table{border-collapse:collapse;width:90%;margin:20px auto}th,td{border:1px solid #ccc;padding:8px;text-align:center}th{background-color:#f2f2f2}button{margin:10px;padding:8px 16px;font-size:14px;cursor:pointer;border:none;border-radius:5px;font-weight:700}#averageGrade{display:none;text-align:center;margin-top:20px}#gradeCalculation{display:none;text-align:center;margin-top:10px}.grade-container{margin-top:20px;text-align:center}.grade{font-size:24px;font-weight:700}#buttonContainer{text-align:center;margin-top:20px}#calculateButton{background-color:green;color:#fff}#clearButton{background-color:red;color:#fff}#addRowButton{background-color:blue;color:#fff}#averageGrade,#gradeCalculation,.grade-container{border:1px solid #ddd;padding:10px;margin-top:10px;text-align:center}@media only screen and (max-width:868px){table{width:100%}}@media only screen and (max-width:868px){td input{width:110%}}@media (max-width:500px){th,td{font-size:10px}}@media (max-width:900px){th,td{font-size:12px}input[type=text],input[type=number]{font-size:12px}}