:root {
    --primary-color: #0084ff;
    --secondary-color: #f3f3f3;
    --text-color: #333;
    --light-text: #737373;
    --background: #f0f2f5;
    --card-background: #fff;
    --border-radius: 10px;
    --shadow: 0 2px 12px rgba(0, 0, 0, 0.08);
    --hover-bg: #f5f5f5;
}

* {
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    margin: 0;
    background-color: var(--background);
    color: var(--text-color);
    line-height: 1.5;
}

.container {
    max-width: 1000px;
    margin: auto;
    padding: 20px;
}

header {
    text-align: center;
    margin-bottom: 20px;
}

header h1 {
    margin-bottom: 10px;
    color: var(--primary-color);
}

.last-updated {
    font-size: 0.9em;
    color: var(--light-text);
    margin-bottom: 20px;
}

.user-info {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 15px;
    margin-top: 10px;
    font-size: 0.9em;
}

.user-info button {
    padding: 5px 10px;
    font-size: 0.9em;
}

.card {
    background: var(--card-background);
    border-radius: var(--border-radius);
    padding: 20px;
    margin-bottom: 30px;
    box-shadow: var(--shadow);
    transition: box-shadow 0.2s ease;
}

.card:hover {
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.12);
}

.card h2 {
    margin-top: 0;
    color: var(--primary-color);
    border-bottom: 1px solid var(--secondary-color);
    padding-bottom: 10px;
}

/* Collapsible Styles */
.collapsible-header {
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 10px 0;
    user-select: none;
    margin: 0;
}

.collapsible-header:hover {
    background-color: var(--hover-bg);
    border-radius: var(--border-radius);
}

.toggle-icon {
    transition: transform 0.3s ease;
    margin-left: 10px;
    font-size: 1.2em;
    background: none;
    border: none;
    color: inherit;
    padding: 5px;
}

.collapsed .toggle-icon {
    transform: rotate(-90deg);
}

.collapsible-content {
    transition: max-height 0.3s ease-out, opacity 0.2s ease;
    overflow: hidden;
    max-height: 2000px;
    opacity: 1;
}

.collapsed + .collapsible-content {
    max-height: 0;
    opacity: 0;
}

/* Search Form */
.search-form {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 15px;
}

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

.form-group label {
    margin-bottom: 5px;
    font-weight: 500;
    font-size: 0.9em;
}

.form-control {
    padding: 10px;
    border: 1px solid #ddd;
    border-radius: 5px;
    font-size: 1em;
}

.btn {
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 10px 15px;
    border-radius: 5px;
    cursor: pointer;
    font-size: 1em;
    transition: background-color 0.2s;
}

.btn:hover {
    background-color: #0069d9;
}

.btn-full {
    margin-top: 10px;
    grid-column: 1 / -1;
}

/* Participants */
.participants-list {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
    gap: 15px;
    list-style-type: none;
    padding: 0;
    margin-top: 15px;
}

.participant-card {
    display: flex;
    align-items: center;
    justify-content: space-between;
    background: var(--secondary-color);
    padding: 10px 15px;
    border-radius: 5px;
}

.participant-info {
    flex-grow: 1;
}

.participant-name {
    font-weight: 500;
}

.message-count {
    font-size: 0.8em;
    color: var(--light-text);
}

.participant-actions a {
    text-decoration: none;
    color: var(--primary-color);
    font-size: 1.2em;
    margin-left: 10px;
}

.participant-actions a:hover {
    color: #0069d9;
}

/* Messages */
.message-stats {
    margin-bottom: 15px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.9em;
    color: var(--light-text);
}

.message {
    background: var(--card-background);
    border-left: 4px solid var(--primary-color);
    margin-bottom: 20px;
    padding: 15px;
    border-radius: 5px;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    transition: transform 0.2s;
}

.message:hover {
    transform: translateX(2px);
}

.message-header {
    display: flex;
    justify-content: space-between;
    margin-bottom: 10px;
}

.sender {
    font-weight: bold;
    color: var(--primary-color);
}

.timestamp {
    font-size: 0.85em;
    color: var(--light-text);
}

.content {
    white-space: pre-wrap;
    word-break: break-word;
}

.content a {
    color: var(--primary-color);
    text-decoration: none;
}

.content a:hover {
    text-decoration: underline;
}

.reactions {
    margin-top: 10px;
    font-size: 0.9em;
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.reaction {
    background: var(--secondary-color);
    padding: 3px 8px;
    border-radius: 12px;
    display: inline-flex;
    align-items: center;
}

.attachments {
    margin-top: 10px;
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

.attachment {
    display: inline-block;
    padding: 5px 10px;
    background: var(--secondary-color);
    border-radius: 5px;
    font-size: 0.9em;
    text-decoration: none;
    color: var(--primary-color);
}

.attachment:hover {
    background: var(--hover-bg);
}

/* Pagination */
.pagination {
    display: flex;
    justify-content: center;
    margin-top: 20px;
}

.pagination a, .pagination span {
    padding: 8px 12px;
    margin: 0 5px;
    border-radius: 3px;
    text-decoration: none;
}

.pagination a {
    background: var(--secondary-color);
    color: var(--text-color);
    cursor: pointer;
}

.pagination a:hover {
    background: var(--hover-bg);
}

.pagination .current {
    background: var(--primary-color);
    color: white;
}

.no-messages {
    text-align: center;
    padding: 30px;
    color: var(--light-text);
}

/* Responsive Design */
@media (max-width: 700px) {
    .search-form {
        grid-template-columns: 1fr;
    }
    
    .participants-list {
        grid-template-columns: 1fr;
    }
    
    .message-header {
        flex-direction: column;
    }
    
    .timestamp {
        margin-top: 5px;
    }
}