#mode-selector {
    display: flex;
    gap: 0;
    justify-content: center;
    margin: 1rem 0;
}

.mode-btn {
    padding: 8px 24px;
    border: 2px solid #362A8D;
    background: white;
    color: #362A8D;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

.mode-btn:first-child {
    border-radius: 5px 0 0 5px;
}

.mode-btn:last-child {
    border-radius: 0 5px 5px 0;
}

.mode-btn.active {
    background: #362A8D;
    color: white;
}

#number-display {
    display: flex;
    justify-content: center;
    align-items: center;
    margin: 1.5rem 0;
    padding: 1.5rem 2rem;
    border: 2px solid #dee2e6;
    border-radius: 12px;
    background: white;
    min-height: 60px;
}

#display-number {
    font-family: 'Courier New', Courier, monospace;
    font-size: 2.5rem;
    font-weight: bold;
    letter-spacing: 2px;
    color: #333;
}

#display-number .sig-digit {
    color: #28a745;
    background: #e6f9e8;
    padding: 0 2px;
    border-radius: 3px;
}

#display-number .nonsig-digit {
    color: #999;
}

#answer-input {
    width: 120px;
    padding: 10px;
    font-size: 1.2rem;
    text-align: center;
    border: 2px solid #dee2e6;
    border-radius: 5px;
    font-family: 'Courier New', Courier, monospace;
}

#answer-input:focus {
    outline: none;
    border-color: #6153cc;
}