box_menu > li:nth-child(2) { 
	font-size: 36px; 
	transition: .8s; 
} 
 
.btn_menu_img_on > .box_menu > li:nth-child(2) { 
	font-size: 0px; 
	transition: .8s; 
} 
 
.btn_menu input[type=checkbox]:checked ~ .btn_menu_img_on > .box_menu > li:nth-child(3) { 
	font-size: 36px; 
	transition: 1s; 
} 
 
.btn_menu_img_on > .box_menu > li:nth-child(3) { 
	font-size: 0px; 
	transition: .6s; 
} 
 
.btn_menu input[type=checkbox]:checked ~ .btn_menu_img_on > .box_menu > li:nth-child(4) { 
	font-size: 36px; 
	transition: 1.2s; 
} 
 
.btn_menu_img_on > .box_menu > li:nth-child(4) { 
	font-size: 0px; 
	transition: .4s; 
} 
 
.btn_menu input[type=checkbox]:checked ~ .btn_menu_img_on > .box_menu > li:nth-child(5) { 
	font-size: 36px; 
	transition: 1.4s; 
} 
 
.btn_menu_img_on > .box_menu > li:nth-child(5) { 
	font-size: 0px; 
	transition: .2s; 
}

<meta name="viewport" content="width=device-width, initial-scale=1"> 
<link rel="stylesheet" href="main.css"> 
 
<body> 
	<div class="nav_menu"> 
		<div class="btn_menu"> 
			<input type="checkbox" id="spinner-form4" /> 
			<label for="spinner-form4" class="btn_menu_img_on"> 
				<div class="btn_menu_img diagonal part-1"></div> 
				<div class="btn_menu_img horizontal"></div> 
				<div class="btn_menu_img diagonal part-2"></div> 
					<ul class="box_menu"> 
						<li><a href="#">Текст1</a><div></div></li> 
						<li><a href="#">Текст1Текст12</a></li> 
						<li><a href="#">Текст1Текст1Текст13</a></li> 
						<li><a href="#">Текст1Текст1Текст1Текст14</a></li> 
						<li><a href="#">Текст1Текст1Текст1Текст1Текст15</a></li> 
					</ul> 
			</label> 
		</div> 
	</div> 
</body>