:root {
    --primary-gray: #667687;
    --blue-gray: #6699cc;
    --dark-gray: #222;
}

body {
    min-height: 100vh;
}

.page-header {
    padding: 50px 20px 40px;
    background-color: var(--blue-gray);
}

.page-heading {
    text-transform: uppercase;
    font-size: 4em;
    text-align: center;
}

.page-footer {
    padding: 10px 40px;
    font-size: 1.2em;
    background-color: var(--dark-gray);
    color: white;
    text-align: right;
}

#main-display {
    width: 100%;
}
.game-box,
.game-box:focus {
    outline: none;
    box-shadow: none;
    border-radius: 0;
    width: 60px;
    height: 60px;
    text-align: center;
    font-size: 2em;
}

.game-row {
    border-left: 4px solid var(--primary-gray);
    border-right: 4px solid var(--primary-gray);
}

.game-row:first-of-type {
    border-top: 4px solid var(--primary-gray);
}

.game-row:last-of-type {
    border-bottom: 4px solid var(--primary-gray);
}

.left-box {
    border-left: 1.5px solid var(--primary-gray);
}

.right-box {
    border-right: 1.5px solid var(--primary-gray);
}

.top-box {
    border-top: 1.5px solid var(--primary-gray);
}

.bottom-box {
    border-bottom: 1.5px solid var(--primary-gray);
}

.input-button {
    font-size: 1.5em;
    background-color: var(--primary-gray);
    color: white;
}

.btn {
    text-transform: uppercase;
}

.input-button:hover {
    color: white;
}

.input-button-active {
    background-color: var(--dark-gray);
}
.form-select {
    width: 30%;
    height: 48px;
}

.conflict,
.conflict:hover,
.conflict:focus {
    color: red;
}

#new-game {
    width: 30%;
    height: 48px;
}

#start-timer {
    height: 48px;
}

#result {
    text-align: center;
}

#timer-display {
    padding: 5px;
    font-size: 3em;
    letter-spacing: 4px;
    margin-bottom: 0;
}

#result-display {
    height: 40px;
    font-size: 2em;
    text-transform: uppercase;
}

@media only screen and (max-width: 900px) {
    .game-box,
    .game-box:focus {
        width: 50px;
        height: 50px;
        text-align: center;
        font-size: 1.35em;
    }
    .input-button {
        font-size: 1.2em;
        background-color: var(--primary-gray);
        color: white;
    }
    .input-button-active {
        background-color: var(--dark-gray);
    }
}

@media only screen and (max-width: 767.98px) {
    .form-select {
        height: 42px;
    }
    #new-game {
        height: 42px;
    }
    #board-controls {
        width: 100%;
    }
    .game-box,
    .game-box:focus {
        width: 45px;
        height: 45px;
        text-align: center;
        font-size: 1.5em;
    }
    .input-button {
        font-size: 1.2em;
        background-color: var(--primary-gray);
        color: white;
    }
    .input-button-active {
        background-color: var(--dark-gray);
    }
    #board {
        margin: 0 0 20px;
    }
    .page-heading {
        font-size: 3.2em;
    }
}

@media only screen and (max-width: 575.98px) {
    #new-game {
        width: 100%;
        height: 42px;
    }
    .form-select {
        width: 100%;
        height: 42px;
        margin-bottom: 15px;
    }
    .game-box,
    .game-box:focus {
        width: 30px;
        height: 30px;
        text-align: center;
        font-size: 1em;
        padding: 5px;
    }
    .input-button {
        font-size: 0.8em;
        background-color: var(--primary-gray);
        padding: 3px 8px;
        color: white;
        margin: 2px !important;
    }
    .input-button-active {
        background-color: var(--dark-gray);
    }
    #board {
        margin: 0 0 20px;
    }
    .page-heading {
        font-size: 3.2em;
    }
}