    <style>
        *{box-sizing:border-box;margin:0;padding:0;}
        body{
            padding:16px;
            background:#1e2227;
            color:#eee;
            font-family:system-ui, sans-serif;
        }
        .wrap{
            max-width:1240px;
            margin:0 auto;
            width:100%;
        }
        .row{
            display:grid;
            grid-template-columns:1fr 1fr;
            gap:12px;
            margin:12px 0;
        }
        textarea{
            width:100%;
            min-height:220px;
            background:#2b3038;
            color:#fff;
            border:1px solid #444b56;
            padding:10px;
            font-family:monospace;
            font-size:13px;
            resize:vertical;
        }
        .ctrl-bar{
            display:flex;
            flex-wrap:wrap;
            gap:8px;
            margin:10px 0;
            align-items:center;
        }
        select,input{
            padding:6px 10px;
            font-size:14px;
        }
        button{
            padding:6px 10px;
            font-size:14px;
            border:none;
            color:#fff;
            border-radius:4px;
            cursor:pointer;
        }
        #btnRandKey{
            background:#2563eb;
        }
        #btnRandKey:hover{
            background:#1d4ed8;
        }
        #btnEnc{
            background:#16a34a;
        }
        #btnEnc:hover{
            background:#15803d;
        }
        #btnDec{
            background:#f97316;
        }
        #btnDec:hover{
            background:#ea580c;
        }
        #btnGenEmbed{
            background:#9333ea;
        }
        #btnGenEmbed:hover{
            background:#7e22ce;
        }
        #btnCopyEmbed{
            background:#b91c1c;
        }
        #btnCopyEmbed:hover{
            background:#991b1b;
        }
        #btnPreview{
            background:#0891b2;
        }
        #btnPreview:hover{
            background:#0e7490;
        }
        #btnClear{
            background:#dc2626;
        }
        #btnClear:hover{
            background:#b91c1c;
        }
        .key-row{
            display:flex;
            gap:8px;
            align-items:center;
            margin:8px 0;
        }
        .key-row input{
            flex:1;
        }
        .iv-wrap{
            display:none;
        }
        .info{
            color:#bbb;
            font-size:12px;
            margin:6px 0;
        }
        .preview-title{
            margin:8px 0 4px;
        }
        #previewIframe{
            width:100%;
            min-height:240px;
            border:1px solid #444b56;
            background:#fff;
        }
        @media(max-width:720px){
            .row{
                grid-template-columns:1fr;
                width:100%;
            }
        }
    </style>