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

body {
    font-family: Arial, Helvetica, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    padding: 10px;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    background: white;
    border-radius: 20px;
    padding: 20px;
    box-shadow: 0 10px 40px rgba(0,0,0,0.2);
}

h1 {
    color: #667eea;
    text-align: center;
    margin-bottom: 20px;
    font-size: 2em;
}

h2 {
    color: #667eea;
    text-align: center;
    margin-bottom: 20px;
    font-size: 1.5em;
}

.grade-selector {
    text-align: center;
    margin-bottom: 20px;
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    justify-content: center;
    align-items: center;
}

.grade-selector label {
    font-size: 1em;
    color: #333;
    font-weight: bold;
}

.grade-selector select {
    padding: 8px 12px;
    font-size: 1em;
    border: 2px solid #667eea;
    border-radius: 10px;
    cursor: pointer;
    font-family: Arial, Helvetica, sans-serif;
}

.subject-buttons {
    display: flex;
    gap: 15px;
    justify-content: center;
    margin-bottom: 20px;
    flex-wrap: wrap;
}

.subject-btn {
    padding: 15px 30px;
    font-size: 1.3em;
    border: none;
    border-radius: 15px;
    cursor: pointer;
    transition: transform 0.2s;
    font-weight: bold;
    font-family: Arial, Helvetica, sans-serif;
}

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

.math-btn { background: #ff6b6b; color: white; }
.english-btn { background: #4ecdc4; color: white; }

.topic-options {
    display: none;
    text-align: center;
    margin-bottom: 20px;
}

.topic-grid {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    justify-content: center;
}

.topic-btn {
    padding: 12px 20px;
    font-size: 1em;
    border: none;
    border-radius: 15px;
    cursor: pointer;
    transition: transform 0.2s;
    font-weight: bold;
    color: white;
    font-family: Arial, Helvetica, sans-serif;
}

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

.question-area {
    display: none;
    text-align: center;
}

.question {
    font-size: 1.5em;
    color: #333;
    margin: 20px 0;
    min-height: 60px;
    font-family: Arial, Helvetica, sans-serif;
    font-weight: bold;
    font-style: normal;
    line-height: 1.4;
}

.answer-input {
    padding: 12px;
    font-size: 1.2em;
    border: 3px solid #667eea;
    border-radius: 10px;
    width: 100%;
    max-width: 300px;
    text-align: center;
    font-family: Arial, Helvetica, sans-serif;
}

.submit-btn {
    padding: 12px 30px;
    font-size: 1.1em;
    background: #51cf66;
    color: white;
    border: none;
    border-radius: 10px;
    cursor: pointer;
    margin: 10px 5px;
    font-weight: bold;
    font-family: Arial, Helvetica, sans-serif;
}

.submit-btn:hover { background: #40c057; }

.next-btn {
    padding: 12px 30px;
    font-size: 1.1em;
    background: #667eea;
    color: white;
    border: none;
    border-radius: 10px;
    cursor: pointer;
    margin: 10px 5px;
    font-weight: bold;
    font-family: Arial, Helvetica, sans-serif;
}

.feedback {
    font-size: 1.2em;
    margin: 15px 0;
    min-height: 40px;
    font-family: Arial, Helvetica, sans-serif;
}

.correct { color: #51cf66; }
.incorrect { color: #ff6b6b; }

.score {
    text-align: center;
    font-size: 1.1em;
    color: #667eea;
    margin-top: 15px;
    font-family: Arial, Helvetica, sans-serif;
    font-weight: bold;
}

.back-btn {
    background: #868e96;
    color: white;
    padding: 8px 15px;
    border: none;
    border-radius: 10px;
    cursor: pointer;
    font-size: 0.9em;
    margin-right: 5px;
    font-family: Arial, Helvetica, sans-serif;
}

.nav-buttons {
    margin-bottom: 15px;
    display: flex;
    flex-wrap: wrap;
    gap: 5px;
    justify-content: center;
}

.change-topic-btn {
    background: #5c7cfa;
    color: white;
    padding: 8px 15px;
    border: none;
    border-radius: 10px;
    cursor: pointer;
    font-size: 0.9em;
    margin-right: 5px;
    font-family: Arial, Helvetica, sans-serif;
}

.change-subject-btn {
    background: #ff6b6b;
    color: white;
    padding: 8px 15px;
    border: none;
    border-radius: 10px;
    cursor: pointer;
    font-size: 0.9em;
    font-family: Arial, Helvetica, sans-serif;
}

.options {
    display: flex;
    flex-direction: column;
    gap: 10px;
    max-width: 400px;
    margin: 15px auto;
}

.option-btn {
    padding: 12px;
    font-size: 1.1em;
    border: 3px solid #667eea;
    background: white;
    border-radius: 10px;
    cursor: pointer;
    transition: all 0.2s;
    font-family: Arial, Helvetica, sans-serif;
}

.option-btn:hover { background: #f0f0f0; }
.option-btn.selected { background: #667eea; color: white; }

/* Mobile responsiveness */
@media (max-width: 600px) {
    body {
        padding: 5px;
    }
    
    .container {
        padding: 15px;
        border-radius: 15px;
    }
    
    h1 {
        font-size: 1.5em;
        margin-bottom: 15px;
    }
    
    h2 {
        font-size: 1.2em;
    }
    
    .grade-selector {
        font-size: 0.9em;
    }
    
    .grade-selector select {
        padding: 6px 10px;
        font-size: 0.9em;
    }
    
    .subject-btn {
        padding: 12px 20px;
        font-size: 1.1em;
    }
    
    .topic-btn {
        padding: 10px 15px;
        font-size: 0.9em;
    }
    
    .question {
        font-size: 1.3em;
        margin: 15px 0;
    }
    
    .answer-input {
        font-size: 1.1em;
        padding: 10px;
    }
    
    .submit-btn, .next-btn {
        padding: 10px 20px;
        font-size: 1em;
    }
    
    .feedback {
        font-size: 1.1em;
    }
    
    .score {
        font-size: 1em;
    }
}