:root {
    --bg-color: #f0f2f5;
    --card-bg: #ffffff;
    --text-primary: #333333;
    --text-secondary: #666666;
    --accent-color: #007bff;
    --card-shadow: 0 4px 12px rgba(0,0,0,0.08);
    --card-hover-shadow: 0 8px 16px rgba(0,0,0,0.12);
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-primary);
    line-height: 1.6;
    padding: 40px 20px;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
}

.container[aria-label="在线留言"] {
    margin-top: 56px;
}

header {
    text-align: center;
    margin-bottom: 40px;
}

h1 {
    font-size: 2.5rem;
    color: var(--text-primary);
    margin-bottom: 10px;
}

.grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 24px;
}

.card {
    background: var(--card-bg);
    border-radius: 12px;
    padding: 24px;
    box-shadow: var(--card-shadow);
    transition: transform 0.2s ease, box-shadow 0.2s ease;
    text-decoration: none;
    color: inherit;
    display: flex;
    flex-direction: row; /* Changed to row */
    align-items: center; /* Center items vertically */
    border-top: 4px solid var(--accent-color);
    gap: 16px; /* Space between logo and text */
}

.card-logo {
    width: 48px;
    height: 48px;
    border-radius: 8px; /* Optional: adds rounded corners to logo */
    object-fit: contain; /* Ensures logo fits within the box */
    flex-shrink: 0; /* Prevents logo from shrinking */
}

.card-content {
    display: flex;
    flex-direction: column;
    overflow: hidden; /* To help with long URLs */
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: var(--card-hover-shadow);
}

.card-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.card-url {
    font-size: 0.875rem;
    color: var(--text-secondary);
    word-break: break-all;
}

/* Customize border colors for different categories if needed */
.card:nth-child(1) { border-color: #e74c3c; } /* Science */
.card:nth-child(2) { border-color: #3498db; } /* IEEE */
.card:nth-child(3) { border-color: #e74c3c; } /* Science */
.card:nth-child(4) { border-color: #3498db; } /* IEEE */
.card:nth-child(5) { border-color: #9b59b6; } /* Conf */
.card:nth-child(6) { border-color: #9b59b6; } /* Conf */