/* 
=========================
Base Styles and Variables
=========================
*/
:root {
    /* Light Theme Colors */
    --primary-color: #0f172a;
    --secondary-color: #475569;
    --accent-color: #6366f1;
    --background-color: #ffffff;
    --background-alt: #f7fafc;
    --text-color: #0f172a;
    --text-light: #475569;
    --border-color: #e2e8f0;
    --shadow-color: rgba(0, 0, 0, 0.08);
    --gradient-primary: linear-gradient(90deg, #6366f1, #8b5cf6);
    --gradient-secondary: linear-gradient(90deg, #0f172a, #1e293b);
    
    /* Typography */
    --font-heading: 'Space Grotesk', sans-serif;
    --font-body: 'Inter', sans-serif;
    
    /* Spacing */
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 2rem;
    --spacing-xl: 4rem;
    
    /* Transitions */
    --transition-fast: 0.3s ease;
    --transition-slow: 0.6s ease;
}

/* Dark Theme Colors - Applied with .dark-mode class */
.dark-mode {
    --primary-color: #e2e8f0;
    --secondary-color: #cbd5e1;
    --accent-color: #818cf8;
    --background-color: #0f172a;
    --background-alt: #1e293b;
    --text-color: #f1f5f9;
    --text-light: #cbd5e1;
    --border-color: #334155;
    --shadow-color: rgba(0, 0, 0, 0.25);
    --gradient-primary: linear-gradient(90deg, #818cf8, #c084fc);
    --gradient-secondary: linear-gradient(90deg, #0f172a, #1e293b);
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-body);
    color: var(--text-color);
    background-color: var(--background-color);
    line-height: 1.6;
    transition: background-color var(--transition-fast), color var(--transition-fast);
}

h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-heading);
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: var(--spacing-md);
}

h1 {
    font-size: 2.5rem;
}

h2 {
    font-size: 2rem;
}

h3 {
    font-size: 1.75rem;
}

p {
    margin-bottom: var(--spacing-md);
}

a {
    color: var(--accent-color);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--primary-color);
}

ul {
    list-style: none;
}

img {
    max-width: 100%;
    height: auto;
}

.container {
    width: 90%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

.section-title {
    text-align: center;
    margin-bottom: var(--spacing-xl);
    position: relative;
    font-weight: 700;
    background-image: var(--gradient-primary);
    background-clip: text;
    -webkit-background-clip: text;
    color: transparent;
    display: inline-block;
    padding: 0 var(--spacing-lg);
    left: 50%;
    transform: translateX(-50%);
}

.section-title:before {
    content: '';
    position: absolute;
    width: 100%;
    height: 2px;
    background-image: var(--gradient-primary);
    bottom: -10px;
    left: 0;
    border-radius: 2px;
}

/* 
=======================
Header & Navigation
=======================
*/
#header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background-color: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    box-shadow: 0 2px 10px var(--shadow-color);
    z-index: 1000;
    transition: all var(--transition-fast);
}

.dark-mode #header {
    background-color: rgba(15, 23, 42, 0.9);
}

#header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md) var(--spacing-md);
}

.logo a {
    font-family: var(--font-heading);
    font-size: 1.5rem;
    font-weight: 700;
    text-decoration: none;
    display: flex;
    align-items: center;
    justify-content: center;
}

.logo-text {
    background-image: var(--gradient-primary);
    background-clip: text;
    -webkit-background-clip: text;
    color: transparent;
    position: relative;
}

nav {
    display: flex;
    align-items: center;
}

.nav-links {
    display: flex;
    gap: var(--spacing-lg);
}

.nav-links a {
    color: var(--text-color);
    font-weight: 600;
    position: relative;
}

.nav-links a:after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--accent-color);
    transition: width var(--transition-fast);
}

.nav-links a:hover:after,
.nav-links a.active:after {
    width: 100%;
}

.theme-toggle {
    margin-left: var(--spacing-lg);
    cursor: pointer;
    font-size: 1.2rem;
    color: var(--text-color);
    transition: color var(--transition-fast);
}

.theme-toggle:hover {
    color: var(--accent-color);
}

.hamburger {
    display: none;
    cursor: pointer;
    margin-left: var(--spacing-md);
}

.hamburger span {
    display: block;
    width: 25px;
    height: 3px;
    background-color: var(--text-color);
    margin: 5px 0;
    transition: transform var(--transition-fast), opacity var(--transition-fast);
}

/* 
=======================
Hero Section
=======================
*/
.hero {
    padding: calc(80px + var(--spacing-xl)) 0 var(--spacing-xl);
    background-image: radial-gradient(circle at 80% 20%, var(--background-alt) 0%, var(--background-color) 100%);
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    width: 300px;
    height: 300px;
    border-radius: 50%;
    background: var(--gradient-primary);
    opacity: 0.05;
    top: -150px;
    right: -100px;
    z-index: 0;
}

.hero::after {
    content: '';
    position: absolute;
    width: 200px;
    height: 200px;
    border-radius: 50%;
    background: var(--gradient-primary);
    opacity: 0.05;
    bottom: -100px;
    left: -50px;
    z-index: 0;
}

.hero-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: var(--spacing-xl);
}

.hero-text {
    flex: 1;
}

.hero-text h1 {
    font-size: 4rem;
    margin-bottom: var(--spacing-sm);
    background-image: var(--gradient-primary);
    background-clip: text;
    -webkit-background-clip: text;
    color: transparent;
    display: inline-block;
}

.hero-text h2 {
    font-family: var(--font-body);
    font-weight: 400;
    font-size: 1.5rem;
    color: var(--text-light);
    margin-bottom: var(--spacing-lg);
    letter-spacing: 0.5px;
}

.hero-image {
    flex: 1;
    text-align: center;
}

.hero-image img {
    max-height: 500px;
    border-radius: 5px;
    box-shadow: 0 10px 30px var(--shadow-color);
}

.scroll-indicator {
    text-align: center;
    margin-top: var(--spacing-xl);
    animation: bounce 2s infinite;
}

.scroll-indicator a {
    color: var(--text-light);
    font-size: 1.5rem;
}

@keyframes bounce {
    0%, 20%, 50%, 80%, 100% {
        transform: translateY(0);
    }
    40% {
        transform: translateY(-20px);
    }
    60% {
        transform: translateY(-10px);
    }
}

/* 
=======================
Button Styles
=======================
*/
.btn {
    display: inline-block;
    padding: 12px 30px;
    background-image: var(--gradient-primary);
    color: white;
    border-radius: 6px;
    font-weight: 600;
    text-align: center;
    transition: all var(--transition-fast);
    border: none;
    cursor: pointer;
    position: relative;
    overflow: hidden;
    z-index: 1;
}

.btn:before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background-image: var(--gradient-secondary);
    transition: left 0.4s ease;
    z-index: -1;
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 25px var(--shadow-color);
    color: white;
}

.btn:hover:before {
    left: 0;
}

.btn-small {
    padding: 8px 15px;
    font-size: 0.9rem;
}

.view-more {
    display: block;
    width: 200px;
    margin: var(--spacing-lg) auto 0;
}

/* 
=======================
About Section
=======================
*/
.about {
    padding: var(--spacing-xl) 0;
}

.about-content {
    display: flex;
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
}

.about-text {
    flex: 1;
}

.timeline {
    flex: 1;
}

.timeline h3 {
    margin-bottom: var(--spacing-lg);
}

.timeline-item {
    position: relative;
    padding-left: 30px;
    margin-bottom: var(--spacing-lg);
}

.timeline-dot {
    position: absolute;
    left: 0;
    top: 6px;
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background-image: var(--gradient-primary);
    box-shadow: 0 0 0 4px rgba(99, 102, 241, 0.1);
}

.timeline-item:not(:last-child)::before {
    content: '';
    position: absolute;
    left: 8px;
    top: 22px;
    bottom: -30px;
    width: 2px;
    background-image: linear-gradient(to bottom, var(--accent-color), transparent);
}

.timeline-content h4 {
    margin-bottom: var(--spacing-sm);
}

.timeline-content p {
    margin-bottom: var(--spacing-sm);
    color: var(--text-light);
}

/* 
=======================
Books Section
=======================
*/
.books {
    padding: var(--spacing-xl) 0;
    background-color: var(--background-alt);
}

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

.book-card {
    background-color: var(--background-color);
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 5px 15px var(--shadow-color);
    transition: transform var(--transition-fast), box-shadow var(--transition-fast);
    position: relative;
    z-index: 1;
}

.book-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-image: var(--gradient-primary);
    opacity: 0;
    transition: opacity var(--transition-fast);
    z-index: -1;
    border-radius: 12px;
}

.dark-mode .book-card::before {
    opacity: 0.03;
}

.book-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 25px var(--shadow-color);
}

.book-card:hover::before {
    opacity: 0.05;
}

.dark-mode .book-card:hover::before {
    opacity: 0.08;
}

.book-cover {
    text-align: center;
    padding: var(--spacing-md);
    background-color: var(--background-alt);
}

.book-cover img {
    max-height: 300px;
}

.book-info {
    padding: var(--spacing-md);
}

.book-meta {
    color: var(--text-light);
    font-size: 0.9rem;
    margin-bottom: var(--spacing-md);
}

.book-links {
    display: flex;
    gap: var(--spacing-md);
    margin-top: var(--spacing-md);
}

/* 
=======================
Research Section
=======================
*/
.research {
    padding: var(--spacing-xl) 0;
}

.research-item {
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
    border-left: 3px solid;
    border-image: var(--gradient-primary) 1;
    background-color: var(--background-alt);
    border-radius: 0 12px 12px 0;
    transition: transform var(--transition-fast), box-shadow var(--transition-fast);
    position: relative;
}

.research-item::before {
    content: '';
    position: absolute;
    inset: 0;
    border-radius: 0 12px 12px 0;
    background-image: var(--gradient-primary);
    opacity: 0;
    transition: opacity var(--transition-fast);
    z-index: 0;
    pointer-events: none;
}

.dark-mode .research-item::before {
    opacity: 0.03;
}

.research-item:hover {
    transform: translateX(5px);
    box-shadow: 0 5px 15px var(--shadow-color);
}

.research-item:hover::before {
    opacity: 0.05;
}

.dark-mode .research-item:hover::before {
    opacity: 0.08;
}

.research-item > * {
    position: relative;
    z-index: 1;
}

.research-meta {
    color: var(--text-light);
    font-style: italic;
    margin-bottom: var(--spacing-md);
}

.research-abstract {
    margin-bottom: var(--spacing-md);
}

.research-links a {
    display: inline-flex;
    align-items: center;
    gap: 5px;
}

/* 
=======================
Testimonials Section
=======================
*/
.testimonials {
    padding: var(--spacing-xl) 0;
    background-color: var(--background-alt);
}

.testimonials-slider {
    position: relative;
    max-width: 800px;
    margin: 0 auto;
}

.testimonial-item {
    padding: var(--spacing-lg);
    text-align: center;
    display: none;
}

.testimonial-item.active {
    display: block;
    animation: fadeIn 1s;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.testimonial-text {
    font-size: 1.2rem;
    font-style: italic;
    margin-bottom: var(--spacing-md);
}

.testimonial-author {
    font-weight: 600;
    color: var(--text-light);
}

.testimonial-controls {
    display: flex;
    justify-content: center;
    gap: var(--spacing-md);
    margin-top: var(--spacing-lg);
}

.testimonial-controls button {
    background: none;
    border: 2px solid var(--accent-color);
    color: var(--accent-color);
    width: 40px;
    height: 40px;
    border-radius: 50%;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.testimonial-controls button:hover {
    background-color: var(--accent-color);
    color: white;
}

/* 
=======================
Blog Section
=======================
*/
.blog {
    padding: var(--spacing-xl) 0;
}

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

.blog-card {
    background-color: var(--background-color);
    border-radius: 16px;
    overflow: hidden;
    box-shadow: 0 5px 15px var(--shadow-color);
    transition: all var(--transition-fast);
    position: relative;
}

.blog-card::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 5px;
    background-image: var(--gradient-primary);
    opacity: 0;
    transition: opacity var(--transition-fast);
}

.blog-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 30px var(--shadow-color);
}

.blog-card:hover::after {
    opacity: 1;
}

.blog-image img {
    width: 100%;
    height: 200px;
    object-fit: cover;
}

.blog-content {
    padding: var(--spacing-md);
}

.blog-date {
    color: var(--text-light);
    font-size: 0.9rem;
    margin-bottom: var(--spacing-md);
}

.read-more {
    display: inline-block;
    margin-top: var(--spacing-sm);
    font-weight: 600;
}

/* 
=======================
Contact Section
=======================
*/
.contact {
    padding: var(--spacing-xl) 0;
    background-color: var(--background-alt);
}

.contact-content {
    display: flex;
    gap: var(--spacing-xl);
}

.contact-info, .contact-form {
    flex: 1;
}

.contact-info p {
    display: flex;
    align-items: center;
    margin-bottom: var(--spacing-md);
}

.contact-info i {
    width: 25px;
    margin-right: var(--spacing-sm);
    color: var(--accent-color);
}

.social-links {
    display: flex;
    gap: var(--spacing-md);
    margin: var(--spacing-lg) 0;
}

.social-links a {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background-image: var(--gradient-primary);
    color: white;
    transition: all var(--transition-fast);
    position: relative;
    overflow: hidden;
    z-index: 1;
}

.social-links a:before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-image: var(--gradient-secondary);
    opacity: 0;
    transition: opacity var(--transition-fast);
    z-index: -1;
}

.social-links a:hover {
    transform: translateY(-3px);
    box-shadow: 0 5px 10px var(--shadow-color);
}

.social-links a:hover:before {
    opacity: 1;
}

.office-hours {
    font-style: italic;
    color: var(--text-light);
}

.form-group {
    margin-bottom: var(--spacing-md);
}

label {
    display: block;
    margin-bottom: var(--spacing-sm);
    font-weight: 600;
}

input, textarea {
    width: 100%;
    padding: 10px;
    border: 1px solid var(--border-color);
    border-radius: 5px;
    background-color: var(--background-color);
    color: var(--text-color);
    transition: border-color var(--transition-fast);
}

input:focus, textarea:focus {
    outline: none;
    border-color: var(--accent-color);
}

.error-message {
    color: #e53e3e;
    font-size: 0.9rem;
    margin-top: 5px;
    display: none;
}

.error-message.show {
    display: block;
}

/* 
=======================
Footer
=======================
*/
footer {
    padding: var(--spacing-lg) 0;
    background-image: var(--gradient-secondary);
    color: white;
    position: relative;
    overflow: hidden;
}

footer::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background-image: var(--gradient-primary);
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-lg);
}

.footer-logo h3 {
    margin-bottom: 5px;
}

.footer-nav ul {
    display: flex;
    gap: var(--spacing-md);
}

.footer-nav a {
    color: white;
    opacity: 0.8;
    transition: opacity var(--transition-fast);
}

.footer-nav a:hover {
    opacity: 1;
}

.copyright {
    text-align: center;
    padding-top: var(--spacing-md);
    border-top: 1px solid rgba(255, 255, 255, 0.2);
    font-size: 0.9rem;
    opacity: 0.8;
}

/* 
=======================
Back to Top Button
=======================
*/
#backToTop {
    position: fixed;
    bottom: 20px;
    right: 20px;
    width: 45px;
    height: 45px;
    background-image: var(--gradient-primary);
    color: white;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    display: none;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
    z-index: 999;
    box-shadow: 0 4px 12px rgba(99, 102, 241, 0.25);
}

#backToTop:hover {
    transform: translateY(-3px);
    box-shadow: 0 6px 18px rgba(99, 102, 241, 0.4);
}

#backToTop.show {
    display: flex;
    animation: fadeIn 0.3s;
}

/* 
=======================
Responsive Styles
=======================
*/
@media (max-width: 992px) {
    h1 {
        font-size: 2.2rem;
    }
    
    .hero-content {
        flex-direction: column-reverse;
        text-align: center;
    }
    
    .about-content {
        flex-direction: column;
    }
    
    .contact-content {
        flex-direction: column;
    }
}

@media (max-width: 768px) {
    .nav-links {
        position: fixed;
        top: 70px;
        left: 0;
        width: 100%;
        flex-direction: column;
        gap: 0;
        background-color: var(--background-color);
        box-shadow: 0 5px 10px var(--shadow-color);
        padding: 0;
        max-height: 0;
        overflow: hidden;
        transition: max-height var(--transition-fast);
    }
    
    .nav-links.show {
        max-height: 500px;
        padding: var(--spacing-md) 0;
    }
    
    .nav-links li {
        width: 100%;
        text-align: center;
    }
    
    .nav-links a {
        display: block;
        padding: var(--spacing-md);
    }
    
    .hamburger {
        display: block;
    }
    
    .nav-active .hamburger span:nth-child(1) {
        transform: rotate(-45deg) translate(-5px, 6px);
    }
    
    .nav-active .hamburger span:nth-child(2) {
        opacity: 0;
    }
    
    .nav-active .hamburger span:nth-child(3) {
        transform: rotate(45deg) translate(-5px, -6px);
    }
    
    .footer-content {
        flex-direction: column;
        gap: var(--spacing-md);
        text-align: center;
    }
    
    .footer-nav ul {
        justify-content: center;
        flex-wrap: wrap;
    }
}

@media (max-width: 576px) {
    html {
        font-size: 14px;
    }
    
    .section-title {
        margin-bottom: var(--spacing-lg);
    }
    
    .books-grid, .blog-grid {
        grid-template-columns: 1fr;
    }
    
    .testimonial-text {
        font-size: 1rem;
    }
}