tictactoe1.css

@import url('https://fonts.googleapis.com/css?family=Mandali|Raleway:900&display=swap');

input[type="radio"] {
  position: absolute;
  top: -9999em;
}

html, body {
  font-family: Mandali, Arial, sans-serif;
  font-size: 16px;
}

.center {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}
#board {
  width: 50vmin;
  height: 50vmin;
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  grid-template-rows: 1fr 1fr 1fr;
}

.tile {
  margin: 5%;
  position: relative;
}

.tile label,
.tile div {
  display: block;
  height: 100%;
  width: 100%;
  position: absolute;
  top: 0;
  left: 0;
  background: rgba(0,0,0,0.10);
  font-family: Raleway, Courier, 'Courier New', Sans, sans-serif;
  font-weight: bolder;
}

.tile div {
  display: none;
  overflow: hidden;
  text-shadow: 0 1px 6px rgba(0,0,0,0.85)
}

label[for$='-x'] {
  z-index: 1;
}

input:checked ~ #board label[for$='-o'] {
  z-index: 2;
}

input:checked ~ input:checked ~ #board label[for$='-x'] {
  z-index: 3;
}

input:checked ~ input:checked ~ input:checked ~ #board label[for$='-o'] {
  z-index: 4;
}

input:checked ~ input:checked ~ input:checked ~ input:checked ~ #board label[for$='-x'] {
  z-index: 5;
}

input:checked ~ input:checked ~ input:checked ~ input:checked ~ input:checked ~ #board label[for$='-o'] {
  z-index: 6;
}

input:checked ~ input:checked ~ input:checked ~ input:checked ~ input:checked ~ input:checked ~ #board label[for$='-x'] {
  z-index: 7;
}

input:checked ~ input:checked ~ input:checked ~ input:checked ~ input:checked ~ input:checked ~ input:checked ~ #board label[for$='-o'] {
  z-index: 8;
}

input:checked ~ input:checked ~ input:checked ~ input:checked ~ input:checked ~ input:checked ~ input:checked ~ input:checked ~ #board label[for$='-x'] {
  z-index: 9;
}

input[id*='-0-']:checked ~ #board label[for*='-0-'],
input[id*='-1-']:checked ~ #board label[for*='-1-'],
input[id*='-2-']:checked ~ #board label[for*='-2-'],
input[id*='-3-']:checked ~ #board label[for*='-3-'],
input[id*='-4-']:checked ~ #board label[for*='-4-'],
input[id*='-5-']:checked ~ #board label[for*='-5-'],
input[id*='-6-']:checked ~ #board label[for*='-6-'],
input[id*='-7-']:checked ~ #board label[for*='-7-'],
input[id*='-8-']:checked ~ #board label[for*='-8-'] {
  display: none;
}

input[id*='-0-']:checked ~ #board #tile-0 div,
input[id*='-1-']:checked ~ #board #tile-1 div,
input[id*='-2-']:checked ~ #board #tile-2 div,
input[id*='-3-']:checked ~ #board #tile-3 div,
input[id*='-4-']:checked ~ #board #tile-4 div,
input[id*='-5-']:checked ~ #board #tile-5 div,
input[id*='-6-']:checked ~ #board #tile-6 div,
input[id*='-7-']:checked ~ #board #tile-7 div,
input[id*='-8-']:checked ~ #board #tile-8 div {
  display: block;
}

input[id*='-0-x']:checked ~ #board #tile-0 div::before,
input[id*='-1-x']:checked ~ #board #tile-1 div::before,
input[id*='-2-x']:checked ~ #board #tile-2 div::before,
input[id*='-3-x']:checked ~ #board #tile-3 div::before,
input[id*='-4-x']:checked ~ #board #tile-4 div::before,
input[id*='-5-x']:checked ~ #board #tile-5 div::before,
input[id*='-6-x']:checked ~ #board #tile-6 div::before,
input[id*='-7-x']:checked ~ #board #tile-7 div::before,
input[id*='-8-x']:checked ~ #board #tile-8 div::before {
  content: "X";
  background: #004974;
  color: #89dcf6;
}

input[id*='-0-o']:checked ~ #board #tile-0 div::before,
input[id*='-1-o']:checked ~ #board #tile-1 div::before,
input[id*='-2-o']:checked ~ #board #tile-2 div::before,
input[id*='-3-o']:checked ~ #board #tile-3 div::before,
input[id*='-4-o']:checked ~ #board #tile-4 div::before,
input[id*='-5-o']:checked ~ #board #tile-5 div::before,
input[id*='-6-o']:checked ~ #board #tile-6 div::before,
input[id*='-7-o']:checked ~ #board #tile-7 div::before,
input[id*='-8-o']:checked ~ #board #tile-8 div::before {
  content: "O";
  background: #a60011;
  color: #ffc7b5;
}

.tile label:hover {
  cursor: pointer;
  background: rgba(0,0,0,0.25);
}

.tile label::before,
.tile div::before {
  color: #000;
  position: absolute;
  text-align:center;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  font-size: 7.5vmin;
  font-weight: bold;
}

.tile div::before {
  padding: 100%;
}

.tile label[for$='-o']:hover::before {
  content: "O";
}

.tile label[for$='-x']:hover::before {
  content: "X";
}

#tile-0 {
  grid-column: 1;
  grid-row: 1;
}
#tile-0 label,
#tile-0 div {
  border-radius: 10% 0 0 0;
}
#tile-1 {
  grid-column: 2;
  grid-row: 1;
}
#tile-2 {
  grid-column: 3;
  grid-row: 1;
}
#tile-2 label,
#tile-2 div {
  border-radius: 0 10% 0 0;
}
#tile-3 {
  grid-column: 1;
  grid-row: 2;
}
#tile-4 {
  grid-column: 2;
  grid-row: 2;
}
#tile-5 {
  grid-column: 3;
  grid-row: 2;
}
#tile-6 {
  grid-column: 1;
  grid-row: 3;
}
#tile-6 label,
#tile-6 div {
  border-radius: 0 0 0 10%;
}
#tile-7 {
  grid-column: 2;
  grid-row: 3;
}
#tile-8 {
  grid-column: 3;
  grid-row: 3;
}
#tile-8 label,
#tile-8 div {
  border-radius: 0 0 10% 0;
}

#end {
  background: rgba(255,255,255,0.85);
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  display: none;
}

#message {
  text-align: center;
  font-size: 2rem;
  line-height: 2.2rem;
  font-weight: bold;
}

#message::before {
  content: "Tied game!"
}

#message input {
  background: #000;
  color: #fff;
  font-size: 1rem;
  padding: 0.5rem 1.75rem;
  margin: auto auto;
  margin-top: 2rem;
}

input:checked ~ input:checked ~ input:checked ~ input:checked ~ input:checked ~ input:checked ~ input:checked ~ input:checked ~ input:checked ~ #end,
#cell-0-x:checked ~ #cell-1-x:checked ~ #cell-2-x:checked ~ #end,
#cell-3-x:checked ~ #cell-4-x:checked ~ #cell-5-x:checked ~ #end,
#cell-6-x:checked ~ #cell-7-x:checked ~ #cell-8-x:checked ~ #end,
#cell-0-x:checked ~ #cell-3-x:checked ~ #cell-6-x:checked ~ #end,
#cell-1-x:checked ~ #cell-4-x:checked ~ #cell-7-x:checked ~ #end,
#cell-2-x:checked ~ #cell-5-x:checked ~ #cell-8-x:checked ~ #end,
#cell-0-x:checked ~ #cell-4-x:checked ~ #cell-8-x:checked ~ #end,
#cell-2-x:checked ~ #cell-4-x:checked ~ #cell-6-x:checked ~ #end,
#cell-0-o:checked ~ #cell-1-o:checked ~ #cell-2-o:checked ~ #end,
#cell-3-o:checked ~ #cell-4-o:checked ~ #cell-5-o:checked ~ #end,
#cell-6-o:checked ~ #cell-7-o:checked ~ #cell-8-o:checked ~ #end,
#cell-0-o:checked ~ #cell-3-o:checked ~ #cell-6-o:checked ~ #end,
#cell-1-o:checked ~ #cell-4-o:checked ~ #cell-7-o:checked ~ #end,
#cell-2-o:checked ~ #cell-5-o:checked ~ #cell-8-o:checked ~ #end,
#cell-0-o:checked ~ #cell-4-o:checked ~ #cell-8-o:checked ~ #end,
#cell-2-o:checked ~ #cell-4-o:checked ~ #cell-6-o:checked ~ #end {
  display: block;
}

#cell-0-x:checked ~ #cell-1-x:checked ~ #cell-2-x:checked ~ #end #message::before,
#cell-3-x:checked ~ #cell-4-x:checked ~ #cell-5-x:checked ~ #end #message::before,
#cell-6-x:checked ~ #cell-7-x:checked ~ #cell-8-x:checked ~ #end #message::before,
#cell-0-x:checked ~ #cell-3-x:checked ~ #cell-6-x:checked ~ #end #message::before,
#cell-1-x:checked ~ #cell-4-x:checked ~ #cell-7-x:checked ~ #end #message::before,
#cell-2-x:checked ~ #cell-5-x:checked ~ #cell-8-x:checked ~ #end #message::before,
#cell-0-x:checked ~ #cell-4-x:checked ~ #cell-8-x:checked ~ #end #message::before,
#cell-2-x:checked ~ #cell-4-x:checked ~ #cell-6-x:checked ~ #end #message::before {
  content: "Player 1 won!";
}

#cell-0-o:checked ~ #cell-1-o:checked ~ #cell-2-o:checked ~ #end #message::before,
#cell-3-o:checked ~ #cell-4-o:checked ~ #cell-5-o:checked ~ #end #message::before,
#cell-6-o:checked ~ #cell-7-o:checked ~ #cell-8-o:checked ~ #end #message::before,
#cell-0-o:checked ~ #cell-3-o:checked ~ #cell-6-o:checked ~ #end #message::before,
#cell-1-o:checked ~ #cell-4-o:checked ~ #cell-7-o:checked ~ #end #message::before,
#cell-2-o:checked ~ #cell-5-o:checked ~ #cell-8-o:checked ~ #end #message::before,
#cell-0-o:checked ~ #cell-4-o:checked ~ #cell-8-o:checked ~ #end #message::before,
#cell-2-o:checked ~ #cell-4-o:checked ~ #cell-6-o:checked ~ #end #message::before {
  content: "Player 2 won!";
}