.bkbg-btc-app {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    -webkit-font-smoothing: antialiased;
}

/* Card */
.bkbg-btc-card {
    margin: 0 auto;
    padding: 40px;
    box-shadow: 0 4px 32px rgba(0,0,0,0.10);
}

/* Title / subtitle */
.bkbg-btc-title {
    text-align: center;
    font-family: var(--bkbg-btc-title-font-family, inherit);
    font-size: var(--bkbg-btc-title-font-size-d, 28px);
    font-weight: var(--bkbg-btc-title-font-weight, 800);
    font-style: var(--bkbg-btc-title-font-style, normal);
    text-transform: var(--bkbg-btc-title-text-transform, none);
    text-decoration: var(--bkbg-btc-title-text-decoration, none);
    line-height: var(--bkbg-btc-title-line-height-d, 1.2);
    letter-spacing: var(--bkbg-btc-title-letter-spacing-d, normal);
    word-spacing: var(--bkbg-btc-title-word-spacing-d, normal);
    margin-bottom: 6px;
}
.bkbg-btc-subtitle {
    text-align: center;
    font-family: var(--bkbg-btc-sub-font-family, inherit);
    font-size: var(--bkbg-btc-sub-font-size-d, 15px);
    font-weight: var(--bkbg-btc-sub-font-weight, normal);
    font-style: var(--bkbg-btc-sub-font-style, normal);
    text-transform: var(--bkbg-btc-sub-text-transform, none);
    text-decoration: var(--bkbg-btc-sub-text-decoration, none);
    line-height: var(--bkbg-btc-sub-line-height-d, 1.5);
    letter-spacing: var(--bkbg-btc-sub-letter-spacing-d, normal);
    word-spacing: var(--bkbg-btc-sub-word-spacing-d, normal);
    color: #6b7280;
    margin-bottom: 28px;
}

/* Tabs */
.bkbg-btc-tabs {
    display: flex;
    gap: 8px;
    margin-bottom: 24px;
}
.bkbg-btc-tab {
    flex: 1;
    padding: 10px;
    font-size: 14px;
    font-weight: 700;
    border: 2px solid #d1d5db;
    border-radius: 8px;
    background: transparent;
    cursor: pointer;
    transition: background 0.18s, color 0.18s, border-color 0.18s;
}

/* Mode toggle */
.bkbg-btc-mode-row {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-bottom: 20px;
    flex-wrap: wrap;
}
.bkbg-btc-mode-label {
    font-size: 13px;
    font-weight: 600;
    color: #6b7280;
    margin-right: 4px;
}
.bkbg-btc-mode-btn {
    padding: 6px 16px;
    font-size: 13px;
    font-weight: 600;
    border-radius: 99px;
    border: 2px solid #d1d5db;
    background: transparent;
    color: #6b7280;
    cursor: pointer;
    transition: all 0.18s;
}

/* Label */
.bkbg-btc-lbl {
    display: block;
    font-size: 12px;
    font-weight: 600;
    margin-bottom: 6px;
    letter-spacing: 0.04em;
    text-transform: uppercase;
}

/* Input textarea */
.bkbg-btc-textarea {
    width: 100%;
    min-height: 90px;
    padding: 12px 14px;
    border: 1.5px solid #d1d5db;
    border-radius: 8px;
    font-size: 14px;
    font-family: 'Courier New', Courier, monospace;
    background: #f9fafb;
    color: #111827;
    resize: vertical;
    box-sizing: border-box;
    outline: none;
    transition: border-color 0.15s;
    margin-bottom: 0;
}
.bkbg-btc-textarea:focus { border-color: #6b7280; }

/* Convert button */
.bkbg-btc-convert-btn {
    width: 100%;
    margin: 14px 0;
    padding: 12px;
    font-size: 15px;
    font-weight: 700;
    color: #fff;
    border: none;
    border-radius: 10px;
    cursor: pointer;
    transition: opacity 0.2s, transform 0.1s;
}
.bkbg-btc-convert-btn:hover { opacity: 0.88; transform: translateY(-1px); }
.bkbg-btc-convert-btn:active { transform: translateY(0); }

/* Output */
.bkbg-btc-output {
    border-radius: 8px;
    padding: 14px;
    font-family: 'Courier New', Courier, monospace;
    font-size: 13px;
    min-height: 80px;
    word-break: break-all;
    white-space: pre-wrap;
    line-height: 1.6;
    margin-bottom: 10px;
}
.bkbg-btc-output-empty { color: #9ca3af; font-style: italic; }
.bkbg-btc-error { color: #ef4444; font-size: 13px; font-family: sans-serif; }

/* Copy button */
.bkbg-btc-copy-btn {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 7px 16px;
    font-size: 13px;
    font-weight: 600;
    border: 1.5px solid #d1d5db;
    border-radius: 8px;
    background: #fff;
    color: #374151;
    cursor: pointer;
    transition: all 0.18s;
}
.bkbg-btc-copy-btn:hover { background: #f3f4f6; }

/* Stats row */
.bkbg-btc-stats {
    display: flex;
    gap: 16px;
    margin-top: 10px;
    font-size: 12px;
    color: #9ca3af;
    flex-wrap: wrap;
}
.bkbg-btc-stat { font-weight: 600; }

/* Divider */
.bkbg-btc-divider {
    border: none;
    border-top: 1.5px solid #e5e7eb;
    margin: 28px 0;
}

/* ASCII table */
.bkbg-btc-ascii-title {
    font-size: 16px;
    font-weight: 700;
    margin-bottom: 14px;
}
.bkbg-btc-ascii-filters {
    display: flex;
    gap: 8px;
    margin-bottom: 14px;
    flex-wrap: wrap;
}
.bkbg-btc-ascii-filter-btn {
    padding: 5px 14px;
    font-size: 12px;
    font-weight: 700;
    border-radius: 99px;
    border: 1.5px solid #d1d5db;
    background: transparent;
    color: #6b7280;
    cursor: pointer;
    transition: all 0.18s;
}
.bkbg-btc-ascii-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 12px;
    font-family: 'Courier New', Courier, monospace;
}
.bkbg-btc-ascii-table th {
    background: #f3f4f6;
    padding: 6px 8px;
    text-align: center;
    font-weight: 700;
    border: 1px solid #e5e7eb;
    color: #6b7280;
}
.bkbg-btc-ascii-table td {
    padding: 5px 8px;
    text-align: center;
    border: 1px solid #e5e7eb;
    color: #374151;
    cursor: pointer;
    transition: background 0.1s;
}
.bkbg-btc-ascii-table td:hover { background: #ede9fe55; }
.bkbg-btc-ascii-char { font-weight: 700; font-size: 14px; color: #111827; }
.bkbg-btc-ascii-dim { color: #9ca3af; }

@media (max-width: 1024px) {
    .bkbg-btc-title {
        font-size: var(--bkbg-btc-title-font-size-t, var(--bkbg-btc-title-font-size-d, 28px));
        line-height: var(--bkbg-btc-title-line-height-t, var(--bkbg-btc-title-line-height-d, 1.2));
        letter-spacing: var(--bkbg-btc-title-letter-spacing-t, var(--bkbg-btc-title-letter-spacing-d, normal));
        word-spacing: var(--bkbg-btc-title-word-spacing-t, var(--bkbg-btc-title-word-spacing-d, normal));
    }
    .bkbg-btc-subtitle {
        font-size: var(--bkbg-btc-sub-font-size-t, var(--bkbg-btc-sub-font-size-d, 15px));
        line-height: var(--bkbg-btc-sub-line-height-t, var(--bkbg-btc-sub-line-height-d, 1.5));
        letter-spacing: var(--bkbg-btc-sub-letter-spacing-t, var(--bkbg-btc-sub-letter-spacing-d, normal));
        word-spacing: var(--bkbg-btc-sub-word-spacing-t, var(--bkbg-btc-sub-word-spacing-d, normal));
    }
}

@media (max-width: 767px) {
    .bkbg-btc-title {
        font-size: var(--bkbg-btc-title-font-size-m, var(--bkbg-btc-title-font-size-t, var(--bkbg-btc-title-font-size-d, 28px)));
        line-height: var(--bkbg-btc-title-line-height-m, var(--bkbg-btc-title-line-height-t, var(--bkbg-btc-title-line-height-d, 1.2)));
        letter-spacing: var(--bkbg-btc-title-letter-spacing-m, var(--bkbg-btc-title-letter-spacing-t, var(--bkbg-btc-title-letter-spacing-d, normal)));
        word-spacing: var(--bkbg-btc-title-word-spacing-m, var(--bkbg-btc-title-word-spacing-t, var(--bkbg-btc-title-word-spacing-d, normal)));
    }
    .bkbg-btc-subtitle {
        font-size: var(--bkbg-btc-sub-font-size-m, var(--bkbg-btc-sub-font-size-t, var(--bkbg-btc-sub-font-size-d, 15px)));
        line-height: var(--bkbg-btc-sub-line-height-m, var(--bkbg-btc-sub-line-height-t, var(--bkbg-btc-sub-line-height-d, 1.5)));
        letter-spacing: var(--bkbg-btc-sub-letter-spacing-m, var(--bkbg-btc-sub-letter-spacing-t, var(--bkbg-btc-sub-letter-spacing-d, normal)));
        word-spacing: var(--bkbg-btc-sub-word-spacing-m, var(--bkbg-btc-sub-word-spacing-t, var(--bkbg-btc-sub-word-spacing-d, normal)));
    }
}

@media (max-width: 500px) {
    .bkbg-btc-card { padding: 24px 16px; }
    .bkbg-btc-tabs { flex-wrap: wrap; }
    .bkbg-btc-ascii-table th,
    .bkbg-btc-ascii-table td { padding: 4px 4px; }
}