.base64-tool {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.input-group,
.output-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.input-group label,
.output-group label {
    font-weight: 600;
    color: #2d3748;
    font-size: 1rem;
}

.input-group textarea,
.output-group textarea {
    width: 100%;
    min-height: 6rem;
    padding: 0.714rem;
    border: 1px solid #cbd5e0;
    border-radius: 0.5rem;
    font-family: 'Segoe UI', 'Microsoft YaHei', monospace;
    font-size: 0.929rem;
    resize: vertical;
    transition: border-color 0.3s;
}

.input-group textarea:focus,
.output-group textarea:focus {
    outline: none;
    border-color: #3a8ffe;
    box-shadow: 0 0 0 2px rgba(58, 143, 254, 0.2);
}

.button-group {
    display: flex;
    gap: 0.714rem;
    flex-wrap: wrap;
}

.button-group button {
    padding: 0.5rem 1rem;
    background-color: #3a8ffe;
    color: white;
    border: none;
    border-radius: 0.5rem;
    cursor: pointer;
    font-size: 0.929rem;
    font-weight: 600;
    transition: background-color 0.3s, transform 0.2s;
    flex: 1;
    min-width: 8rem;
    text-align: center;
}

.button-group button:hover {
    background-color: #2a78e0;
    transform: translateY(-2px);
}

.button-group button:active {
    transform: translateY(0);
}

#clear-btn {
    background-color: #e2e8f0;
    color: #4a5568;
}

#clear-btn:hover {
    background-color: #cbd5e0;
}