web/web_responsive/static/src/components/command_palette/main.scss

.o_command_palette {
    .o_command_palette_exit {
        display: none;
    }

    @include media-breakpoint-down(sm) {
        .o_command_palette_root {
            display: flex;
            max-height: 100vh;
            max-height: 100dvh;
            flex-direction: column;
            height: 100%;
            justify-content: space-between;
        }
        .o_command_palette_exit {
            display: block;
        }
        .o_command_palette_search {
            flex-shrink: 0;
        }
        .o_command_palette_listbox {
            max-height: unset;
        }
        .o_command_palette_footer {
            flex-shrink: 0;
        }
    }
}