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