body {
    background-image: url(../bg/chess.gif);
}

h1 {
    font-size: 1.55em;
    text-align: center;
    text-decoration: underline;
}

p {
    letter-spacing: 1px;
    font-family: Arial, Helvetica, sans-serif;
}

.discrete {
    color: inherit;
}

.three-col {
    width: 95%;
    height: 90vh;
    display: grid;
    grid-template-columns: clamp(250px, 20%, 500px) 1fr clamp(200px, 15%, 600px);
    gap: 10px;
    margin-inline: auto;
}

.window {
    height: 100%;
}

#left-top, #left-bottom, #center, #right {
    background: red;
}

img {
    max-width: 100%;
}

/* LEFT TOP */

#left-top {
    grid-row: 1 / 2;
}

nav {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
}

/* LEFT BOTTOM */

#left-bottom {
    grid-row: 2 / 3;
}

iframe {
    width: 100%;
    height: 90%;
    overflow-y: scroll;
}

/* CENTER */

#center {
    grid-row: 1 / 3;
}

/* RIGHT */

#right {
    grid-row: 1 / 3;
}

h2 {
    font-size: 1.25em;
    text-decoration: underline;
}

.bullet {
    height: 12px;
}

/* MEDIA QUERIES */

@media (max-width: 1000px) {
    .three-col {
        grid-template-columns: 72% 28%;
        grid-template-rows: 1fr 2fr 2fr 1fr;
        height: 95vh;
    }
    
    #left-top {
        grid-row: 1 / 2;
        grid-column: 1 / 2;
    }

    #left-bottom {
        grid-row: 4 / 5;
        grid-column: 1 / 3;
    }

    #center {
        grid-row: 2 / 4;
        grid-column: 1 / 2;
    }

    #right {
        grid-row: 1 / 4;
        grid-column: 2 / 3;
    }
}

@media (max-width: 500px) {
    .three-col {
        grid-template-columns: 45% 55%;
        grid-template-rows: 1fr 60% 1fr;
    }

    #left-top {
        grid-row: 1 / 2;
        grid-column: 1 / 3;
    }

    #left-bottom {
        grid-row: 3 / 4;
        grid-column: 1 / 2;
    }

    #center {
        grid-row: 2 / 3;
        grid-column: 1 / 3;
    }

    #right {
        grid-row: 3 / 4;
        grid-column: 2 / 3;
    }

    .tree-view {
        overflow-y: scroll;
    }
}

@media (max-width: 400px) {
    .three-col {
        grid-template-columns: 45% 55%;
        grid-template-rows: 1fr 60% 1fr 1fr;
    }

    #left-top {
        grid-row: 1 / 2;
        grid-column: 1 / 3;
    }

    #left-bottom {
        grid-row: 4 / 5;
        grid-column: 1 / 3;
    }

    #center {
        grid-row: 2 / 3;
        grid-column: 1 / 3;
    }

    #right {
        grid-row: 3 / 4;
        grid-column: 1 / 3;
    }

    .tree-view {
        overflow-y: scroll;
    }
}