body {
    font-family: 'Roboto', sans-serif;
    margin: 0;
    padding: 0;
    color: #333;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

.header {
    background-color: #28a745; /* Màu xanh lá cây */
    height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    padding: 0 20px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.logo {
    height: 40px;
    margin-right: 15px;
}

.header-title {
    margin: 0;
    font-size: 1.5rem;
    font-weight: bold;
    text-transform: uppercase;
}

.main-content {
    display: flex;
    flex: 1;
    overflow: hidden;
    position: relative;
}

.column {
    flex: 1;
    padding: 20px;
    border-right: 1px solid #ddd;
    box-sizing: border-box;
    overflow-y: auto;
    max-height: calc(100vh - 60px - 40px); /* Adjust for header and footer */
}

.column:last-child {
    border-right: none;
}

.menu-column {
    background-color: #f8f9fa;
}

.terms-column {
    background-color: #fff;
}

.details-column {
    background-color: #f1f1f1;
}

#searchInput {
    width: 100%;
    padding: 10px;
    margin-bottom: 20px;
    border: 1px solid #ccc;
    border-radius: 5px;
    font-size: 1rem;
    box-sizing: border-box;
}

ul {
    list-style-type: none;
    padding: 0;
    margin: 0;
}

li {
    cursor: pointer;
    padding: 10px 15px;
    border-bottom: 1px solid #eee;
    transition: background-color 0.3s;
}

li:hover, li.active {
    background-color: #e2e6ea;
}

.footer {
    height: 40px;
    background-color: #343a40;
    color: #fff;
    text-align: center;
    padding: 10px 0;
    font-size: 0.8rem;
    margin-top: auto;
}

#term-details {
    padding: 10px;
}

#term-title {
    font-size: 1.2rem;
    color: #007bff;
    margin-top: 0;
}

#term-definition {
    font-size: 1rem;
    line-height: 1.6;
}

#term-formula-container {
    margin-top: 15px;
    padding: 10px;
    background-color: #fff;
    border-radius: 5px;
    border-left: 3px solid #007bff;
}

#formula-label {
    color: #0056b3;
    font-size: 0.9rem;
}

#term-formula {
    font-family: 'Courier New', Courier, monospace;
    white-space: pre-wrap;
    font-size: 0.9rem;
    margin: 5px 0 0;
}

/* Responsive design */
@media (max-width: 768px) {
    .main-content {
        flex-direction: column;
    }

    .column {
        max-height: 33vh; /* Divide screen vertically on small devices */
        border-right: none;
        border-bottom: 1px solid #ddd;
    }
}