/* ===========================
   Academic Research Project Stylesheet
   Clean, Professional, Information-focused
   =========================== */

/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Source Sans Pro', 'Helvetica Neue', Arial, sans-serif;
    font-size: 16px;
    line-height: 1.6;
    color: #333;
    background: #fff;
}

.container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Header */
.header {
    background: #f8f8f8;
    border-bottom: 3px solid #2c5aa0;
    padding: 40px 0;
    text-align: center;
}

.header h1 {
    font-size: 28px;
    font-weight: 700;
    color: #1a1a1a;
    margin-bottom: 10px;
    line-height: 1.3;
}

.authors {
    font-size: 18px;
    color: #555;
    margin-bottom: 5px;
}

.date {
    font-size: 14px;
    color: #777;
}

/* Navigation */
.nav-bar {
    background: #fff;
    border-bottom: 1px solid #ddd;
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav-links {
    display: flex;
    justify-content: center;
    list-style: none;
    padding: 15px 0;
}

.nav-links li {
    margin: 0 20px;
}

.nav-links a {
    color: #555;
    text-decoration: none;
    font-weight: 500;
    font-size: 15px;
    transition: color 0.2s;
}

.nav-links a:hover {
    color: #2c5aa0;
}

/* Sections */
.section {
    padding: 50px 0;
}

.section-gray {
    background: #f9f9f9;
}

.section h2 {
    font-size: 24px;
    font-weight: 600;
    color: #1a1a1a;
    margin-bottom: 20px;
    border-bottom: 2px solid #2c5aa0;
    padding-bottom: 10px;
}

.section h3 {
    font-size: 18px;
    font-weight: 600;
    color: #333;
    margin: 20px 0 10px;
}

.section-intro {
    color: #666;
    margin-bottom: 20px;
    font-size: 15px;
}

/* Abstract */
.abstract-text {
    font-size: 16px;
    line-height: 1.8;
    color: #444;
    text-align: justify;
    margin-bottom: 30px;
}

/* Key Metrics */
.key-metrics {
    display: flex;
    justify-content: space-around;
    margin: 30px 0;
    padding: 20px 0;
    border-top: 1px solid #ddd;
    border-bottom: 1px solid #ddd;
}

.metric {
    text-align: center;
}

.metric-number {
    display: block;
    font-size: 32px;
    font-weight: 700;
    color: #2c5aa0;
    line-height: 1;
}

.metric-label {
    display: block;
    font-size: 13px;
    color: #666;
    margin-top: 5px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

/* Methods */
.method-overview {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 30px;
    margin-top: 20px;
}

.method-block {
    background: #fff;
    padding: 20px;
    border: 1px solid #ddd;
    border-radius: 4px;
}

.method-block h3 {
    margin-top: 0;
    margin-bottom: 15px;
    color: #2c5aa0;
}

.method-block ul {
    list-style: none;
}

.method-block li {
    padding: 5px 0;
    color: #555;
    font-size: 15px;
    border-bottom: 1px solid #f0f0f0;
}

.method-block li:last-child {
    border-bottom: none;
}

/* Robot Platforms */
.platforms-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 30px;
    margin-top: 20px;
}

.platform-card {
    border: 1px solid #ddd;
    border-radius: 4px;
    padding: 20px;
}

.platform-card h3 {
    margin-top: 0;
    margin-bottom: 15px;
    color: #2c5aa0;
}

.platform-specs table {
    width: 100%;
    font-size: 14px;
}

.platform-specs td {
    padding: 8px 0;
    border-bottom: 1px solid #f0f0f0;
}

.platform-specs td:first-child {
    color: #666;
    width: 40%;
}

.platform-specs td:last-child {
    color: #333;
    font-weight: 500;
}

.platform-specs tr:last-child td {
    border-bottom: none;
}

/* Results Table */
.results-table {
    margin-top: 20px;
}

.data-table {
    width: 100%;
    border-collapse: collapse;
    background: #fff;
    font-size: 14px;
}

.data-table th {
    background: #2c5aa0;
    color: white;
    padding: 12px;
    text-align: left;
    font-weight: 600;
}

.data-table td {
    padding: 10px 12px;
    border-bottom: 1px solid #ddd;
}

.data-table tbody tr:hover {
    background: #f9f9f9;
}

.data-table tbody tr:last-child td {
    border-bottom: none;
}

/* Videos Section */
.video-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 20px;
    margin: 20px 0 40px;
}

.video-item {
    border: 1px solid #ddd;
    border-radius: 4px;
    padding: 15px;
    background: #fff;
}

.video-item h4 {
    font-size: 16px;
    font-weight: 600;
    color: #333;
    margin-bottom: 10px;
}

.video-pair {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 10px;
}

.video-box {
    position: relative;
    border: 1px solid #ddd;
    border-radius: 3px;
    overflow: hidden;
}

.video-label {
    position: absolute;
    top: 5px;
    left: 5px;
    background: rgba(0, 0, 0, 0.7);
    color: white;
    padding: 2px 8px;
    font-size: 11px;
    border-radius: 2px;
    z-index: 1;
}

.video-placeholder {
    background: #f0f0f0;
    height: 80px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: background 0.2s;
}

.video-placeholder:hover {
    background: #e0e0e0;
}

.video-placeholder span {
    color: #555;
    font-size: 13px;
    font-weight: 500;
}

/* Footer */
.footer {
    background: #333;
    color: #ccc;
    text-align: center;
    padding: 30px 0;
    margin-top: 50px;
}

.footer p {
    margin: 5px 0;
    font-size: 14px;
}

/* Responsive Design */
@media (max-width: 768px) {
    .header h1 {
        font-size: 24px;
    }
    
    .nav-links {
        flex-wrap: wrap;
    }
    
    .nav-links li {
        margin: 5px 10px;
    }
    
    .key-metrics {
        flex-wrap: wrap;
    }
    
    .metric {
        width: 50%;
        margin: 10px 0;
    }
    
    .method-overview,
    .platforms-grid {
        grid-template-columns: 1fr;
    }
    
    .video-container {
        grid-template-columns: 1fr;
    }
    
    .video-placeholder {
        height: 150px;
    }
    
    .data-table {
        font-size: 12px;
    }
    
    .data-table th,
    .data-table td {
        padding: 8px;
    }
}

@media (max-width: 480px) {
    .header h1 {
        font-size: 20px;
    }
    
    .metric-number {
        font-size: 24px;
    }
    
    .video-placeholder {
        height: 120px;
    }
}