/* Reset and base styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Helvetica Neue', Arial, sans-serif;
    background: #f8f9fa;
    color: #212529;
    line-height: 1.6;
    font-weight: 400;
}

.container {
    max-width: 600px;
    margin: 0 auto;
    padding: 20px;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header styles */
header {
    margin-bottom: 40px;
    padding: 40px 20px;
    background: #ffffff;
    border-bottom: 3px solid #000000;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    max-width: 100%;
}

.title-section {
    flex: 1;
    text-align: center;
}

.language-toggle {
    background: #000000;
    color: #ffffff;
    border: 2px solid #000000;
    padding: 8px 16px;
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    min-width: 40px;
}

.language-toggle:hover {
    background: #ffffff;
    color: #000000;
}

header h1 {
    font-size: 2.5rem;
    color: #000000;
    margin-bottom: 10px;
    font-weight: 700;
    letter-spacing: -0.02em;
    text-transform: uppercase;
}

.subtitle {
    font-size: 1.1rem;
    color: #6c757d;
    font-weight: 400;
    text-transform: uppercase;
    letter-spacing: 0.1em;
}

/* Main content */
main {
    flex: 1;
    display: flex;
    flex-direction: column;
}

/* Screen management */
.screen {
    display: none;
    background: #ffffff;
    border: 2px solid #000000;
    padding: 40px;
    margin-bottom: 20px;
}

.screen.active {
    display: block;
}

/* Welcome screen */
.welcome-content {
    text-align: center;
}

.welcome-content h2 {
    font-size: 2rem;
    color: #000000;
    margin-bottom: 30px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: -0.01em;
}

.welcome-content p {
    font-size: 1.2rem;
    color: #495057;
    margin-bottom: 50px;
    font-weight: 400;
}

/* Difficulty buttons */
.difficulty-buttons {
    display: flex;
    flex-direction: column;
    gap: 15px;
    margin-bottom: 50px;
}

.difficulty-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 25px;
    border: 2px solid #000000;
    background: #ffffff;
    font-size: 1.3rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.difficulty-btn.easy {
    border-color: #000000;
    color: #000000;
}

.difficulty-btn.easy:hover {
    background: #00933c;
    border-color: #00933c;
    color: #ffffff;
}

.difficulty-btn.easy:hover .difficulty-text {
    color: #ffffff;
}

.difficulty-btn.normal {
    border-color: #000000;
    color: #000000;
}

.difficulty-btn.normal:hover {
    background: #ff6319;
    border-color: #ff6319;
    color: #ffffff;
}

.difficulty-btn.normal:hover .difficulty-text {
    color: #ffffff;
}

.difficulty-btn.hard {
    border-color: #000000;
    color: #000000;
}

.difficulty-btn.hard:hover {
    background: #ee352e;
    border-color: #ee352e;
    color: #ffffff;
}

.difficulty-btn.hard:hover .difficulty-text {
    color: #ffffff;
}



/* Instructions */
.instructions {
    text-align: left;
    background: #f8f9fa;
    padding: 30px;
    border: 1px solid #dee2e6;
}

.instructions h3 {
    font-size: 1.2rem;
    color: #000000;
    margin-bottom: 20px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.instructions ul {
    list-style: none;
    padding-left: 0;
}

.instructions li {
    font-size: 1.1rem;
    color: #495057;
    margin-bottom: 12px;
    padding-left: 30px;
    position: relative;
    font-weight: 400;
}

.instructions li:before {
    content: "•";
    position: absolute;
    left: 0;
    color: #000000;
    font-weight: bold;
    font-size: 1.5rem;
    line-height: 1;
}

/* Quiz screen */
.quiz-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 40px;
    flex-wrap: wrap;
    gap: 20px;
    padding-bottom: 20px;
    border-bottom: 1px solid #dee2e6;
}

.progress-info {
    flex: 1;
    min-width: 200px;
}

#question-counter {
    font-size: 1.1rem;
    color: #000000;
    font-weight: 600;
    display: block;
    margin-bottom: 10px;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.progress-bar {
    width: 100%;
    height: 8px;
    background: #e9ecef;
    border: 1px solid #dee2e6;
}

#progress-fill {
    height: 100%;
    background: #000000;
    width: 0%;
    transition: width 0.3s ease;
}

.score-info {
    text-align: right;
}

#current-score {
    font-size: 1.1rem;
    color: #000000;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

/* Question container */
.question-container {
    margin-bottom: 40px;
}

#question-text {
    font-size: 1.6rem;
    color: #000000;
    margin-bottom: 40px;
    line-height: 1.4;
    font-weight: 500;
}

/* Options */
.options-container {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.option-btn {
    display: flex;
    align-items: center;
    gap: 20px;
    padding: 20px 25px;
    border: 2px solid #dee2e6;
    background: #ffffff;
    cursor: pointer;
    transition: all 0.2s ease;
    font-size: 1.1rem;
    text-align: left;
    min-height: 60px;
}

.option-btn:hover {
    border-color: #000000;
    background: #f8f9fa;
}

.option-btn.selected {
    border-color: #000000;
    background: #f8f9fa;
}

.option-btn.correct {
    border-color: #00933c;
    background: #ffffff;
}

.option-btn.incorrect {
    border-color: #dc3545;
    background: #ffffff;
}

.option-letter {
    background: #000000;
    color: #ffffff;
    width: 35px;
    height: 35px;
    border-radius: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
    font-size: 1rem;
    flex-shrink: 0;
    text-transform: uppercase;
}

.option-btn.selected .option-letter {
    background: #000000;
}

.option-btn.correct .option-letter {
    background: #00933c;
}

.option-btn.incorrect .option-letter {
    background: #dc3545;
}

.option-text {
    flex: 1;
    font-weight: 400;
    color: #212529;
}

/* Quiz controls */
.quiz-controls {
    text-align: center;
    padding-top: 30px;
    border-top: 1px solid #dee2e6;
}

.next-btn {
    background: #000000;
    color: #ffffff;
    border: 2px solid #000000;
    padding: 18px 40px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.next-btn:hover:not(:disabled) {
    background: #ffffff;
    color: #000000;
}

.next-btn:disabled {
    background: #6c757d;
    border-color: #6c757d;
    cursor: not-allowed;
}

/* Results screen */
.results-content {
    text-align: center;
}

.results-content h2 {
    font-size: 2rem;
    color: #000000;
    margin-bottom: 40px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: -0.01em;
}

.score-display {
    margin-bottom: 40px;
    padding: 40px;
    border: 2px solid #000000;
    background: #f8f9fa;
}

.final-score {
    font-size: 1.5rem;
    color: #000000;
    margin-bottom: 20px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.score-percentage {
    font-size: 3.5rem;
    font-weight: 700;
    color: #000000;
    margin-bottom: 20px;
    letter-spacing: -0.02em;
}

.performance-message {
    margin-bottom: 50px;
}

#performance-text {
    font-size: 1.2rem;
    color: #495057;
    font-weight: 400;
}

.action-buttons {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.action-btn {
    padding: 18px 30px;
    border: 2px solid #000000;
    background: #ffffff;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.action-btn:hover {
    background: #000000;
    color: #ffffff;
}

.action-btn.primary {
    background: #000000;
    color: #ffffff;
}

.action-btn.primary:hover {
    background: #ffffff;
    color: #000000;
}

.action-btn.secondary {
    background: #ffffff;
    color: #000000;
}

.action-btn.secondary:hover {
    background: #000000;
    color: #ffffff;
}

/* Footer */
footer {
    text-align: center;
    margin-top: auto;
    padding: 30px 20px;
    background: #ffffff;
    border-top: 1px solid #dee2e6;
}

footer p {
    font-size: 1rem;
    color: #6c757d;
    font-weight: 400;
    text-transform: uppercase;
    letter-spacing: 0.1em;
}

/* Mobile responsiveness */
@media (max-width: 768px) {
    .container {
        padding: 15px;
    }
    
    header {
        padding: 30px 15px;
    }
    
    .header-content {
        flex-direction: column;
        align-items: center;
        gap: 20px;
    }
    
    .title-section {
        order: 2;
    }
    
    .language-toggle {
        order: 1;
        align-self: flex-end;
    }
    
    header h1 {
        font-size: 2rem;
    }
    
    .subtitle {
        font-size: 1rem;
    }
    
    .screen {
        padding: 25px;
    }
    
    .welcome-content h2 {
        font-size: 1.6rem;
    }
    
    .welcome-content p {
        font-size: 1.1rem;
    }
    
    .difficulty-btn {
        padding: 20px;
        font-size: 1.1rem;
    }
    
    .quiz-header {
        flex-direction: column;
        align-items: stretch;
    }
    
    .progress-info, .score-info {
        text-align: center;
    }
    
    #question-text {
        font-size: 1.4rem;
    }
    
    .option-btn {
        padding: 15px 20px;
        font-size: 1rem;
        min-height: 55px;
    }
    
    .option-letter {
        width: 30px;
        height: 30px;
        font-size: 0.9rem;
    }
    
    .next-btn {
        padding: 15px 30px;
        font-size: 1rem;
    }
    
    .results-content h2 {
        font-size: 1.6rem;
    }
    
    .final-score {
        font-size: 1.3rem;
    }
    
    .score-percentage {
        font-size: 2.5rem;
    }
    
    #performance-text {
        font-size: 1.1rem;
    }
    
    .action-btn {
        padding: 15px 25px;
        font-size: 1rem;
    }
}

@media (max-width: 480px) {
    header h1 {
        font-size: 1.8rem;
    }
    
    .welcome-content h2 {
        font-size: 1.4rem;
    }
    
    #question-text {
        font-size: 1.2rem;
    }
    
    .option-btn {
        padding: 12px 15px;
        font-size: 0.95rem;
    }
    
    .option-letter {
        width: 28px;
        height: 28px;
        font-size: 0.85rem;
    }
}