EDIT 7/5/23: @kiophen did a real grown up execution of this thank u so much god. you should just use their implementation. i made some tweaks on my personal version but i'm not at my pc rn, just comment to remind me and i'll paste them in here sometime. original post below the fold
EDIT 2 7/5/23: my colors in kiophen's tool are #2b2b47, #f0f0f0, #f5dcbf, #b5306b and i set the contrast slider to -.46 ish. other tweaks:
more color fixes for my tastes:
svg text,
.fill-foreground-500 svg,
.prose-stone,
h3 {
color: var(--color-prose-100) !important;
}
[class*="text-foreground"],
span.conotifs-label,
.prose-stone a {
color: var(--color-notWhite) !important;
}
nav [href*="compose"] {
background: var(--color-accent) !important;
color: var(--color-notWhite) !important;
}
nav [href*="compose"]:hover {
background: var(--color-notWhite) !important;
color: var(--color-accent) !important;
}
.fill-composeButton {
color: var(--color-notWhite) !important;
fill: var(--color-accent);
}
.fill-composeButton:hover {
color: var(--color-accent) !important;
fill: var(--color-notWhite);
}
[href="https://cohost.org/"],
span.conotifs-label a,
.header-controls a {
color: var(--color-accent) !important;
}
[class*="border-gray"] {
border-color: var(--color-dark0);
}
button[class*="hover"]:hover {
color: var(--color-accent) !important;
background-color: var(--color-dark3) !important;
}
.hover\:bg-foreground-100:hover {
background-color: var(--color-accent);
color: var(--color-prose-100) !important;
}
tightening up the display spacings:
.gap-12 {
gap: 1rem;
}
.p-3 {
padding: .4rem .75rem;
}
div.flex.flex-col.items-center.m-3.gap-3 > .p-3 {
padding: 0;
}
.my-4 {
margin-top: .5rem;
margin-bottom: .5rem;
}
:not(svg):not(.mask).cohost-shadow-light {
box-shadow: 0 1px 10px rgb(25 25 25 / 30%), 0 2px 4px rgb(0 0 0 / 25%);
}
.lg\:pt-16 {
padding-top: 1rem;
}
also stuff for the notification popover by @blep (i had to hardcode the width idk why)
.conotifs-popover .inner-popover {
width: 1002px;
max-width: 1002px;
background: var(--color-dark1)
}
.conotifs-popover .inner-popover .inner-container {
max-width: 1000px;
}
.inner-grouped-shroud {
display: none;
}
.inner-loading {
background-color: var(--color-dark1)
}

i love the default colors so iโm not sure how much support/watch iโll be able to offer in the future, but I think the foundation ought to be decent for folks to build out more, and i am gonna use it to do a dark theme for myself (i use light mode on most other stuff so afaik i canโt easily flip a switch to make cohost use dark)