Instagram full-screen, no sidebar DMs

style.css

/* Hide scrollbar */
html[data-js-focus-visible] {
    overflow-y: hidden !important;
}

/* Hide sidebar */
body > div:nth-child(2) > div > div > div:nth-child(2) > div > div > div > div:nth-child(1) > div:nth-child(1) > div:nth-child(1) {
    display: none !important;
}

/* Remove sidebar space on the left */
body > div:nth-child(2) > div > div > div:nth-child(2) > div > div > div:nth-child(1) > div:nth-child(1) > div:nth-child(2) {
    width: 100% !important;
}

/* Remove sidebar space on the bottom */
body > div:nth-child(2) > div > div > div:nth-child(2) > div > div > div > div:nth-child(1) > div:nth-child(1) > div:nth-child(2) > section > div > div > div {
    min-height: 100vh !important;
    height: 100% !important;
}