/* ===========================
   CSS Variables & Design Tokens
   =========================== */
:root {
    /* Colors - Smoker Status */
    --color-smoker: #E74C3C;
    --color-non-smoker: #3498DB;
    
    /* Colors - Gender */
    --color-male: #9B59B6;
    --color-female: #E91E63;
    
    /* Colors - Regional */
    --color-northeast: #1ABC9C;
    --color-northwest: #F39C12;
    --color-southeast: #27AE60;
    --color-southwest: #E67E22;
    
    /* Neutral Colors */
    --color-bg-primary: #0A0E27;
    --color-bg-secondary: #151B3D;
    --color-bg-card: #1E2749;
    --color-text-primary: #FFFFFF;
    --color-text-secondary: #A0AEC0;
    --color-border: #2D3748;
    
    /* Accent Colors */
    --color-accent: #667EEA;
    --color-accent-light: #7F9CF5;
    --color-success: #48BB78;
    --color-warning: #F6AD55;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    
    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 2rem;
    --font-size-4xl: 2.5rem;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.2);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.3);
    --shadow-glow: 0 0 20px rgba(102, 126, 234, 0.4);
    
    /* Transitions */
    --transition-fast: 150ms ease-in-out;
    --transition-base: 300ms ease-in-out;
    --transition-slow: 500ms ease-in-out;
}

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

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    background: linear-gradient(135deg, var(--color-bg-primary) 0%, var(--color-bg-secondary) 100%);
    color: var(--color-text-primary);
    line-height: 1.6;
    min-height: 100vh;
    overflow-x: hidden;
}

/* ===========================
   Header Styles
   =========================== */
.dashboard-header {
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.1) 0%, rgba(118, 75, 162, 0.1) 100%);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--color-border);
    padding: var(--spacing-lg) var(--spacing-xl);
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow-lg);
}

.header-content {
    text-align: center;
    margin-bottom: var(--spacing-md);
}

.dashboard-title {
    font-size: var(--font-size-4xl);
    font-weight: 800;
    background: linear-gradient(135deg, #667EEA 0%, #764BA2 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: var(--spacing-xs);
    letter-spacing: -0.02em;
}

.dashboard-subtitle {
    font-size: var(--font-size-lg);
    color: var(--color-text-secondary);
    font-weight: 400;
}

/* Filter Controls */
.filter-controls {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-md);
    justify-content: center;
    align-items: flex-end;
    max-width: 1400px;
    margin: 0 auto;
}

.filter-group {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.filter-group label {
    font-size: var(--font-size-sm);
    font-weight: 600;
    color: var(--color-text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.filter-select,
.range-input {
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    color: var(--color-text-primary);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-md);
    font-size: var(--font-size-base);
    font-family: var(--font-family);
    transition: all var(--transition-base);
    cursor: pointer;
}

.filter-select {
    min-width: 150px;
}

.filter-select:hover,
.filter-select:focus,
.range-input:hover,
.range-input:focus {
    border-color: var(--color-accent);
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
    outline: none;
}

.range-filter .range-inputs {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
}

.range-input {
    width: 70px;
}

.reset-btn {
    background: linear-gradient(135deg, var(--color-accent) 0%, var(--color-accent-light) 100%);
    color: white;
    border: none;
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-md);
    font-size: var(--font-size-base);
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-base);
    box-shadow: var(--shadow-md);
}

.reset-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

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

/* ===========================
   Main Dashboard
   =========================== */
.dashboard-main {
    max-width: 1600px;
    margin: 0 auto;
    padding: var(--spacing-xl);
}

/* KPI Cards Section */
.kpi-section {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-xl);
}

.kpi-card {
    background: linear-gradient(135deg, var(--color-bg-card) 0%, rgba(30, 39, 73, 0.8) 100%);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-xl);
    padding: var(--spacing-lg);
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    transition: all var(--transition-base);
    cursor: pointer;
    position: relative;
    overflow: hidden;
}

.kpi-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.1) 0%, rgba(118, 75, 162, 0.1) 100%);
    opacity: 0;
    transition: opacity var(--transition-base);
}

.kpi-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
    border-color: var(--color-accent);
}

.kpi-card:hover::before {
    opacity: 1;
}

.kpi-icon {
    font-size: var(--font-size-4xl);
    filter: drop-shadow(0 4px 8px rgba(0, 0, 0, 0.3));
}

.kpi-content {
    flex: 1;
    position: relative;
    z-index: 1;
}

.kpi-label {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: var(--spacing-xs);
}

.kpi-value {
    font-size: var(--font-size-3xl);
    font-weight: 800;
    color: var(--color-text-primary);
    line-height: 1;
}

/* Charts Grid */
.charts-grid {
    display: grid;
    grid-template-columns: repeat(12, 1fr);
    gap: var(--spacing-lg);
}

.chart-container {
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-xl);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-md);
    transition: all var(--transition-base);
}

.chart-container:hover {
    box-shadow: var(--shadow-xl);
    border-color: rgba(102, 126, 234, 0.3);
}

.chart-large {
    grid-column: span 12;
}

.chart-medium {
    grid-column: span 6;
}

.chart-header {
    margin-bottom: var(--spacing-md);
}

.chart-title {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    color: var(--color-text-primary);
    margin-bottom: var(--spacing-xs);
}

.chart-description {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}

.chart-canvas {
    min-height: 400px;
    position: relative;
}

/* ===========================
   Footer
   =========================== */
.dashboard-footer {
    text-align: center;
    padding: var(--spacing-lg);
    color: var(--color-text-secondary);
    font-size: var(--font-size-sm);
    border-top: 1px solid var(--color-border);
    margin-top: var(--spacing-xl);
}

/* ===========================
   Loading Overlay
   =========================== */
.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(10, 14, 39, 0.95);
    backdrop-filter: blur(10px);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    z-index: 9999;
    transition: opacity var(--transition-slow);
}

.loading-overlay.hidden {
    opacity: 0;
    pointer-events: none;
}

.loading-spinner {
    width: 60px;
    height: 60px;
    border: 4px solid rgba(102, 126, 234, 0.2);
    border-top-color: var(--color-accent);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

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

.loading-text {
    margin-top: var(--spacing-md);
    font-size: var(--font-size-lg);
    color: var(--color-text-secondary);
}

/* ===========================
   Responsive Design
   =========================== */
@media (max-width: 1024px) {
    .chart-medium {
        grid-column: span 12;
    }
    
    .filter-controls {
        flex-direction: column;
        align-items: stretch;
    }
    
    .filter-select {
        width: 100%;
    }
}

@media (max-width: 768px) {
    .dashboard-header {
        padding: var(--spacing-md);
    }
    
    .dashboard-title {
        font-size: var(--font-size-3xl);
    }
    
    .dashboard-main {
        padding: var(--spacing-md);
    }
    
    .kpi-section {
        grid-template-columns: 1fr;
    }
    
    .chart-canvas {
        min-height: 300px;
    }
}

/* ===========================
   Utility Classes
   =========================== */
.text-center {
    text-align: center;
}

.hidden {
    display: none !important;
}

.fade-in {
    animation: fadeIn var(--transition-slow) ease-in;
}

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