Reply Comment Thread Card

<!DOCTYPE html>
<title>My Example</title>

<style>
/* This is an optional body style to provide a background for the page */
body {
    background-color: #f3f4f6;
    font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, 'Noto Sans', sans-serif;
}

/* Optional: a container to center the card on the page for demonstration */
.demo-container-thread {
    display: flex;
    justify-content: center;
    padding: 2rem;
}

/* === Comment Thread Card Styles === */
.thread-card {
    --thread-radius: 12px;
    --thread-shadow: 0 4px 10px rgba(0,0,0,0.06);

background-color: #ffffff;
    border-radius: var(--thread-radius);
    box-shadow: var(--thread-shadow);
    max-width: 600px;
    width: 100%;
}

/* Individual comment styles (reused) */
.thread-comment-item {
    display: flex;
    gap: 1rem;
    align-items: flex-start;
    padding: 1.25rem;
}
.thread-comment-item:not(:last-child) {
    border-bottom: 1px solid #f3f4f6;
}

.thread-avatar {
    width: 44px;
    height: 44px;
    border-radius: 50%;
    object-fit: cover;
    flex-shrink: 0;
}
.thread-main-content {
    flex-grow: 1;
}

.thread-header {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 0.25rem;
}
.thread-author { font-weight: 600; color: #111827; }
.thread-handle { font-size: 0.9rem; color: #6b7280; }
.thread-time { font-size: 0.875rem; color: #6b7280; }

.thread-text {
    font-size: 1rem;
    line-height: 1.6;
    color: #374151;
    margin: 0;
}
.thread-text p { margin: 0 0 1em; }
.thread-text p:last-child { margin-bottom: 0; }

/* The container for nested replies */
.thread-replies {
    padding-left: 3rem; /* Indentation for replies */
    position: relative;
    border-top: 1px solid #f3f4f6;
    background-color: #fafafa;
}

/* The vertical "thread line" connecting replies */
.thread-replies::before {
    content: '';
    position: absolute;
    left: 41px; /* Aligns with avatars */
    top: 0;
    bottom: 0;
    width: 2px;
    background-color: #e5e7eb;
}

</style>

<div class="demo-container-thread">
    <section class="thread-card">
        
        
        <article class="thread-comment-item">
            <img src="https://placehold.co/88x88/f59e0b/ffffff/png?text=F" alt="Avatar of Felix" class="thread-avatar">
            <div class="thread-main-content">
                <header class="thread-header">
                    <span class="thread-author">Felix Quinn</span>
                    <span class="thread-handle">@felixquinn</span>
                    <time class="thread-time" datetime="2025-11-01T10:00:00Z">&bull; Nov 1, 2025</time>
                </header>
                <div class="thread-text">
                    <p>Does anyone know if it's possible to animate CSS Grid tracks? I'm trying to create a smooth collapse/expand animation for a sidebar.</p>
                </div>
            </div>
        </article>
        
        
        <div class="thread-replies">
            
            <article class="thread-comment-item">
                <img src="https://placehold.co/88x88/1d4ed8/ffffff/png?text=N" alt="Avatar of Nora" class="thread-avatar">
                <div class="thread-main-content">
                    <header class="thread-header">
                        <span class="thread-author">Nora Ives</span>
                        <span class="thread-handle">@nora_dev</span>
                        <time class="thread-time" datetime="2025-11-01T10:15:00Z">&bull; Nov 1, 2025</time>
                    </header>
                    <div class="thread-text">
                        <p>Yes! You can transition the 'grid-template-rows' or 'grid-template-columns' properties. Setting a row from '1fr' to '0fr' will animate its height smoothly.</p>
                    </div>
                </div>
            </article>
            
            
            <article class="thread-comment-item">
                <img src="https://placehold.co/88x88/ec4899/ffffff/png?text=E" alt="Avatar of Elara" class="thread-avatar">
                <div class="thread-main-content">
                    <header class="thread-header">
                        <span class="thread-author">Elara Vance</span>
                        <span class="thread-handle">@elara_ux</span>
                        <time class="thread-time" datetime="2025-11-01T10:20:00Z">&bull; Nov 1, 2025</time>
                    </header>
                    <div class="thread-text">
                        <p>Exactly what Nora said. Just make sure the content inside the track has 'overflow: hidden' or it might spill out during the animation.</p>
                    </div>
                </div>
            </article>
        </div>
        
    </section>
</div>