/* ===================================
   QuiziX CZ - Moderní CSS Design
   =================================== */

/* Reset a základní nastavení */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* Barvy */
    --primary: #6366f1;
    --primary-dark: #4f46e5;
    --primary-light: #818cf8;
    --secondary: #ec4899;
    --success: #10b981;
    --warning: #f59e0b;
    --danger: #ef4444;
    --dark: #1e293b;
    --light: #f8fafc;
    --gray: #64748b;
    --gray-light: #e2e8f0;
    --white: #ffffff;
    
    /* Gradient */
    --gradient-primary: linear-gradient(135deg, #6366f1 0%, #ec4899 100%);
    --gradient-success: linear-gradient(135deg, #10b981 0%, #059669 100%);
    --gradient-warning: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
    
    /* 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);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    
    /* Border radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
    
    /* Transitions */
    --transition: all 0.3s ease;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: var(--light);
    color: var(--dark);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

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

/* ===================================
   NAVIGACE
   =================================== */

.navbar {
    background: var(--white);
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 100;
    border-bottom: 1px solid var(--gray-light);
}

.nav-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md) 0;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    text-decoration: none;
    color: var(--dark);
    font-weight: 700;
    font-size: 1.5rem;
    transition: var(--transition);
}

.logo:hover {
    opacity: 0.8;
}

.logo-image {
    height: 45px;
    width: auto;
    object-fit: contain;
}

.logo-icon {
    font-size: 2rem;
}

.logo-text {
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-links {
    display: flex;
    gap: var(--spacing-md);
}

.nav-link {
    text-decoration: none;
    color: var(--gray);
    font-weight: 500;
    padding: 0.5rem 1rem;
    border-radius: var(--radius-md);
    transition: var(--transition);
}

.nav-link:hover,
.nav-link.active {
    color: var(--primary);
    background: rgba(99, 102, 241, 0.1);
}

/* ===================================
   HERO SEKCE
   =================================== */

.hero {
    position: relative;
    color: var(--white);
    padding: var(--spacing-xl) 0;
    text-align: center;
    min-height: 400px;
    display: flex;
    align-items: center;
    overflow: hidden;
}

.hero-with-image {
    min-height: 500px;
}

.hero-background {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0;
}

.hero-bg-image {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.hero-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.85) 0%, rgba(118, 75, 162, 0.85) 100%);
}

.hero > .container {
    position: relative;
    z-index: 1;
}

.hero-content {
    max-width: 800px;
    margin: 0 auto;
    position: relative;
    z-index: 1;
}

.hero-title {
    font-size: 3rem;
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: var(--spacing-md);
}

.gradient-text {
    background: linear-gradient(135deg, #fbbf24 0%, #f59e0b 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    display: inline-block;
}

.hero-subtitle {
    font-size: 1.25rem;
    opacity: 0.9;
    margin-bottom: var(--spacing-xl);
    line-height: 1.8;
}

.hero-stats {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-lg);
    max-width: 600px;
    margin: 0 auto;
}

.stat-item {
    background: rgba(255, 255, 255, 0.1);
    padding: var(--spacing-md);
    border-radius: var(--radius-xl);
    backdrop-filter: blur(10px);
}

.stat-number {
    font-size: 2.5rem;
    font-weight: 800;
    margin-bottom: 0.5rem;
}

.stat-label {
    font-size: 0.875rem;
    opacity: 0.8;
}

/* ===================================
   SEKCE S KVÍZY
   =================================== */

.quizzes-section {
    padding: var(--spacing-xl) 0;
    flex: 1;
}

.section-header {
    text-align: center;
    margin-bottom: var(--spacing-xl);
}

.section-title {
    font-size: 2.5rem;
    font-weight: 800;
    color: var(--dark);
    margin-bottom: var(--spacing-sm);
}

.section-subtitle {
    font-size: 1.125rem;
    color: var(--gray);
}

/* ===================================
   GRID KVÍZŮ
   =================================== */

.quiz-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: var(--spacing-lg);
}

.quiz-card {
    background: var(--white);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-md);
    overflow: hidden;
    transition: var(--transition);
    cursor: pointer;
    display: flex;
    flex-direction: column;
}

.quiz-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
}

.quiz-image {
    position: relative;
    width: 100%;
    height: 200px;
    overflow: hidden;
    background: var(--gradient-primary);
}

.quiz-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: var(--transition);
}

.quiz-card:hover .quiz-image img {
    transform: scale(1.05);
}

.quiz-placeholder {
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--gradient-primary);
}

.placeholder-icon {
    font-size: 4rem;
}

.quiz-badge {
    position: absolute;
    top: var(--spacing-sm);
    right: var(--spacing-sm);
    padding: 0.375rem 0.75rem;
    border-radius: var(--radius-lg);
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    background: var(--white);
    color: var(--dark);
}

.quiz-badge-lehka {
    background: var(--success);
    color: var(--white);
}

.quiz-badge-stredni {
    background: var(--warning);
    color: var(--white);
}

.quiz-badge-tezka {
    background: var(--danger);
    color: var(--white);
}

.quiz-content {
    padding: var(--spacing-md);
    display: flex;
    flex-direction: column;
    flex: 1;
}

.quiz-category {
    display: inline-block;
    color: var(--primary);
    font-size: 0.875rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: var(--spacing-xs);
}

.quiz-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--dark);
    margin-bottom: var(--spacing-sm);
    line-height: 1.3;
}

.quiz-description {
    color: var(--gray);
    margin-bottom: var(--spacing-md);
    line-height: 1.6;
    flex: 1;
}

.quiz-meta {
    display: flex;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
    padding-top: var(--spacing-sm);
    border-top: 1px solid var(--gray-light);
}

.meta-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--gray);
    font-size: 0.875rem;
}

.meta-icon {
    font-size: 1rem;
}

/* ===================================
   TLAČÍTKA
   =================================== */

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius-lg);
    font-weight: 600;
    font-size: 1rem;
    text-decoration: none;
    border: none;
    cursor: pointer;
    transition: var(--transition);
    text-align: center;
}

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

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

.btn-block {
    width: 100%;
}

.btn-icon {
    font-size: 1.25rem;
    transition: var(--transition);
}

.btn:hover .btn-icon {
    transform: translateX(3px);
}

/* ===================================
   PRÁZDNÝ STAV
   =================================== */

.empty-state {
    text-align: center;
    padding: var(--spacing-xl);
    background: var(--white);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-md);
}

.empty-icon {
    font-size: 4rem;
    margin-bottom: var(--spacing-md);
}

.empty-state h3 {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--dark);
    margin-bottom: var(--spacing-sm);
}

.empty-state p {
    color: var(--gray);
    margin-bottom: var(--spacing-lg);
}

/* ===================================
   FOOTER
   =================================== */

.footer {
    background: var(--dark);
    color: var(--white);
    padding: var(--spacing-xl) 0 var(--spacing-lg);
    margin-top: auto;
}

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

.footer-left .logo {
    color: var(--white);
    margin-bottom: var(--spacing-sm);
}

.footer-text {
    color: rgba(255, 255, 255, 0.7);
    font-size: 0.875rem;
}

.footer-right {
    text-align: right;
}

.footer-right p {
    color: rgba(255, 255, 255, 0.7);
    font-size: 0.875rem;
}

/* ===================================
   FILTRY TÉMAT A OBTÍŽNOSTI
   =================================== */

.topics-filter,
.difficulty-filter {
    background: var(--white);
    padding: var(--spacing-lg);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-md);
    margin-bottom: var(--spacing-lg);
}

.filter-title {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: var(--spacing-md);
    color: var(--dark);
}

.topics-buttons,
.difficulty-buttons {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
}

.topic-btn,
.diff-btn {
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius-lg);
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition);
    border: 2px solid var(--gray-light);
    background: var(--light);
    color: var(--dark);
    white-space: nowrap;
}

.topic-btn:hover,
.diff-btn:hover {
    border-color: var(--primary);
    background: rgba(99, 102, 241, 0.1);
    transform: translateY(-2px);
}

.topic-btn.active {
    background: var(--gradient-primary);
    color: var(--white);
    border-color: transparent;
}

.diff-btn.active {
    color: var(--white);
    border-color: transparent;
}

.diff-lehka.active {
    background: var(--success);
}

.diff-stredni.active {
    background: var(--warning);
}

.diff-tezka.active {
    background: var(--danger);
}

/* ===================================
   STRÁNKOVÁNÍ
   =================================== */

.pagination {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: var(--spacing-md);
    margin-top: var(--spacing-xl);
    padding: var(--spacing-lg);
    background: var(--white);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-md);
}

.pagination-info {
    font-weight: 600;
    color: var(--gray);
}

/* ===================================
   REKLAMNÍ BANNER
   =================================== */

.ad-banner-section {
    padding: var(--spacing-xl) 0;
    background: var(--light);
}

.ad-banner {
    background: var(--white);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-md);
    padding: var(--spacing-lg);
    text-align: center;
    border: 2px dashed var(--gray-light);
}

.ad-label {
    font-size: 0.75rem;
    color: var(--gray);
    text-transform: uppercase;
    letter-spacing: 0.1em;
    margin-bottom: var(--spacing-sm);
}

.ad-placeholder {
    min-height: 90px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    background: var(--light);
    border-radius: var(--radius-md);
    padding: var(--spacing-md);
}

.ad-placeholder p {
    margin: 0.25rem 0;
}

/* ===================================
   RESPONZIVITA - MOBILY
   =================================== */

@media (max-width: 768px) {
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-subtitle {
        font-size: 1rem;
    }
    
    .hero-with-image {
        min-height: 350px;
    }
    
    .hero-stats {
        grid-template-columns: 1fr;
        gap: var(--spacing-sm);
    }
    
    .stat-number {
        font-size: 2rem;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .quiz-grid {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        flex-direction: column;
        text-align: center;
        gap: var(--spacing-md);
    }
    
    .footer-right {
        text-align: center;
    }
    
    .nav-links {
        gap: var(--spacing-xs);
    }
    
    .nav-link {
        padding: 0.5rem;
        font-size: 0.875rem;
    }
    
    .topics-buttons,
    .difficulty-buttons {
        flex-direction: column;
    }
    
    .topic-btn,
    .diff-btn {
        width: 100%;
        text-align: center;
    }
    
    .pagination {
        flex-direction: column;
        gap: var(--spacing-sm);
    }
    
    .ad-placeholder {
        min-height: 100px;
    }
    
    .logo-image {
        height: 35px;
    }
}

@media (max-width: 480px) {
    .logo-text {
        display: none;
    }
    
    .hero-title {
        font-size: 1.5rem;
    }
    
    .container {
        padding: 0 var(--spacing-sm);
    }
}