.letters-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 25px;
    contain: content;
    will-change: transform;
}

.letter-card {
    background: white;
    border-radius: 12px;
    padding: 25px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    border: 1px solid var(--section-border);
    contain: layout style paint;
}

.letter-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 20px rgba(0,0,0,0.15);
}

.letter-image {
    width: 100%;
    height: 200px;
    object-fit: cover;
}

.letter-content {
    display: flex;
    flex-direction: column;
    gap: 12px;
    height: 100%;
}

.letter-title {
    font-size: 1.4em;
    color: var(--primary-color);
    margin: 0;
    line-height: 1.4;
}

.letter-excerpt {
    color: #666;
    font-size: 0.95em;
    line-height: 1.6;
    margin: 0;
    flex-grow: 1;
}

.letter-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: auto;
}

.letter-date {
    color: #888;
    font-size: 0.9em;
}

.letter-tag {
    display: inline-block;
    padding: 4px 12px;
    background: var(--accent-color);
    color: white;
    border-radius: 15px;
    font-size: 0.85em;
    font-weight: 500;
}

.letter-categories {
    display: flex;
    gap: 15px;
    margin-bottom: 30px;
    flex-wrap: wrap;
    contain: content;
}

.category-button {
    padding: 8px 16px;
    border: 2px solid var(--accent-color);
    background: none;
    color: var(--accent-color);
    border-radius: 20px;
    cursor: pointer;
    font-weight: 500;
    transition: all 0.3s ease;
    contain: content;
}

.category-button:hover {
    background: var(--accent-color);
    color: white;
}

.category-button.active {
    background: var(--accent-color);
    color: white;
}

@media (max-width: 768px) {
    .letters-grid {
        grid-template-columns: 1fr;
        gap: 20px;
    }

    .letter-card {
        padding: 20px;
    }

    .letter-title {
        font-size: 1.2em;
    }
}