/**
 * Leave and Attendance Management System - Modern Design System
 * Premium UI with gradients, glassmorphism, and smooth animations
 */

/* ========================================
   CSS Custom Properties (Design Tokens)
   ======================================== */

:root {
    /* Primary Colors - Vibrant Purple/Blue Gradient Theme */
    --primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --primary-gradient-hover: linear-gradient(135deg, #5568d3 0%, #63408b 100%);
    --accent-gradient: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    --success-gradient: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
    --warning-gradient: linear-gradient(135deg, #fa709a 0%, #fee140 100%);
    --danger-gradient: linear-gradient(135deg, #ff6b6b 0%, #ee5a6f 100%);
    
    /* Solid Colors */
    --primary: #667eea;
    --primary-dark: #5568d3;
    --secondary: #764ba2;
    --accent: #f5576c;
    --success: #00f2fe;
    --warning: #fee140;
    --danger: #ff6b6b;
    --info: #4facfe;
    
    /* Neutral Colors */
    --white: #ffffff;
    --gray-50: #f9fafb;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-300: #d1d5db;
    --gray-400: #9ca3af;
    --gray-500: #6b7280;
    --gray-600: #4b5563;
    --gray-700: #374151;
    --gray-800: #1f2937;
    --gray-900: #111827;
    
    /* Background */
    --bg-primary: #f8f9fa;
    --bg-secondary: #ffffff;
    --bg-dark: #1a1a2e;
    --bg-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 50%, #f093fb 100%);
    
    /* Text Colors */
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --text-light: #9ca3af;
    --text-white: #ffffff;
    
    /* 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), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
    --shadow-glow: 0 0 20px rgba(102, 126, 234, 0.4);
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
    --radius-full: 9999px;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 0.75rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    
    /* Typography */
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 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: 1.875rem;
    --font-size-4xl: 2.25rem;
    
    /* Transitions */
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-base: 300ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 500ms cubic-bezier(0.4, 0, 0.2, 1);
}

/* ========================================
   Reset & Base Styles
   ======================================== */

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

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-sans);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--text-primary);
    background: var(--bg-primary);
    overflow-x: hidden;
}

/* ========================================
   Typography
   ======================================== */

h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

h1 { font-size: var(--font-size-4xl); }
h2 { font-size: var(--font-size-3xl); }
h3 { font-size: var(--font-size-2xl); }
h4 { font-size: var(--font-size-xl); }
h5 { font-size: var(--font-size-lg); }
h6 { font-size: var(--font-size-base); }

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

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

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

/* ========================================
   Animated Background
   ======================================== */

.animated-bg {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--bg-gradient);
    z-index: -1;
    animation: gradientShift 15s ease infinite;
}

@keyframes gradientShift {
    0%, 100% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
}

.animated-bg::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(255,255,255,0.1) 1px, transparent 1px);
    background-size: 50px 50px;
    animation: moveBackground 20s linear infinite;
}

@keyframes moveBackground {
    0% { transform: translate(0, 0); }
    100% { transform: translate(50px, 50px); }
}

/* ========================================
   Glass Card Effect
   ======================================== */

.glass-card {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border-radius: var(--radius-2xl);
    border: 1px solid rgba(255, 255, 255, 0.3);
    box-shadow: var(--shadow-2xl);
    padding: var(--spacing-2xl);
    transition: transform var(--transition-base), box-shadow var(--transition-base);
}

.glass-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-2xl), var(--shadow-glow);
}

/* ========================================
   Buttons
   ======================================== */

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
    padding: 0.75rem 1.5rem;
    font-size: var(--font-size-base);
    font-weight: 600;
    border: none;
    border-radius: var(--radius-lg);
    cursor: pointer;
    transition: all var(--transition-base);
    text-decoration: none;
    position: relative;
    overflow: hidden;
}

.btn::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.3);
    transform: translate(-50%, -50%);
    transition: width var(--transition-base), height var(--transition-base);
}

.btn:hover::before {
    width: 300px;
    height: 300px;
}

.btn-primary {
    background: var(--primary-gradient);
    color: var(--white);
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    background: var(--primary-gradient-hover);
    box-shadow: var(--shadow-lg), var(--shadow-glow);
    transform: translateY(-2px);
}

.btn-secondary {
    background: var(--gray-200);
    color: var(--text-primary);
}

.btn-secondary:hover {
    background: var(--gray-300);
}

.btn-success {
    background: var(--success-gradient);
    color: var(--white);
}

.btn-danger {
    background: var(--danger-gradient);
    color: var(--white);
}

.btn-sm {
    padding: 0.5rem 1rem;
    font-size: var(--font-size-sm);
}

.btn-lg {
    padding: 1rem 2rem;
    font-size: var(--font-size-lg);
}

.btn-block {
    width: 100%;
}

/* ========================================
   Forms
   ======================================== */

.form-group {
    margin-bottom: var(--spacing-lg);
}

.form-label {
    display: block;
    margin-bottom: var(--spacing-xs);
    font-weight: 600;
    color: var(--text-primary);
    font-size: var(--font-size-sm);
}

.form-control {
    width: 100%;
    padding: 0.75rem 1rem;
    font-size: var(--font-size-base);
    font-family: var(--font-sans);
    color: var(--text-primary);
    background: var(--white);
    border: 2px solid var(--gray-200);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.form-control:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.form-control::placeholder {
    color: var(--gray-400);
}

select.form-control {
    cursor: pointer;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%236b7280' d='M6 9L1 4h10z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 1rem center;
    padding-right: 2.5rem;
}

textarea.form-control {
    resize: vertical;
    min-height: 100px;
}

.form-check {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    margin-bottom: var(--spacing-sm);
}

.form-check input[type="checkbox"] {
    width: 1.25rem;
    height: 1.25rem;
    cursor: pointer;
}

/* ========================================
   Cards
   ======================================== */

.card {
    background: var(--white);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-md);
    padding: var(--spacing-xl);
    transition: all var(--transition-base);
}

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

.card-header {
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-md);
    border-bottom: 2px solid var(--gray-100);
}

.card-title {
    font-size: var(--font-size-xl);
    font-weight: 700;
    margin-bottom: 0;
}

.card-body {
    margin-bottom: var(--spacing-md);
}

.card-footer {
    margin-top: var(--spacing-lg);
    padding-top: var(--spacing-md);
    border-top: 2px solid var(--gray-100);
}

/* ========================================
   Stats Cards
   ======================================== */

.stat-card {
    background: var(--white);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-md);
    position: relative;
    overflow: hidden;
    transition: all var(--transition-base);
}

.stat-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 100%;
    background: var(--primary-gradient);
}

.stat-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
}

.stat-value {
    font-size: var(--font-size-3xl);
    font-weight: 700;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: var(--spacing-xs);
}

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

/* ========================================
   Tables
   ======================================== */

.table-container {
    background: var(--white);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-md);
    overflow: hidden;
}

table {
    width: 100%;
    border-collapse: collapse;
}

thead {
    background: var(--gray-50);
}

th {
    padding: 1rem;
    text-align: left;
    font-weight: 700;
    font-size: var(--font-size-sm);
    color: var(--text-primary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    border-bottom: 2px solid var(--gray-200);
}

td {
    padding: 1rem;
    border-bottom: 1px solid var(--gray-100);
    color: var(--text-secondary);
}

tr:hover {
    background: var(--gray-50);
}

/* ========================================
   Badges
   ======================================== */

.badge {
    display: inline-flex;
    align-items: center;
    padding: 0.25rem 0.75rem;
    font-size: var(--font-size-xs);
    font-weight: 600;
    border-radius: var(--radius-full);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.badge-primary { background: rgba(102, 126, 234, 0.1); color: var(--primary); }
.badge-success { background: rgba(0, 242, 254, 0.1); color: #00a8b5; }
.badge-warning { background: rgba(254, 225, 64, 0.2); color: #d4a500; }
.badge-danger { background: rgba(255, 107, 107, 0.1); color: var(--danger); }
.badge-info { background: rgba(79, 172, 254, 0.1); color: var(--info); }

/* ========================================
   Alerts
   ======================================== */

.alert {
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--radius-lg);
    margin-bottom: var(--spacing-lg);
    border-left: 4px solid;
    animation: slideIn var(--transition-base);
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.alert-success {
    background: rgba(0, 242, 254, 0.1);
    border-color: var(--success);
    color: #00a8b5;
}

.alert-danger {
    background: rgba(255, 107, 107, 0.1);
    border-color: var(--danger);
    color: var(--danger);
}

.alert-warning {
    background: rgba(254, 225, 64, 0.2);
    border-color: var(--warning);
    color: #d4a500;
}

.alert-info {
    background: rgba(79, 172, 254, 0.1);
    border-color: var(--info);
    color: var(--info);
}

/* ========================================
   Grid System
   ======================================== */

.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.row {
    display: flex;
    flex-wrap: wrap;
    margin: 0 calc(var(--spacing-md) * -1);
}

.col {
    flex: 1;
    padding: 0 var(--spacing-md);
    margin-bottom: var(--spacing-lg);
}

.col-1 { flex: 0 0 8.333%; max-width: 8.333%; }
.col-2 { flex: 0 0 16.666%; max-width: 16.666%; }
.col-3 { flex: 0 0 25%; max-width: 25%; }
.col-4 { flex: 0 0 33.333%; max-width: 33.333%; }
.col-6 { flex: 0 0 50%; max-width: 50%; }
.col-8 { flex: 0 0 66.666%; max-width: 66.666%; }
.col-12 { flex: 0 0 100%; max-width: 100%; }

/* ========================================
   Utilities
   ======================================== */

.text-center { text-align: center; }
.text-right { text-align: right; }
.text-left { text-align: left; }

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

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

.d-flex { display: flex; }
.align-items-center { align-items: center; }
.justify-content-between { justify-content: space-between; }
.justify-content-center { justify-content: center; }
.gap-1 { gap: var(--spacing-xs); }
.gap-2 { gap: var(--spacing-md); }
.gap-3 { gap: var(--spacing-lg); }

/* ========================================
   Responsive Design
   ======================================== */

@media (max-width: 768px) {
    .col-1, .col-2, .col-3, .col-4, .col-6, .col-8 {
        flex: 0 0 100%;
        max-width: 100%;
    }
    
    h1 { font-size: var(--font-size-3xl); }
    h2 { font-size: var(--font-size-2xl); }
    h3 { font-size: var(--font-size-xl); }
    
    .glass-card {
        padding: var(--spacing-lg);
    }
}