:root {
    --step: 28px;
    --gap: 6px;
    --pitch: calc(var(--step) + var(--gap));
    --track: calc(16 * var(--step) + 15 * var(--gap));
}

* {
    box-sizing: border-box;
}

html,
body {
    margin: 0;
}

body {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    font-family: times new roman;
    background: #fff;
    color: #111;
}

main {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 28px;
    padding: 48px calc(8 * var(--pitch) + 24px);
}

h1 {
    margin: 0;
    font-size: 1rem;
    font-weight: 400;
    letter-spacing: 0.12em;
}

.transport {
    display: flex;
    align-items: center;
    gap: 16px;
}

.transport button,
.bpm input {
    font: inherit;
    color: inherit;
    background: #fff;
    border: 1px solid #111;
    border-radius: 0;
}

.transport button {
    padding: 4px 14px;
    cursor: pointer;
}

.bpm {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.85rem;
}

.bpm input {
    width: 4.2em;
    padding: 4px 6px;
}

.sequencer {
    display: flex;
    flex-direction: column;
    gap: 28px;
}

.row {
    display: grid;
    grid-template-columns: 4.5em var(--track) 4.5em;
    column-gap: 16px;
    row-gap: 10px;
    align-items: center;
}

.row-select {
    grid-column: 1;
    grid-row: 1;
}

.row-slider {
    grid-column: 2;
    grid-row: 1;
    width: 100%;
}

.row-curve {
    grid-column: 3;
    grid-row: 1;
}

.steps {
    grid-column: 2;
    grid-row: 2;
    display: flex;
    gap: var(--gap);
}

.row[data-color="red"] { --color: #ff0000; }
.row[data-color="green"] { --color: #00ff00; }
.row[data-color="blue"] { --color: #0000ff; }

select {
    font: inherit;
    color: inherit;
    background: #fff;
    border: 1px solid #111;
    border-radius: 0;
    padding: 3px 4px;
    width: 100%;
}

.step {
    --disp: 0;
    flex: 0 0 var(--step);
    height: var(--step);
    padding: 0;
    border: 1px solid var(--color);
    border-radius: 0;
    background: transparent;
    cursor: pointer;
    appearance: none;
    transform: translateX(calc(var(--disp) * var(--pitch)));
}

.step.on {
    background: var(--color);
}

.step.bump {
    z-index: 1;
    animation: bump 160ms ease-out;
}

@keyframes bump {
    0% { transform: translateX(calc(var(--disp) * var(--pitch))) scale(1); }
    35% { transform: translateX(calc(var(--disp) * var(--pitch))) scale(1.22); }
    100% { transform: translateX(calc(var(--disp) * var(--pitch))) scale(1); }
}

.step.now:not(.on) {
    background: color-mix(in srgb, var(--color) 35%, transparent);
}

input[type="range"] {
    -webkit-appearance: none;
    appearance: none;
    height: 18px;
    background: transparent;
    margin: 0;
}

input[type="range"]::-webkit-slider-runnable-track {
    height: 1px;
    background: var(--color);
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 10px;
    height: 18px;
    margin-top: -8.5px;
    background: var(--color);
    border: 0;
    border-radius: 0;
    cursor: pointer;
}

input[type="range"]::-moz-range-track {
    height: 1px;
    background: var(--color);
    border: 0;
}

input[type="range"]::-moz-range-thumb {
    width: 10px;
    height: 18px;
    background: var(--color);
    border: 0;
    border-radius: 0;
    cursor: pointer;
}

@media (max-width: 600px) {
    :root {
        --step: min(18px, calc((100vw - 7em - 28px) / 16 - 2px));
        --gap: 2px;
    }

    body {
        overflow-x: hidden;
        font-size: 13px;
    }

    main {
        gap: 16px;
        padding: 16px 8px;
        width: 100%;
    }

    .sequencer {
        gap: 16px;
        width: 100%;
    }

    .row {
        grid-template-columns: 2.8em var(--track) 2.8em;
        column-gap: 4px;
        row-gap: 6px;
        justify-content: center;
        width: 100%;
    }

    select {
        padding: 2px;
    }
}