body { font-family: sans-serif; background: #eee; padding: 20px; }
.container { max-width: 800px; margin: auto; background: white; padding: 20px; border-radius: 8px; }
.hidden { display: none !important; }
.grid { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
.card { padding: 20px; background: #3498db; color: white; cursor: pointer; text-align: center; border-radius: 5px; }
.q-item { margin-bottom: 15px; padding: 10px; border-bottom: 1px solid #ccc; }
.btn { padding: 10px 20px; background: #2ecc71; color: white; border: none; cursor: pointer; }
input, textarea { width: 100%; margin-bottom: 10px; padding: 8px; box-sizing: border-box; }
.progress-container {
    width: 100%;
    height: 12px;
    background-color: #e0e0e0;
    border-radius: 10px;
    margin-bottom: 20px;
    overflow: hidden;
}

#progress-bar {
    height: 100%;
    width: 0%; /* Bắt đầu từ 0% */
    background: linear-gradient(90deg, #2ecc71, #27ae60);
    transition: width 0.4s ease;
}

.quiz-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}
table { width: 100%; border-collapse: collapse; margin-top: 20px; }
@keyframes shake {
  0% { transform: translateX(0); }
  25% { transform: translateX(-5px); }
  50% { transform: translateX(5px); }
  75% { transform: translateX(-5px); }
  100% { transform: translateX(0); }
}

.cheat-warning {
    border: 2px solid red !important;
    animation: shake 0.5s;
}