How to draw line on a webpage using html, css and javascript

Question

I am currently working on a "tic tac toe like" game. This is the link.
I started upgrading some of its functionalities and I have a problem.
I used the image included below as the background image of the game and I positioned nine input fields, one on each edge/side of the image with css.
I no longer want to use a background image.
Is there any way I can draw those lines with css, javascript and/or html?
Please I will be very happy if it can be done with pure html, css and javascript or with jquery

Answer 1

you can also use gradients :

the idea

background: 
      linear-gradient(0deg,black,black) repeat-y center, 
      linear-gradient(0deg,black,black) repeat-x center,
      linear-gradient(26deg, transparent calc(50% - 2px), black calc(50% - 1px) , black calc(50% + 2px), transparent calc(50% + 2px)),
      linear-gradient(-26deg, transparent calc(50% - 2px), black calc(50% - 1px) , black calc(50% + 2px), transparent calc(50% + 2px)) yellow;
  background-size: 3px 100%, 100% 3px, auto,auto;

here is a snippet with margin and size of inputs updated too, the snippet uses also a background-color and a shadow.

body {
    color: black;
    width: 26.8cm;
    overflow: scroll;
    background-color: white;
}

.welcome{
  padding:20px;
  text-align: center;
  background: #ccc;
}
.transit{
  transition: 5s;
}
#player{
  color: green;
}
.gamelet { /*This style is for the boxes containing the hexadecimal color codes*/
    width: 5.6cm;
    display: inline-block;
    vertical-align: top;
}

.gamelet2 {
    margin-top: 4.3cm;
}

.fr { /*This style is for the red box only*/
    margin-left: -0.3cm;
  width:0.6cm;
}

.sr { /*This style is for the green box only*/
    margin:0 9.6cm;
  width:0.6cm;
}

.tr { /*This style is for the blue box only*/
   margin-right:-0.3cm;
  width:0.6cm;
}
div:nth-child(1),
div:nth-child(2),
div:nth-child(3){margin-top:-0.3cm;}
div:nth-child(7),
div:nth-child(8),
div:nth-child(9){margin-bottom:-0.3cm;}
.gamelet1 {
    border-radius: 90px;
    width: 0.6cm;
    cursor: pointer;
}

.board {
    background: 
      linear-gradient(0deg,black,black) repeat-y center, 
      linear-gradient(0deg,black,black) repeat-x center,
      linear-gradient(26deg, transparent calc(50% - 2px), black calc(50% - 1px) , black calc(50% + 2px), transparent calc(50% + 2px)),
      linear-gradient(-26deg, transparent calc(50% - 2px), black calc(50% - 1px) , black calc(50% + 2px), transparent calc(50% + 2px)) yellow;
  background-size: 3px 100%, 100% 3px, auto,auto;
   box-shadow: 0 0 0 0.6cm yellow; 
  border:solid;
  margin: 2cm 3cm;
}

/*//styles from bootstrap*/
.alert-danger {
  color: #a94442;
  background-color: #f2dede;
  border-color: #ebccd1;
  text-align: center;
  padding:20px;
  display: none;
}

.alert-success {
  color: #3c763d;
  background-color: #dff0d8;
  border-color: #d6e9c6;
  text-align: center;
  padding:20px;
  display: none;
}

.alert-info {
  color: #31708f;
  background-color: #d9edf7;
  border-color: #bce8f1;
  text-align: center;
  padding:20px;
}

<script src="https://kofimokome.github.io/tic-tac-toe/TTT_files/TTTscript.js"></script>
<form name="game" class="board">
  <div class="gamelet fr"><input onclick="C_11(cplayer); autoname(0);" name="C11" type="text" class="gamelet1" /></div>
  <div class="gamelet sr"><input onclick="C_12(cplayer); autoname(1);" name="C12" type="text" class="gamelet1" /></div>
  <div class="gamelet tr"><input onclick="C_13(cplayer); autoname(2);" name="C13" type="text" class="gamelet1" /></div>
  <div class="gamelet fr"><input onclick="C_21(cplayer); autoname(3);" name="C21" type="text" class="gamelet1 gamelet2" /></div>
  <div class="gamelet sr"><input onclick="C_22(cplayer); autoname(4);" name="C22" type="text" class="gamelet1 gamelet2" /></div>
  <div class="gamelet tr"><input onclick="C_23(cplayer); autoname(5);" name="C23" type="text" class="gamelet1 gamelet2" /></div>
  <div class="gamelet fr"><input onclick="C_31(cplayer); autoname(6);" name="C31" type="text" class="gamelet1 gamelet2" /></div>
  <div class="gamelet sr"><input onclick="C_32(cplayer); autoname(7);" name="C32" type="text" class="gamelet1 gamelet2" /></div>
  <div class="gamelet tr"><input onclick="C_33(cplayer); autoname(8);" name="C33" type="text" class="gamelet1 gamelet2" /></div>
</form>

a codepen to fork & play with

NOTE:

IDs can only be used once per document, use class instead if multiple use (code snippet for #gamelet turned into .gamelet )

Answer 2

You can use 2 elements and their pseudo elements to draw the lines with absolute positioning in and transform: rotate()

div {
  width: 25%;
  border: 1px solid black;
  margin: auto;
  overflow: hidden;
}
span {
  display: block;
  padding-bottom: 100%;
}
div,span {
  position: relative;
}
div::after,div::before,span::after,span::before {
  content: '';
  position: absolute;
  background: black;
}
div::after {
  top: 50%;
  left: 0; right: 0;
  height: 1px;
}
div::before {
  width: 1px;
  left: 50%;
  top: 0; bottom: 0;
}
span::before,span::after {
  height: 1px;
  top: 50%;
  left: -25%;
  right: -25%;
  background: red;
}
span::before {
  transform: rotate(45deg);
}
span::after {
  transform: rotate(-45deg);
}

<div><span></span></div>