.furnace-filter-calculator {
    max-width: 600px;
    margin: 2rem auto;
    padding: 2rem;
    background: #fff;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}

.ffc-title {
    color: #2c3e50;
    margin-bottom: 1.5rem;
    font-size: 1.5rem;
    text-align: center;
}

.ffc-form {
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
}

.ffc-field {
    display: flex;
    flex-direction: column;
}

.ffc-field label {
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: #34495e;
    font-size: 0.95rem;
}

.ffc-field select {
    padding: 0.75rem;
    border: 2px solid #ddd;
    border-radius: 4px;
    font-size: 1rem;
    transition: border-color 0.3s;
    background-color: #fff;
}

.ffc-field select:focus {
    outline: none;
    border-color: #e74c3c;
}

.ffc-checkboxes {
    background: #f8f9fa;
    padding: 1rem;
    border-radius: 6px;
    border: 2px solid #e9ecef;
}

.ffc-checkbox-group-label {
    display: block;
    margin-bottom: 0.75rem;
    font-weight: 600;
    color: #34495e;
    font-size: 0.95rem;
}

.ffc-checkbox-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.ffc-checkbox-label {
    display: flex;
    align-items: center;
    font-weight: 400;
    color: #555;
    cursor: pointer;
    padding: 0.25rem 0;
}

.ffc-checkbox-label input[type="checkbox"] {
    margin-right: 0.5rem;
    width: 18px;
    height: 18px;
    cursor: pointer;
}

.ffc-checkbox-label span {
    user-select: none;
}

.ffc-button {
    background: #e74c3c;
    color: white;
    padding: 1rem 2rem;
    border: none;
    border-radius: 4px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    margin-top: 1rem;
    transition: background 0.3s;
}

.ffc-button:hover {
    background: #c0392b;
}

.ffc-results {
    margin-top: 2rem;
    padding: 1.5rem;
    background: #ecf0f1;
    border-radius: 6px;
    border-left: 4px solid #e74c3c;
}

.ffc-results h3 {
    color: #2c3e50;
    margin-bottom: 1rem;
    font-size: 1.25rem;
}

.ffc-interval {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: #2c3e50;
}

.ffc-interval span {
    color: #e74c3c;
    font-weight: bold;
}

.ffc-guidance {
    margin: 1rem 0;
    padding: 1rem;
    background: white;
    border-radius: 4px;
}

.ffc-tips {
    margin-top: 1.5rem;
}

.ffc-tips h4 {
    color: #34495e;
    margin-bottom: 0.75rem;
}

.ffc-tips ul {
    margin: 0;
    padding-left: 1.5rem;
}

.ffc-tips li {
    margin-bottom: 0.5rem;
    color: #555;
}

@media (max-width: 640px) {
    .furnace-filter-calculator {
        padding: 1.5rem 1rem;
    }
    
    .ffc-title {
        font-size: 1.25rem;
    }
}