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

:root {
    --primary-color: #6366f1;
    --primary-dark: #4f46e5;
    --primary-light: #818cf8;
    --secondary-color: #f59e0b;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --danger-color: #ef4444;
    --dark-bg: #0f172a;
    --dark-surface: #1e293b;
    --dark-border: #334155;
    --light-bg: #f8fafc;
    --light-surface: #ffffff;
    --light-border: #e2e8f0;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --text-muted: #94a3b8;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
    --border-radius: 12px;
    --border-radius-lg: 16px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
}

/* App Container */
.app-container {
    display: flex;
    min-height: 100vh;
    background: var(--light-bg);
}

/* Sidebar Navigation */
.sidebar {
    width: 280px;
    background: var(--light-surface);
    border-right: 1px solid var(--light-border);
    display: flex;
    flex-direction: column;
    box-shadow: var(--shadow-lg);
    position: fixed;
    height: 100vh;
    z-index: 1000;
}

.sidebar-header {
    padding: 24px;
    border-bottom: 1px solid var(--light-border);
}

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary-color);
}

.logo i {
    font-size: 1.5rem;
}

.nav-tabs {
    flex: 1;
    padding: 16px 0;
    overflow-y: auto;
}

.nav-tab {
    width: 100%;
    padding: 16px 24px;
    background: none;
    border: none;
    display: flex;
    align-items: center;
    gap: 12px;
    color: var(--text-secondary);
    font-size: 0.95rem;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    position: relative;
    text-align: left;
}

.nav-tab:hover {
    background: rgba(99, 102, 241, 0.05);
    color: var(--primary-color);
}

.nav-tab.active {
    background: var(--primary-color);
    color: white;
    box-shadow: var(--shadow-md);
}

.nav-tab.active::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 4px;
    background: var(--secondary-color);
}

.nav-tab i {
    font-size: 1.1rem;
    width: 20px;
    text-align: center;
}

.sidebar-footer {
    padding: 24px;
    border-top: 1px solid var(--light-border);
    text-align: center;
}

.sidebar-footer p {
    font-size: 0.85rem;
    color: var(--text-muted);
    margin: 0;
}

/* Main Content */
.main-content {
    flex: 1;
    margin-left: 280px;
    padding: 32px;
    background: var(--light-bg);
    min-height: 100vh;
}

/* Tab Content */
.tab-content {
    display: none;
    animation: fadeInUp 0.5s ease-out;
}

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

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.tab-header {
    margin-bottom: 32px;
    text-align: center;
}

.tab-header h1 {
    font-size: 2.5rem;
    font-weight: 800;
    color: var(--text-primary);
    margin-bottom: 8px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.tab-header p {
    font-size: 1.1rem;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto;
}

/* Calculator Container */
.calculator-container {
    max-width: 1000px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 32px;
    align-items: start;
}

/* Input Section */
.input-section {
    background: var(--light-surface);
    border-radius: var(--border-radius-lg);
    padding: 32px;
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--light-border);
}

.input-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 24px;
    margin-bottom: 32px;
}

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

.input-group.full-width {
    grid-column: 1 / -1;
}

.input-group label {
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 8px;
    font-size: 0.9rem;
}

.input-wrapper {
    position: relative;
    display: flex;
    align-items: center;
}

.input-wrapper i {
    position: absolute;
    left: 12px;
    color: var(--text-muted);
    font-size: 0.9rem;
    z-index: 1;
}

.input-wrapper input,
.input-wrapper select {
    width: 100%;
    padding: 12px 12px 12px 40px;
    border: 2px solid var(--light-border);
    border-radius: var(--border-radius);
    font-size: 1rem;
    transition: var(--transition);
    background: var(--light-bg);
    color: var(--text-primary);
}

.input-wrapper input:focus,
.input-wrapper select:focus {
    outline: none;
    border-color: var(--primary-color);
    background: white;
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.input-wrapper input::placeholder {
    color: var(--text-muted);
}

/* Calculate Button */
.calculate-btn {
    width: 100%;
    padding: 16px 24px;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: white;
    border: none;
    border-radius: var(--border-radius);
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    box-shadow: var(--shadow-md);
}

.calculate-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-xl);
    background: linear-gradient(135deg, var(--primary-dark), var(--primary-color));
}

.calculate-btn:active {
    transform: translateY(0);
}

/* Result Section */
.result-section {
    background: var(--light-surface);
    border-radius: var(--border-radius-lg);
    padding: 32px;
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--light-border);
    min-height: 400px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.result-placeholder {
    text-align: center;
    color: var(--text-muted);
}

.result-placeholder i {
    font-size: 3rem;
    margin-bottom: 16px;
    color: var(--primary-light);
}

.result-placeholder h3 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.result-placeholder p {
    font-size: 1rem;
    line-height: 1.6;
}

/* Results */
.result {
    width: 100%;
    animation: slideInUp 0.5s ease-out;
}

@keyframes slideInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.result h3 {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 20px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.result p {
    margin-bottom: 12px;
    font-weight: 500;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 8px 0;
    border-bottom: 1px solid var(--light-border);
}

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

.result .highlight {
    color: var(--primary-color);
    font-weight: 700;
    font-size: 1.1rem;
}

.result .category {
    display: inline-block;
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
    margin: 4px 0;
}

.category.underweight {
    background: rgba(239, 68, 68, 0.1);
    color: var(--danger-color);
}

.category.normal {
    background: rgba(16, 185, 129, 0.1);
    color: var(--success-color);
}

.category.overweight {
    background: rgba(245, 158, 11, 0.1);
    color: var(--warning-color);
}

.category.obese {
    background: rgba(239, 68, 68, 0.1);
    color: var(--danger-color);
}

.result small {
    color: var(--text-muted);
    font-size: 0.85rem;
    line-height: 1.5;
    display: block;
    margin-top: 16px;
    padding-top: 16px;
    border-top: 1px solid var(--light-border);
}

/* Responsive Design */
@media (max-width: 1200px) {
    .calculator-container {
        grid-template-columns: 1fr;
        gap: 24px;
    }
}

@media (max-width: 768px) {
    .sidebar {
        transform: translateX(-100%);
        transition: var(--transition);
        width: 280px;
    }
    
    .sidebar.open {
        transform: translateX(0);
    }
    
    .main-content {
        margin-left: 0;
        padding: 20px;
    }
    
    .input-grid {
        grid-template-columns: 1fr;
        gap: 20px;
    }
    
    .tab-header h1 {
        font-size: 2rem;
    }
    
    .input-section,
    .result-section {
        padding: 24px;
    }
    
    /* Mobile menu toggle - SHOW ON MOBILE with higher specificity */
    body .mobile-menu-toggle {
        display: flex !important;
        align-items: center;
        justify-content: center;
        position: fixed;
        top: 20px;
        left: 20px;
        z-index: 1001;
        background: var(--primary-color);
        color: white;
        border: none;
        border-radius: 8px;
        padding: 12px;
        cursor: pointer;
        box-shadow: var(--shadow-md);
        width: 44px;
        height: 44px;
        transition: var(--transition);
    }
    
    body .mobile-menu-toggle:hover {
        background: var(--primary-dark);
        transform: scale(1.05);
    }
    
    /* Overlay for mobile menu */
    .sidebar-overlay {
        display: none;
        position: fixed;
        top: 0;
        left: 0;
        right: 0;
        bottom: 0;
        background: rgba(0, 0, 0, 0.5);
        z-index: 999;
    }
    
    .sidebar-overlay.open {
        display: block;
    }
    
    /* Footer adjustments for mobile */
    footer {
        padding: 24px 20px;
        margin-top: 32px;
    }
    
    .disclaimer {
        padding: 16px;
        margin-bottom: 16px;
    }
    
    .disclaimer p {
        font-size: 0.9rem;
        flex-direction: column;
        text-align: center;
        gap: 8px;
    }
    
    /* Burger Menu Icon - ensure it shows on mobile */
    body .burger-icon {
        display: flex;
        flex-direction: column;
        justify-content: space-between;
        width: 20px;
        height: 16px;
        transition: var(--transition);
    }
    
    body .burger-icon span {
        display: block;
        width: 100%;
        height: 2px;
        background: white;
        border-radius: 1px;
        transition: var(--transition);
        transform-origin: center;
    }
    
    /* Burger Menu Animation */
    body .mobile-menu-toggle.open .burger-icon span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }
    
    body .mobile-menu-toggle.open .burger-icon span:nth-child(2) {
        opacity: 0;
    }
    
    body .mobile-menu-toggle.open .burger-icon span:nth-child(3) {
        transform: rotate(-45deg) translate(7px, -6px);
    }
}

@media (max-width: 480px) {
    .main-content {
        padding: 16px;
    }
    
    .input-section,
    .result-section {
        padding: 20px;
    }
    
    .tab-header h1 {
        font-size: 1.8rem;
    }
    
    .calculate-btn {
        padding: 14px 20px;
        font-size: 1rem;
    }
    
    .input-wrapper input,
    .input-wrapper select {
        padding: 10px 10px 10px 35px;
        font-size: 0.95rem;
    }
    
    .input-wrapper i {
        left: 10px;
        font-size: 0.85rem;
    }
    
    .nav-tab {
        padding: 14px 20px;
        font-size: 0.9rem;
    }
    
    .nav-tab i {
        font-size: 1rem;
        width: 18px;
    }
    
    .sidebar-header {
        padding: 20px;
    }
    
    .logo {
        font-size: 1.1rem;
    }
    
    .logo i {
        font-size: 1.3rem;
    }
    
    .sidebar-footer {
        padding: 20px;
        text-align: center;
    }
    
    .sidebar-footer p {
        font-size: 0.85rem;
        color: var(--text-muted);
    }
}

/* Hide mobile menu toggle on desktop */
.mobile-menu-toggle {
    display: none;
}

/* Loading Animation */
.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    border-top-color: white;
    animation: spin 1s ease-in-out infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

/* Error States */
.error {
    color: var(--danger-color);
    background: rgba(239, 68, 68, 0.1);
    border: 1px solid rgba(239, 68, 68, 0.2);
    border-radius: var(--border-radius);
    padding: 16px;
    margin-top: 16px;
    font-weight: 500;
}

/* Success States */
.success {
    color: var(--success-color);
    background: rgba(16, 185, 129, 0.1);
    border: 1px solid rgba(16, 185, 129, 0.2);
    border-radius: var(--border-radius);
    padding: 16px;
    margin-top: 16px;
    font-weight: 500;
}

/* Footer */
footer {
    background: var(--light-surface);
    border-top: 1px solid var(--light-border);
    padding: 32px;
    margin-top: 40px;
    text-align: center;
}

.disclaimer {
    background: rgba(99, 102, 241, 0.1);
    border: 1px solid rgba(99, 102, 241, 0.2);
    border-radius: var(--border-radius);
    padding: 20px;
    margin-bottom: 20px;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

.disclaimer p {
    color: var(--primary-dark);
    font-weight: 500;
    margin: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    font-size: 0.95rem;
    line-height: 1.5;
}

.disclaimer i {
    color: var(--primary-color);
    font-size: 1.1rem;
}

footer > p {
    color: var(--text-muted);
    font-size: 0.9rem;
    margin: 0;
}

/* Mobile Menu Toggle - Base Styles */
.mobile-menu-toggle {
    display: none;
    position: fixed;
    top: 20px;
    left: 20px;
    z-index: 1001;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: 8px;
    padding: 12px;
    cursor: pointer;
    box-shadow: var(--shadow-md);
    width: 44px;
    height: 44px;
    transition: var(--transition);
    align-items: center;
    justify-content: center;
}

.mobile-menu-toggle:hover {
    background: var(--primary-dark);
    transform: scale(1.05);
}

/* Burger Menu Icon */
.burger-icon {
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    width: 20px;
    height: 16px;
    transition: var(--transition);
}

.burger-icon span {
    display: block;
    width: 100%;
    height: 2px;
    background: white;
    border-radius: 1px;
    transition: var(--transition);
    transform-origin: center;
}

/* Burger Menu Animation */
.mobile-menu-toggle.open .burger-icon span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
}

.mobile-menu-toggle.open .burger-icon span:nth-child(2) {
    opacity: 0;
}

.mobile-menu-toggle.open .burger-icon span:nth-child(3) {
    transform: rotate(-45deg) translate(7px, -6px);
}