styles.css

*,
::before,
::after {
    box-sizing: border-box;
}

body {
    margin: 0 auto;
    padding: 100px;
    display: flex;
    flex-direction: column;
    align-items: center;
    font-family: 'Indie Flower', 'Caveat', Arial, Helvetica, sans-serif;
    font-weight: 400;
    font-style: normal;
    font-size: 28px;
    line-height: 28px;
    letter-spacing: 3px;
}
header {
    margin: 50px;
    text-align: center;
    font-size: 63px;
    line-height: 48px;
    letter-spacing: 7px;
}
input {
    border: 0;
    border-bottom: 1px solid;
}
button {
    margin-top: 30px;
    margin-bottom: 50px;
    padding: 0 22px;
    background-color: rgb(0, 0, 0, 0);
    border-radius: 4px;
    border: 1px solid black;
    font-family: inherit;
    font-size: 28px;
    align-self: center;
}
button:hover {
    cursor: pointer;
    transform: scale(1.05);
    transition: 0.5s;
    border: 0px;
    background: linear-gradient(90deg, rgba(131,58,180,0.8) 0%, rgba(253,29,29,0.8) 50%, rgba(252,176,69,0.8) 100%);
    color: white;
}
h1 {
    text-align: center;
    line-height: 48px;
}
h2 {
    align-self: center;
    margin-bottom: 70px;
}

.intro {
    width: 100%;
    height: 250px;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
}
.players-block {
    width: 100%;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
}
.player-intro {
    display: flex;
    justify-content: space-between;
    margin-bottom: 15px;
}
.player-intro span {
    margin-right: 15px;
    font-size: 22px;
}
.radio {
    margin-left: 25px;
}
.radio-block {
    width: 5%;
    display: flex;
    align-self: flex-end;
}
span.radio-block  {
    font-size: 22px;
    padding-right: 40px;
}
.radio-item {
    position: absolute;
    z-index: -1;
    opacity: 0;
  }
.radio-item+label {
    display: inline-flex;
    align-items: center;
    user-select: none;
}
.radio-item+label::before {
    content: '';
    display: inline-block;
    width: 0.5em;
    height: 0.5em;
    border: 1px solid #adb5bd;
    border-radius: 50%;
    background-repeat: no-repeat;
    background-position: center center;
    background-size: 70% 80%;
}
.radio-item:checked+label::before {
    border: 5px solid rgba(131,58,180,1);
    background-color: white;
  }
.radio-item:not(:disabled):active+label::before {
    border: 5px solid rgba(131,58,180,1);
    background-color: white;
}

.game-field {
    height: 600px;
    display: none;
    flex-direction: column;
    justify-content: space-between;
    align-items: center;
}
.players {
    display: flex;
    justify-content: space-between;
}
.player1 {
    margin-right: 30px;
    color: rgba(253,29,29,1);
}
.player2 {
    color: rgba(252,176,69,1);
}
.cells {
    display: grid;
    grid-template-columns: repeat(3, 100px);
}
.cell {
    border: 2px solid rgba(131,58,180,0.7);
    box-shadow: 0 0 0 2px rgba(131,58,180,0.7);
    height: 100px;
    width: 100px;
    font-size: 70px;
    display: flex;
    justify-content: center;
    align-items: center;
}
.cell:hover {
    cursor: pointer;
}