/* --- General Styles & Reset --- */
:root {
    --primary-light: #ffffff;
    --secondary-light: #f4f4f4;
    --text-light: #333333;
    --accent-light: #007bff; /* Blue accent */
    --hover-light: #e0e0e0;

    --primary-dark: #1a1a1a; /* Darker background */
    --secondary-dark: #2c2c2c; /* Slightly lighter dark */
    --text-dark: #e0e0e0; /* Light text */
    --accent-dark: #61dafb; /* Lighter blue/cyan accent for dark mode */
    --hover-dark: #3a3a3a;

    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    --font-mono: 'Fira Code', monospace;

    --transition-speed: 0.3s;
}

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

body {
    font-family: var(--font-sans);
    line-height: 1.6;
    transition: background-color var(--transition-speed) ease, color var(--transition-speed) ease;
    background-color: var(--primary-dark);
    color: var(--text-dark);
    overflow-x: hidden; /* Prevent horizontal scroll caused by animations */
}

body.light-mode {
    background-color: var(--primary-light);
    color: var(--text-light);
}

h1, h2, h3, h4, h5, h6 {
    margin-bottom: 0.8rem;
    font-weight: 600; /* Slightly bolder */
}

a {
    text-decoration: none;
    transition: color var(--transition-speed) ease;
}

body.light-mode a { color: var(--accent-light); }
body.dark-mode a { color: var(--accent-dark); }
body.light-mode a:hover { color: #0056b3; }
body.dark-mode a:hover { color: #81e6ff; }


ul {
    list-style: none;
    padding: 0;
}

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

.section {
    padding: 6rem 2rem;
    max-width: 1100px;
    margin: 0 auto;
    text-align: center;
}

.section-title {
    font-size: 2.5rem;
    margin-bottom: 3rem;
    position: relative;
    display: inline-block;
}

/* Underline effect for titles */
.section-title::after {
    content: '';
    display: block;
    width: 60px;
    height: 3px;
    background: var(--accent-dark);
    margin: 0.5rem auto 0;
    transition: background-color var(--transition-speed) ease;
}
body.light-mode .section-title::after {
    background: var(--accent-light);
}

/* --- Navbar --- */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    transition: background-color var(--transition-speed) ease, box-shadow var(--transition-speed) ease;
    background-color: rgba(26, 26, 26, 0.8); /* Semi-transparent dark */
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    padding: 0.8rem 0;
}

body.light-mode .navbar {
    background-color: rgba(255, 255, 255, 0.8); /* Semi-transparent light */
}

.navbar-container {
    max-width: 1100px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 2rem;
}

.nav-logo {
    font-size: 1.8rem;
    font-weight: bold;
    color: var(--text-dark);
}
body.light-mode .nav-logo { color: var(--text-light); }

.navbar-menu {
    display: flex;
}

.navbar-nav {
    display: flex;
    align-items: center;
    list-style: none;
}

.nav-item {
    margin-left: 1.5rem;
}

.nav-link {
    font-size: 1rem;
    font-weight: 500;
    color: var(--text-dark);
    transition: color var(--transition-speed) ease;
    position: relative; /* For underline effect */
    padding-bottom: 0.3rem;
}
body.light-mode .nav-link { color: var(--text-light); }
.nav-link:hover {
    color: var(--accent-dark);
}
body.light-mode .nav-link:hover {
    color: var(--accent-light);
}
/* Underline effect on hover/active */
.nav-link::after {
    content: '';
    position: absolute;
    width: 0;
    height: 2px;
    bottom: 0;
    left: 0;
    background-color: var(--accent-dark);
    transition: width 0.3s ease;
}
body.light-mode .nav-link::after { background-color: var(--accent-light); }
.nav-link:hover::after,
.nav-link.active::after { /* Add .active class via JS on scroll */
    width: 100%;
}


.navbar-toggler {
    display: none; /* Hidden on desktop */
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
}

.toggler-icon {
    display: block;
    width: 25px;
    height: 3px;
    background-color: var(--text-dark);
    margin: 5px 0;
    transition: background-color var(--transition-speed) ease, transform 0.3s ease, opacity 0.3s ease;
}
body.light-mode .toggler-icon { background-color: var(--text-light); }

/* --- Night Mode Toggle --- */
.night-mode-toggle {
    background: none;
    border: none;
    color: var(--text-dark);
    cursor: pointer;
    font-size: 1.5rem; /* Adjust size */
    padding: 0.3rem;
    margin-left: 1rem;
    transition: color var(--transition-speed) ease;
    line-height: 1; /* Prevent extra space */
}
body.light-mode .night-mode-toggle { color: var(--text-light); }
.night-mode-toggle:hover {
    color: var(--accent-dark);
}
body.light-mode .night-mode-toggle:hover {
    color: var(--accent-light);
}

/* --- Hero Section --- */
.hero-section {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    /* Optional background gradient or image */
    background: linear-gradient(135deg, #1f1f1f 0%, #101010 100%);
    padding-top: 80px; /* Account for navbar */
}
body.light-mode .hero-section {
    background: linear-gradient(135deg, #eef2f3 0%, #ffffff 100%);
}

.hero-content h1 {
    font-size: 3.5rem;
    margin-bottom: 0.5rem;
    font-weight: 700;
}

.hero-content .subtitle {
    font-size: 1.5rem;
    color: #aaa; /* Subtler text */
    margin-bottom: 2rem;
}
body.light-mode .hero-content .subtitle { color: #666; }


/* --- CTA Button --- */
.cta-button {
    display: inline-block;
    padding: 0.8rem 1.8rem;
    border: 2px solid var(--accent-dark);
    color: var(--accent-dark);
    border-radius: 5px;
    font-size: 1rem;
    font-weight: 500;
    transition: background-color var(--transition-speed) ease, color var(--transition-speed) ease, transform 0.2s ease;
}
body.light-mode .cta-button {
    border-color: var(--accent-light);
    color: var(--accent-light);
}

.cta-button:hover {
    background-color: var(--accent-dark);
    color: var(--primary-dark);
    transform: translateY(-2px);
}
body.light-mode .cta-button:hover {
    background-color: var(--accent-light);
    color: var(--primary-light);
}

/* --- About Section --- */
.about-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: left; /* Or center if preferred */
    line-height: 1.8;
    font-size: 1.1rem;
}

/* --- Skills Section --- */
.skills-grid {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 1.5rem;
    margin-top: 2rem;
}

.skill-item {
    background-color: var(--secondary-dark);
    padding: 0.8rem 1.5rem;
    border-radius: 20px; /* Pill shape */
    font-size: 1rem;
    font-weight: 500;
    transition: background-color var(--transition-speed) ease, transform 0.2s ease;
    border: 1px solid var(--hover-dark);
}
body.light-mode .skill-item {
    background-color: var(--secondary-light);
    border-color: var(--hover-light);
}

.skill-item:hover {
    transform: translateY(-3px);
    background-color: var(--hover-dark);
}
body.light-mode .skill-item:hover {
    background-color: var(--hover-light);
}

/* --- Projects Section --- */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
    text-align: left;
}

.project-card {
    background-color: var(--secondary-dark);
    padding: 1.5rem;
    border-radius: 8px;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    border: 1px solid var(--hover-dark);
}
body.light-mode .project-card {
    background-color: var(--secondary-light);
    border-color: var(--hover-light);
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.05);
}

.project-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.2);
}
body.light-mode .project-card:hover {
     box-shadow: 0 8px 16px rgba(0, 0, 0, 0.1);
}

.project-card h3 {
    margin-bottom: 0.5rem;
    color: var(--accent-dark);
}
body.light-mode .project-card h3 { color: var(--accent-light); }

.project-card p {
    font-size: 0.95rem;
    margin-bottom: 1rem;
}

/* --- Styles for Project Topics --- */
.project-topics {
    margin-bottom: 1rem; /* Space below topics, before links */
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem; /* Space between badges */
}

.topic-badge {
    background-color: var(--hover-dark); /* Use hover color for subtle contrast */
    color: var(--accent-dark); /* Use accent color for text */
    padding: 0.2rem 0.6rem;
    border-radius: 12px; /* Pill shape */
    font-size: 0.8rem;
    font-weight: 500;
    border: 1px solid var(--secondary-dark); /* Subtle border */
}

body.light-mode .topic-badge {
    background-color: var(--hover-light);
    color: var(--accent-light);
    border-color: var(--secondary-light);
}
/* --- End Styles for Project Topics --- */

/* Container for project links */
.project-links {
    margin-top: 1rem; /* Add space above links */
    display: flex;
    gap: 1rem; /* Space between links */
    flex-wrap: wrap; /* Allow links to wrap */
}

/* Style for loading message */
.loading-message {
    width: 100%;
    text-align: center;
    padding: 1rem;
    font-style: italic;
    color: #aaa;
}
body.light-mode .loading-message {
    color: #666;
}

/* --- Certifications Section --- */
.certifications-list {
    list-style: disc; /* Or none */
    padding-left: 20px; /* Indent if using disc */
    max-width: 700px;
    margin: 1rem auto 0;
    text-align: left;
}

.certifications-list li {
    margin-bottom: 0.8rem;
    font-size: 1.1rem;
}

body.light-mode .social-links a:hover { color: var(--accent-light); }

/* Utility class to hide elements */
.hidden {
    display: none !important; /* Use important to override other display properties if needed */
}

/* --- Resume Section --- */
#resume p {
    margin-bottom: 1.5rem;
    font-size: 1.1rem;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

/* --- Contact Section --- */
.contact-container {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 3rem;
    max-width: 900px;
    margin: 2rem auto 0;
    text-align: left;
}

.contact-info {
    flex-basis: 400px;
}

.contact-info p {
    margin-bottom: 1rem;
    font-size: 1.1rem;
}

.social-links {
    margin-top: 1.5rem;
}

.social-links a {
    font-size: 2rem; /* Icon size */
    margin-right: 1.5rem;
    color: var(--text-dark);
    transition: color var(--transition-speed) ease, transform 0.2s ease;
}
body.light-mode .social-links a { color: var(--text-light); }

.social-links a:hover {
    color: var(--accent-dark);
    transform: translateY(-3px);
}
body.light-mode .social-links a:hover { color: var(--accent-light); }

/* Optional Contact Form Styles (if uncommented) */
/*
#contact-form {
    flex-basis: 400px;
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

#contact-form input,
#contact-form textarea {
    width: 100%;
    padding: 0.8rem;
    border: 1px solid var(--hover-dark);
    border-radius: 5px;
    background-color: var(--secondary-dark);
    color: var(--text-dark);
    font-family: var(--font-sans);
    font-size: 1rem;
}
body.light-mode #contact-form input,
body.light-mode #contact-form textarea {
    background-color: var(--secondary-light);
    color: var(--text-light);
    border-color: var(--hover-light);
}

#contact-form textarea {
    min-height: 120px;
    resize: vertical;
}

#contact-form button {
    padding: 0.8rem 1.5rem;
    background-color: var(--accent-dark);
    color: var(--primary-dark);
    border: none;
    border-radius: 5px;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 500;
    transition: background-color var(--transition-speed) ease, transform 0.2s ease;
    align-self: flex-start;
}
body.light-mode #contact-form button {
    background-color: var(--accent-light);
    color: var(--primary-light);
}

#contact-form button:hover {
    filter: brightness(1.1);
    transform: translateY(-2px);
}
*/

/* --- Footer --- */
footer {
    text-align: center;
    padding: 2rem;
    margin-top: 3rem;
    border-top: 1px solid var(--hover-dark);
    font-size: 0.9rem;
    color: #aaa;
}
body.light-mode footer {
    border-top-color: var(--hover-light);
    color: #666;
}

/* --- Scroll to Top Button --- */
.scroll-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    background-color: var(--accent-dark);
    color: var(--primary-dark);
    border: none;
    border-radius: 50%;
    width: 50px;
    height: 50px;
    font-size: 1.5rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s ease, visibility 0.3s ease, transform 0.3s ease;
    z-index: 999;
}
body.light-mode .scroll-to-top {
    background-color: var(--accent-light);
    color: var(--primary-light);
}

.scroll-to-top.visible {
    opacity: 1;
    visibility: visible;
}

.scroll-to-top:hover {
    transform: scale(1.1);
}

/* --- Responsive Design --- */
@media (max-width: 768px) {
    .section {
        padding: 4rem 1rem;
    }

    .section-title {
        font-size: 2rem;
    }

    .hero-content h1 {
        font-size: 2.5rem;
    }
    .hero-content .subtitle {
        font-size: 1.2rem;
    }

    .navbar-menu {
        display: none; /* Hide menu by default */
        position: absolute;
        top: 100%; /* Position below navbar */
        left: 0;
        width: 100%;
        background-color: var(--primary-dark); /* Match navbar */
        flex-direction: column;
        text-align: center;
        border-top: 1px solid var(--hover-dark);
        padding: 1rem 0;
        opacity: 0;
        visibility: hidden;
        transform: translateY(-10px);
        transition: opacity 0.3s ease, visibility 0.3s ease, transform 0.3s ease;
    }
    body.light-mode .navbar-menu {
        background-color: var(--primary-light);
        border-top-color: var(--hover-light);
    }

    .navbar-menu.active {
        display: flex;
        opacity: 1;
        visibility: visible;
        transform: translateY(0);
    }

    .navbar-nav {
        flex-direction: column;
        width: 100%;
    }

    .nav-item {
        margin: 0.8rem 0;
        margin-left: 0; /* Reset margin */
        width: 100%;
    }

    .nav-link {
        display: block; /* Make link take full width */
        padding: 0.5rem 0;
    }

    /* Keep toggle button inside item list */
    .nav-item:has(.night-mode-toggle) {
        margin-top: 1rem;
    }
    .night-mode-toggle { margin-left: 0; } /* Reset margin */


    .navbar-toggler {
        display: block; /* Show toggler */
    }

    /* Animate toggler icon to 'X' */
    .navbar-toggler.active .toggler-icon:nth-child(1) {
        transform: rotate(45deg) translate(6px, 6px);
    }
    .navbar-toggler.active .toggler-icon:nth-child(2) {
        opacity: 0;
    }
    .navbar-toggler.active .toggler-icon:nth-child(3) {
        transform: rotate(-45deg) translate(6px, -6px);
    }


    .skills-grid {
        gap: 1rem;
    }
    .skill-item {
        padding: 0.6rem 1.2rem;
        font-size: 0.9rem;
    }

    .projects-grid {
        grid-template-columns: 1fr; /* Stack projects */
    }

    .contact-container {
        flex-direction: column;
        align-items: center;
        text-align: center;
    }
    .contact-info, #contact-form {
        flex-basis: 100%;
        max-width: 400px; /* Limit width on mobile */
    }
    .contact-info { text-align: center;}
    .social-links { text-align: center; }
     /*#contact-form button { align-self: center; }*/

    .scroll-to-top {
        width: 45px;
        height: 45px;
        font-size: 1.3rem;
        bottom: 1rem;
        right: 1rem;
    }
}