Trilium/apps/client/src/widgets/NoteDetail.css

.component.note-detail {
    max-width: var(--max-content-width); /* Inherited from .note-split */
    font-family: var(--detail-font-family);
    font-size: var(--detail-font-size);
    contain: none;

    &.fixed-tree {
        display: flex;
        flex-direction: column;
        height: 100%;

        .fixed-note-tree-container {
            height: 60%;
            border-bottom: 1px solid var(--main-border-color);
            overflow: auto;

            .tree-wrapper {
                padding: 0;
            }

            .tree {
                padding: 0;
            }

            ul {
                margin: 0;
            }
        }
    }
}

body.prefers-centered-content .note-detail {
    /* Horizontally center the widget in its parent when the "Keep content centered" option is on */
    margin-inline: auto;
}

.note-detail > * {
    contain: none;
}