Discord light theme with a dark theme server and channel list to get a classic light theme look

classic-light-theme.css

/* windows top bar background color is transparent and based on the whole app background color */
.appMount-3lHmkl, .typeWindows-1za-n7, .platform-win {
    --background-tertiary:#202225;
}

/* this contains everything below the windows top bar. set the background-tertiary back to the light theme color,
 * otherwise the search bar background and border around wells in the chat section will be dark which we don't want */
.container-2lgZY8 {
    --background-tertiary:#e3e5e8;
}

/* channel sidebar has a top left rounded corner where a white background peeks out so get rid of it */
.platform-win .sidebar-2K8pFh {
    border-top-left-radius: 0px;
}

/* css vars taken from dark theme and applied to server list, channel list, windows top bar */
.guilds-1SWlCJ, .sidebar-2K8pFh, .titleBar-AC4pGV {
    --activity-card-background:#202225;
    --background-accent:#4f545c;
    --background-floating:#18191c;
    --background-modifier-accent:hsla(0,0%,100%,0.06);
    --background-modifier-active:rgba(79,84,92,0.24);
    --background-modifier-hover:rgba(79,84,92,0.16);
    --background-modifier-selected:rgba(79,84,92,0.32);
    --background-primary:#36393f;
    --background-secondary:#2f3136;
    --background-tertiary:#202225;
    --channels-default:#8e9297;
    --channeltextarea-background:#40444b;
    --deprecated-card-bg:rgba(32,34,37,0.6);
    --deprecated-card-editable-bg:rgba(32,34,37,0.3);
    --deprecated-panel-background:#292b2f;
    --deprecated-quickswitcher-input-background:#72767d;
    --deprecated-quickswitcher-input-placeholder:hsla(0,0%,100%,0.3);
    --deprecated-store-bg:#36393f;
    --deprecated-text-input-bg:rgba(0,0,0,0.1);
    --deprecated-text-input-border:rgba(0,0,0,0.3);
    --deprecated-text-input-border-disabled:#202225;
    --deprecated-text-input-border-hover:#040405;
    --deprecated-text-input-prefix:#dcddde;
    --elevation-high:0 8px 16px rgba(0,0,0,0.24);
    --elevation-low:0 1px 0 rgba(4,4,5,0.2),0 1.5px 0 rgba(6,6,7,0.05),0 2px 0 rgba(4,4,5,0.05);
    --guild-header-text-shadow:0 1px 1px rgba(0,0,0,0.4);
    --header-primary:#fff;
    --header-secondary:#b9bbbe;
    --interactive-active:#fff;
    --interactive-hover:#dcddde;
    --interactive-muted:#4f545c;
    --interactive-normal:#b9bbbe;
    --logo-primary:#fff;
    --text-link:#00b0f4;
    --text-muted:#72767d;
    --text-normal:#dcddde;
}