:root {
    --primary: #6366f1;
    --primary-dark: #4f46e5;
    --secondary: #22d3ee;
    --accent: #f472b6;
    --success: #22c55e;
    --warning: #f59e0b;
    --danger: #ef4444;
    --bg-dark: #0f172a;
    --bg-card: #1e293b;
    --bg-card-hover: #334155;
    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;
    --border: #334155;
    --glass-bg: rgba(30, 41, 59, 0.8);
    --glass-border: rgba(255, 255, 255, 0.1);
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: var(--bg-dark);
    color: var(--text-primary);
    min-height: 100vh;
    line-height: 1.6;
}

/* Animated background */
body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: 
        radial-gradient(ellipse at 20% 20%, rgba(99, 102, 241, 0.15) 0%, transparent 50%),
        radial-gradient(ellipse at 80% 80%, rgba(34, 211, 238, 0.1) 0%, transparent 50%),
        radial-gradient(ellipse at 50% 50%, rgba(244, 114, 182, 0.05) 0%, transparent 70%);
    z-index: -1;
    animation: bgPulse 10s ease-in-out infinite;
}

@keyframes bgPulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.7; }
}

/* Entry animation */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.animate-in {
    animation: fadeInUp 0.5s ease-out forwards;
    opacity: 0;
}


/* Header */
header {
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--glass-border);
    padding: 1rem 2rem;
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-content {
    max-width: 1400px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    text-decoration: none;
    color: var(--text-primary);
}

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

.logo-text {
    font-size: 1.5rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

nav ul {
    display: flex;
    list-style: none;
    gap: 1.5rem;
}

nav a {
    color: var(--text-secondary);
    text-decoration: none;
    padding: 0.5rem 1rem;
    border-radius: 0.5rem;
    transition: all 0.3s ease;
}

nav a:hover, nav a.active {
    color: var(--text-primary);
    background: var(--bg-card);
}

/* Main content */
main {
    max-width: 1400px;
    margin: 0 auto;
    padding: 2rem;
}

/* Page title */
.page-title {
    text-align: center;
    margin-bottom: 3rem;
}

.page-title h1 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.page-title p {
    color: var(--text-secondary);
    font-size: 1.1rem;
}

/* Lessons grid */
.lessons-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 1.5rem;
}

.lesson-card {
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    border: 1px solid var(--glass-border);
    border-radius: 1rem;
    padding: 1.5rem;
    transition: all 0.3s ease;
    cursor: pointer;
    text-decoration: none;
    color: inherit;
}

.lesson-card:hover {
    transform: translateY(-5px);
    border-color: var(--primary);
    box-shadow: 0 20px 40px rgba(99, 102, 241, 0.2);
}

.lesson-number {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 3rem;
    height: 3rem;
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    border-radius: 0.75rem;
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

.lesson-card h3 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.lesson-card p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 1rem;
}

.lesson-topics {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.topic-tag {
    background: var(--bg-card);
    padding: 0.25rem 0.75rem;
    border-radius: 1rem;
    font-size: 0.8rem;
    color: var(--text-muted);
}

/* Learning modes */
.modes-nav {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 2rem;
    flex-wrap: wrap;
    justify-content: center;
}

.mode-btn {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1.25rem;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 0.75rem;
    color: var(--text-secondary);
    text-decoration: none;
    transition: all 0.3s ease;
    font-size: 0.95rem;
}

.mode-btn:hover {
    background: var(--bg-card-hover);
    color: var(--text-primary);
    border-color: var(--primary);
}

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

.mode-btn .icon {
    font-size: 1.2rem;
}

/* Content sections */
.content-section {
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    border: 1px solid var(--glass-border);
    border-radius: 1rem;
    padding: 2rem;
    margin-bottom: 2rem;
}

.section-title {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 1.5rem;
    margin-bottom: 1.5rem;
    color: var(--primary);
}

.section-title .icon {
    font-size: 1.5rem;
}

/* Grammar tables */
.grammar-table {
    width: 100%;
    border-collapse: collapse;
    margin: 1rem 0;
}

.grammar-table th,
.grammar-table td {
    padding: 0.75rem 1rem;
    text-align: left;
    border: 1px solid var(--border);
}

.grammar-table th {
    background: var(--primary);
    color: white;
    font-weight: 600;
}

.grammar-table tr:nth-child(even) {
    background: var(--bg-card);
}

.grammar-table tr:hover {
    background: var(--bg-card-hover);
}

/* Vocabulary list */
.vocab-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
    gap: 1rem;
}

.vocab-item {
    background: var(--bg-card);
    padding: 1rem;
    border-radius: 0.75rem;
    border-left: 4px solid var(--secondary);
    transition: all 0.3s ease;
}

.vocab-item:hover {
    transform: translateX(5px);
    background: var(--bg-card-hover);
}

.vocab-spanish {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--secondary);
    margin-bottom: 0.25rem;
}

.vocab-polish {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* Flashcards */
.flashcards-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 2rem;
    padding: 2rem;
}

.flashcard {
    width: 100%;
    max-width: 500px;
    height: 300px;
    perspective: 1000px;
    cursor: pointer;
}

.flashcard-inner {
    width: 100%;
    height: 100%;
    position: relative;
    transform-style: preserve-3d;
    transition: transform 0.6s ease;
}

.flashcard.flipped .flashcard-inner {
    transform: rotateY(180deg);
}

.flashcard-front,
.flashcard-back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 2rem;
    border-radius: 1rem;
    text-align: center;
}

.flashcard-front {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
}

.flashcard-back {
    background: linear-gradient(135deg, var(--secondary) 0%, #0891b2 100%);
    transform: rotateY(180deg);
}

.flashcard-word {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

.flashcard-hint {
    font-size: 1rem;
    opacity: 0.8;
}

.flashcard-controls {
    display: flex;
    gap: 1rem;
}

.flashcard-btn {
    padding: 0.75rem 2rem;
    border: none;
    border-radius: 0.75rem;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.3s ease;
}

.flashcard-btn.prev,
.flashcard-btn.next {
    background: var(--bg-card);
    color: var(--text-primary);
    border: 1px solid var(--border);
}

.flashcard-btn:hover {
    transform: scale(1.05);
}

.flashcard-progress {
    color: var(--text-secondary);
    font-size: 1rem;
}

/* Quiz styles */
.quiz-container {
    max-width: 800px;
    margin: 0 auto;
}

.quiz-question {
    background: var(--bg-card);
    padding: 2rem;
    border-radius: 1rem;
    margin-bottom: 1.5rem;
}

.question-number {
    color: var(--primary);
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.question-text {
    font-size: 1.25rem;
    margin-bottom: 1.5rem;
}

.quiz-options {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.quiz-option {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem 1.5rem;
    background: var(--bg-dark);
    border: 2px solid var(--border);
    border-radius: 0.75rem;
    cursor: pointer;
    transition: all 0.3s ease;
}

.quiz-option:hover {
    border-color: var(--primary);
    background: var(--bg-card-hover);
}

.quiz-option.selected {
    border-color: var(--primary);
    background: rgba(99, 102, 241, 0.1);
}

.quiz-option.correct {
    border-color: var(--success);
    background: rgba(34, 197, 94, 0.1);
}

.quiz-option.incorrect {
    border-color: var(--danger);
    background: rgba(239, 68, 68, 0.1);
}

.option-letter {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 2rem;
    height: 2rem;
    background: var(--bg-card);
    border-radius: 0.5rem;
    font-weight: 600;
}

.quiz-feedback {
    padding: 1rem;
    border-radius: 0.75rem;
    margin-top: 1rem;
    display: none;
}

.quiz-feedback.show {
    display: block;
}

.quiz-feedback.correct {
    background: rgba(34, 197, 94, 0.1);
    border: 1px solid var(--success);
    color: var(--success);
}

.quiz-feedback.incorrect {
    background: rgba(239, 68, 68, 0.1);
    border: 1px solid var(--danger);
    color: var(--danger);
}

.quiz-submit {
    display: block;
    width: 100%;
    padding: 1rem;
    background: var(--primary);
    color: white;
    border: none;
    border-radius: 0.75rem;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    margin-top: 2rem;
}

.quiz-submit:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
}

.quiz-result {
    text-align: center;
    padding: 3rem;
    background: var(--bg-card);
    border-radius: 1rem;
    margin-top: 2rem;
}

.quiz-score {
    font-size: 4rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* Exercise styles */
.exercise-item {
    background: var(--bg-card);
    padding: 1.5rem;
    border-radius: 1rem;
    margin-bottom: 1rem;
}

.exercise-sentence {
    font-size: 1.1rem;
    margin-bottom: 1rem;
    line-height: 2;
}

.exercise-input {
    display: inline-block;
    min-width: 150px;
    padding: 0.5rem 1rem;
    background: var(--bg-dark);
    border: 2px solid var(--border);
    border-radius: 0.5rem;
    color: var(--text-primary);
    font-size: 1rem;
    text-align: center;
    transition: all 0.3s ease;
}

.exercise-input:focus {
    outline: none;
    border-color: var(--primary);
}

.exercise-input.correct {
    border-color: var(--success);
    background: rgba(34, 197, 94, 0.1);
}

.exercise-input.incorrect {
    border-color: var(--danger);
    background: rgba(239, 68, 68, 0.1);
}

.check-btn {
    padding: 0.5rem 1.5rem;
    background: var(--secondary);
    color: var(--bg-dark);
    border: none;
    border-radius: 0.5rem;
    cursor: pointer;
    font-weight: 600;
    margin-left: 1rem;
    transition: all 0.3s ease;
}

.check-btn:hover {
    transform: scale(1.05);
}

.hint-btn {
    padding: 0.5rem 1rem;
    background: var(--warning);
    color: var(--bg-dark);
    border: none;
    border-radius: 0.5rem;
    cursor: pointer;
    font-size: 0.9rem;
    margin-left: 0.5rem;
}

.exercise-hint {
    display: none;
    margin-top: 0.5rem;
    padding: 0.5rem;
    background: rgba(245, 158, 11, 0.1);
    border-radius: 0.5rem;
    color: var(--warning);
    font-size: 0.9rem;
}

.exercise-hint.show {
    display: block;
}

/* Summary cards */
.summary-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
}

.summary-card {
    background: var(--bg-card);
    border-radius: 1rem;
    padding: 1.5rem;
    border-left: 4px solid var(--primary);
}

.summary-card h4 {
    color: var(--primary);
    margin-bottom: 1rem;
    font-size: 1.1rem;
}

.summary-card ul {
    list-style: none;
}

.summary-card li {
    padding: 0.5rem 0;
    border-bottom: 1px solid var(--border);
    display: flex;
    justify-content: space-between;
}

.summary-card li:last-child {
    border-bottom: none;
}

/* Info boxes */
.info-box {
    padding: 1rem 1.5rem;
    border-radius: 0.75rem;
    margin: 1rem 0;
}

.info-box.tip {
    background: rgba(34, 197, 94, 0.1);
    border-left: 4px solid var(--success);
}

.info-box.warning {
    background: rgba(245, 158, 11, 0.1);
    border-left: 4px solid var(--warning);
}

.info-box.note {
    background: rgba(99, 102, 241, 0.1);
    border-left: 4px solid var(--primary);
}

.info-box-title {
    font-weight: 600;
    margin-bottom: 0.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    border-radius: 0.75rem;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
    border: none;
}

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

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
}

.btn-secondary {
    background: var(--bg-card);
    color: var(--text-primary);
    border: 1px solid var(--border);
}

.btn-secondary:hover {
    background: var(--bg-card-hover);
    border-color: var(--primary);
}

/* Navigation arrows */
.lesson-nav {
    display: flex;
    justify-content: space-between;
    margin-top: 3rem;
    padding-top: 2rem;
    border-top: 1px solid var(--border);
}

.nav-arrow {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 1rem 1.5rem;
    background: var(--bg-card);
    border-radius: 0.75rem;
    color: var(--text-primary);
    text-decoration: none;
    transition: all 0.3s ease;
}

.nav-arrow:hover {
    background: var(--primary);
}

/* Example sentences */
.example {
    background: var(--bg-card);
    padding: 1rem 1.5rem;
    border-radius: 0.75rem;
    margin: 0.75rem 0;
    border-left: 3px solid var(--accent);
}

.example-spanish {
    font-size: 1.1rem;
    font-weight: 500;
    color: var(--accent);
}

.example-polish {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-top: 0.25rem;
}

/* Responsive */
@media (max-width: 768px) {
    header {
        padding: 1rem;
    }
    
    .header-content {
        flex-direction: column;
        gap: 1rem;
    }
    
    nav ul {
        gap: 0.5rem;
    }
    
    main {
        padding: 1rem;
    }
    
    .page-title h1 {
        font-size: 1.75rem;
    }
    
    .lessons-grid {
        grid-template-columns: 1fr;
    }
    
    .modes-nav {
        flex-direction: column;
    }
    
    .mode-btn {
        justify-content: center;
    }
    
    .flashcard {
        height: 250px;
    }
    
    .flashcard-word {
        font-size: 1.5rem;
    }
}

/* Animations */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

.animate-in {
    animation: fadeIn 0.5s ease forwards;
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(-5px); }
    75% { transform: translateX(5px); }
}

.shake {
    animation: shake 0.3s ease;
}

@keyframes pulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.05); }
}

.pulse {
    animation: pulse 0.3s ease;
}

/* Conjugation highlight */
.conjugation-ending {
    color: var(--accent);
    font-weight: 700;
}

/* Progress bar */
.progress-bar {
    width: 100%;
    height: 8px;
    background: var(--bg-card);
    border-radius: 4px;
    overflow: hidden;
    margin: 1rem 0;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary) 0%, var(--secondary) 100%);
    border-radius: 4px;
    transition: width 0.5s ease;
}

/* Matching exercise */
.matching-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
}

.matching-item {
    padding: 1rem;
    background: var(--bg-card);
    border: 2px solid var(--border);
    border-radius: 0.75rem;
    cursor: pointer;
    text-align: center;
    transition: all 0.3s ease;
}

.matching-item:hover {
    border-color: var(--primary);
}

.matching-item.selected {
    border-color: var(--primary);
    background: rgba(99, 102, 241, 0.1);
}

.matching-item.matched {
    border-color: var(--success);
    background: rgba(34, 197, 94, 0.1);
    pointer-events: none;
}

/* Breadcrumb */
.breadcrumb {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
    color: var(--text-muted);
    font-size: 0.9rem;
}

.breadcrumb a {
    color: var(--text-secondary);
    text-decoration: none;
}

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

/* Scrollbar */
::-webkit-scrollbar {
    width: 10px;
}

::-webkit-scrollbar-track {
    background: var(--bg-dark);
}

::-webkit-scrollbar-thumb {
    background: var(--bg-card);
    border-radius: 5px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--bg-card-hover);
}

/* Exercise input states */
.exercise-input.almost {
    border-color: var(--warning);
    background: rgba(245, 158, 11, 0.1);
}

/* Answer feedback */
.answer-feedback {
    display: inline-block;
    margin-left: 0.5rem;
    font-size: 0.9rem;
    vertical-align: middle;
}

.answer-feedback .hint-text {
    color: var(--warning);
    font-style: italic;
}

.answer-feedback .correct-answer {
    color: var(--danger);
}

.answer-feedback .correct-answer strong {
    color: var(--success);
    font-weight: 600;
}

/* Shake animation for wrong answers */
@keyframes shake {
    0%, 100% { transform: translateX(0); }
    20%, 60% { transform: translateX(-5px); }
    40%, 80% { transform: translateX(5px); }
}

.exercise-input.shake {
    animation: shake 0.3s ease;
}

/* Better disabled state for flashcard buttons */
.flashcard-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
}

/* Progress bar for flashcards */
.progress-bar {
    width: 100%;
    max-width: 500px;
    height: 6px;
    background: var(--bg-card);
    border-radius: 3px;
    overflow: hidden;
    margin-bottom: 1rem;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    border-radius: 3px;
    transition: width 0.3s ease;
}