/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #212529;
    --secondary-color: #DEE2E6;
    --background-color: #F8F9FA;
    --surface-color: #FFFFFF;
    --text-primary: #212529;
    --text-secondary: #6c757d;
    --border-color: #E9ECEF;
    --success-color: #28a745;
    --warning-color: #ffc107;
    --error-color: #dc3545;
    --shadow-light: 0 2px 4px rgba(0, 0, 0, 0.1);
    --shadow-medium: 0 4px 8px rgba(0, 0, 0, 0.15);
    --shadow-heavy: 0 8px 16px rgba(0, 0, 0, 0.2);
    --border-radius: 8px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--background-color);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.app-container {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Header Styles */
.app-header {
    background: linear-gradient(135deg, var(--primary-color) 0%, #495057 100%);
    color: white;
    padding: 2rem 0;
    text-align: center;
    box-shadow: var(--shadow-medium);
}

.app-title {
    font-size: 2.5rem;
    font-weight: 300;
    margin-bottom: 0.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1rem;
}

.title-icon {
    font-size: 3rem;
}

.app-subtitle {
    font-size: 1.1rem;
    opacity: 0.9;
    font-weight: 300;
}

/* Main Content */
.main-content {
    flex: 1;
    padding: 2rem 0;
}

/* Calculator Selector */
.calculator-selector {
    margin-bottom: 3rem;
}

.calculator-selector h2 {
    text-align: center;
    margin-bottom: 2rem;
    color: var(--text-primary);
    font-weight: 400;
}

.calculator-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.calc-card {
    background: var(--surface-color);
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 2rem 1.5rem;
    text-align: center;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: var(--shadow-light);
}

.calc-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-medium);
    border-color: var(--primary-color);
}

.calc-card.active {
    border-color: var(--primary-color);
    background: linear-gradient(135deg, var(--primary-color) 0%, #495057 100%);
    color: white;
    box-shadow: var(--shadow-medium);
}

.card-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.calc-card h3 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
    font-weight: 500;
}

.calc-card p {
    font-size: 0.9rem;
    opacity: 0.8;
}

/* Form Styles */
.calculator-forms {
    background: var(--surface-color);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-medium);
    overflow: hidden;
}

.calc-form {
    display: none;
    padding: 2rem;
}

.calc-form.active {
    display: block;
}

.form-header {
    text-align: center;
    margin-bottom: 2rem;
    padding-bottom: 1rem;
    border-bottom: 2px solid var(--border-color);
}

.form-header h2 {
    color: var(--text-primary);
    margin-bottom: 0.5rem;
    font-weight: 400;
}

.form-header p {
    color: var(--text-secondary);
    font-size: 1rem;
}

.form-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.form-group {
    display: flex;
    flex-direction: column;
}

.form-group label {
    font-weight: 500;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.form-group input,
.form-group select {
    padding: 0.75rem;
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: 1rem;
    transition: var(--transition);
    background: var(--surface-color);
}

.form-group input:focus,
.form-group select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(33, 37, 41, 0.1);
}

.form-group input:invalid,
.form-group select:invalid {
    border-color: var(--error-color);
}

/* Openings Section */
.openings-section {
    margin: 2rem 0;
    padding: 1.5rem;
    background: var(--background-color);
    border-radius: var(--border-radius);
    border: 1px solid var(--border-color);
}

.openings-section h3 {
    margin-bottom: 1rem;
    color: var(--text-primary);
    font-weight: 500;
}

.opening-item {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr auto;
    gap: 1rem;
    align-items: end;
    margin-bottom: 1rem;
    padding: 1rem;
    background: var(--surface-color);
    border-radius: var(--border-radius);
    border: 1px solid var(--border-color);
}

.remove-opening {
    background: var(--error-color);
    color: white;
    border: none;
    border-radius: var(--border-radius);
    padding: 0.5rem 1rem;
    cursor: pointer;
    transition: var(--transition);
    font-size: 0.9rem;
}

.remove-opening:hover {
    background: #c82333;
}

/* Button Styles */
.btn-primary,
.btn-secondary {
    padding: 0.75rem 2rem;
    border: none;
    border-radius: var(--border-radius);
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    text-decoration: none;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color) 0%, #495057 100%);
    color: white;
    box-shadow: var(--shadow-light);
}

.btn-primary:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow-medium);
}

.btn-secondary {
    background: var(--surface-color);
    color: var(--text-primary);
    border: 2px solid var(--border-color);
}

.btn-secondary:hover {
    background: var(--background-color);
    border-color: var(--primary-color);
}

.btn-primary:disabled,
.btn-secondary:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none;
}

/* Results Section */
.results-section {
    background: var(--surface-color);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-medium);
    margin-top: 2rem;
    overflow: hidden;
}

.results-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem 2rem;
    background: var(--background-color);
    border-bottom: 1px solid var(--border-color);
}

.results-header h2 {
    color: var(--text-primary);
    font-weight: 500;
}

.results-content {
    padding: 2rem;
}

.result-category {
    margin-bottom: 2rem;
}

.result-category h3 {
    color: var(--text-primary);
    margin-bottom: 1rem;
    font-weight: 500;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.result-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
}

.result-item {
    background: var(--background-color);
    padding: 1.5rem;
    border-radius: var(--border-radius);
    border: 1px solid var(--border-color);
    text-align: center;
}

.result-value {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.result-label {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.result-unit {
    font-size: 1rem;
    color: var(--text-secondary);
}

.results-actions {
    padding: 1.5rem 2rem;
    background: var(--background-color);
    border-top: 1px solid var(--border-color);
    display: flex;
    gap: 1rem;
    justify-content: center;
}

/* Saved Calculations */
.saved-calculations {
    background: var(--surface-color);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-medium);
    margin-top: 2rem;
    padding: 2rem;
}

.saved-calculations h2 {
    margin-bottom: 1.5rem;
    color: var(--text-primary);
    font-weight: 500;
}

.saved-item {
    background: var(--background-color);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    margin-bottom: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.saved-info h4 {
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

.saved-info p {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.saved-actions {
    display: flex;
    gap: 0.5rem;
}

.saved-actions button {
    padding: 0.5rem 1rem;
    font-size: 0.9rem;
}

/* Loading Spinner */
.loading-spinner {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
}

.spinner {
    width: 50px;
    height: 50px;
    border: 4px solid var(--border-color);
    border-top: 4px solid var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

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

/* Toast Notifications */
.toast-container {
    position: fixed;
    top: 20px;
    right: 20px;
    z-index: 1001;
}

.toast {
    background: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 1rem 1.5rem;
    margin-bottom: 0.5rem;
    box-shadow: var(--shadow-medium);
    display: flex;
    align-items: center;
    gap: 0.5rem;
    animation: slideIn 0.3s ease-out;
    max-width: 300px;
}

.toast.success {
    border-color: var(--success-color);
    background: #d4edda;
    color: #155724;
}

.toast.error {
    border-color: var(--error-color);
    background: #f8d7da;
    color: #721c24;
}

.toast.warning {
    border-color: var(--warning-color);
    background: #fff3cd;
    color: #856404;
}

@keyframes slideIn {
    from {
        transform: translateX(100%);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

/* Footer */
.app-footer {
    background: var(--primary-color);
    color: white;
    text-align: center;
    padding: 1.5rem 0;
    margin-top: auto;
}

.app-footer p {
    color: white;
    font-size: 0.9;
    opacity: 0.9;
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 0 15px;
    }
    
    .app-title {
        font-size: 2rem;
        flex-direction: column;
        gap: 0.5rem;
    }
    
    .title-icon {
        font-size: 2.5rem;
    }
    
    .calculator-cards {
        grid-template-columns: 1fr;
    }
    
    .form-grid {
        grid-template-columns: 1fr;
    }
    
    .opening-item {
        grid-template-columns: 1fr;
        gap: 0.5rem;
    }
    
    .results-header {
        flex-direction: column;
        gap: 1rem;
        text-align: center;
    }
    
    .results-actions {
        flex-direction: column;
    }
    
    .saved-item {
        flex-direction: column;
        gap: 1rem;
        text-align: center;
    }
    
    .toast-container {
        left: 20px;
        right: 20px;
        top: 20px;
    }
    
    .toast {
        max-width: none;
    }
}

@media (max-width: 480px) {
    .main-content {
        padding: 1rem 0;
    }
    
    .calc-form {
        padding: 1rem;
    }
    
    .results-content {
        padding: 1rem;
    }
    
    .result-grid {
        grid-template-columns: 1fr;
    }
}

/* Print Styles */
@media print {
    .app-header,
    .calculator-selector,
    .calculator-forms,
    .results-actions,
    .app-footer {
        display: none !important;
    }
    
    .results-section {
        box-shadow: none;
        border: 1px solid #000;
    }
    
    .container {
        max-width: none;
        padding: 0;
    }
    
    body {
        background: white;
    }
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Focus indicators for keyboard navigation */
button:focus,
input:focus,
select:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    :root {
        --border-color: #000000;
        --text-secondary: #000000;
    }
}