style.css

body {
  background-color: rgb(32, 32, 32);
  background-image: url("https://janschreiber.github.io/img2/black-chalk.jpg");
  color: rgb(230, 230, 230);
  text-align: center;
  font-family: 'Indie Flower', 'Comic Sans', cursive;
  font-size: 0.7em;
}
h1 {
  line-height: 1em;
  margin-bottom: 0;
  padding-bottom: 5px;
  font-size: 2.8em;
  font-weight: bold;
}
h2 {
  font-size: 1.3em;
  font-weight: bold;
  padding: 0;
  margin: 0;

}
h3 {
  font-size: 1.1em;
  text-decoration: underline;
  text-decoration-style: dashed;
  padding: 0;
  margin: 10px 0 2px 0;
}
table {
  margin: 2% auto;
  border-collapse: collapse;
}
#table_game {
  position: relative;
  font-size: 120px;
  margin: 1% auto;
  border-collapse: collapse;
}
.td_game {
  border: 4px solid rgb(230, 230, 230);
  width: 90px;
  height: 90px;
  padding: 0;
  vertical-align: middle;
  text-align: center;
}
.fixed {
  width: 90px;
  height: 90px;
  line-height: 90px;
  display: block;
  overflow: hidden;
  cursor: pointer;
}
.td_list {
  text-align: center;
  font-size: 1.3em;
  font-weight: bold;
}
.th_list {
  font-size: 1.3em;
  font-weight: bold;
  text-align: center;
  text-decoration: underline;
}
#restart {
  font-size: 3em;
  width: 1em;
  height: 0.9em;
  cursor: pointer;
  margin: 0 auto;
  overflow: hidden;
}
.x {
  color: darksalmon;
  position: relative;
  top: -8px;
  font-size: 1.2em;
  cursor: default;
}
.o {
  color: aquamarine;
  position: relative;
  top: -7px;
  font-size: 1.0em;
  cursor: default;
}

/* modal background */
.modal {
  display: none;
  position: fixed;
  z-index: 1;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  overflow: auto; /* enable scroll if needed */
  background-color: black; /* fallback color */
  background-color: rgba(0, 0, 0, 0.6);
}

/* modal content */
.modal-content {
  background-color: rgb(240, 240, 240);
  color: rgb(32, 32, 32);
  font-size: 2em;
  font-weight: bold;
  /* 16 % from the top and centered */
  margin: 16% auto;
  padding: 20px;
  border: 2px solid black;
  border-radius: 10px;
  width: 380px;
  max-width: 80%;
}
.modal-content p {
  margin: 0;
  padding: 0;
}

/* close button for modal dialog */
.close {
  color: rgb(170, 170, 170);
  float: right;
  position: relative;
  top: -25px;
  right: -10px;
  font-size: 34px;
  font-weight: bold;
}
.close:hover,
.close:focus {
  color: black;
  text-decoration: none;
  cursor: pointer;
}

.win-color {
  background-color: rgb(240, 240, 240);
}