body {
    font-family: 'Courier New', Courier, monospace;
    text-align: center;
    touch-action: none;
    color: #f1faee;
}

#board {
    width: 300px;
    height: 300px;
    margin: 50px auto 0;
    position: relative;
    background-color: #457b9d;
    border: 2px solid #022543;
    
}

table {
    border-collapse: collapse;
    position: absolute;
    top: 0;
    left: 0;
}

td {
    width: 100px;
    height: 100px;

}

.piece {
    width: 100px;
    height: 100px;
    position: absolute;
    background-size: 300px 300px;
    cursor: move;
    border: 1px solid #022543;
    z-index: 1;
}

.button-54 {
  font-family: 'Courier New', Courier, monospace;
  font-size: 16px;
  letter-spacing: 2px;
  text-decoration: none;
  text-transform: uppercase;
  background-color: #f1faee;
  color: #022543;
  cursor: pointer;
  border: 3px solid;
  padding: 0.25em 0.5em;
  box-shadow: 1px 1px 0px 0px, 2px 2px 0px 0px, 3px 3px 0px 0px, 4px 4px 0px 0px, 5px 5px 0px 0px;
  position: relative;
  user-select: none;
  -webkit-user-select: none;
  touch-action: manipulation;
}

.button-54:active {
  box-shadow: 0px 0px 0px 0px;
  top: 5px;
  left: 5px;
}
.flash {
    animation: flashBorder 0.3s linear infinite;
}

.popup {
position: fixed;
top: 0;
left: 0;
width: 100%;
height: 100%;
background: rgba(2, 37, 67, 0.8);
display: flex;
justify-content: center;
align-items: center;

opacity: 0;
pointer-events: none;
transition: opacity 0.3s ease;
}

.popup.show {
opacity: 1;
pointer-events: all;
}

.popup-box {
background: #f1faee;
color: #022543;
padding: 25px 35px;
border-radius: 12px;
text-align: center;
box-shadow: 5px 5px 0px #022543;
}

@keyframes flashBorder {
    0%   { border-color: #022543; }
    50%  { border-color: #457b9d; }  
    100% { border-color: #022543; }
}


@media (min-width: 768px) {
  .button-54 {
    padding: 0.25em 0.75em;
  }
}