body { font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif; background-color: #f0f2f5; color: #333; margin: 0; padding: 20px; }
.container { max-width: 800px; margin: 40px auto; background: white; padding: 40px; border-radius: 12px; box-shadow: 0 6px 20px rgba(0,0,0,0.08); }
h1 { color: #2c3e50; text-align: center; margin-bottom: 5px; }
.subtitle { text-align: center; color: #7f8c8d; margin-bottom: 30px; }
.matiere-card { background: #f8f9fa; border-left: 5px solid #3498db; padding: 15px 20px; margin-bottom: 15px; border-radius: 4px; }
.matiere-card h3 { margin: 0 0 10px 0; color: #2c3e50; }
.chapitre-btn { background: #3498db; color: white; border: none; padding: 8px 15px; margin: 5px 5px 5px 0; border-radius: 4px; cursor: pointer; transition: background 0.2s; }
.chapitre-btn:hover { background: #2980b9; }
.question-card { margin-bottom: 25px; padding: 20px; border: 1px solid #e2e8f0; border-radius: 8px; background: #fff; }
.question-title { font-weight: bold; margin-bottom: 12px; color: #2d3748; }
.options label { display: block; margin: 8px 0; padding: 10px 12px; background: #f7fafc; border: 1px solid #e2e8f0; border-radius: 6px; cursor: pointer; transition: background 0.2s; }
.options label:hover { background: #edf2f7; }
input[type="radio"] { margin-right: 10px; }
.btn, .btn-back { display: inline-block; background: #2ecc71; color: white; border: none; padding: 12px 20px; font-size: 1em; border-radius: 6px; cursor: pointer; font-weight: bold; margin-top: 20px; }
.btn-back { background: #95a5a6; margin-bottom: 20px; margin-top: 0; }
.btn:hover { background: #27ae60; }
.btn-back:hover { background: #7f8c8d; }
#results-container { margin-top: 30px; padding: 20px; background: #e8f8f5; border: 1px solid #a3e4d7; border-radius: 8px; display: none; }
.correct { color: #27ae60; font-weight: bold; }
.incorrect { color: #c0392b; font-weight: bold; }
.rationale { font-size: 0.9em; color: #555; margin-top: 8px; padding-left: 15px; border-left: 3px solid #cbd5e0; }