u1-code {
    font-family: Consolas, "Courier New", Courier, monospace;
    display:block;
    overflow:auto;
}
u1-code > :where(script, style) {
    display:block;
}

/* new */
u1-code:not(:has(>*)) {
    white-space: pre;
}
u1-code > :is(pre, code, style, script, textarea),
u1-code > pre > code {
    padding:0;
    margin:0;
    font: inherit;
    display:block;
    background:transparent;
}
u1-code > :where(textarea) {
    width:100%;
    border:0;
    height:10rem;

    @supports (field-sizing:content) {
        field-sizing:content;
        height:auto;
        resize: none;
    }

    /* does not work
    min-height: -webkit-fill-available;
    min-height: stretch;
    */
}

u1-code:not(:defined) > [slot="tools"]{
    display:none;
}