:root {
    --primary: #4a90e2;
    --secondary: #4a5568;
    --tertiary: #6a93a2;
    --success: #2ecc71;
    --danger: #e74c3c;
    --bg: #f5f7fa;
    --card: #ffffff;
    --text: #333333;
}

body {
    font-family: 'Segoe UI', Arial, sans-serif;
    background-color: var(--bg);
    color: var(--text);
    margin: 0;
    padding: 20px;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    user-select: none;
}

.container {
    background-color: var(--card);
    border-radius: 12px;
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.08);
    width: 100%;
    max-width: 650px;
    padding: 30px;
    box-sizing: border-box;
}

h2, h3 { margin-top: 0; color: #2d3748; }

.set-grid {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.menu-select-btn {
    background-color: #f8fafc;
    border: 2px solid #e2e8f0;
    color: var(--text);
    padding: 16px 20px;
    font-size: 1.05rem;
    font-weight: 600;
    border-radius: 8px;
    cursor: pointer;
    text-align: left;
    transition: all 0.2s ease;
    width: 100%;
}

.menu-select-btn:hover {
    background-color: #ebf8ff;
    border-color: var(--primary);
    color: #2b6cb0;
    transform: translateY(-2px);
}

.section-divider {
    border: 0;
    border-top: 2px dashed #e2e8f0;
    margin: 30px 0;
}

.social-links {
  display: flex;
  justify-content: space-between;
  align-items: center;
  width: 100%;
  box-sizing: border-box;
  padding: 0 16px;
}
/* Responsive layout for mobile devices */
@media (max-width: 690px) {
  .social-links {
    flex-direction: column;
    align-items: flex-start;
    gap: 20px;
  }
}


#set-title {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary);
    text-align: center;
}
.quiz-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 2px solid #edf2f7;
    padding-bottom: 15px;
    margin-bottom: 20px;
}

#progress { font-weight: bold; color: #718096; }
#question-text { font-size: 1.25rem; font-weight: 600; margin-bottom: 20px; line-height: 1.6; }
.options-grid { display: flex; flex-direction: column; gap: 12px; }

.option-btn {
    background-color: #f8fafc;
    border: 2px solid #e2e8f0;
    border-radius: 8px;
    padding: 14px 20px;
    font-size: 1rem;
    text-align: left;
    cursor: pointer;
    transition: all 0.2s ease;
    width: 100%;
}

.option-btn:hover:not([disabled]) { background-color: #edf2f7; border-color: #cbd5e0; }
.option-btn.correct { background-color: #d4edda !important; border-color: var(--success) !important; color: #155724; font-weight: bold; }
.option-btn.wrong { background-color: #f8d7da !important; border-color: var(--danger) !important; color: #721c24; }

.explain-card {
    background-color: #ebf8ff;
    border-left: 4px solid var(--primary);
    padding: 15px 20px;
    border-radius: 4px;
    margin-top: 20px;
}

.explain-card strong { color: #2b6cb0; font-size: 0.95rem; text-transform: uppercase; }
#explanation-text { margin: 5px 0 0 0; line-height: 1.5; color: #2d3748; }

.quiz-footer { margin-top: 25px; min-height: 50px; display: flex; flex-direction: column; align-items: center; gap: 15px; }
.action-buttons { display: flex; gap: 12px; flex-wrap: wrap; }
.feedback-msg { font-weight: 600; font-size: 1.1rem; }
.feedback-msg.correct { color: var(--success); }
.feedback-msg.wrong { color: var(--danger); }

.btn {
    background-color: var(--primary);
    color: white;
    border: none;
    padding: 12px 28px;
    font-size: 1rem;
    border-radius: 8px;
    cursor: pointer;
    font-weight: bold;
    text-align: center;
}
.btn:hover { background-color: #357abd; }

.btn-success { background-color: var(--success); flex: 1; padding: 15px; font-size: 1.1rem; }
.btn-success:hover { background-color: #27ae60; }

.btn-secondary { background-color: var(--secondary); flex: 1; padding: 15px; font-size: 1.1rem; }
.btn-secondary:hover { background-color: #2d3748; }

.btn-tertiary { background-color: var(--tertiary); flex: 1; padding: 20px; font-size: 1.1rem; flex-basis: 100%; }
.btn-secondary:hover { background-color: #576a8c; }
.btn-tertiary:hover {background-color:#422b58}
#next-btn {flex:2; background-color: var(--primary); color: white; border: none; padding: 12px 28px; font-size: 1rem; border-radius: 8px; cursor: pointer; font-weight: bold; text-align: center;}
#next-btn:hover { background-color: #2d3748; transition: background-color 0.6s ease; }
.hidden { display: none !important; }
.text-center { text-align: center; }
.score-display { font-size: 1.6rem; margin: 20px 0; font-weight: bold; color: var(--primary); }