/**
 * Modern Design System for Okuuchu
 * Современная дизайн-система для образовательной платформы
 */

/* ===== CSS CUSTOM PROPERTIES ===== */
:root {
    /* Primary Colors */
    --primary-50: #f0f9ff;
    --primary-100: #e0f2fe;
    --primary-200: #bae6fd;
    --primary-300: #7dd3fc;
    --primary-400: #38bdf8;
    --primary-500: #0ea5e9;
    --primary-600: #0284c7;
    --primary-700: #0369a1;
    --primary-800: #075985;
    --primary-900: #0c4a6e;
    
    /* Neutral Colors */
    --neutral-50: #fafafa;
    --neutral-100: #f5f5f5;
    --neutral-200: #e5e5e5;
    --neutral-300: #d4d4d4;
    --neutral-400: #a3a3a3;
    --neutral-500: #737373;
    --neutral-600: #525252;
    --neutral-700: #404040;
    --neutral-800: #262626;
    --neutral-900: #171717;
    
    /* Success Colors */
    --success-50: #f0fdf4;
    --success-100: #dcfce7;
    --success-200: #bbf7d0;
    --success-300: #86efac;
    --success-400: #4ade80;
    --success-500: #22c55e;
    --success-600: #16a34a;
    --success-700: #15803d;
    --success-800: #166534;
    --success-900: #14532d;
    
    /* Warning Colors */
    --warning-50: #fffbeb;
    --warning-100: #fef3c7;
    --warning-200: #fde68a;
    --warning-300: #fcd34d;
    --warning-400: #fbbf24;
    --warning-500: #f59e0b;
    --warning-600: #d97706;
    --warning-700: #b45309;
    --warning-800: #92400e;
    --warning-900: #78350f;
    
    /* Error Colors */
    --error-50: #fef2f2;
    --error-100: #fee2e2;
    --error-200: #fecaca;
    --error-300: #fca5a5;
    --error-400: #f87171;
    --error-500: #ef4444;
    --error-600: #dc2626;
    --error-700: #b91c1c;
    --error-800: #991b1b;
    --error-900: #7f1d1d;
    
    /* Typography */
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', 'Monaco', 'Cascadia Code', monospace;
    
    /* Spacing Scale */
    --space-1: 0.25rem;   /* 4px */
    --space-2: 0.5rem;    /* 8px */
    --space-3: 0.75rem;   /* 12px */
    --space-4: 1rem;      /* 16px */
    --space-5: 1.25rem;   /* 20px */
    --space-6: 1.5rem;    /* 24px */
    --space-8: 2rem;      /* 32px */
    --space-10: 2.5rem;   /* 40px */
    --space-12: 3rem;     /* 48px */
    --space-16: 4rem;     /* 64px */
    --space-20: 5rem;     /* 80px */
    --space-24: 6rem;     /* 96px */
    
    /* 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;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
    --shadow-2xl: 0 25px 50px -12px rgb(0 0 0 / 0.25);
    
    /* Transitions */
    --transition-fast: 150ms ease-in-out;
    --transition-normal: 250ms ease-in-out;
    --transition-slow: 350ms ease-in-out;
    
    /* 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;
}

/* ===== RESET & BASE STYLES ===== */
*,
*::before,
*::after {
    box-sizing: border-box;
}

html {
    font-size: 16px;
    line-height: 1.5;
    -webkit-text-size-adjust: 100%;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    margin: 0;
    font-family: var(--font-sans);
    font-size: 1rem;
    font-weight: 400;
    line-height: 1.6;
    color: var(--neutral-900);
    background-color: var(--neutral-50);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ===== TYPOGRAPHY ===== */
h1, h2, h3, h4, h5, h6 {
    margin: 0;
    font-weight: 600;
    line-height: 1.25;
    color: var(--neutral-900);
}

h1 { font-size: 2.5rem; }    /* 40px */
h2 { font-size: 2rem; }      /* 32px */
h3 { font-size: 1.5rem; }    /* 24px */
h4 { font-size: 1.25rem; }   /* 20px */
h5 { font-size: 1.125rem; }  /* 18px */
h6 { font-size: 1rem; }      /* 16px */

p {
    margin: 0 0 var(--space-4) 0;
    color: var(--neutral-700);
}

a {
    color: var(--primary-600);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--primary-700);
    text-decoration: underline;
}

/* ===== LAYOUT COMPONENTS ===== */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--space-4);
}

.container-fluid {
    width: 100%;
    padding: 0 var(--space-4);
}

.grid {
    display: grid;
    gap: var(--space-6);
}

.grid-cols-1 { grid-template-columns: repeat(1, minmax(0, 1fr)); }
.grid-cols-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid-cols-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid-cols-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }

.flex {
    display: flex;
}

.flex-col {
    flex-direction: column;
}

.items-center {
    align-items: center;
}

.justify-center {
    justify-content: center;
}

.justify-between {
    justify-content: space-between;
}

.gap-2 { gap: var(--space-2); }
.gap-4 { gap: var(--space-4); }
.gap-6 { gap: var(--space-6); }
.gap-8 { gap: var(--space-8); }

/* ===== CARD COMPONENT ===== */
.card {
    background: white;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--neutral-200);
    overflow: hidden;
    transition: all var(--transition-normal);
}

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

.card-header {
    padding: var(--space-6);
    border-bottom: 1px solid var(--neutral-200);
    background: var(--neutral-50);
}

.card-body {
    padding: var(--space-6);
}

.card-footer {
    padding: var(--space-6);
    border-top: 1px solid var(--neutral-200);
    background: var(--neutral-50);
}

/* ===== BUTTON COMPONENTS ===== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-2);
    padding: var(--space-3) var(--space-6);
    font-size: 0.875rem;
    font-weight: 500;
    line-height: 1;
    text-align: center;
    text-decoration: none;
    border: 1px solid transparent;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
    user-select: none;
    white-space: nowrap;
}

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

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

.btn-primary:hover:not(:disabled) {
    background: var(--primary-700);
    border-color: var(--primary-700);
    color: white;
    text-decoration: none;
}

.btn-secondary {
    background: var(--neutral-100);
    color: var(--neutral-900);
    border-color: var(--neutral-300);
}

.btn-secondary:hover:not(:disabled) {
    background: var(--neutral-200);
    border-color: var(--neutral-400);
    color: var(--neutral-900);
    text-decoration: none;
}

.btn-outline {
    background: transparent;
    color: var(--primary-600);
    border-color: var(--primary-600);
}

.btn-outline:hover:not(:disabled) {
    background: var(--primary-600);
    color: white;
    text-decoration: none;
}

.btn-ghost {
    background: transparent;
    color: var(--neutral-600);
    border-color: transparent;
}

.btn-ghost:hover:not(:disabled) {
    background: var(--neutral-100);
    color: var(--neutral-900);
    text-decoration: none;
}

.btn-sm {
    padding: var(--space-2) var(--space-4);
    font-size: 0.75rem;
}

.btn-lg {
    padding: var(--space-4) var(--space-8);
    font-size: 1rem;
}

/* ===== FORM COMPONENTS ===== */
.form-group {
    margin-bottom: var(--space-6);
}

.form-label {
    display: block;
    margin-bottom: var(--space-2);
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--neutral-700);
}

.form-control {
    display: block;
    width: 100%;
    padding: var(--space-3) var(--space-4);
    font-size: 0.875rem;
    line-height: 1.5;
    color: var(--neutral-900);
    background: white;
    border: 1px solid var(--neutral-300);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.form-control:focus {
    outline: none;
    border-color: var(--primary-500);
    box-shadow: 0 0 0 3px rgb(14 165 233 / 0.1);
}

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

.form-control.is-invalid {
    border-color: var(--error-500);
}

.form-control.is-invalid:focus {
    border-color: var(--error-500);
    box-shadow: 0 0 0 3px rgb(239 68 68 / 0.1);
}

.invalid-feedback {
    display: block;
    margin-top: var(--space-1);
    font-size: 0.75rem;
    color: var(--error-600);
}

/* ===== NAVIGATION ===== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: var(--z-fixed);
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--neutral-200);
    box-shadow: var(--shadow-sm);
}

.navbar-brand {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--neutral-900);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: var(--space-2);
}

.navbar-brand:hover {
    color: var(--primary-600);
    text-decoration: none;
}

.navbar-nav {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    list-style: none;
    margin: 0;
    padding: 0;
}

.nav-link {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    padding: var(--space-3) var(--space-4);
    color: var(--neutral-600);
    text-decoration: none;
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
    font-weight: 500;
}

.nav-link:hover {
    color: var(--primary-600);
    background: var(--primary-50);
    text-decoration: none;
}

.nav-link.active {
    color: var(--primary-600);
    background: var(--primary-50);
}

/* ===== DROPDOWN ===== */
.dropdown {
    position: relative;
}

.dropdown-menu {
    position: absolute;
    top: 100%;
    left: 0;
    z-index: var(--z-dropdown);
    min-width: 200px;
    padding: var(--space-2);
    margin-top: var(--space-2);
    background: white;
    border: 1px solid var(--neutral-200);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: all var(--transition-fast);
}

.dropdown:hover .dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.dropdown-item {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    padding: var(--space-3) var(--space-4);
    color: var(--neutral-700);
    text-decoration: none;
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
    font-size: 0.875rem;
}

.dropdown-item:hover {
    background: var(--neutral-100);
    color: var(--neutral-900);
    text-decoration: none;
}

/* ===== BADGE ===== */
.badge {
    display: inline-flex;
    align-items: center;
    padding: var(--space-1) var(--space-2);
    font-size: 0.75rem;
    font-weight: 500;
    line-height: 1;
    border-radius: var(--radius-full);
    text-transform: uppercase;
    letter-spacing: 0.025em;
}

.badge-primary {
    background: var(--primary-100);
    color: var(--primary-800);
}

.badge-success {
    background: var(--success-100);
    color: var(--success-800);
}

.badge-warning {
    background: var(--warning-100);
    color: var(--warning-800);
}

.badge-error {
    background: var(--error-100);
    color: var(--error-800);
}

/* ===== ALERT ===== */
.alert {
    padding: var(--space-4);
    margin-bottom: var(--space-4);
    border: 1px solid transparent;
    border-radius: var(--radius-lg);
    font-size: 0.875rem;
}

.alert-success {
    background: var(--success-50);
    border-color: var(--success-200);
    color: var(--success-800);
}

.alert-warning {
    background: var(--warning-50);
    border-color: var(--warning-200);
    color: var(--warning-800);
}

.alert-error {
    background: var(--error-50);
    border-color: var(--error-200);
    color: var(--error-800);
}

.alert-info {
    background: var(--primary-50);
    border-color: var(--primary-200);
    color: var(--primary-800);
}

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

.font-bold { font-weight: 700; }
.font-semibold { font-weight: 600; }
.font-medium { font-weight: 500; }

.text-sm { font-size: 0.875rem; }
.text-lg { font-size: 1.125rem; }
.text-xl { font-size: 1.25rem; }

.text-primary { color: var(--primary-600); }
.text-success { color: var(--success-600); }
.text-warning { color: var(--warning-600); }
.text-error { color: var(--error-600); }

.mb-0 { margin-bottom: 0; }
.mb-2 { margin-bottom: var(--space-2); }
.mb-4 { margin-bottom: var(--space-4); }
.mb-6 { margin-bottom: var(--space-6); }
.mb-8 { margin-bottom: var(--space-8); }

.mt-0 { margin-top: 0; }
.mt-2 { margin-top: var(--space-2); }
.mt-4 { margin-top: var(--space-4); }
.mt-6 { margin-top: var(--space-6); }
.mt-8 { margin-top: var(--space-8); }

.p-0 { padding: 0; }
.p-2 { padding: var(--space-2); }
.p-4 { padding: var(--space-4); }
.p-6 { padding: var(--space-6); }
.p-8 { padding: var(--space-8); }

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

.hidden { display: none; }
.block { display: block; }
.inline-block { display: inline-block; }
.flex { display: flex; }
.grid { display: grid; }

/* ===== RESPONSIVE DESIGN ===== */
@media (min-width: 640px) {
    .sm\:grid-cols-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
    .sm\:grid-cols-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}

@media (min-width: 768px) {
    .md\:grid-cols-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
    .md\:grid-cols-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
    .md\:grid-cols-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
}

@media (min-width: 1024px) {
    .lg\:grid-cols-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
    .lg\:grid-cols-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
    .lg\:grid-cols-5 { grid-template-columns: repeat(5, minmax(0, 1fr)); }
}

/* ===== ANIMATIONS ===== */
@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

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

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

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

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

.animate-slide-in-down {
    animation: slideInDown var(--transition-normal) ease-out;
}

/* ===== 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\:ring:focus {
    outline: 2px solid var(--primary-500);
    outline-offset: 2px;
}

/* ===== REDUCED MOTION ===== */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}