.rebar-calculator {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    max-width: 1000px;
    margin: 0 auto;
    padding: 20px;
    background: #f8f9fa;
    border-radius: 10px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

.rebar-calculator h2 {
    color: #2c3e50;
    text-align: center;
    margin-bottom: 25px;
    font-weight: 600;
}

.rc-tabs {
    display: flex;
    border-bottom: 2px solid #ddd;
    margin-bottom: 20px;
}

.rc-tab {
    padding: 12px 20px;
    cursor: pointer;
    background: #e9ecef;
    border: none;
    border-radius: 5px 5px 0 0;
    margin-right: 5px;
    font-weight: 500;
    transition: all 0.3s ease;
}

.rc-tab.active {
    background: #3498db;
    color: white;
}

.rc-tab:hover:not(.active) {
    background: #dee2e6;
}

.rc-tab-content {
    display: none;
    padding: 20px;
    background: white;
    border-radius: 0 0 5px 5px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}

.rc-tab-content.active {
    display: block;
}

.rc-form-group {
    margin-bottom: 15px;
}

.rc-form-group label {
    display: block;
    margin-bottom: 5px;
    font-weight: 500;
    color: #495057;
}

.rc-form-group input,
.rc-form-group select {
    width: 100%;
    padding: 10px;
    border: 1px solid #ced4da;
    border-radius: 4px;
    font-size: 16px;
    transition: border-color 0.15s ease-in-out, box-shadow 0.15s ease-in-out;
}

.rc-form-group input:focus,
.rc-form-group select:focus {
    border-color: #3498db;
    outline: 0;
    box-shadow: 0 0 0 0.2rem rgba(52, 152, 219, 0.25);
}

.rc-calculate-btn {
    background: #2ecc71;
    color: white;
    border: none;
    padding: 12px 20px;
    border-radius: 4px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    width: 100%;
    transition: background 0.3s ease;
}

.rc-calculate-btn:hover {
    background: #27ae60;
}

.rc-results {
    margin-top: 25px;
    padding: 20px;
    background: #e8f4fc;
    border-radius: 5px;
    border-left: 4px solid #3498db;
    display: none;
}

.rc-results h3 {
    margin-top: 0;
    color: #2c3e50;
}

.rc-result-item {
    display: flex;
    justify-content: space-between;
    padding: 8px 0;
    border-bottom: 1px solid #d6e9f7;
}

.rc-result-item:last-child {
    border-bottom: none;
}

.rc-result-label {
    font-weight: 500;
    color: #495057;
}

.rc-result-value {
    font-weight: 600;
    color: #2c3e50;
}

.rc-error {
    color: #e74c3c;
    padding: 10px;
    background: #fde8e8;
    border-radius: 4px;
    margin-top: 15px;
    display: none;
}

.rc-advanced-toggle {
    background: none;
    border: none;
    color: #3498db;
    cursor: pointer;
    font-size: 14px;
    margin-bottom: 15px;
    padding: 0;
    text-decoration: underline;
}

.rc-advanced-settings {
    display: none;
    margin-top: 15px;
    padding: 15px;
    background: #f1f8ff;
    border-radius: 4px;
    border-left: 3px solid #3498db;
}

.rc-loading {
    display: none;
    text-align: center;
    padding: 20px;
}

.rc-loading-spinner {
    border: 4px solid #f3f3f3;
    border-top: 4px solid #3498db;
    border-radius: 50%;
    width: 30px;
    height: 30px;
    animation: spin 1s linear infinite;
    margin: 0 auto;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

.rc-visualization {
    margin-top: 25px;
    padding: 15px;
    background: white;
    border-radius: 5px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.05);
}

.rc-visualization canvas {
    max-width: 100%;
    border: 1px solid #ddd;
}

@media (max-width: 768px) {
    .rebar-calculator {
        padding: 15px;
    }
    
    .rc-tabs {
        flex-wrap: wrap;
    }
    
    .rc-tab {
        margin-bottom: 5px;
    }
}