body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

.tab-btn {
    cursor: pointer;
    transition: all 0.3s;
}

.tab-btn.active {
    border-bottom: 2px solid #3b82f6;
    color: #3b82f6;
}

.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
}

#student-list li, #exam-list li {
    padding: 10px;
    border-radius: 5px;
    background: #f8fafc;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

#student-list li:hover, #exam-list li:hover {
    background: #f1f5f9;
}

.grade-input {
    width: 80px;
    padding: 5px;
    border: 1px solid #e2e8f0;
    border-radius: 4px;
    text-align: center;
}

@media (max-width: 640px) {
    .tabs {
        overflow-x: auto;
        white-space: nowrap;
    }
    .tab-btn {
        flex: none;
    }
}