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

:root {
    /* Dark Theme Colors */
    --bg-primary: #0a0a0a;
    --bg-secondary: #1a1a1a;
    --bg-card: #222222;
    --bg-card-hover: #2a2a2a;
    
    /* Text Colors */
    --text-primary: #ffffff;
    --text-secondary: #e0e0e0;
    --text-muted: #a0a0a0;
    
    /* Accent Colors */
    --accent-primary: #6366f1;
    --accent-secondary: #8b5cf6;
    --accent-hover: #7c3aed;
    
    /* Border & Shadow */
    --border-color: #333333;
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.5);
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    
    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition-normal: 0.3s ease;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen',
        'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue',
        sans-serif;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    background: var(--bg-primary);
    color: var(--text-secondary);
    line-height: 1.6;
    min-height: 100vh;
}

/* ===== Container ===== */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: var(--spacing-md) var(--spacing-md);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* ===== Header Section ===== */
.header {
    padding: var(--spacing-sm) var(--spacing-md);
    background: linear-gradient(135deg, var(--bg-secondary) 0%, var(--bg-primary) 100%);
    border-radius: var(--radius-lg);
    margin-bottom: var(--spacing-md);
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-color);
    text-align: center;
    position: relative;
}

.profile-image {
    position: absolute;
    top: var(--spacing-sm);
    left: var(--spacing-md);
    width: 145px;
    height: 145px;
    border-radius: 50%;
    object-fit: cover;
    border: 3px solid var(--accent-primary);
    box-shadow: var(--shadow-md);
}

.name {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin: 0;
    padding-top: 0;
    line-height: 1;
    background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    letter-spacing: -0.02em;
    text-align: center;
}

.subtitle {
    font-size: 0.85rem;
    color: var(--text-muted);
    margin: 0.35rem 0 0.5rem 0;
    font-weight: 400;
    letter-spacing: 0.01em;
    text-align: center;
}

.contact-bar {
    display: flex;
    flex-direction: row;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    margin-bottom: var(--spacing-sm);
}

.contact-link {
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-muted);
    text-decoration: none;
    width: 1.5rem;
    height: 1.5rem;
    border-radius: 50%;
    transition: all var(--transition-normal);
    background: transparent;
    border: 1px solid var(--border-color);
}

.contact-link:hover {
    color: var(--accent-primary);
    background: var(--bg-card);
    border-color: var(--accent-primary);
    transform: scale(1.1);
}

.contact-link i {
    font-size: 0.8rem;
}

.contact-link span {
    display: none;
}

/* ===== Tab Navigation ===== */
.tab-navigation {
    display: flex;
    justify-content: center;
    gap: var(--spacing-xs);
    margin-top: var(--spacing-sm);
    padding: 0;
    background: transparent;
    border: none;
    box-shadow: none;
}

.tab-button {
    display: flex;
    align-items: center;
    gap: 0.35rem;
    padding: 0.4rem 0.85rem;
    background: var(--bg-card);
    color: var(--text-muted);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: 0.8rem;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition-normal);
    position: relative;
}

.tab-button:hover {
    color: var(--text-secondary);
    background: var(--bg-card-hover);
}

.tab-button.active {
    color: var(--text-primary);
    background: var(--accent-primary);
    box-shadow: var(--shadow-sm);
    border-color: var(--accent-primary);
}

.tab-button i {
    font-size: 0.9rem;
}

/* ===== Content Section ===== */
.content {
    flex: 1;
    margin-bottom: var(--spacing-lg);
}

.tab-content {
    display: none;
    animation: fadeIn var(--transition-normal);
}

.tab-content.active {
    display: block;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.section-title {
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-sm);
    border-bottom: 2px solid var(--accent-primary);
    display: none; /* Hidden as requested */
}

/* ===== Category Section ===== */
.category {
    margin-bottom: var(--spacing-lg);
}

.category-title {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--accent-secondary);
    margin-bottom: var(--spacing-md);
}

/* ===== Items Grid ===== */
.items-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: var(--spacing-md);
}

.item-card {
    background: var(--bg-card);
    padding: var(--spacing-md);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-sm);
}

.item-card:hover {
    background: var(--bg-card-hover);
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
    border-color: var(--accent-primary);
}

.item-title {
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
}

.item-link {
    color: var(--accent-primary);
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    transition: color var(--transition-fast);
}

.item-link:hover {
    color: var(--accent-hover);
    text-decoration: underline;
}

.item-link i {
    font-size: 0.9rem;
}

.item-description {
    color: var(--text-muted);
    font-size: 0.95rem;
    line-height: 1.5;
}

/* ===== Blog Index Structure ===== */
.blog-index {
    max-width: 900px;
    margin: 0 auto;
}

.index-topic {
    background: var(--bg-card);
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
    margin-bottom: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
}

.topic-title {
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--accent-primary);
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-sm);
    border-bottom: 2px solid var(--accent-primary);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.topic-title i {
    font-size: 1.5rem;
}

.index-subtopic {
    margin-bottom: var(--spacing-lg);
    padding-left: var(--spacing-md);
    border-left: 3px solid var(--border-color);
    transition: border-color var(--transition-normal);
}

.index-subtopic:hover {
    border-left-color: var(--accent-secondary);
}

.index-subtopic:last-child {
    margin-bottom: 0;
}

.subtopic-title {
    font-size: 1.3rem;
    font-weight: 600;
    color: var(--accent-secondary);
    margin-bottom: var(--spacing-md);
    padding-left: var(--spacing-sm);
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
}

.subtopic-title i {
    font-size: 0.9rem;
    color: var(--text-muted);
}

.blog-links {
    list-style: none;
    padding-left: var(--spacing-lg);
}

.blog-item {
    margin-bottom: var(--spacing-sm);
    position: relative;
}

.blog-item:last-child {
    margin-bottom: 0;
}

.blog-link {
    color: var(--text-secondary);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm);
    border-radius: var(--radius-md);
    transition: all var(--transition-normal);
    background: transparent;
    border: 1px solid transparent;
}

.blog-link:hover {
    color: var(--accent-primary);
    background: var(--bg-card-hover);
    border-color: var(--accent-primary);
    padding-left: calc(var(--spacing-sm) + 0.5rem);
}

.blog-link i.fa-file-alt {
    font-size: 0.9rem;
    color: var(--text-muted);
}

.blog-link .external-icon {
    font-size: 0.75rem;
    margin-left: auto;
    opacity: 0.5;
    transition: opacity var(--transition-fast);
}

.blog-link:hover .external-icon {
    opacity: 1;
}

/* ===== Research & Projects Section Specific Styles ===== */
#research .items-grid,
#projects .items-grid {
    grid-template-columns: 1fr;
    gap: var(--spacing-md);
}

#research .item-card {
    display: flex;
    flex-direction: column;
}

#projects .item-card {
    display: grid;
    grid-template-columns: minmax(220px, 32%) 1fr;
    gap: var(--spacing-lg);
    align-items: start;
}

#research .item-title,
#projects .item-title {
    margin-bottom: 0;
}

#research .item-description {
    margin-top: var(--spacing-xs);
}

#projects .item-description {
    margin-top: 0;
}

#projects .item-description ul {
    margin: 0;
    padding-left: 1.25rem;
}

#projects .item-description li {
    margin-bottom: var(--spacing-xs);
}

#projects .item-description li:last-child {
    margin-bottom: 0;
}

@media (max-width: 768px) {
    #projects .item-card {
        grid-template-columns: 1fr;
        gap: var(--spacing-sm);
    }
}

/* ===== Empty State ===== */
.empty-state {
    text-align: center;
    padding: var(--spacing-xl) var(--spacing-md);
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    border: 2px dashed var(--border-color);
}

.empty-state i {
    font-size: 4rem;
    color: var(--text-muted);
    margin-bottom: var(--spacing-md);
    opacity: 0.5;
}

.empty-state p {
    color: var(--text-muted);
    font-size: 1.1rem;
    margin-bottom: var(--spacing-xs);
}

.empty-hint {
    font-size: 0.9rem;
    color: var(--text-muted);
    opacity: 0.7;
}

/* ===== Footer ===== */
.footer {
    text-align: center;
    padding: var(--spacing-lg) 0;
    color: var(--text-muted);
    font-size: 0.9rem;
    border-top: 1px solid var(--border-color);
    margin-top: auto;
}

.footer-contact-bar {
    padding-top: var(--spacing-xs);
}

/* ===== Responsive Design ===== */
@media (max-width: 768px) {
    .profile-image {
        width: 60px;
        height: 60px;
        top: var(--spacing-xs);
        left: var(--spacing-sm);
    }
    
    .name {
        font-size: 1.75rem;
    }
    
    .subtitle {
        font-size: 0.75rem;
    }
    
    .contact-bar {
        gap: 0.4rem;
    }
    
    .contact-link {
        width: 1.4rem;
        height: 1.4rem;
    }
    
    .contact-link i {
        font-size: 0.75rem;
    }
    
    .tab-navigation {
        flex-direction: column;
    }
    
    .tab-button {
        width: 100%;
        justify-content: center;
    }
    
    .items-grid {
        grid-template-columns: 1fr;
    }
    
    .section-title {
        font-size: 1.5rem;
    }
    
    .category-title {
        font-size: 1.2rem;
    }
    
    /* Blog Index Responsive */
    .index-topic {
        padding: var(--spacing-md);
    }
    
    .topic-title {
        font-size: 1.4rem;
    }
    
    .subtopic-title {
        font-size: 1.1rem;
    }
    
    .index-subtopic {
        padding-left: var(--spacing-sm);
    }
    
    .blog-links {
        padding-left: var(--spacing-md);
    }
}

@media (max-width: 480px) {
    .container {
        padding: var(--spacing-md) var(--spacing-sm);
    }
    
    .header {
        padding: var(--spacing-sm);
    }
    
    .profile-image {
        width: 90px;
        height: 90px;
        top: var(--spacing-xs);
        left: var(--spacing-xs);
    }
    
    .name {
        font-size: 1.5rem;
    }
    
    .subtitle {
        font-size: 0.7rem;
    }
    
    .contact-bar {
        gap: 0.4rem;
    }
    
    .contact-link {
        width: 1.3rem;
        height: 1.3rem;
    }
    
    .contact-link i {
        font-size: 0.7rem;
    }
    
    /* Blog Index Mobile */
    .index-topic {
        padding: var(--spacing-sm);
    }
    
    .topic-title {
        font-size: 1.2rem;
        flex-direction: column;
        align-items: flex-start;
    }
    
    .subtopic-title {
        font-size: 1rem;
    }
    
    .blog-link {
        font-size: 0.9rem;
    }
}

/* ===== Scrollbar Styling ===== */
::-webkit-scrollbar {
    width: 10px;
}

::-webkit-scrollbar-track {
    background: var(--bg-secondary);
}

::-webkit-scrollbar-thumb {
    background: var(--accent-primary);
    border-radius: var(--radius-sm);
}

::-webkit-scrollbar-thumb:hover {
    background: var(--accent-hover);
}

/* ===== Selection Styling ===== */
::selection {
    background: var(--accent-primary);
    color: var(--text-primary);
}

::-moz-selection {
    background: var(--accent-primary);
    color: var(--text-primary);
}