styles.css

/* 1. GLOBAL RESET & VARIABLES */
:root {
    /* CSS Variables allow you to change colors in one place */
    --primary-color: #2c3e50;    /* Dark Blue - Professional */
    --accent-color: #3498db;     /* Light Blue - For links/buttons */
    --bg-light: #f4f4f4;         /* Light Gray - For alternate sections */
    --text-color: #333;          /* Dark Gray - Easy to read text */
    --white: #ffffff;
}

/* The 'wildcard' selector (*) resets default browser spacing */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box; /* Ensures padding doesn't increase element width */
}

body {
    font-family: 'Roboto', sans-serif;
    line-height: 1.6;
    color: var(--text-color);
}

/* 2. REUSABLE UTILITY CLASSES */
.container {
    max-width: 1100px; /* Limits width on large screens */
    margin: 0 auto;    /* Centers content horizontally */
    padding: 0 20px;
}

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

/* 3. HEADER & NAVIGATION */
header {
    background: var(--primary-color);
    color: var(--white);
    padding: 20px 0;
    position: sticky; /* Keeps header at top when scrolling */
    top: 0;
    z-index: 1000;
}

header .container {
    display: flex;             /* Places Logo and Nav side-by-side */
    justify-content: space-between;
    align-items: center;
}

header ul {
    list-style: none;
    display: flex;             /* Places menu items in a horizontal row */
}

header ul li {
    margin-left: 20px;
}

header ul li a {
    color: var(--white);
    font-weight: bold;
}

/* 4. HERO SECTION */
.hero {
    background: var(--white);
    padding: 100px 0;
    text-align: center;
}

.hero h2 {
    font-size: 2.5rem;
    color: var(--primary-color);
}

.subtitle {
    font-size: 1.2rem;
    color: #666;
    margin-bottom: 20px;
}

.bio {
    max-width: 700px;
    margin: 0 auto 30px auto; /* Centers the text block */
}

.btn {
    background: var(--accent-color);
    color: var(--white);
    padding: 10px 20px;
    border-radius: 5px;
    transition: background 0.3s; /* Smooth color change on hover */
}

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

/* 5. SECTIONS GENERAL STYLING */
section {
    padding: 60px 0;
}

.section-gray {
    background: var(--bg-light);
}

.section-title {
    text-align: center;
    font-size: 2rem;
    margin-bottom: 40px;
    color: var(--primary-color);
}

/* 6. SKILLS GRID (Using CSS Grid) */
.skills-grid {
    display: grid;
    /* Creates columns that automatically fit the screen width */
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
}

.skill-card {
    background: var(--white);
    padding: 20px;
    text-align: center;
    border-radius: 5px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1); /* Subtle shadow effect */
    font-weight: bold;
}

/* 7. EXPERIENCE TIMELINE */
.timeline-item {
    background: var(--white);
    padding: 20px;
    margin-bottom: 20px;
    border-left: 4px solid var(--accent-color); /* The colored line on the left */
    box-shadow: 0 2px 5px rgba(0,0,0,0.05);
}

.timeline-item h4 {
    font-size: 1.2rem;
}

.timeline-item .date {
    font-size: 0.9rem;
    color: #777;
    display: block;      /* Forces date to its own line */
    margin-bottom: 10px;
}

.timeline-item .institution {
    font-weight: bold;
    color: var(--primary-color);
}

/* 8. PUBLICATIONS LIST */
.pub-list {
    list-style: none;
    max-width: 800px;
    margin: 0 auto;
}

.pub-list li {
    background: var(--white);
    margin-bottom: 15px;
    padding: 15px;
    border-radius: 5px;
    border: 1px solid #ddd;
}

/* 9. FOOTER */
footer {
    background: var(--primary-color);
    color: var(--white);
    text-align: center;
    padding: 40px 0;
}

/* 10. MEDIA QUERIES (Mobile Responsiveness) */
@media (max-width: 768px) {
    header .container {
        flex-direction: column; /* Stack logo and menu on mobile */
    }

    header ul {
        margin-top: 20px;
    }
    
    .hero h2 {
        font-size: 2rem;
    }
}