/**
 * ============================================================
 * MYSCHOOLEXAM - MODERN UI FRAMEWORK
 * ============================================================
 * Enhanced CSS with modern design patterns, animations,
 * responsive utilities, and accessibility improvements
 * Last Updated: September 1, 2026
 */

/* ============================================================
   DESIGN TOKENS & VARIABLES
   ============================================================ */

:root {
    /* Modern Color Palette */
    --color-primary-50: #f0f9ff;
    --color-primary-100: #e0f2fe;
    --color-primary-200: #bae6fd;
    --color-primary-300: #7dd3fc;
    --color-primary-400: #38bdf8;
    --color-primary-500: #0ea5e9;
    --color-primary-600: #0284c7;
    --color-primary-700: #0369a1;
    --color-primary-800: #075985;
    --color-primary-900: #0c3d66;

    --color-success-50: #f0fdf4;
    --color-success-500: #10b981;
    --color-success-600: #059669;
    --color-success-700: #047857;
    --color-success-900: #064e3b;

    --color-danger-50: #fef2f2;
    --color-danger-500: #ef4444;
    --color-danger-600: #dc2626;
    --color-danger-700: #b91c1c;
    --color-danger-900: #7f1d1d;

    --color-warning-50: #fffbeb;
    --color-warning-500: #f59e0b;
    --color-warning-600: #d97706;
    --color-warning-700: #b45309;
    --color-warning-900: #78350f;

    --color-neutral-50: #fafafa;
    --color-neutral-100: #f3f4f6;
    --color-neutral-200: #e5e7eb;
    --color-neutral-300: #d1d5db;
    --color-neutral-400: #9ca3af;
    --color-neutral-500: #6b7280;
    --color-neutral-600: #4b5563;
    --color-neutral-700: #374151;
    --color-neutral-800: #1f2937;
    --color-neutral-900: #111827;

    /* Semantic Colors */
    --color-text-primary: #111827;
    --color-text-secondary: #4b5563;
    --color-text-tertiary: #9ca3af;
    --color-text-inverse: #ffffff;

    --color-bg-primary: #ffffff;
    --color-bg-secondary: #f9fafb;
    --color-bg-tertiary: #f3f4f6;

    --color-border-light: #e5e7eb;
    --color-border-base: #d1d5db;
    --color-border-dark: #9ca3af;

    /* Spacing Scale (4px base) */
    --spacing-0: 0;
    --spacing-1: 0.25rem;  /* 4px */
    --spacing-2: 0.5rem;   /* 8px */
    --spacing-3: 0.75rem;  /* 12px */
    --spacing-4: 1rem;     /* 16px */
    --spacing-5: 1.25rem;  /* 20px */
    --spacing-6: 1.5rem;   /* 24px */
    --spacing-7: 1.75rem;  /* 28px */
    --spacing-8: 2rem;     /* 32px */
    --spacing-10: 2.5rem;  /* 40px */
    --spacing-12: 3rem;    /* 48px */
    --spacing-16: 4rem;    /* 64px */
    --spacing-20: 5rem;    /* 80px */

    /* Typography Scale */
    --font-size-xs: 0.75rem;    /* 12px */
    --font-size-sm: 0.875rem;   /* 14px */
    --font-size-base: 1rem;     /* 16px */
    --font-size-lg: 1.125rem;   /* 18px */
    --font-size-xl: 1.25rem;    /* 20px */
    --font-size-2xl: 1.5rem;    /* 24px */
    --font-size-3xl: 1.875rem;  /* 30px */
    --font-size-4xl: 2.25rem;   /* 36px */
    --font-size-5xl: 3rem;      /* 48px */

    --line-height-tight: 1.25;
    --line-height-normal: 1.5;
    --line-height-relaxed: 1.75;
    --line-height-loose: 2;

    /* Font Weights */
    --font-weight-light: 300;
    --font-weight-normal: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;
    --font-weight-extrabold: 800;

    /* Shadows */
    --shadow-none: 0;
    --shadow-xs: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-sm: 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);
    --shadow-inner: inset 0 2px 4px 0 rgba(0, 0, 0, 0.06);

    /* Radii */
    --radius-none: 0;
    --radius-xs: 0.125rem;   /* 2px */
    --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 ease-in-out;
    --transition-normal: 300ms ease-in-out;
    --transition-slow: 500ms ease-in-out;

    --easing-linear: linear;
    --easing-ease-in: cubic-bezier(0.4, 0, 1, 1);
    --easing-ease-out: cubic-bezier(0, 0, 0.2, 1);
    --easing-ease-in-out: cubic-bezier(0.4, 0, 0.2, 1);

    /* Z-Index Scale */
    --z-hide: -1;
    --z-base: 0;
    --z-dropdown: 10;
    --z-sticky: 20;
    --z-modal-backdrop: 30;
    --z-modal: 40;
    --z-popover: 50;
    --z-notification: 60;
    --z-tooltip: 70;

    /* Breakpoints (Mobile-First) */
    --breakpoint-sm: 640px;   /* Small devices */
    --breakpoint-md: 768px;   /* Tablets */
    --breakpoint-lg: 1024px;  /* Laptops */
    --breakpoint-xl: 1280px;  /* Desktops */
    --breakpoint-2xl: 1536px; /* Large desktops */
}

/* ============================================================
   GLOBAL STYLES
   ============================================================ */

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

body {
    margin: 0;
    padding: 0;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen',
        'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif;
    font-size: var(--font-size-base);
    line-height: var(--line-height-normal);
    color: var(--color-text-primary);
    background-color: var(--color-bg-primary);
    overflow-x: hidden;
}

* {
    box-sizing: border-box;
}

/* ============================================================
   UTILITY CLASSES
   ============================================================ */

/* Display Utilities */
.d-none { display: none !important; }
.d-inline { display: inline !important; }
.d-inline-block { display: inline-block !important; }
.d-block { display: block !important; }
.d-flex { display: flex !important; }
.d-inline-flex { display: inline-flex !important; }
.d-grid { display: grid !important; }

/* Flex Utilities */
.flex-row { flex-direction: row; }
.flex-col { flex-direction: column; }
.flex-wrap { flex-wrap: wrap; }
.flex-nowrap { flex-wrap: nowrap; }
.justify-start { justify-content: flex-start; }
.justify-center { justify-content: center; }
.justify-end { justify-content: flex-end; }
.justify-between { justify-content: space-between; }
.justify-around { justify-content: space-around; }
.items-start { align-items: flex-start; }
.items-center { align-items: center; }
.items-end { align-items: flex-end; }
.items-stretch { align-items: stretch; }
.gap-0 { gap: var(--spacing-0); }
.gap-1 { gap: var(--spacing-1); }
.gap-2 { gap: var(--spacing-2); }
.gap-3 { gap: var(--spacing-3); }
.gap-4 { gap: var(--spacing-4); }
.gap-6 { gap: var(--spacing-6); }
.gap-8 { gap: var(--spacing-8); }

/* Spacing Utilities */
.p-0 { padding: 0; }
.p-1 { padding: var(--spacing-1); }
.p-2 { padding: var(--spacing-2); }
.p-3 { padding: var(--spacing-3); }
.p-4 { padding: var(--spacing-4); }
.p-6 { padding: var(--spacing-6); }
.p-8 { padding: var(--spacing-8); }

.m-0 { margin: 0; }
.m-1 { margin: var(--spacing-1); }
.m-2 { margin: var(--spacing-2); }
.m-3 { margin: var(--spacing-3); }
.m-4 { margin: var(--spacing-4); }
.m-6 { margin: var(--spacing-6); }
.m-8 { margin: var(--spacing-8); }

.mx-auto { margin-left: auto; margin-right: auto; }
.my-auto { margin-top: auto; margin-bottom: auto; }

/* Size Utilities */
.w-full { width: 100%; }
.w-auto { width: auto; }
.h-auto { height: auto; }
.h-full { height: 100%; }
.h-screen { height: 100vh; }
.max-w-full { max-width: 100%; }
.max-w-container { max-width: 1280px; }

/* Text Utilities */
.text-left { text-align: left; }
.text-center { text-align: center; }
.text-right { text-align: right; }
.text-justify { text-align: justify; }

.text-xs { font-size: var(--font-size-xs); }
.text-sm { font-size: var(--font-size-sm); }
.text-base { font-size: var(--font-size-base); }
.text-lg { font-size: var(--font-size-lg); }
.text-xl { font-size: var(--font-size-xl); }
.text-2xl { font-size: var(--font-size-2xl); }
.text-3xl { font-size: var(--font-size-3xl); }
.text-4xl { font-size: var(--font-size-4xl); }

.font-light { font-weight: var(--font-weight-light); }
.font-normal { font-weight: var(--font-weight-normal); }
.font-medium { font-weight: var(--font-weight-medium); }
.font-semibold { font-weight: var(--font-weight-semibold); }
.font-bold { font-weight: var(--font-weight-bold); }
.font-extrabold { font-weight: var(--font-weight-extrabold); }

.leading-tight { line-height: var(--line-height-tight); }
.leading-normal { line-height: var(--line-height-normal); }
.leading-relaxed { line-height: var(--line-height-relaxed); }
.leading-loose { line-height: var(--line-height-loose); }

.text-primary { color: var(--color-primary-600); }
.text-secondary { color: var(--color-text-secondary); }
.text-tertiary { color: var(--color-text-tertiary); }
.text-success { color: var(--color-success-600); }
.text-danger { color: var(--color-danger-600); }
.text-warning { color: var(--color-warning-600); }

/* Background Utilities */
.bg-primary { background-color: var(--color-primary-600); color: white; }
.bg-secondary { background-color: var(--color-bg-secondary); }
.bg-tertiary { background-color: var(--color-bg-tertiary); }
.bg-success { background-color: var(--color-success-50); color: var(--color-success-700); }
.bg-danger { background-color: var(--color-danger-50); color: var(--color-danger-700); }
.bg-warning { background-color: var(--color-warning-50); color: var(--color-warning-700); }

/* Border Utilities */
.border { border: 1px solid var(--color-border-base); }
.border-t { border-top: 1px solid var(--color-border-base); }
.border-b { border-bottom: 1px solid var(--color-border-base); }
.border-l { border-left: 1px solid var(--color-border-base); }
.border-r { border-right: 1px solid var(--color-border-base); }

.rounded-none { border-radius: var(--radius-none); }
.rounded-xs { border-radius: var(--radius-xs); }
.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-2xl { border-radius: var(--radius-2xl); }
.rounded-full { border-radius: var(--radius-full); }

/* Shadow Utilities */
.shadow-none { box-shadow: var(--shadow-none); }
.shadow-xs { box-shadow: var(--shadow-xs); }
.shadow-sm { box-shadow: var(--shadow-sm); }
.shadow-md { box-shadow: var(--shadow-md); }
.shadow-lg { box-shadow: var(--shadow-lg); }
.shadow-xl { box-shadow: var(--shadow-xl); }
.shadow-2xl { box-shadow: var(--shadow-2xl); }

/* Opacity Utilities */
.opacity-0 { opacity: 0; }
.opacity-25 { opacity: 0.25; }
.opacity-50 { opacity: 0.5; }
.opacity-75 { opacity: 0.75; }
.opacity-100 { opacity: 1; }

/* ============================================================
   MODERN COMPONENT STYLES
   ============================================================ */

/* Buttons with Modern Design */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-2);
    padding: var(--spacing-3) var(--spacing-4);
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-semibold);
    border: none;
    border-radius: var(--radius-lg);
    cursor: pointer;
    transition: all var(--transition-normal);
    outline: none;
    position: relative;
    overflow: hidden;
}

.btn:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn:active:not(:disabled) {
    transform: translateY(0);
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.btn-primary {
    background-color: var(--color-primary-600);
    color: white;
}

.btn-primary:hover:not(:disabled) {
    background-color: var(--color-primary-700);
}

.btn-secondary {
    background-color: var(--color-neutral-100);
    color: var(--color-text-primary);
    border: 1px solid var(--color-border-base);
}

.btn-secondary:hover:not(:disabled) {
    background-color: var(--color-neutral-200);
}

.btn-success {
    background-color: var(--color-success-600);
    color: white;
}

.btn-danger {
    background-color: var(--color-danger-600);
    color: white;
}

.btn-warning {
    background-color: var(--color-warning-600);
    color: white;
}

.btn-sm {
    padding: var(--spacing-2) var(--spacing-3);
    font-size: var(--font-size-sm);
}

.btn-lg {
    padding: var(--spacing-4) var(--spacing-6);
    font-size: var(--font-size-lg);
}

.btn-full {
    width: 100%;
}

/* Form Elements */
.form-group {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-2);
    margin-bottom: var(--spacing-4);
}

.form-label {
    font-weight: var(--font-weight-semibold);
    color: var(--color-text-primary);
    font-size: var(--font-size-sm);
}

.form-input,
.form-select,
.form-textarea {
    padding: var(--spacing-3) var(--spacing-4);
    border: 1px solid var(--color-border-base);
    border-radius: var(--radius-lg);
    font-size: var(--font-size-base);
    font-family: inherit;
    transition: all var(--transition-normal);
    background-color: var(--color-bg-primary);
    color: var(--color-text-primary);
}

.form-input:focus,
.form-select:focus,
.form-textarea:focus {
    outline: none;
    border-color: var(--color-primary-600);
    box-shadow: 0 0 0 3px rgba(6, 132, 199, 0.1);
}

.form-input:disabled,
.form-select:disabled,
.form-textarea:disabled {
    background-color: var(--color-bg-tertiary);
    color: var(--color-text-tertiary);
    cursor: not-allowed;
}

.form-error {
    display: flex;
    align-items: center;
    gap: var(--spacing-2);
    padding: var(--spacing-2) var(--spacing-3);
    background-color: var(--color-danger-50);
    color: var(--color-danger-700);
    border-radius: var(--radius-md);
    font-size: var(--font-size-sm);
    border-left: 4px solid var(--color-danger-600);
}

.form-success {
    display: flex;
    align-items: center;
    gap: var(--spacing-2);
    padding: var(--spacing-2) var(--spacing-3);
    background-color: var(--color-success-50);
    color: var(--color-success-700);
    border-radius: var(--radius-md);
    font-size: var(--font-size-sm);
    border-left: 4px solid var(--color-success-600);
}

/* Cards */
.card {
    background-color: var(--color-bg-primary);
    border: 1px solid var(--color-border-base);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-sm);
    padding: var(--spacing-6);
    transition: all var(--transition-normal);
}

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

.card-header {
    border-bottom: 1px solid var(--color-border-base);
    padding-bottom: var(--spacing-4);
    margin-bottom: var(--spacing-4);
}

.card-body {
    flex: 1;
}

.card-footer {
    border-top: 1px solid var(--color-border-base);
    padding-top: var(--spacing-4);
    margin-top: var(--spacing-4);
}

/* Badges */
.badge {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-2);
    padding: var(--spacing-1) var(--spacing-3);
    border-radius: var(--radius-full);
    font-size: var(--font-size-xs);
    font-weight: var(--font-weight-semibold);
}

.badge-primary {
    background-color: var(--color-primary-100);
    color: var(--color-primary-700);
}

.badge-success {
    background-color: var(--color-success-100);
    color: var(--color-success-700);
}

.badge-danger {
    background-color: var(--color-danger-100);
    color: var(--color-danger-700);
}

.badge-warning {
    background-color: var(--color-warning-100);
    color: var(--color-warning-700);
}

/* Loading States */
@keyframes spin {
    to { transform: rotate(360deg); }
}

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.5; }
}

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

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.animate-spin {
    animation: spin 1s linear infinite;
}

.animate-pulse {
    animation: pulse 2s cubic-bezier(0.4, 0, 0.6, 1) infinite;
}

.animate-slideInUp {
    animation: slideInUp var(--transition-normal) ease-out;
}

.animate-fadeIn {
    animation: fadeIn var(--transition-normal) ease-out;
}

/* Loading Spinner */
.spinner {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid var(--color-neutral-200);
    border-top-color: var(--color-primary-600);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

/* ============================================================
   RESPONSIVE UTILITIES
   ============================================================ */

@media (max-width: 768px) {
    .hidden-mobile { display: none !important; }
    .text-sm-center { text-align: center; }
    .flex-mobile-col { flex-direction: column; }
}

@media (min-width: 768px) {
    .hidden-desktop { display: none !important; }
}

/* ============================================================
   ACCESSIBILITY
   ============================================================ */

/* Focus visible for keyboard navigation */
.btn:focus-visible,
.form-input:focus-visible,
.form-select:focus-visible,
a:focus-visible {
    outline: 2px solid var(--color-primary-600);
    outline-offset: 2px;
}

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

/* Reduce motion for users who prefer it */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* High contrast mode support */
@media (prefers-contrast: more) {
    .card {
        border-width: 2px;
    }

    .btn {
        border: 2px solid currentColor;
    }
}

/* Dark mode support (optional) */
@media (prefers-color-scheme: dark) {
    :root {
        --color-text-primary: #f5f5f5;
        --color-text-secondary: #d1d5db;
        --color-bg-primary: #1f2937;
        --color-bg-secondary: #111827;
        --color-bg-tertiary: #0f1419;
        --color-border-base: #374151;
    }
}