Module:Message box/mbox.css

.mbox {
    box-sizing: border-box;
    margin: 0.5em 0;
    border: 1px solid #a2a9b1;
    border-left: 4px solid #36c;
    background-color: #f8f9fa;
    color: #202122;
    display: flex;
    flex-direction: row;
    align-items: stretch;
    width: max-content;
    max-width: 100%;
}

.mbox-body {
    display: flex;
    flex-direction: row;
    align-items: stretch;
    width: 100%;
}

.mbox-text, .mbox-text {
    border: none;
    padding: 0.4em 0.9em;
    width: 100%;
    flex: 1 1 auto;
    font-size: 90%;
    line-height: 1.5;
}

.mbox-text > .mbox-text-span {
    display: inline;
}

.mbox-image {
    border: none;
    padding: 0.4em 0 0.4em 0.9em;
    text-align: center;
    flex: 0 0 auto;
}

.mbox-imageright {
    border: none;
    padding: 0.4em 0.9em 0.4em 0;
    text-align: center;
    flex: 0 0 auto;
}

.mbox-empty-cell {
    border: none;
    padding: 0;
    width: 1px;
}

.hide-when-compact {
    display: inline;
}

/* Type color accents */
.mbox-speedy  { border-left-color: #b32424; }
.mbox-delete  { border-left-color: #b32424; }
.mbox-content { border-left-color: #f28500; }
.mbox-style   { border-left-color: #fc3; }
.mbox-move    { border-left-color: #9932cc; }
.mbox-protection { border-left-color: #a2a9b1; }
.mbox-notice  { border-left-color: #36c; }
.mbox-license { border-left-color: #36c; }
.mbox-featured { border-left-color: #c8b100; }
.mbox-policy  { border-left-color: #00803b; }
.mbox-guideline { border-left-color: #00803b; }
.mbox-rule    { border-left-color: #f28500; }
.mbox-draft   { border-left-color: #a2a9b1; }
.mbox-setindex { border-left-color: #a2a9b1; }
.mbox-disambig { border-left-color: #a2a9b1; }

/* Small variant */
.mbox-small {
    font-size: 90%;
    width: 238px;
    max-width: 100%;
    margin: 0.25em 0;
}