* {
    margin: 0;
    padding: 0;
    user-select: none;
    font-family: 'Open sans', 'Segoe UI', sans-serif;
    outline: none;
    user-select: none;
}

html, body {
    width: 100%;
    height: 100%;
    margin: 0;
    padding: 0;
}

:root {
    --border-size: 0.21rem;
}

#new-game-btn {
    text-align: center;
    font-size: x-large;
    cursor: pointer;
}

.center {
    width:100vw;
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: flex-start;
    flex-direction: column;
}

#message {
   font-weight: bolder;
   font-size: 150% !important;
   text-align: center;
   height: 5vh;
   width: 100%;
   padding-top: 1%;
}

.hidden {
    visibility: hidden;
}

#footer {
    position: fixed;
    bottom: 0;
    left: 50%;
    width: 100%;
    text-align: center;
    padding: 0.5rem;
    font-size: 1.33em;
    transform: translateX(-50%);
    font-family: monospace !important;
}

#footer * {
    font-family: monospace !important;
}

#board {
    display: grid;
    grid-template-columns: repeat(3, 7rem);
    grid-template-rows: repeat(3, 7rem);
    margin-top: 2.5%;
    font-size: 3rem;
}

@media only screen and (max-width: 600px) {
    #board {
        display: grid;
        grid-template-columns: repeat(3, 5.5rem);
        grid-template-rows: repeat(3, 5.5rem);
        margin-top: 4.5%;
        font-size: 3rem;
    }
  }

#difficulties {
    padding-top: 1%;
}

#difficulties .btn {
    margin: 0.5rem;
}

#difficulties #imp {
    display: block;
}

.btn-stocky {
    padding: 0.1rem 1rem !important;
}

.btn-large {
    font-weight: bold;
    font-size: larger;
}

#choose-player {
    padding-top: 5%;
}

#choose-player .btn {
    padding: 0.5rem;
    font-size: x-large;
}
/*
#choose-player .btn.btn-selected {
    background-color: lime;
    color: whitesmoke;
}

#imp.btn-selected {
    background-color: darkmagenta;
    color: white;
}

#ez.btn-selected {
    background-color: lawngreen;
    color: navy;
}

#med.btn-selected {
    background-color: darkorange;
    color: white;
}

#hd.btn-selected {
    background-color: darkred;
    color: white;
}
*/
.btn-selected {
    background-color: black;
    color: white;
}

.br-bottom {
    border-bottom: var(--border-size) solid #000 !important;
}

.br-left {
    border-left: var(--border-size) solid #000 !important;
}

.br-right {
    border-right: var(--border-size) solid #000 !important;
}

.br-top {
    border-top: var(--border-size) solid #000 !important;
}

#board div {
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 4.5rem;
    cursor: pointer;
    color: #000;
    background: none;
    border: none;
}

.cell {
    width: 100%;
    height: 100%;
    cursor: pointer;
}

#options {
    margin-top: 2%;
    text-align: center;
}

.btn {
    outline: none;
    padding: 0.5rem;
    border: none;
    font-weight: 500;
    cursor: pointer;
}