/* ==========================================================================
   SchoolPay Finance System - Unified Design System v3.0
   Professional, Consistent, Accessible UI Framework
   ========================================================================== */

/* =====================================================================
   1. CSS VARIABLES & DESIGN TOKENS
   ===================================================================== */
:root {
    /* Primary Colors */
    --primary-900: #1a365d;
    --primary-800: #1e40af;
    --primary-700: #2563eb;
    --primary-600: #3b82f6;
    --primary-500: #60a5fa;
    --primary: var(--primary-700);

    /* Secondary Colors */
    --secondary-900: #0c4a6e;
    --secondary-800: #075985;
    --secondary-700: #0369a1;
    --secondary-600: #0284c7;
    --secondary-500: #0ea5e9;
    --secondary: var(--secondary-600);

    /* Accent/Success Colors */
    --success-900: #065f46;
    --success-800: #047857;
    --success-700: #059669;
    --success-600: #10b981;
    --success-500: #34d399;
    --success: var(--success-600);

    /* Warning Colors */
    --warning-900: #78350f;
    --warning-800: #92400e;
    --warning-700: #b45309;
    --warning-600: #d97706;
    --warning-500: #f59e0b;
    --warning: var(--warning-600);

    /* Danger/Error Colors */
    --danger-900: #7f1d1d;
    --danger-800: #991b1b;
    --danger-700: #b91c1c;
    --danger-600: #dc2626;
    --danger-500: #ef4444;
    --danger: var(--danger-600);

    /* Neutral Colors */
    --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;

    /* Semantic Colors */
    --white: #ffffff;
    --black: #000000;
    --light: var(--gray-50);
    --dark: var(--gray-800);
    --border: var(--gray-200);
    --text-primary: var(--gray-900);
    --text-secondary: var(--gray-600);
    --text-muted: var(--gray-500);

    /* Background Colors */
    --bg-primary: #ffffff;
    --bg-secondary: var(--gray-50);
    --bg-tertiary: var(--gray-100);
    --card-bg: var(--white);

    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
    --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);

    /* Spacing Scale */
    --spacing-xs: 0.25rem;   /* 4px */
    --spacing-sm: 0.5rem;    /* 8px */
    --spacing-md: 1rem;      /* 16px */
    --spacing-lg: 1.5rem;    /* 24px */
    --spacing-xl: 2rem;      /* 32px */
    --spacing-2xl: 3rem;     /* 48px */
    --spacing-3xl: 4rem;     /* 64px */

    /* Border Radius */
    --radius-sm: 0.375rem;   /* 6px */
    --radius-md: 0.5rem;     /* 8px */
    --radius-lg: 0.75rem;    /* 12px */
    --radius-xl: 1rem;       /* 16px */
    --radius-2xl: 1.5rem;    /* 24px */
    --radius-full: 9999px;

    /* 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);

    /* Typography */
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-mono: 'Fira Code', 'Courier New', monospace;

    /* Font Sizes */
    --text-xs: 0.75rem;      /* 12px */
    --text-sm: 0.875rem;     /* 14px */
    --text-base: 1rem;       /* 16px */
    --text-lg: 1.125rem;     /* 18px */
    --text-xl: 1.25rem;      /* 20px */
    --text-2xl: 1.5rem;      /* 24px */
    --text-3xl: 1.875rem;    /* 30px */
    --text-4xl: 2.25rem;     /* 36px */

    /* Z-Index Scale */
    --z-dropdown: 1000;
    --z-sticky: 1020;
    --z-fixed: 1030;
    --z-modal-backdrop: 1040;
    --z-modal: 1050;
    --z-popover: 1060;
    --z-tooltip: 1070;
}

/* =====================================================================
   2. GLOBAL RESET & BASE STYLES
   ===================================================================== */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

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

body {
    font-family: var(--font-sans);
    font-size: var(--text-base);
    line-height: 1.6;
    color: var(--text-primary);
    background: linear-gradient(135deg, #f5f7fa 0%, #e8ecf1 100%);
    min-height: 100vh;
    overflow-x: hidden;
}

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

h1 { font-size: var(--text-4xl); }
h2 { font-size: var(--text-3xl); }
h3 { font-size: var(--text-2xl); }
h4 { font-size: var(--text-xl); }
h5 { font-size: var(--text-lg); }
h6 { font-size: var(--text-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-800);
}

strong, b {
    font-weight: 600;
}

/* =====================================================================
   4. LAYOUT CONTAINERS
   ===================================================================== */
.container {
    width: 100%;
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

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

.container-sm {
    max-width: 640px;
}

.container-md {
    max-width: 768px;
}

.container-lg {
    max-width: 1024px;
}

/* =====================================================================
   5. HEADER & NAVIGATION
   ===================================================================== */
header {
    background: linear-gradient(135deg, #1e293b 0%, #0f172a 100%);
    color: var(--white);
    box-shadow: var(--shadow-lg);
    position: sticky;
    top: 0;
    z-index: var(--z-sticky);
    margin-bottom: var(--spacing-2xl);
}

.header-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.header-top {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-lg) 0;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.header-brand {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.brand-icon {
    width: 54px;
    height: 54px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-xl);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--text-2xl);
    backdrop-filter: blur(10px);
}

.brand-text h1 {
    font-size: var(--text-2xl);
    font-weight: 700;
    margin: 0;
    color: var(--white);
}

.brand-text .subtitle {
    font-size: var(--text-sm);
    opacity: 0.85;
    font-weight: 400;
    margin-top: var(--spacing-xs);
    color: var(--gray-300);
}

.header-actions {
    display: flex;
    align-items: center;
    gap: var(--spacing-lg);
}

.notification-btn {
    width: 44px;
    height: 44px;
    border-radius: var(--radius-full);
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.2);
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    position: relative;
    font-size: var(--text-xl);
    color: var(--white);
    transition: all var(--transition-fast);
}

.notification-btn:hover {
    background: rgba(255, 255, 255, 0.2);
    transform: scale(1.05);
}

.notification-badge {
    position: absolute;
    top: -5px;
    right: -5px;
    width: 22px;
    height: 22px;
    background: var(--danger);
    border-radius: var(--radius-full);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--text-xs);
    font-weight: 700;
    border: 2px solid #0f172a;
}

.user-info {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-sm) var(--spacing-lg);
    background: rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-full);
    border: 1px solid rgba(255, 255, 255, 0.2);
    backdrop-filter: blur(10px);
}

.user-avatar {
    width: 40px;
    height: 40px;
    border-radius: var(--radius-full);
    background: linear-gradient(135deg, var(--success-600), var(--success-700));
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    color: var(--white);
}

.user-details {
    display: flex;
    flex-direction: column;
}

.user-name {
    font-weight: 600;
    font-size: var(--text-sm);
    color: var(--white);
}

.user-role {
    font-size: var(--text-xs);
    opacity: 0.75;
    color: var(--gray-300);
}

/* Navigation */
nav {
    padding: var(--spacing-md) 0;
}

.nav-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-links {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
}

.nav-links a {
    color: var(--white);
    text-decoration: none;
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--radius-lg);
    font-weight: 500;
    font-size: var(--text-sm);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    transition: all var(--transition-fast);
    white-space: nowrap;
}

.nav-links a:hover,
.nav-links a.active {
    background: rgba(255, 255, 255, 0.15);
}

.nav-links a.active {
    background: rgba(255, 255, 255, 0.2);
    font-weight: 600;
}

.mobile-menu-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--white);
    font-size: var(--text-2xl);
    cursor: pointer;
    padding: var(--spacing-sm);
}

/* =====================================================================
   6. CARDS & PANELS
   ===================================================================== */
.card {
    background: var(--card-bg);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow);
    padding: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
    border: 1px solid var(--border);
    transition: box-shadow var(--transition-fast);
}

.card:hover {
    box-shadow: var(--shadow-md);
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-lg);
    border-bottom: 2px solid var(--border);
}

.card-title {
    font-size: var(--text-2xl);
    font-weight: 700;
    color: var(--text-primary);
    margin: 0;
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.card-title i {
    color: var(--primary);
}

.card-body {
    padding: 0;
}

.card-footer {
    margin-top: var(--spacing-lg);
    padding-top: var(--spacing-lg);
    border-top: 1px solid var(--border);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

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

.summary-card,
.kpi-box {
    background: var(--card-bg);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow);
    position: relative;
    overflow: hidden;
    transition: all var(--transition-base);
    border: 1px solid var(--border);
}

.summary-card:hover,
.kpi-box:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

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

.summary-card.success::before,
.summary-card.income::before { background: var(--success); }
.summary-card.warning::before { background: var(--warning); }
.summary-card.danger::before { background: var(--danger); }
.summary-card.info::before { background: var(--secondary); }
.summary-card.expense::before { background: var(--warning); }

.card-icon {
    position: absolute;
    top: var(--spacing-lg);
    right: var(--spacing-lg);
    width: 54px;
    height: 54px;
    background: rgba(37, 99, 235, 0.1);
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--text-2xl);
    color: var(--primary);
}

.summary-card.success .card-icon,
.summary-card.income .card-icon { background: rgba(16, 185, 129, 0.1); color: var(--success); }
.summary-card.warning .card-icon,
.summary-card.expense .card-icon { background: rgba(217, 119, 6, 0.1); color: var(--warning); }
.summary-card.danger .card-icon { background: rgba(220, 38, 38, 0.1); color: var(--danger); }

.card-label,
.kpi-box h2 {
    font-size: var(--text-sm);
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: var(--spacing-sm);
}

.card-value,
.kpi-box p {
    font-size: var(--text-4xl);
    font-weight: 700;
    color: var(--text-primary);
    margin: 0;
}

.summary-card.success .card-value,
.summary-card.income .card-value { color: var(--success); }
.summary-card.warning .card-value,
.summary-card.expense .card-value { color: var(--warning); }
.summary-card.danger .card-value { color: var(--danger); }

/* =====================================================================
   7. BUTTONS
   ===================================================================== */
button,
.btn,
a.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-lg);
    font-size: var(--text-sm);
    font-weight: 600;
    font-family: var(--font-sans);
    line-height: 1;
    text-align: center;
    text-decoration: none;
    white-space: nowrap;
    border: 1px solid transparent;
    border-radius: var(--radius-lg);
    cursor: pointer;
    transition: all var(--transition-fast);
    box-shadow: var(--shadow-sm);
}

button:disabled,
.btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    pointer-events: none;
}

button:hover,
.btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

button:active,
.btn:active {
    transform: translateY(0);
    box-shadow: var(--shadow-sm);
}

/* Button Variants */
.btn-primary {
    background: linear-gradient(135deg, var(--primary-600), var(--primary-700));
    color: var(--white);
}

.btn-primary:hover {
    background: linear-gradient(135deg, var(--primary-700), var(--primary-800));
}

.btn-secondary {
    background: var(--gray-100);
    color: var(--text-primary);
    border-color: var(--border);
}

.btn-secondary:hover {
    background: var(--gray-200);
    border-color: var(--gray-300);
}

.btn-success {
    background: linear-gradient(135deg, var(--success-600), var(--success-700));
    color: var(--white);
}

.btn-success:hover {
    background: linear-gradient(135deg, var(--success-700), var(--success-800));
}

.btn-danger {
    background: linear-gradient(135deg, var(--danger-600), var(--danger-700));
    color: var(--white);
}

.btn-danger:hover {
    background: linear-gradient(135deg, var(--danger-700), var(--danger-800));
}

.btn-warning {
    background: linear-gradient(135deg, var(--warning-600), var(--warning-700));
    color: var(--white);
}

.btn-warning:hover {
    background: linear-gradient(135deg, var(--warning-700), var(--warning-800));
}

.btn-info {
    background: linear-gradient(135deg, var(--secondary-600), var(--secondary-700));
    color: var(--white);
}

.btn-info:hover {
    background: linear-gradient(135deg, var(--secondary-700), var(--secondary-800));
}

/* Button Sizes */
.btn-sm {
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: var(--text-xs);
}

.btn-lg {
    padding: var(--spacing-lg) var(--spacing-2xl);
    font-size: var(--text-lg);
}

/* Icon Buttons */
.btn-icon {
    width: 40px;
    height: 40px;
    padding: 0;
    border-radius: var(--radius-full);
    font-size: var(--text-base);
}

.btn-icon.btn-sm {
    width: 32px;
    height: 32px;
    font-size: var(--text-sm);
}

.btn-icon.btn-lg {
    width: 48px;
    height: 48px;
    font-size: var(--text-xl);
}

/* Button Group */
.btn-group,
.action-buttons {
    display: inline-flex;
    gap: var(--spacing-sm);
}

/* =====================================================================
   8. FORMS
   ===================================================================== */
.form-group {
    margin-bottom: var(--spacing-lg);
}

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

.form-group label.required::after {
    content: ' *';
    color: var(--danger);
}

input[type="text"],
input[type="email"],
input[type="password"],
input[type="number"],
input[type="tel"],
input[type="url"],
input[type="date"],
input[type="time"],
input[type="datetime-local"],
input[type="month"],
input[type="week"],
input[type="search"],
select,
textarea,
.form-control {
    width: 100%;
    padding: var(--spacing-md);
    font-size: var(--text-sm);
    font-family: var(--font-sans);
    line-height: 1.5;
    color: var(--text-primary);
    background-color: var(--white);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    transition: all var(--transition-fast);
    box-shadow: var(--shadow-sm);
}

input:focus,
select:focus,
textarea:focus,
.form-control:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

input:disabled,
select:disabled,
textarea:disabled,
.form-control:disabled {
    background-color: var(--gray-100);
    cursor: not-allowed;
    opacity: 0.6;
}

select {
    cursor: pointer;
    appearance: none;
    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' fill='none' viewBox='0 0 20 20'%3e%3cpath stroke='%236b7280' stroke-linecap='round' stroke-linejoin='round' stroke-width='1.5' d='M6 8l4 4 4-4'/%3e%3c/svg%3e");
    background-position: right var(--spacing-md) center;
    background-repeat: no-repeat;
    background-size: 1.5em 1.5em;
    padding-right: 2.5rem;
}

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

.form-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
}

.form-actions {
    display: flex;
    gap: var(--spacing-md);
    justify-content: flex-end;
    margin-top: var(--spacing-xl);
    padding-top: var(--spacing-xl);
    border-top: 1px solid var(--border);
}

.form-section {
    margin-bottom: var(--spacing-xl);
    padding-bottom: var(--spacing-xl);
    border-bottom: 1px solid var(--border);
}

.form-section:last-child {
    border-bottom: none;
    margin-bottom: 0;
    padding-bottom: 0;
}

.filter-controls {
    display: flex;
    gap: var(--spacing-lg);
    align-items: flex-end;
    flex-wrap: wrap;
    padding: var(--spacing-lg);
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    margin-bottom: var(--spacing-lg);
}

/* Radio & Checkbox */
.radio-group,
.checkbox-group {
    display: flex;
    gap: var(--spacing-lg);
    flex-wrap: wrap;
}

.radio-group label,
.checkbox-group label {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-weight: 500;
    cursor: pointer;
}

/* =====================================================================
   9. TABLES
   ===================================================================== */
.table-container {
    overflow-x: auto;
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow);
    border: 1px solid var(--border);
    margin: var(--spacing-lg) 0;
    background: var(--white);
}

table,
.table {
    width: 100%;
    border-collapse: collapse;
    border-spacing: 0;
}

table thead th,
.table thead th {
    background: var(--gray-100);
    color: var(--text-primary);
    padding: var(--spacing-lg);
    text-align: left;
    font-weight: 700;
    font-size: var(--text-sm);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    border-bottom: 2px solid var(--border);
    white-space: nowrap;
}

table tbody td,
.table tbody td {
    padding: var(--spacing-lg);
    border-bottom: 1px solid var(--border);
    color: var(--text-primary);
    font-size: var(--text-sm);
}

table tbody tr:last-child td,
.table tbody tr:last-child td {
    border-bottom: none;
}

table tbody tr:hover,
.table tbody tr:hover {
    background: var(--gray-50);
}

.table-actions {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-lg);
}

/* =====================================================================
   10. TABS
   ===================================================================== */
.tab-container {
    background: var(--card-bg);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow);
    overflow: hidden;
    margin-bottom: var(--spacing-xl);
    border: 1px solid var(--border);
}

.tabs {
    display: flex;
    background: var(--gray-100);
    padding: var(--spacing-sm);
    gap: var(--spacing-sm);
    flex-wrap: wrap;
    border-bottom: 1px solid var(--border);
}

.tab,
.tab-link {
    flex: 1;
    padding: var(--spacing-md) var(--spacing-lg);
    text-align: center;
    font-size: var(--text-sm);
    font-weight: 600;
    color: var(--text-secondary);
    background: transparent;
    border: none;
    border-radius: var(--radius-lg);
    cursor: pointer;
    transition: all var(--transition-fast);
    min-width: 120px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
}

.tab:hover,
.tab-link:hover {
    background: rgba(255, 255, 255, 0.6);
    color: var(--text-primary);
}

.tab.active,
.tab-link.active {
    background: var(--white);
    color: var(--primary);
    box-shadow: var(--shadow-sm);
}

.tab-content {
    padding: var(--spacing-xl);
    display: none;
}

.tab-content.active {
    display: block;
    animation: fadeIn 0.3s ease;
}

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

/* =====================================================================
   11. MODALS
   ===================================================================== */
.modal {
    display: none;
    position: fixed;
    z-index: var(--z-modal);
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(4px);
    align-items: center;
    justify-content: center;
    padding: var(--spacing-md);
    overflow-y: auto;
}

.modal.active {
    display: flex;
}

.modal-content {
    background-color: var(--card-bg);
    border-radius: var(--radius-2xl);
    box-shadow: var(--shadow-2xl);
    width: 90%;
    max-width: 600px;
    max-height: calc(100vh - 2rem);
    margin: auto;
    display: flex;
    flex-direction: column;
    animation: modalSlideIn 0.3s ease;
    position: relative;
}

@keyframes modalSlideIn {
    from {
        opacity: 0;
        transform: translateY(-50px) scale(0.9);
    }
    to {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}

.modal-header {
    padding: var(--spacing-xl);
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid var(--border);
    flex-shrink: 0;
    background: var(--card-bg);
    border-radius: var(--radius-2xl) var(--radius-2xl) 0 0;
    position: sticky;
    top: 0;
    z-index: 1;
}

.modal-header h3 {
    margin: 0;
    padding: 0;
    border: none;
    font-size: var(--text-2xl);
    font-weight: 700;
    color: var(--text-primary);
}

.modal-body {
    padding: var(--spacing-xl);
    overflow-y: auto;
    overflow-x: hidden;
    flex: 1 1 auto;
    min-height: 0;
}

.modal-body::-webkit-scrollbar {
    width: 8px;
}

.modal-body::-webkit-scrollbar-track {
    background: var(--gray-100);
    border-radius: var(--radius-sm);
}

.modal-body::-webkit-scrollbar-thumb {
    background: var(--gray-400);
    border-radius: var(--radius-sm);
}

.modal-body::-webkit-scrollbar-thumb:hover {
    background: var(--gray-500);
}

.modal-footer {
    padding: var(--spacing-xl);
    border-top: 1px solid var(--border);
    display: flex;
    justify-content: flex-end;
    gap: var(--spacing-md);
    flex-shrink: 0;
    background: var(--card-bg);
    border-radius: 0 0 var(--radius-2xl) var(--radius-2xl);
    position: sticky;
    bottom: 0;
    z-index: 1;
}

.close {
    color: var(--text-muted);
    font-size: var(--text-3xl);
    font-weight: bold;
    cursor: pointer;
    transition: color var(--transition-fast);
    line-height: 1;
    border: none;
    background: none;
    padding: 0;
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.close:hover {
    color: var(--danger);
}

/* =====================================================================
   12. BADGES & STATUS
   ===================================================================== */
.badge,
.status-badge {
    display: inline-flex;
    align-items: center;
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-full);
    font-size: var(--text-xs);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    line-height: 1;
}

.badge-primary { background: rgba(37, 99, 235, 0.1); color: var(--primary-700); }
.badge-success { background: rgba(16, 185, 129, 0.1); color: var(--success-700); }
.badge-danger { background: rgba(220, 38, 38, 0.1); color: var(--danger-700); }
.badge-warning { background: rgba(217, 119, 6, 0.1); color: var(--warning-700); }
.badge-info { background: rgba(2, 132, 199, 0.1); color: var(--secondary-700); }
.badge-active { background: rgba(16, 185, 129, 0.1); color: var(--success-700); }
.badge-inactive { background: rgba(107, 114, 128, 0.1); color: var(--gray-700); }

/* Status-specific */
.status-Paid,
.status-active { background: rgba(16, 185, 129, 0.1); color: var(--success-700); }
.status-Unpaid { background: rgba(220, 38, 38, 0.1); color: var(--danger-700); }
.status-Partially\.Paid,
.status-Draft { background: rgba(217, 119, 6, 0.1); color: var(--warning-700); }

/* =====================================================================
   13. ALERTS & MESSAGES
   ===================================================================== */
.alert {
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
    margin-bottom: var(--spacing-lg);
    border-left: 4px solid;
    display: flex;
    align-items: start;
    gap: var(--spacing-md);
}

.alert-success {
    background: rgba(16, 185, 129, 0.1);
    border-color: var(--success-600);
    color: var(--success-900);
}

.alert-danger,
.alert-error {
    background: rgba(220, 38, 38, 0.1);
    border-color: var(--danger-600);
    color: var(--danger-900);
}

.alert-warning {
    background: rgba(217, 119, 6, 0.1);
    border-color: var(--warning-600);
    color: var(--warning-900);
}

.alert-info {
    background: rgba(2, 132, 199, 0.1);
    border-color: var(--secondary-600);
    color: var(--secondary-900);
}

/* =====================================================================
   14. UTILITIES
   ===================================================================== */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

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

.bg-primary { background-color: var(--primary); }
.bg-success { background-color: var(--success); }
.bg-danger { background-color: var(--danger); }
.bg-warning { background-color: var(--warning); }

.d-none { display: none !important; }
.d-block { display: block !important; }
.d-flex { display: flex !important; }
.d-grid { display: grid !important; }

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

.gap-sm { gap: var(--spacing-sm); }
.gap-md { gap: var(--spacing-md); }
.gap-lg { gap: var(--spacing-lg); }

.mt-sm { margin-top: var(--spacing-sm); }
.mt-md { margin-top: var(--spacing-md); }
.mt-lg { margin-top: var(--spacing-lg); }
.mt-xl { margin-top: var(--spacing-xl); }

.mb-sm { margin-bottom: var(--spacing-sm); }
.mb-md { margin-bottom: var(--spacing-md); }
.mb-lg { margin-bottom: var(--spacing-lg); }
.mb-xl { margin-bottom: var(--spacing-xl); }

.p-sm { padding: var(--spacing-sm); }
.p-md { padding: var(--spacing-md); }
.p-lg { padding: var(--spacing-lg); }
.p-xl { padding: var(--spacing-xl); }

.rounded-sm { border-radius: var(--radius-sm); }
.rounded-md { border-radius: var(--radius-md); }
.rounded-lg { border-radius: var(--radius-lg); }
.rounded-xl { border-radius: var(--radius-xl); }
.rounded-full { border-radius: var(--radius-full); }

.shadow-sm { box-shadow: var(--shadow-sm); }
.shadow { box-shadow: var(--shadow); }
.shadow-md { box-shadow: var(--shadow-md); }
.shadow-lg { box-shadow: var(--shadow-lg); }

.amount {
    font-family: var(--font-mono);
    font-weight: 600;
    text-align: right;
}

/* =====================================================================
   15. RESPONSIVE DESIGN
   ===================================================================== */
@media (max-width: 1024px) {
    .container {
        padding: 0 var(--spacing-md);
    }
}

@media (max-width: 768px) {
    .container { padding: 10px; }
    h1 { font-size: 24px; }
    .tabs, .filter-controls, .form-actions { flex-direction: column; }
    .tab-link { width: 100%; margin: 4px 0; }
    .card { padding: 20px; }
    .summary-cards, .dashboard-grid { grid-template-columns: 1fr; }
    .nav-links { display: none; flex-direction: column; width: 100%; margin-top: 1rem; }
    .nav-links.active { display: flex; }
    .nav-links a { width: 100%; justify-content: center; }
    .mobile-menu-toggle { display: block; }
    .user-details { display: none; }
}

/* ===== STUDENT FORM TABS ===== */
.student-form-tabs {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 20px;
    padding-bottom: 15px;
    border-bottom: 2px solid var(--border);
}

.student-tab-btn {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 10px 16px;
    background: var(--light);
    border: 1px solid var(--border);
    border-radius: 8px;
    cursor: pointer;
    font-size: 14px;
    font-weight: 500;
    color: var(--dark);
    transition: all 0.2s ease;
}

.student-tab-btn:hover {
    background: var(--primary);
    color: white;
    border-color: var(--primary);
}

.student-tab-btn.active {
    background: var(--primary);
    color: white;
    border-color: var(--primary);
}

.student-tab-btn i {
    font-size: 14px;
}

.student-form-section {
    display: none;
    animation: fadeIn 0.3s ease;
}

.student-form-section.active {
    display: block;
}

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

.student-form-section h4 {
    display: flex;
    align-items: center;
    gap: 8px;
    margin: 0 0 15px 0;
    padding: 10px 0;
    color: var(--primary);
    font-size: 16px;
    border-bottom: 1px solid var(--border);
}

.student-form-section h4 i {
    color: var(--secondary);
}

/* Form Grid Layouts */
.form-grid-2 {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 15px;
    margin-bottom: 15px;
}

.form-grid-3 {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 15px;
    margin-bottom: 15px;
}

/* Required field indicator */
.required {
    color: var(--danger);
    font-weight: bold;
}

/* Responsive adjustments for student form */
@media (max-width: 768px) {
    .student-form-tabs {
        flex-direction: column;
    }

    .student-tab-btn {
        width: 100%;
        justify-content: center;
    }

    .form-grid-2,
    .form-grid-3 {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 992px) {
    .form-grid-3 {
        grid-template-columns: repeat(2, 1fr);
    }
}