/**
 * Main Stylesheet
 * Mobile-first responsive design
 */

/* ===== CSS Variables ===== */
:root {
    /* Colors */
    --primary-color: #007bff;
    --primary-dark: #0056b3;
    --secondary-color: #6c757d;
    --success-color: #28a745;
    --danger-color: #dc3545;
    --warning-color: #ffc107;
    --info-color: #17a2b8;
    
    /* Neutral Colors */
    --white: #ffffff;
    --light-gray: #f8f9fa;
    --gray: #dee2e6;
    --dark-gray: #6c757d;
    --black: #212529;
    
    /* Text Colors */
    --text-primary: #212529;
    --text-secondary: #6c757d;
    --text-muted: #868e96;
    
    /* Background Colors */
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --bg-dark: #343a40;
    
    /* Border */
    --border-color: #dee2e6;
    --border-radius: 8px;
    --border-radius-sm: 4px;
    --border-radius-lg: 12px;
    
    /* Spacing */
    --spacing-xs: 4px;
    --spacing-sm: 8px;
    --spacing-md: 16px;
    --spacing-lg: 24px;
    --spacing-xl: 32px;
    --spacing-xxl: 48px;
    
    /* Typography */
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-size-base: 16px;
    --font-size-sm: 14px;
    --font-size-lg: 18px;
    --font-size-xl: 24px;
    --font-size-xxl: 32px;
    
    --line-height-base: 1.5;
    --line-height-tight: 1.25;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
    
    /* Transitions */
    --transition-fast: 150ms ease-in-out;
    --transition-base: 300ms ease-in-out;
    
    /* Layout */
    --max-width: 1200px;
    --header-height: 60px;
    --footer-height: 60px;
}

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

html {
    font-size: var(--font-size-base);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: var(--line-height-base);
    color: var(--text-primary);
    background-color: var(--bg-secondary);
    min-height: 100vh;
}

/* ===== Typography ===== */
h1, h2, h3, h4, h5, h6 {
    margin-bottom: var(--spacing-md);
    font-weight: 600;
    line-height: var(--line-height-tight);
    color: var(--text-primary);
}

h1 { font-size: var(--font-size-xxl); }
h2 { font-size: var(--font-size-xl); }
h3 { font-size: var(--font-size-lg); }
h4 { font-size: var(--font-size-base); }
h5 { font-size: var(--font-size-sm); }
h6 { font-size: var(--font-size-sm); }

p {
    margin-bottom: var(--spacing-md);
}

a {
    color: var(--primary-color);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--primary-dark);
    text-decoration: underline;
}

/* ===== Layout ===== */
.container {
    width: 100%;
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

.container-fluid {
    width: 100%;
    padding: 0 var(--spacing-md);
}

/* ===== Grid System ===== */
.row {
    display: flex;
    flex-wrap: wrap;
    margin: 0 calc(var(--spacing-md) * -0.5);
}

.col {
    flex: 1;
    padding: 0 calc(var(--spacing-md) * 0.5);
}

.col-12 { flex: 0 0 100%; max-width: 100%; }
.col-6 { flex: 0 0 50%; max-width: 50%; }
.col-4 { flex: 0 0 33.333%; max-width: 33.333%; }
.col-3 { flex: 0 0 25%; max-width: 25%; }

/* Mobile: Full width columns */
@media (max-width: 767px) {
    .col-6, .col-4, .col-3 {
        flex: 0 0 100%;
        max-width: 100%;
    }
}

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

.text-primary { color: var(--primary-color); }
.text-secondary { color: var(--text-secondary); }
.text-muted { color: var(--text-muted); }
.text-success { color: var(--success-color); }
.text-danger { color: var(--danger-color); }
.text-warning { color: var(--warning-color); }

.bg-primary { background-color: var(--primary-color); color: var(--white); }
.bg-secondary { background-color: var(--bg-secondary); }
.bg-white { background-color: var(--white); }
.bg-light { background-color: var(--light-gray); }

.mt-0 { margin-top: 0; }
.mt-1 { margin-top: var(--spacing-sm); }
.mt-2 { margin-top: var(--spacing-md); }
.mt-3 { margin-top: var(--spacing-lg); }
.mt-4 { margin-top: var(--spacing-xl); }

.mb-0 { margin-bottom: 0; }
.mb-1 { margin-bottom: var(--spacing-sm); }
.mb-2 { margin-bottom: var(--spacing-md); }
.mb-3 { margin-bottom: var(--spacing-lg); }
.mb-4 { margin-bottom: var(--spacing-xl); }

.p-0 { padding: 0; }
.p-1 { padding: var(--spacing-sm); }
.p-2 { padding: var(--spacing-md); }
.p-3 { padding: var(--spacing-lg); }
.p-4 { padding: var(--spacing-xl); }

.d-none { display: none; }
.d-block { display: block; }
.d-flex { display: flex; }
.d-inline-block { display: inline-block; }

.flex-column { flex-direction: column; }
.justify-content-between { justify-content: space-between; }
.justify-content-center { justify-content: center; }
.align-items-center { align-items: center; }

.w-100 { width: 100%; }
.h-100 { height: 100%; }

/* ===== Loading Spinner ===== */
.spinner {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid rgba(0, 0, 0, 0.1);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

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

.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(255, 255, 255, 0.9);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 9999;
}

.loading-overlay .spinner {
    width: 50px;
    height: 50px;
    border-width: 5px;
}

/* ===== Accessibility ===== */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

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

/* ===== Print Styles ===== */
@media print {
    body {
        background: white;
    }
    
    .no-print {
        display: none !important;
    }
    
    a[href]:after {
        content: " (" attr(href) ")";
    }
}