diff --git a/addons/im_livechat/static/src/legacy/public_livechat.scss b/addons/im_livechat/static/src/legacy/public_livechat.scss
index 1b826d272f9..d09343dcda5 100644
--- a/addons/im_livechat/static/src/legacy/public_livechat.scss
+++ b/addons/im_livechat/static/src/legacy/public_livechat.scss
@@ -426,25 +426,6 @@ $o-mail-thread-window-zindex: $zindex-modal + 1 !default;
             }
         }
     }
-    .o_thread_title {
-        margin-top: 20px;
-        margin-bottom: 20px;
-        font-weight: bold;
-        font-size: 125%;
-
-        &.o_neutral_face_icon:before {
-            @extend %o-nocontent-init-image;
-            width: 120px;
-            height: 140px;
-            background: transparent url(/web/static/img/neutral_face.svg) no-repeat center;
-        }
-    }
-
-    .o_mail_no_content {
-        @include o-position-absolute(30%, 0, 0, 0);
-        text-align: center;
-        font-size: 115%;
-    }
 
     .o_thread_message .o_thread_message_core .o_mail_read_more {
         display: block;
diff --git a/addons/mail/static/src/scss/mail_activity.scss b/addons/mail/static/src/scss/mail_activity.scss
index c2dc1a62c5d..6bede520855 100644
--- a/addons/mail/static/src/scss/mail_activity.scss
+++ b/addons/mail/static/src/scss/mail_activity.scss
@@ -4,127 +4,6 @@
         display: block;
     }
 
-    .o_thread_date_separator.o_border_dashed {
-        border-bottom-style: dashed;
-
-        &[data-bs-toggle="collapse"] {
-            cursor: pointer;
-
-            .o_chatter_planned_activities_summary {
-                display: none;
-            }
-
-            &.collapsed {
-                margin-bottom: 0;
-                transition: margin 0.8s ease 0s;
-
-                .o_chatter_planned_activities_summary {
-                    display: inline-block;
-
-                    span {
-                        padding: 0 5px;
-                        border-radius: 100%;
-                        font-size: 11px;
-                    }
-                }
-
-                i.fa-caret-down:before {
-                    content: '\f0da';
-                }
-            }
-        }
-    }
-
-    #o_chatter_planned_activities {
-        .o_thread_message {
-            .o_thread_message_sidebar {
-                .o_avatar_stack {
-                    position: relative;
-                    text-align: left;
-                    margin-bottom: 8px;
-
-                    img {
-                        width: 31px;
-                        height: 31px;
-                        object-fit: cover;
-                    }
-
-                    .o_avatar_icon {
-                        @include o-position-absolute($right: -5px, $bottom: -5px);
-                        width: 25px;
-                        height: 25px;
-                        object-fit: cover;
-                        padding: 6px 5px;
-                        text-align: center;
-                        line-height: 1.2;
-                        color: white;
-                        border-radius: 100%;
-                        border: 2px solid white;
-                    }
-                }
-            }
-
-            .o_mail_info {
-                .o_activity_summary {
-                    @include o-text-overflow;
-                    max-width: 290px;
-                    vertical-align: middle;
-                }
-                .o_activity_info {
-                    vertical-align: baseline;
-                    padding: 4px 6px;
-                    background: map-get($theme-colors, 'light');
-                    border-radius: 2px 2px 0 0;
-                    @include o-hover-opacity(1, 1);
-
-                    &.collapsed {
-                        @include o-hover-opacity(0.5, 1);
-                        background: transparent;
-                    }
-                }
-            }
-
-            .o_thread_message_collapse .dl-horizontal.card {
-                display: inline-block;
-                margin-bottom: 0;
-
-                dt {
-                    max-width: 80px;
-                }
-                dd {
-                    margin-left: 95px;
-                }
-            }
-
-            .o_thread_message_note {
-                margin: 2px 0 5px;
-                padding: 0px;
-            }
-            .o_thread_message_warning {
-                margin: 2px 0 5px;
-            }
-
-            .o_activity_template_preview,.o_activity_template_send {
-                font-weight: bold;
-                color: $o-brand-primary;
-                cursor: pointer;
-                &:hover:not(.active) {
-                    color: darken($o-brand-primary, 15%);
-                    border-color: darken($o-brand-primary, 15%);
-                }
-            }
-
-            .o_thread_message_tools {
-                .o_activity_link {
-                    padding: 0 $input-btn-padding-x;
-                }
-                .o_activity_done {
-                    padding-left: 0;
-                }
-            }
-        }
-    }
-
     .o_activity_color_default {
         color: #dddddd;
     }
diff --git a/addons/mail/static/src/scss/thread.scss b/addons/mail/static/src/scss/thread.scss
deleted file mode 100644
index 4c2b3b071e4..00000000000
--- a/addons/mail/static/src/scss/thread.scss
+++ /dev/null
@@ -1,165 +0,0 @@
-.o_mail_activity {
-
-    .o_thread_date_separator {
-        margin-top: 15px;
-        margin-bottom: 30px;
-        @include media-breakpoint-down(md) {
-            margin-top: 0px;
-            margin-bottom: 15px;
-        }
-        border-bottom: 1px solid map-get($grays, '400');
-        text-align: center;
-
-        .o_thread_date {
-            position: relative;
-            top: 10px;
-            margin: 0 auto;
-            padding: 0 10px;
-            font-weight: bold;
-            background: white;
-        }
-    }
-
-    .o_thread_message {
-        display: flex;
-        padding: 4px $o-horizontal-padding;
-        margin-bottom: 0px;
-
-        .o_thread_message_sidebar {
-            flex: 0 0 $o-mail-thread-avatar-size;
-            margin-right: 10px;
-            margin-top: 2px;
-            text-align: center;
-            font-size: smaller;
-            .o_thread_message_sidebar_image {
-                position: relative;
-                height: $o-mail-thread-avatar-size;
-
-                .o_updatable_im_status {
-                    width: $o-mail-thread-avatar-size;
-                }
-            }
-
-            @include media-breakpoint-down(md) {
-                margin-top: 4px;
-                font-size: x-small;
-            }
-
-            .o_thread_message_avatar {
-                width: $o-mail-thread-avatar-size;
-                height: $o-mail-thread-avatar-size;
-                object-fit: cover;
-            }
-        }
-        .o_thread_icon {
-            cursor: pointer;
-            opacity: 0;
-        }
-
-        &:hover {
-            .o_thread_icon {
-                display: inline-block;
-                opacity: $o-mail-thread-icon-opacity;
-                &:hover {
-                    opacity: 1;
-                }
-            }
-        }
-
-        .o_mail_redirect {
-            cursor: pointer;
-        }
-
-        .o_thread_message_core {
-            flex: 1 1 auto;
-            min-width: 0;
-            max-width: 100%;
-            word-wrap: break-word;
-            .o_thread_message_content > pre {
-                white-space: pre-wrap;
-                word-break: break-word;
-            }
-
-            .o_mail_note_title {
-                margin-top: 9px;
-            }
-
-            .o_mail_subject {
-                font-style: italic;
-            }
-
-            .o_mail_notification {
-                font-style: italic;
-                color: gray;
-            }
-
-            [summary~=o_mail_notification] { // name conflicts with channel notifications, but is odoo notification buttons to hide in chatter if present
-                display: none;
-            }
-
-            p {
-                margin: 0 0 9px; // Required by the old design to override a general rule on p's
-                &:last-child {
-                    margin-bottom: 0;
-                }
-            }
-            a {
-                display: inline-block;
-                word-break: break-all;
-            }
-            :not(.o_image_box) > img {
-                max-width: 100%;
-                height: auto;
-            }
-
-            .o_mail_body_long {
-                display: none;
-            }
-
-            .o_mail_info {
-                margin-bottom: 2px;
-
-                strong {
-                    color: $headings-color;
-                }
-            }
-
-            .o_thread_message_needaction, .o_thread_message_reply {
-                padding: 4px;
-            }
-        }
-    }
-    .o_thread_title {
-        margin-top: 20px;
-        margin-bottom: 20px;
-        font-weight: bold;
-        font-size: 125%;
-
-        &.o_neutral_face_icon:before {
-            @extend %o-nocontent-init-image;
-            width: 120px;
-            height: 140px;
-            background: transparent url(/web/static/img/neutral_face.svg) no-repeat center;
-        }
-    }
-
-    .o_mail_no_content {
-        @include o-position-absolute(30%, 0, 0, 0);
-        text-align: center;
-        font-size: 115%;
-    }
-
-    .o_thread_message .o_thread_message_core .o_mail_read_more {
-        display: block;
-    }
-}
-
-.o_web_client .popover .o_thread_tooltip_icon {
-    min-width: 1rem;
-}
-
-.o_web_client.o_touch_device {
-    .o_mail_thread .o_thread_icon {
-        opacity: $o-mail-thread-icon-opacity;
-    }
-}