:root { color-scheme: dark; }
        html, body { max-width: 100%; overflow-x: clip; }
        main { min-width: 0; }
        main > * { min-width: 0; }
        @media (max-width: 1023px) { main.grid { grid-template-columns: minmax(0, 1fr); } }
        #catalog .font-semibold, #catalog .text-xs, #catalog .text-sm, #homeFeaturedList, .rich-html { overflow-wrap: anywhere; }
        img, iframe, video, canvas, svg, table, pre { max-width: 100%; }
        .overflow-wrap { overflow-wrap: anywhere; word-break: break-word; }
        select, option, datalist, input, textarea { color-scheme: dark; }
        select option, datalist option { background-color: #1e293b; color: #e2e8f0; }
        select option:checked, select option:hover { background-color: #4f46e5; color: #ffffff; }
        .rich-html { color: #e2e8f0; font-size: .9rem; line-height: 1.65; }
        .rich-html p { margin: 0 0 .6em; }
        .rich-html h1, .rich-html h2, .rich-html h3 { font-weight: 700; margin: .8em 0 .4em; color: #fff; }
        .rich-html h1 { font-size: 1.4em; } .rich-html h2 { font-size: 1.2em; } .rich-html h3 { font-size: 1.05em; }
        .rich-html ul, .rich-html ol { margin: 0 0 .6em 1.4em; }
        .rich-html ul { list-style: disc; } .rich-html ol { list-style: decimal; }
        .rich-html a { color: #93c5fd; text-decoration: underline; }
        .rich-html blockquote { border-left: 3px solid #64748b; padding-left: .8em; color: #cbd5e1; margin: 0 0 .6em; }
        .rich-html img { max-width: 100%; height: auto; border-radius: .5rem; }
        .rich-html table { border-collapse: collapse; width: 100%; margin: 0 0 .6em; }
        .rich-html td, .rich-html th { border: 1px solid #334155; padding: 4px 6px; }
        .rich-html pre { background: #1e293b; padding: .6em; border-radius: .4rem; overflow-x: auto; }
        .rich-html code { background: #1e293b; padding: 1px 4px; border-radius: 3px; }
        /* Dọn list nhập từ ngoài (Moodle/Udemy): <li><div>..</div></li>, tránh xuống dòng/bullet lỗi */
        .rich-html li { margin-bottom: .25em; }
        .rich-html li > div, .rich-html li > p { display: inline; margin: 0; }
        .rich-html ul ul, .rich-html ol ol, .rich-html ul ol, .rich-html ol ul { margin: .2em 0 .2em 1.2em; }