uMatrix/src/css/user-rules.css

html {
    height: 100vh;
    overflow: hidden;
    }
#diff {
    border: 0;
    margin: 0;
    padding: 0;
    white-space: nowrap;
}
#diff .tools > * {
    margin-bottom: 0.5em;
    }
#diff .ruleActions {
    border: 0;
    box-sizing: border-box;
    display: inline-block;
    padding: 0;
    text-align: center;
    vertical-align: top;
    width: 50%;
    }
#diff .ruleActions > h3 {
    font-weight: normal;
    margin: 0 0 0.5em 0;
    }
#diff .ruleActions > div {
    display: flex;
    justify-content: center;
    }
#diff .ruleActions > div > button {
    margin-right: 1em;
    }
#ruleFilter {
    align-items: center;
    direction: ltr;
    display: flex;
    justify-content: center;
    }
#ruleFilter .fa-icon {
    color: #888;
    fill: #888;
    }

body[dir="ltr"] #revertButton > span:nth-of-type(2),
body[dir="rtl"] #commitButton > span:nth-of-type(1) {
    transform: scale(-1, 1);
    }
#revertButton,
#commitButton,
#editSaveButton,
#diff.editing #exportButton,
#diff.editing #importButton {
    opacity: 0.25;
    pointer-events: none;
    }
#diff.dirty:not(.editing) #revertButton,
#diff.dirty:not(.editing) #commitButton,
#diff.editing #editSaveButton {
    opacity: 1;
    pointer-events: auto;
    }

.codeMirrorContainer {
    box-sizing: border-box;
    padding: 0;
    }
.CodeMirror-merge, .CodeMirror-merge-pane, .CodeMirror-merge .CodeMirror {
    box-sizing: border-box;
    height: 100%;
    }
#diff.editing .CodeMirror-merge-copy,
#diff.editing .CodeMirror-merge-copy-reverse {
    display: none;
    }
#diff.editing .CodeMirror-merge-left .CodeMirror {
    color: #888;
    }
#diff.editing .CodeMirror-merge-editor .CodeMirror {
    background-color: #ffe;
    }
body[dir="rtl"] .CodeMirror-merge-pane-rightmost {
    right: unset;
    left: 0;
}