.tool-base64{max-width:720px;margin:0 auto;font-family:-apple-system,"Segoe UI",Roboto,"Microsoft JhengHei",sans-serif;}
.title-base64{font-size:1.5rem;margin:0 0 16px;}
.mode-bar-base64{display:flex;gap:8px;margin-bottom:16px;}
.mode-btn-base64{flex:0 0 auto;padding:8px 18px;border:1px solid #d0d0d0;background:#f7f7f7;border-radius:8px;cursor:pointer;font-size:.95rem;}
.mode-btn-base64.active{background:#2d6cdf;color:#fff;border-color:#2d6cdf;}
.lbl-base64{display:block;font-size:.85rem;color:#666;margin:10px 0 4px;}
.tool-base64 textarea{width:100%;box-sizing:border-box;padding:12px;border:1px solid #d0d0d0;border-radius:8px;font-family:ui-monospace,Menlo,Consolas,monospace;font-size:.95rem;resize:vertical;}
.tool-base64 textarea[readonly]{background:#fafafa;}
.btn-row-base64{display:flex;flex-wrap:wrap;gap:8px;margin:12px 0;}
.btn-row-base64 button{padding:9px 16px;border:none;border-radius:8px;background:#2d6cdf;color:#fff;cursor:pointer;font-size:.9rem;}
.btn-row-base64 button.secondary-base64{background:#eef0f3;color:#333;}
.btn-row-base64 button:hover{opacity:.9;}
.msg-base64{min-height:22px;font-size:.9rem;color:#c0392b;margin-top:6px;}
.msg-base64.ok{color:#27ae60;}