style.css

* {
	box-sizing: border-box;
	margin: 0;
	padding: 0;
}

html, body {
	height: 100%;
        overflow: hidden;
}

body {
        display: grid;
        grid-template-columns: 1fr 150px;
        grid-template-rows: 120px 1fr;
}

#controls_navigation {
	text-align: center;
	padding: 0 20px;

        grid-column: 2/3;
        grid-row: 2/3;

        display: flex;
        flex-direction: column;
        align-items: stretch;
        justify-content: space-between;
}

#scale_selection {
    font-size: 1em;
    line-height: 2.3em;
    height: 2.3em;
    width: 300px;
    vertical-align: middle;
    overflow: hidden;

    background-color: lightgreen;
    position: relative;

    --show_major: 1;
    --semitones_from_c_major: 0;
    grid-row: 2/3;
    grid-column: 2/3;
}

#scale_selection .major {
    width: 100%;
    text-align: center;
    position: absolute;
    top: calc((11 - var(--semitones_from_c_major)) * -2.3em);
    left: calc((var(--show_major) - 1) * 300px);
    transition-property: top left;
    transition-duration: 1s;
}

#scale_selection .minor {
    width: 100%;
    text-align: center;
    position: absolute;
    top: calc((11 - var(--semitones_from_c_major)) * -2.3em);
    left: calc(var(--show_major) * 300px);
    transition-property: top left;
    transition-duration: 1s;
}

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

    display: grid;
    grid-template-rows: 2.3em 2.3em 2.3em;
    grid-template-columns: max-content min-content max-content;
}

#btn_move_up {
    order: 10;
}

#btn_zoom_in_y {
    order: 20;
}

#btn_zoom_out_y {
    order: 30;
}

#btn_move_down {
    order: 40;
}

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

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

#btn_move_tonic_up {
    grid-row: 1/2;
    grid-column: 2/3;
    width: 100%;
}

#btn_move_tonic_down {
    grid-row: 3/4;
    grid-column: 2/3;
    width: 100%;
}

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

canvas {
	height: 100%;
	width: 100%;
        display: block;
}