* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    padding: 20px;
}

.container {
    max-width: 1400px;
    margin: 0 auto;
    background: white;
    border-radius: 15px;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.2);
    overflow: hidden;
}

header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 30px;
    text-align: center;
}

header h1 {
    font-size: 2.5em;
    margin-bottom: 10px;
}

.subtitle {
    font-size: 1.1em;
    opacity: 0.9;
}

.main-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 30px;
    padding: 30px;
}

@media (max-width: 1024px) {
    .main-content {
        grid-template-columns: 1fr;
    }
}

.input-section, .output-section {
    background: #f8f9fa;
    padding: 25px;
    border-radius: 10px;
}

h2 {
    color: #667eea;
    margin-bottom: 20px;
    font-size: 1.8em;
    border-bottom: 3px solid #667eea;
    padding-bottom: 10px;
}

h3 {
    color: #764ba2;
    margin-bottom: 15px;
    font-size: 1.3em;
}

.input-group {
    margin-bottom: 25px;
    background: white;
    padding: 20px;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}

.form-row {
    margin-bottom: 15px;
}

label {
    display: block;
    margin-bottom: 5px;
    color: #333;
    font-weight: 500;
}

input[type="number"], select {
    width: 100%;
    padding: 10px;
    border: 2px solid #ddd;
    border-radius: 5px;
    font-size: 1em;
    transition: border-color 0.3s;
}

input[type="number"]:focus, select:focus {
    outline: none;
    border-color: #667eea;
}

.button-group {
    display: flex;
    gap: 15px;
    margin-top: 25px;
}

.btn-primary, .btn-secondary {
    flex: 1;
    padding: 15px;
    font-size: 1.1em;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-weight: 600;
    transition: all 0.3s;
}

.btn-primary {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(102, 126, 234, 0.4);
}

.btn-secondary {
    background: #6c757d;
    color: white;
}

.btn-secondary:hover {
    background: #5a6268;
    transform: translateY(-2px);
}

.results-container {
    background: white;
    padding: 20px;
    border-radius: 8px;
    min-height: 400px;
}

.placeholder {
    text-align: center;
    color: #999;
    padding: 50px 20px;
    font-size: 1.1em;
}

.result-section {
    margin-bottom: 25px;
    padding: 20px;
    background: #f8f9fa;
    border-radius: 8px;
    border-left: 4px solid #667eea;
}

.result-section h3 {
    margin-bottom: 15px;
    color: #667eea;
}

.result-item {
    margin-bottom: 10px;
    padding: 8px;
    background: white;
    border-radius: 5px;
}

.result-item strong {
    color: #333;
}

.design-type {
    display: inline-block;
    padding: 8px 16px;
    background: #667eea;
    color: white;
    border-radius: 20px;
    font-weight: 600;
    margin-bottom: 15px;
}

.warning {
    background: #fff3cd;
    border-left: 4px solid #ffc107;
    padding: 15px;
    margin-top: 15px;
    border-radius: 5px;
}

.success {
    background: #d4edda;
    border-left: 4px solid #28a745;
    padding: 15px;
    margin-top: 15px;
    border-radius: 5px;
}

.info {
    background: #d1ecf1;
    border-left: 4px solid #17a2b8;
    padding: 15px;
    margin-top: 15px;
    border-radius: 5px;
}

.steel-details {
    background: #e7f3ff;
    padding: 15px;
    border-radius: 5px;
    margin-top: 10px;
}

.steel-details h4 {
    color: #0056b3;
    margin-bottom: 10px;
}

.bar-options {
    margin-left: 20px;
}

.bar-option {
    padding: 8px;
    margin: 5px 0;
    background: white;
    border-radius: 5px;
}

footer {
    background: #2c3e50;
    color: white;
    text-align: center;
    padding: 20px;
    font-size: 0.9em;
}

.formula {
    background: #f8f9fa;
    padding: 10px;
    border-radius: 5px;
    font-family: 'Courier New', monospace;
    margin: 10px 0;
    border-left: 3px solid #764ba2;
}