.sdk-wrapper {
    max-width: 480px;
    margin: 20px auto;
    padding: 20px;
    background: #111827;
    border-radius: 16px;
    color: #ffffff;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.45);
    user-select: none;
    -webkit-user-select: none;
}

.sdk-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 15px;
}

.sdk-header h2 {
    margin: 0;
    font-size: 26px;
    font-weight: 800;
    color: #ffffff;
}

.sdk-controls-top {
    display: flex;
    gap: 10px;
}

.sdk-select {
    background: #1f2937;
    color: #ffffff;
    border: 1px solid #374151;
    padding: 8px 12px;
    border-radius: 8px;
    font-weight: 600;
    font-size: 14px;
    outline: none;
    cursor: pointer;
}

.sdk-btn {
    padding: 8px 14px;
    border: none;
    border-radius: 8px;
    font-weight: 700;
    font-size: 13px;
    cursor: pointer;
    transition: all 0.2s ease;
}

.sdk-btn-primary {
    background: #2563eb;
    color: #ffffff;
}

.sdk-btn-primary:hover {
    background: #1d4ed8;
}

.sdk-stats-bar {
    display: flex;
    justify-content: space-between;
    background: #1f2937;
    padding: 10px 16px;
    border-radius: 10px;
    margin-bottom: 15px;
    font-size: 13px;
    font-weight: 700;
    color: #9ca3af;
}

.sdk-stat span {
    color: #ffffff;
    font-family: monospace;
    font-size: 15px;
}

.sdk-grid {
    display: grid;
    grid-template-columns: repeat(9, 1fr);
    grid-template-rows: repeat(9, 1fr);
    gap: 1px;
    background: #374151;
    border: 3px solid #4b5563;
    border-radius: 8px;
    overflow: hidden;
    width: 100%;
    aspect-ratio: 1;
    margin-bottom: 20px;
}

.sdk-cell {
    background: #1f2937;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 18px;
    font-weight: 700;
    color: #e5e7eb;
    cursor: pointer;
    user-select: none;
}

.sdk-cell.given {
    background: #111827;
    color: #ffffff;
    font-weight: 800;
}

.sdk-cell.selected {
    background: #1d4ed8 !important;
    color: #ffffff !important;
}

.sdk-cell.highlighted {
    background: #374151;
}

.sdk-cell.same-num {
    background: #1e3a8a;
}

.sdk-cell.user-entered {
    color: #60a5fa;
}

.sdk-cell.error {
    background: #991b1b !important;
    color: #ffffff !important;
}

.sdk-numpad {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 8px;
    margin-bottom: 10px;
}

.sdk-num-btn {
    background: #1f2937;
    border: 1px solid #374151;
    color: #ffffff;
    padding: 12px 0;
    border-radius: 8px;
    font-size: 18px;
    font-weight: 800;
    cursor: pointer;
    transition: all 0.15s ease;
}

.sdk-num-btn:hover {
    background: #374151;
    border-color: #6b7280;
}

.sdk-erase-btn {
    grid-column: span 2;
    font-size: 13px;
    background: #374151;
}

.sdk-message {
    text-align: center;
    font-size: 16px;
    font-weight: 800;
    color: #34d399;
    min-height: 24px;
}