:root {
    --primary: #2c3e50;
    --secondary: #3498db;
    --accent: #e74c3c;
    --light: #ecf0f1;
    --dark: #2c3e50;
    --text: #333;
    --transition: all 0.3s ease;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

.error-msg {
    color: red;
}

body {
    color: var(--text);
    line-height: 1.6;
    background-color: #f9f9f9;
}

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

/* Header & Navigation */
header {
    background: linear-gradient(135deg, var(--primary) 0%, var(--dark) 100%);
    color: white;
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.8rem;
    font-weight: 700;
}

.logo span {
    color: var(--secondary);
}

.nav-links {
    display: flex;
    list-style: none;
}

.nav-links li {
    margin-left: 2rem;
}

.nav-links a {
    color: white;
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
    padding: 0.5rem 0;
    position: relative;
}

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

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

.menu-btn {
    display: none;
    font-size: 1.5rem;
    cursor: pointer;
}

/* Hero Section */
.hero {
    background: linear-gradient(rgba(44, 62, 80, 0.8), rgba(44, 62, 80, 0.8)), url('https://images.unsplash.com/photo-1532094349884-543bc11b234d?ixlib=rb-4.0.3') center/cover no-repeat;
    color: white;
    padding: 6rem 0;
    text-align: center;
}

.hero-content {
    max-width: 800px;
    margin: 0 auto;
}

.hero h1 {
    font-size: 3.5rem;
    margin-bottom: 1rem;
}

.hero p {
    font-size: 1.5rem;
    margin-bottom: 2rem;
}

.btn {
    display: inline-block;
    background: var(--secondary);
    color: white;
    padding: 0.8rem 1.8rem;
    border-radius: 30px;
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition);
    border: 2px solid var(--secondary);
}

.btn:hover {
    background: transparent;
    color: var(--secondary);
}

.btn-outline {
    background: transparent;
    border: 2px solid white;
    margin-left: 1rem;
}

.btn-outline:hover {
    background: white;
    color: var(--primary);
}

/* Sections */
section {
    padding: 5rem 0;
}

.section-title {
    text-align: center;
    margin-bottom: 3rem;
}

.section-title h2 {
    font-size: 2.5rem;
    color: var(--primary);
    position: relative;
    display: inline-block;
    padding-bottom: 0.5rem;
}

.section-title h2:after {
    content: '';
    position: absolute;
    width: 50%;
    height: 3px;
    background: var(--secondary);
    bottom: 0;
    left: 25%;
}

/* About */
.about-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: center;
}

.skills {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    margin-top: 2rem;
}

.skill-chip {
    background: var(--light);
    padding: 0.5rem 1.2rem;
    border-radius: 30px;
    font-weight: 500;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
}

/* Experience & Education */
.timeline {
    position: relative;
    max-width: 800px;
    margin: 0 auto;
}

.timeline:before {
    content: '';
    position: absolute;
    left: 50%;
    width: 2px;
    height: 100%;
    background: var(--secondary);
    transform: translateX(-50%);
}

.timeline-item {
    display: flex;
    margin-bottom: 3rem;
    position: relative;
}

.timeline-item:nth-child(odd) {
    justify-content: flex-start;
    padding-right: 50%;
}

.timeline-item:nth-child(even) {
    justify-content: flex-end;
    padding-left: 50%;
}

.timeline-content {
    background: white;
    padding: 1.5rem;
    border-radius: 8px;
    box-shadow: 0 3px 10px rgba(0, 0, 0, 0.1);
    width: 90%;
    position: relative;
}

.timeline-content:before {
    content: '';
    position: absolute;
    top: 20px;
    width: 20px;
    height: 20px;
    background: white;
    transform: rotate(45deg);
}

.timeline-item:nth-child(odd) .timeline-content:before {
    right: -10px;
}

.timeline-item:nth-child(even) .timeline-content:before {
    left: -10px;
}

.timeline-dot {
    position: absolute;
    top: 20px;
    left: 50%;
    width: 20px;
    height: 20px;
    background: var(--secondary);
    border-radius: 50%;
    transform: translateX(-50%);
    z-index: 1;
}

/* Projects */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 2rem;
}

.project-card {
    background: white;
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 3px 10px rgba(0, 0, 0, 0.1);
    transition: var(--transition);
}

.project-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.15);
}

.project-img {
    height: 200px;
    background: var(--light);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--secondary);
    font-size: 3rem;
}

.project-content {
    padding: 1.5rem;
}

.project-content h3 {
    margin-bottom: 0.5rem;
    color: var(--primary);
}

/* Publications */
.publication-list {
    max-width: 800px;
    margin: 0 auto;
}

.publication-item {
    background: white;
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    border-radius: 8px;
    box-shadow: 0 3px 10px rgba(0, 0, 0, 0.1);
}

/* Contact */
.contact-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
}

.contact-info {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.contact-item {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.contact-icon {
    width: 50px;
    height: 50px;
    background: var(--secondary);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.2rem;
}

.contact-form input,
.contact-form textarea,
.contact-form select {
    width: 100%;
    padding: 1rem;
    margin-bottom: 1.5rem;
    border: 1px solid #ddd;
    border-radius: 5px;
    font-size: 1rem;
}

.contact-form textarea {
    min-height: 150px;
    resize: vertical;
}

/* Footer */
footer {
    background: var(--dark);
    color: white;
    padding: 3rem 0;
    text-align: center;
}

.social-links {
    display: flex;
    justify-content: center;
    gap: 1.5rem;
    margin: 2rem 0;
}

.social-links a {
    color: white;
    font-size: 1.5rem;
    transition: var(--transition);
}

.social-links a:hover {
    color: var(--secondary);
}

/* Notification */
.notification {
    position: fixed;
    top: 20px;
    right: 20px;
    padding: 15px 25px;
    background: #27ae60;
    color: white;
    border-radius: 8px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
    transform: translateX(100%);
    opacity: 0;
    transition: transform 0.4s, opacity 0.4s;
    z-index: 1000;
}

.notification.show {
    transform: translateX(0);
    opacity: 1;
}

/* Responsive Design */
@media (max-width: 992px) {

    .about-content,
    .contact-content {
        grid-template-columns: 1fr;
    }

    .timeline:before {
        left: 30px;
    }

    .timeline-item:nth-child(odd),
    .timeline-item:nth-child(even) {
        justify-content: flex-start;
        padding: 0;
        padding-left: 70px;
    }

    .timeline-dot {
        left: 30px;
    }

    .timeline-content:before {
        left: -10px;
        right: auto;
    }
}

@media (max-width: 768px) {
    .nav-links {
        position: fixed;
        top: 70px;
        left: -100%;
        width: 100%;
        height: calc(100vh - 70px);
        background: var(--primary);
        flex-direction: column;
        align-items: center;
        justify-content: center;
        transition: var(--transition);
        gap: 2rem;
    }

    .nav-links.active {
        left: 0;
    }

    .menu-btn {
        display: block;
    }

    .hero h1 {
        font-size: 2.5rem;
    }

    .hero p {
        font-size: 1.2rem;
    }

    .btn {
        margin: 1rem auto;
        width: 80%;
    }

    .btn-outline {
        margin-left: 0;
    }
}