scripts/userstyles/messenger-dynamic-sidebar.user.css

:root {
  --sidebarSpeed: 0.2s;
  --sidebarDelay: 0.1s;
  --actionBarDelay: 0.15s;
  --sidebarEase: "ease";
  --sidebarWidth: 360px;
}

.bdao358l.om3e55n1.g4tp4svg.alzwoclg.cqf1kptm.jez8cy9q.gvxzyvdx.aeinzg81.qp72b3h3.oxkhqvkx.nch0832m.srn514ro.rl78xhln {
  max-width: 0;
  overflow: hidden;
  border-right-color: var(--web-wash);
  transition: max-width var(--sidebarSpeed);
  transition-delay: var(--actionBarDelay);
}
.bdao358l.om3e55n1.g4tp4svg.alzwoclg.cqf1kptm.jez8cy9q.gvxzyvdx.aeinzg81.qp72b3h3.oxkhqvkx.nch0832m.srn514ro.rl78xhln:hover {
  max-width: 211px;
  border-right-color: var(--media-inner-border);
}
/* Header */
.mm98tyaj
  .bdao358l.om3e55n1.g4tp4svg.alzwoclg.jez8cy9q.sl27f92c.i85zmo3j.sr926ui1.jl2a5g8c.anf3k8p9.rj0o91l8.qjfq86k5.p9ctufpz.lth9pzmp {
  opacity: 0;
  height: 0;
  margin: 0 16px;
  overflow: hidden;
  transition: var(--sidebarSpeed);
}
/* Search */
.mm98tyaj .bdao358l.om3e55n1.g4tp4svg.r227ecj6.gt60zsk1.rj2hsocd.f9xcifuu {
  opacity: 0;
  height: 0;
  overflow: hidden;
  transition: var(--sidebarSpeed);
}
/* Text Header */
.mm98tyaj .jxuftiz4.jwegzro5.hl4rid49.icdlwmnq {
  width: 150px;
}
/* Unread Message Indicator */
.mm98tyaj .nmlomj2f[data-visualcompletion="ignore"] {
  position: relative;
  right: 83px;
  transition-delay: var(--sidebarDelay);
}
/* Notification bell */
.mm98tyaj .sr926ui1.alzwoclg.i85zmo3j svg,
.mm98tyaj .sr926ui1.alzwoclg.i85zmo3j .i1ozlmoo {
  display: none;
}
/* Scrollbar */
.mm98tyaj
  .alzwoclg.cqf1kptm.cgu29s5g.i15ihif8.sl4bvocy.lq84ybu9.efm7ts3d.om3e55n1.mfclru0v {
  overflow-y: hidden;
}
/* Hide contents (workaround) */
.i85zmo3j.alzwoclg.rtxb060y.p4zypb3t {
  overflow: hidden;
}
/* Sidebar (not focused) */
.mm98tyaj {
  width: 80px;
  min-width: 80px;
  transition: width var(--sidebarSpeed) var(--sidebarEase);
  transition-delay: var(--sidebarDelay);
}
/* Sidebar (focused) */
.b0ur3jhr:hover .mm98tyaj {
  width: var(--sidebarWidth);
  transition-delay: 0s;
}
/* Header (focused) */
.b0ur3jhr:hover
  .mm98tyaj
  .bdao358l.om3e55n1.g4tp4svg.alzwoclg.jez8cy9q.sl27f92c.i85zmo3j.sr926ui1.jl2a5g8c.anf3k8p9.rj0o91l8.qjfq86k5.p9ctufpz.lth9pzmp {
  opacity: 1;
  height: auto;
  overflow: visible;
  margin: 20px 16px 12px 16px;
}
/* Search (focused) */
.b0ur3jhr:hover
  .mm98tyaj
  .bdao358l.om3e55n1.g4tp4svg.r227ecj6.gt60zsk1.rj2hsocd.f9xcifuu {
  opacity: 1;
  height: auto;
  overflow: visible;
}
/* Unread Message Indicator (focused) */
.b0ur3jhr:hover .mm98tyaj .nmlomj2f[data-visualcompletion="ignore"] {
  right: 0;
  transition-delay: 0s;
}
/* Notification bell (focused) */
.b0ur3jhr:hover .mm98tyaj .sr926ui1.alzwoclg.i85zmo3j svg,
.b0ur3jhr:hover .mm98tyaj .sr926ui1.alzwoclg.i85zmo3j .i1ozlmoo {
  display: block;
}
/* Scrollbar (focused) */
.b0ur3jhr:hover
  .mm98tyaj
  .alzwoclg.cqf1kptm.cgu29s5g.i15ihif8.sl4bvocy.lq84ybu9.efm7ts3d.om3e55n1.mfclru0v {
  overflow-y: scroll;
}