.bkbg-ue-app {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, sans-serif;
    box-sizing: border-box;
}

.bkbg-ue-app *,
.bkbg-ue-app *::before,
.bkbg-ue-app *::after {
    box-sizing: border-box;
}

/* Section */
.bkbg-ue-section {
    padding-top: 60px;
    padding-bottom: 60px;
}

/* Card */
.bkbg-ue-card {
    background: #fff;
    border-radius: 16px;
    padding: 32px;
    max-width: 680px;
    margin: 0 auto;
    box-shadow: 0 4px 24px rgba(0, 0, 0, 0.09);
}

/* Header */
.bkbg-ue-title {
    font-family: var(--bkue-tt-ff, inherit);
    font-size: var(--bkue-tt-fsd, 28px);
    line-height: var(--bkue-tt-lhd, 1.2);
    letter-spacing: var(--bkue-tt-lsd, normal);
    word-spacing: var(--bkue-tt-wsd, normal);
    font-weight: var(--bkue-tt-fw, 700);
    font-style: var(--bkue-tt-fst, normal);
    text-decoration: var(--bkue-tt-td, none);
    text-transform: var(--bkue-tt-tt, none);
    margin: 0 0 6px;
    color: #1e1b4b;
}

.bkbg-ue-subtitle {
    font-family: var(--bkue-st-ff, inherit);
    font-size: var(--bkue-st-fsd, 15px);
    line-height: var(--bkue-st-lhd, 1.5);
    letter-spacing: var(--bkue-st-lsd, normal);
    word-spacing: var(--bkue-st-wsd, normal);
    font-weight: var(--bkue-st-fw, normal);
    font-style: var(--bkue-st-fst, normal);
    text-decoration: var(--bkue-st-td, none);
    text-transform: var(--bkue-st-tt, none);
    color: #6b7280;
    margin: 0 0 22px;
}

/* Tab bar */
.bkbg-ue-tabs {
    display: flex;
    gap: 4px;
    background: #f3f4f6;
    border-radius: 8px;
    padding: 4px;
    margin-bottom: 18px;
}

.bkbg-ue-tab {
    flex: 1;
    padding: 8px;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 14px;
    font-family: inherit;
    font-weight: 500;
    color: #6b7280;
    background: transparent;
    transition: all 0.2s;
}

@media (max-width: 1024px) {
    .bkbg-ue-title {
        font-size: var(--bkue-tt-fst1, var(--bkue-tt-fsd, 28px));
        line-height: var(--bkue-tt-lht, var(--bkue-tt-lhd, 1.2));
        letter-spacing: var(--bkue-tt-lst, var(--bkue-tt-lsd, normal));
        word-spacing: var(--bkue-tt-wst, var(--bkue-tt-wsd, normal));
    }
    .bkbg-ue-subtitle {
        font-size: var(--bkue-st-fst1, var(--bkue-st-fsd, 15px));
        line-height: var(--bkue-st-lht, var(--bkue-st-lhd, 1.5));
        letter-spacing: var(--bkue-st-lst, var(--bkue-st-lsd, normal));
        word-spacing: var(--bkue-st-wst, var(--bkue-st-wsd, normal));
    }
}
@media (max-width: 767px) {
    .bkbg-ue-title {
        font-size: var(--bkue-tt-fsm, var(--bkue-tt-fst1, var(--bkue-tt-fsd, 28px)));
        line-height: var(--bkue-tt-lhm, var(--bkue-tt-lht, var(--bkue-tt-lhd, 1.2)));
        letter-spacing: var(--bkue-tt-lsm, var(--bkue-tt-lst, var(--bkue-tt-lsd, normal)));
        word-spacing: var(--bkue-tt-wsm, var(--bkue-tt-wst, var(--bkue-tt-wsd, normal)));
    }
    .bkbg-ue-subtitle {
        font-size: var(--bkue-st-fsm, var(--bkue-st-fst1, var(--bkue-st-fsd, 15px)));
        line-height: var(--bkue-st-lhm, var(--bkue-st-lht, var(--bkue-st-lhd, 1.5)));
        letter-spacing: var(--bkue-st-lsm, var(--bkue-st-lst, var(--bkue-st-lsd, normal)));
        word-spacing: var(--bkue-st-wsm, var(--bkue-st-wst, var(--bkue-st-wsd, normal)));
    }
}

.bkbg-ue-tab.active {
    background: #6c3fb5;
    color: #fff;
    font-weight: 700;
    box-shadow: 0 1px 6px rgba(108, 63, 181, 0.25);
}

/* Base64 sub-mode toggle */
.bkbg-ue-subtabs {
    display: flex;
    gap: 6px;
    margin-bottom: 14px;
}

.bkbg-ue-subtab {
    padding: 5px 14px;
    border-radius: 6px;
    border: 1.5px solid #d1d5db;
    background: #fff;
    color: #6b7280;
    font-size: 13px;
    font-family: inherit;
    cursor: pointer;
    transition: all 0.2s;
}

.bkbg-ue-subtab.active {
    border-color: #6c3fb5;
    background: rgba(108, 63, 181, 0.08);
    color: #6c3fb5;
    font-weight: 700;
}

/* Labels */
.bkbg-ue-label {
    display: block;
    font-size: 12px;
    font-weight: 600;
    color: #374151;
    margin-bottom: 5px;
    letter-spacing: 0.02em;
}

/* Textarea */
.bkbg-ue-textarea {
    width: 100%;
    padding: 10px 12px;
    border-radius: 10px;
    border: 1.5px solid #e5e7eb;
    background: #f9fafb;
    color: #1f2937;
    font-size: 14px;
    font-family: ui-monospace, 'Cascadia Code', 'Source Code Pro', Menlo, monospace;
    resize: vertical;
    outline: none;
    line-height: 1.6;
    transition: border-color 0.2s, box-shadow 0.2s;
}

.bkbg-ue-textarea:focus {
    border-color: #6c3fb5;
    box-shadow: 0 0 0 3px rgba(108, 63, 181, 0.12);
}

.bkbg-ue-textarea.output {
    background: #f3f4f6;
    border-color: #e5e7eb;
    cursor: text;
    user-select: all;
}

/* Char count */
.bkbg-ue-charcount {
    text-align: right;
    font-size: 12px;
    color: #9ca3af;
    margin-top: -8px;
    margin-bottom: 10px;
}

/* Error box */
.bkbg-ue-error {
    background: #fef2f2;
    border: 1px solid #ef4444;
    color: #ef4444;
    padding: 10px 14px;
    border-radius: 8px;
    font-size: 14px;
    margin-bottom: 12px;
    display: flex;
    gap: 8px;
    align-items: flex-start;
}

.bkbg-ue-error-icon {
    font-size: 16px;
    flex-shrink: 0;
    margin-top: 1px;
}

/* Input/output groups */
.bkbg-ue-group {
    margin-bottom: 16px;
}

/* Buttons row */
.bkbg-ue-actions {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
    margin-top: 6px;
}

.bkbg-ue-btn {
    padding: 8px 18px;
    background: #6c3fb5;
    color: #fff;
    border: none;
    border-radius: 10px;
    font-weight: 700;
    cursor: pointer;
    font-size: 13px;
    font-family: inherit;
    transition: background 0.2s, transform 0.1s;
}

.bkbg-ue-btn:hover {
    background: #5b35a0;
    transform: translateY(-1px);
}

.bkbg-ue-btn.secondary {
    background: #f3f4f6;
    color: #374151;
}

.bkbg-ue-btn.secondary:hover {
    background: #e5e7eb;
    transform: translateY(-1px);
}

.bkbg-ue-btn.copied {
    background: #10b981;
    color: #fff;
}

/* Toast */
.bkbg-ue-toast {
    position: fixed;
    bottom: 24px;
    left: 50%;
    transform: translateX(-50%) translateY(20px);
    background: #1f2937;
    color: #fff;
    padding: 10px 22px;
    border-radius: 8px;
    font-size: 14px;
    font-weight: 600;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.25s, transform 0.25s;
    z-index: 99999;
    white-space: nowrap;
}

.bkbg-ue-toast.show {
    opacity: 1;
    transform: translateX(-50%) translateY(0);
}

@media (max-width: 480px) {
    .bkbg-ue-card {
        padding: 20px 14px;
    }

    .bkbg-ue-tab {
        font-size: 12px;
        padding: 7px 4px;
    }
}