input:invalid {
    z-index: 4;
    /*box-shadow: 1px 1px 3px red;*/
}

div > input[type="number"] {
    width: 50px;
    height: 50px;
    font-size: 23px;
    text-align: center;
    -moz-appearance: textfield;
    border: none;
    float: left;
    margin-right: 1px;
    position: relative
}

.grid-mini {
    float: left;
    margin-right: 3px;
    margin-bottom: 3px;
    margin-top: 3px;
    margin-left: 3px;
}

    .grid-mini:nth-child(2n+1) input[type="number"] {
        background-color: #ffffcc;
    }

    .grid-mini:nth-child(2n) input[type="number"] {
        background-color: #ffcccc;
    }

.grid-row {
    margin-bottom: 1px;
}

    .grid-row:after {
        content: "";
        display: block;
        clear: both;
    }

.game-container {
    width: 477px;
    background: rgba(241, 235, 235, 1);
}

.grid-container, .no-sln {
    width: inherit;
    height: 477px;
}

.grid-container {
    background-color: lightblue;
}

.no-sln {
    position: absolute;
    font-size: 100px;
    text-align: center;
    background: #f2f2f2;
    opacity: 0.5;
}
.back {
    z-index: -1;
}
.front {
    z-index: 4;
}
.game-container > button {
    margin-top: 30px;
    /*margin-left: 40px;*/
    float: right;
}

#reset-btn {
    margin-right: 40px;
}