width: 500px;
height: 500px;
background:
linear-gradient(-45deg, rgba(58,70,83,1) 20%, rgba(0,0,0,0.5) 21%, rgba(0,0,0,0.3) 22%, rgba(255,255,255,0) 30%, rgba(255,255,255,0) 70%, rgba(0,0,0,0.3) 78%, rgba(0,0,0,0.5) 79%, rgba(58,70,83,1) 80%) 0px 0px / 100px 100px repeat repeat, /* -45deg fiber */
linear-gradient(45deg, rgba(255,255,255,0) 20%, rgba(0,0,0,0.3) 28%, rgba(0,0,0,0.6) 29%, rgba(69,90,109,1) 30%, rgba(69,90,109,1) 70%, rgba(0,0,0,0.6) 71%, rgba(0,0,0,0.3) 72%, rgba(255,255,255,0) 80%) 0px 0px / 100px 100px repeat repeat, /* 45deg fiber */
linear-gradient(-45deg, rgba(255,255,255,0) 29%, rgba(58,70,83,1) 30%, rgba(58,70,83,1) 70%, rgba(255,255,255,0) 71%) 0px 0px / 100px 100px repeat repeat, /* -45deg fiber */
linear-gradient(0deg, rgba(1,9,18,1) 0%, rgba(1,9,18,1) 100%) 0px 0px / 100px 100px repeat repeat; /* Background */