body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f4f4f4;
}

header {
    background-color: #2c3e50;
    color: white;
    padding: 1rem;
    text-align: center;
}

#filter {
    margin-top: 1rem;
}

main {
    max-width: 1200px;
    margin: 2rem auto;
    padding: 0 1rem;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
}

section {
    background-color: white;
    padding: 1rem;
    border-radius: 8px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

#inbox {
    grid-column: 1;
}

#email-view,
#compose {
    grid-column: 2;
}

.thread {
    border: 1px solid #ddd;
    margin-bottom: 1rem;
    padding: 0.5rem;
}

.email-item {
    padding: 0.5rem;
    cursor: pointer;
    border-bottom: 1px solid #eee;
}

.email-item:hover {
    background-color: #f9f9f9;
}

.email-item.unread {
    font-weight: bold;
    background-color: #ffe6e6;
    border-left: 4px solid #ff4444;
}

.unread {
    color: red;
    font-weight: bold;
}

form {
    display: flex;
    flex-direction: column;
}

label {
    margin-top: 1rem;
}

input,
textarea {
    padding: 0.5rem;
    margin-top: 0.5rem;
}

button {
    margin-top: 1rem;
    padding: 0.5rem;
    background-color: #3498db;
    color: white;
    border: none;
    cursor: pointer;
}

button:hover {
    background-color: #2980b9;
}

@media (max-width: 768px) {
    main {
        grid-template-columns: 1fr;
    }

    #email-view,
    #compose {
        grid-column: 1;
    }
}