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

body {
    font-family: 'Georgia', 'Times New Roman', serif;
    line-height: 1.6;
    color: #2c3e50;
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    min-height: 100vh;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

header {
    background: linear-gradient(135deg, #2c3e50 0%, #34495e 100%);
    color: white;
    padding: 3rem 0;
    text-align: center;
    margin-bottom: 3rem;
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.3);
}

h1 {
    font-size: 2.8rem;
    margin-bottom: 0.5rem;
    font-weight: 300;
}

.subtitle {
    font-size: 1.2rem;
    opacity: 0.9;
    font-style: italic;
}

.search-filter-section {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
    margin-bottom: 2rem;
}

.search-container {
    position: relative;
    margin-bottom: 1.5rem;
}

.search-input {
    width: 100%;
    padding: 15px 50px 15px 20px;
    font-size: 1.1rem;
    border: 2px solid #e0e6ed;
    border-radius: 10px;
    transition: all 0.3s ease;
    font-family: inherit;
}

.search-input:focus {
    outline: none;
    border-color: #3498db;
    box-shadow: 0 0 0 3px rgba(52, 152, 219, 0.1);
}

.search-icon {
    position: absolute;
    right: 20px;
    top: 50%;
    transform: translateY(-50%);
    color: #7f8c8d;
    font-size: 1.2rem;
}

.filter-tabs {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
    justify-content: center;
}

.filter-tab {
    padding: 10px 20px;
    background: #ecf0f1;
    border: none;
    border-radius: 25px;
    cursor: pointer;
    transition: all 0.3s ease;
    font-family: inherit;
    font-size: 0.95rem;
}

.filter-tab:hover {
    background: #d5dbdb;
    transform: translateY(-2px);
}

.filter-tab.active {
    background: #3498db;
    color: white;
}

.papers-grid {
    display: grid;
    gap: 2rem;
    margin-bottom: 2rem;
}

.paper-card {
    background: white;
    border-radius: 15px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
    padding: 2rem;
    transition: all 0.3s ease;
    border-left: 5px solid #3498db;
    opacity: 1;
    transform: translateY(0);
}

.paper-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 35px rgba(0,0,0,0.15);
}

.paper-card.hidden {
    opacity: 0;
    transform: translateY(20px);
    pointer-events: none;
}

.paper-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 1rem;
    flex-wrap: wrap;
    gap: 1rem;
}

.paper-title {
    font-size: 1.4rem;
    color: #2c3e50;
    margin-bottom: 0.5rem;
    line-height: 1.4;
}

.paper-title a {
    color: inherit;
    text-decoration: none;
    transition: color 0.3s ease;
}

.paper-title a:hover {
    color: #3498db;
}

.paper-authors {
    color: #7f8c8d;
    font-style: italic;
    margin-bottom: 0.5rem;
}

.paper-venue {
    font-size: 0.9rem;
    color: #95a5a6;
    margin-bottom: 1rem;
}

.paper-tags {
    display: flex;
    gap: 8px;
    margin-bottom: 1rem;
    flex-wrap: wrap;
}

.tag {
    background: #3498db;
    color: white;
    padding: 4px 12px;
    border-radius: 15px;
    font-size: 0.8rem;
    font-weight: 500;
}

.tag.ai { background: #e74c3c; }
.tag.ml { background: #f39c12; }
.tag.nlp { background: #9b59b6; }
.tag.cv { background: #27ae60; }
.tag.robotics { background: #34495e; }
.tag.rl { background: #16a085; }
.tag.generative { background: #8e44ad; }
.tag.gpt { background: #c0392b; }

.paper-summary {
    color: #5d6d7e;
    line-height: 1.6;
    margin-bottom: 1.5rem;
}

.paper-actions {
    display: flex;
    gap: 15px;
    align-items: center;
}

.action-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 8px 16px;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    text-decoration: none;
    font-size: 0.9rem;
    transition: all 0.3s ease;
}

.btn-primary {
    background: #3498db;
    color: white;
}

.btn-secondary {
    background: #95a5a6;
    color: white;
}

.action-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0,0,0,0.2);
}

.read-status {
    margin-left: auto;
    padding: 6px 12px;
    border-radius: 15px;
    font-size: 0.8rem;
    font-weight: 500;
}

.status-read {
    background: #d5f4e6;
    color: #27ae60;
}

.status-reading {
    background: #ffeaa7;
    color: #f39c12;
}

.status-planned {
    background: #ddd;
    color: #7f8c8d;
}

.stats-section {
    background: white;
    border-radius: 15px;
    padding: 2rem;
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
    margin-bottom: 2rem;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
}

.stat-card {
    text-align: center;
    padding: 1.5rem;
    background: #f8f9fa;
    border-radius: 10px;
}

.stat-number {
    font-size: 2.5rem;
    font-weight: bold;
    color: #3498db;
    margin-bottom: 0.5rem;
}

.stat-label {
    color: #7f8c8d;
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.no-results {
    text-align: center;
    padding: 3rem;
    color: #7f8c8d;
    font-style: italic;
}

/* Notes page specific styles */
.notes-container {
    max-width: 900px;
    margin: 2rem auto;
    padding: 0 20px;
}

.notes-header {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
    margin-bottom: 2rem;
}

.notes-title {
    color: #2c3e50;
    font-size: 2.2rem;
    margin-bottom: 0.5rem;
}

.notes-meta {
    color: #7f8c8d;
    font-style: italic;
    margin-bottom: 1rem;
}

.back-link {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    color: #3498db;
    text-decoration: none;
    font-size: 0.9rem;
    transition: color 0.3s ease;
    margin-bottom: 1.5rem;
}

.back-link:hover {
    color: #2980b9;
}

.notes-content {
    background: white;
    padding: 2.5rem;
    border-radius: 15px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
    line-height: 1.8;
}

.notes-content h2 {
    color: #2c3e50;
    margin: 2rem 0 1rem 0;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid #ecf0f1;
}

.notes-content h3 {
    color: #34495e;
    margin: 1.5rem 0 0.8rem 0;
}

.notes-content p {
    margin-bottom: 1.2rem;
    color: #5d6d7e;
}

.notes-content ul, .notes-content ol {
    margin: 1rem 0 1rem 2rem;
}

.notes-content li {
    margin-bottom: 0.5rem;
    color: #5d6d7e;
}

.notes-content code {
    background: #f8f9fa;
    padding: 2px 6px;
    border-radius: 4px;
    font-family: 'Courier New', monospace;
    color: #e74c3c;
}

.notes-content blockquote {
    border-left: 4px solid #3498db;
    padding-left: 1.5rem;
    margin: 1.5rem 0;
    font-style: italic;
    color: #7f8c8d;
    background: #f8f9fa;
    padding: 1rem 1.5rem;
    border-radius: 0 8px 8px 0;
}

.highlight {
    background: #fff3cd;
    padding: 2px 4px;
    border-radius: 3px;
}

@media (max-width: 768px) {
    h1 {
        font-size: 2rem;
    }
    
    .paper-header {
        flex-direction: column;
    }
    
    .filter-tabs {
        justify-content: flex-start;
    }
    
    .paper-actions {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .read-status {
        margin-left: 0;
        margin-top: 10px;
    }

    .notes-title {
        font-size: 1.8rem;
    }

    .notes-content {
        padding: 1.5rem;
    }
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.paper-card {
    animation: fadeIn 0.5s ease-out;
}