/* ---
           Professional Portfolio Design for Md. Jahirul Islam
           Designed by Gemini - v10.0 (Dark/Light Mode)
        --- */

        /* 1. VARIABLES & GENERAL STYLES
        -------------------------------------------------- */
        :root {
            --primary-color: #3498db;
            --accent-color: #64ffda;
            --bg-color: #0a192f;
            --section-bg-color: transparent; /* Sections are transparent over the body bg */
            --section-overlay-color: rgba(10, 25, 47, 0.85);
            --card-bg-color: rgba(255, 255, 255, 0.05);
            --card-border-color: rgba(255, 255, 255, 0.1);
            --header-bg-color: rgba(10, 25, 47, 0.85);
            --light-color: #f8f9fa;
            --text-color: #ccd6f6;
            --text-color-dark: #8892b0;
            --shadow-deep: 0 15px 50px rgba(0, 0, 0, 0.2);
            --border-radius: 8px;
        }

        body.light-mode {
            --primary-color: #0056b3;
            --accent-color: #007bff;
            --bg-color: #e9ecef; /* Light gray page background */
            --section-bg-color: #ffffff; /* Sections are white cards */
            --section-overlay-color: transparent; /* No overlay in light mode */
            --card-bg-color: #f8f9fa;
            --card-border-color: #dee2e6;
            --header-bg-color: rgba(255, 255, 255, 0.85);
            --light-color: #212529; /* Dark text */
            --text-color: #495057;
            --text-color-dark: #6c757d;
            --shadow-deep: 0 15px 50px rgba(0, 0, 0, 0.1);
        }


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

        body {
            font-family: 'Poppins', sans-serif;
            line-height: 1.7;
            color: var(--text-color);
            background-color: var(--bg-color);
            overflow-x: hidden;
            cursor: none;
            transition: background-color 0.3s ease;
        }

        .container {
            max-width: 1140px;
            margin: auto;
            padding: 0 20px;
        }

        h1, h2, h3 {
            color: var(--light-color);
            font-weight: 700;
        }

        h1 { font-size: 3.2rem; line-height: 1.2; }
        h2 {
            font-size: 2.5rem;
            text-align: center;
            margin-bottom: 1.5rem;
            background: linear-gradient(90deg, var(--accent-color), var(--light-color));
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            background-clip: text;
        }
        p { color: var(--text-color-dark); margin-bottom: 1rem; }
        
        section {
            padding: 100px 0;
            position: relative;
            z-index: 1;
        }
        
        section:not(.hero) {
            background-size: cover;
            background-position: center center;
            background-attachment: fixed;
            border-radius: var(--border-radius);
            box-shadow: var(--shadow-deep);
            margin: 0 auto 40px auto;
            max-width: 1280px;
            padding: 80px 40px;
            background-color: var(--section-bg-color);
        }

        body.light-mode section:not(.hero) {
            background-image: none !important; /* Remove parallax images in light mode */
        }

        section:not(.hero)::before {
            content: '';
            position: absolute;
            top: 0; left: 0;
            width: 100%; height: 100%;
            background-color: var(--section-overlay-color);
            border-radius: var(--border-radius);
            z-index: -1;
        }

        #about { background-image: url('https://images.unsplash.com/photo-1517694712202-14dd9538aa97?q=80&w=2070&auto=format&fit=crop'); }
        #experience { background-image: url('https://images.unsplash.com/photo-1521737711867-e3b97375f902?q=80&w=1974&auto=format&fit=crop'); }
        #skills { background-image: url('https://images.unsplash.com/photo-1555066931-4365d14bab8c?q=80&w=2070&auto=format&fit=crop'); }
        #workflow { background-image: url('https://images.unsplash.com/photo-1542744173-8e7e53415bb0?q=80&w=2070&auto=format&fit=crop'); }
        #services { background-image: url('https://images.unsplash.com/photo-1550751827-4bd374c3f58b?q=80&w=2070&auto=format&fit=crop'); }
        #portfolio { background-image: url('https://images.unsplash.com/photo-1522199755839-a2bacb67c546?q=80&w=2072&auto=format&fit=crop'); }
        #freelancing { background-image: url('https://images.unsplash.com/photo-1556740758-90de374c12ad?q=80&w=2070&auto=format&fit=crop'); }
        #gallery { background-image: url('https://images.unsplash.com/photo-1511376777868-611b54f68947?q=80&w=2070&auto=format&fit=crop'); }
        #testimonials { background-image: url('https://images.unsplash.com/photo-1587560699334-cc4263443cf1?q=80&w=2070&auto=format&fit=crop'); }
        #contact { background-image: url('https://images.unsplash.com/photo-1486312338219-ce68d2c6f44d?q=80&w=2072&auto=format&fit=crop'); }

        .btn {
            display: inline-block;
            padding: 12px 28px;
            border-radius: var(--border-radius);
            text-decoration: none;
            font-weight: 500;
            transition: all 0.3s ease;
            border: 2px solid var(--accent-color);
            cursor: pointer;
            background-color: transparent;
            color: var(--accent-color);
        }

        .btn:hover {
            background-color: rgba(100, 255, 218, 0.1);
            transform: translateY(-2px);
        }
        
        body.light-mode .btn:hover {
            background-color: rgba(0, 123, 255, 0.1);
        }

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

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

        .btn.btn-secondary {
            margin-left: 15px;
        }
        
        .section-subtitle {
            text-align: center;
            max-width: 700px;
            margin: 0 auto 50px;
            font-size: 1.1rem;
            color: var(--text-color-dark);
        }
        
        section:not(.hero) .section-subtitle, section:not(.hero) p {
             color: var(--text-color);
        }
        
        /* Animation Classes */
        [data-animation] {
            opacity: 0;
            transition: opacity 0.8s ease-out, transform 0.8s ease-out;
        }
        [data-animation="slide-in-left"] { transform: translateX(-50px); }
        [data-animation="slide-in-right"] { transform: translateX(50px); }
        [data-animation="slide-in-up"] { transform: translateY(50px); }
        
        .animated {
            opacity: 1 !important;
            transform: translateX(0) translateY(0) !important;
        }

        /* 2. HEADER & NAVIGATION */
        header {
            background: var(--header-bg-color);
            backdrop-filter: blur(10px);
            -webkit-backdrop-filter: blur(10px);
            padding: 1rem 0;
            position: fixed;
            width: 100%;
            top: 0;
            z-index: 1000;
            border-bottom: 1px solid rgba(255,255,255,0.1);
            transition: background-color 0.3s ease;
        }
        body.light-mode header {
            border-bottom: 1px solid #dee2e6;
        }
        nav { display: flex; justify-content: space-between; align-items: center; }
        nav .logo { color: var(--accent-color); font-size: 1.8rem; font-weight: 700; }
        nav ul { list-style: none; display: flex; align-items: center; }
        nav ul li { margin-left: 30px; }
        nav ul li a { color: var(--light-color); text-decoration: none; font-weight: 500; position: relative; padding: 5px 0; transition: color 0.3s ease; }
        nav ul li a::after { content: ''; position: absolute; bottom: 0; left: 0; width: 0; height: 2px; background: var(--accent-color); transition: width 0.3s ease; }
        nav ul li a:hover::after, nav ul li a.active::after { width: 100%; }
        nav ul li a.active { color: var(--accent-color); }

        .theme-toggle {
            background: none;
            border: none;
            color: var(--light-color);
            font-size: 1.2rem;
            cursor: pointer;
            margin-left: 20px;
        }

        /* 3. HERO SECTION */
        .hero {
            min-height: 100vh;
            display: flex;
            align-items: center;
            justify-content: center;
            text-align: center;
            padding-top: 80px;
            background-image: url('https://scontent.fdac107-1.fna.fbcdn.net/v/t39.30808-6/461804774_945398544301135_1269559797986295193_n.jpg?_nc_cat=101&ccb=1-7&_nc_sid=6ee11a&_nc_ohc=WfmLCkl9smYQ7kNvwFnQJfD&_nc_oc=AdkQOz03oD5MKga57rKMvUL7c-fSsk_CmyZ6_gntJosFcFymF24g4BuywTptrwMqdOk&_nc_zt=23&_nc_ht=scontent.fdac107-1.fna&_nc_gid=w26yJYpcdfCSQ_Ml9DaOcg&oh=00_AfW6kFhDNXcLKu5JAHb0-soxXi6layjFqdlWupLOF64xDQ&oe=68AB5EA0');
            background-size: cover;
            background-position: center;
        }
        .hero::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background-color: rgba(10, 25, 47, 0.7);
            z-index: 1;
        }
        .hero-content {
            position: relative;
            z-index: 2;
        }
        .hero-text { max-width: 800px; }
        .hero .greeting { color: var(--accent-color); }
        .social-links { margin-top: 30px; }
        .social-links a { color: var(--text-color-dark); font-size: 1.4rem; margin: 0 15px; text-decoration: none; transition: all 0.3s ease; }
        .social-links a:hover { color: var(--accent-color); transform: translateY(-3px); }

        /* 4. CONTENT SECTIONS */
        
        /* Alternating Grid Layout */
        .alternating-grid {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 50px;
            align-items: center;
        }
        
        .profile-image img {
            width: 350px;
            height: 350px;
            border-radius: 50%;
            object-fit: cover;
            border: 4px solid var(--accent-color);
            box-shadow: 0 0 25px rgba(100, 255, 218, 0.2);
        }

        /* Experience Section */
        .timeline {
            position: relative;
            max-width: 800px;
            margin: 50px auto 0;
            padding: 20px 0;
        }
        .timeline::before {
            content: '';
            position: absolute;
            top: 0;
            left: 10px;
            height: 100%;
            width: 2px;
            background: var(--accent-color);
            opacity: 0.3;
        }
        .timeline-item {
            position: relative;
            margin-bottom: 50px;
            padding-left: 40px;
        }
        .timeline-dot {
            position: absolute;
            left: 0;
            top: 5px;
            width: 22px;
            height: 22px;
            border-radius: 50%;
            background-color: var(--accent-color);
            border: 4px solid var(--section-bg-color);
        }
        .timeline-content h3 {
            font-size: 1.5rem;
            color: var(--accent-color);
        }
        .timeline-content .company {
            font-weight: 500;
            color: var(--light-color);
            display: block;
            margin-bottom: 5px;
        }
        .timeline-content .date {
            font-size: 0.9rem;
            color: var(--text-color-dark);
            display: block;
            margin-bottom: 15px;
        }
        .timeline-content ul {
            list-style-type: none;
            padding-left: 0;
        }
        .timeline-content ul li {
            padding-left: 20px;
            position: relative;
            margin-bottom: 10px;
            color: var(--text-color);
        }
        .timeline-content ul li::before {
            content: '▹';
            position: absolute;
            left: 0;
            color: var(--accent-color);
        }

        /* Skills Section */
        .skills-grid { display: grid; grid-template-columns: 1fr; gap: 40px; }
        .skill-bar h3 { color: var(--text-color); font-size: 1rem; margin-bottom: 8px; font-weight: 500; }
        .bar-container { background-color: rgba(255, 255, 255, 0.1); width: 100%; border-radius: 5px; overflow: hidden; }
        body.light-mode .bar-container { background-color: #e9ecef; }
        .bar { background-color: var(--accent-color); height: 10px; width: 0; border-radius: 5px; transition: width 1.5s ease-out; }

        /* Workflow Section */
        .workflow-steps { display: grid; grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); gap: 30px; text-align: center; }
        .workflow-step .icon { color: var(--accent-color); font-size: 3rem; margin-bottom: 20px; display: inline-block; transition: transform 0.3s ease; }
        .workflow-step:hover .icon { transform: scale(1.1) rotate(5deg); }
        
        /* Cards */
        .card, .testimonial-card {
            background: var(--card-bg-color);
            border: 1px solid var(--card-border-color);
            backdrop-filter: blur(5px);
            -webkit-backdrop-filter: blur(5px);
            transform-style: preserve-3d;
            transition: transform 0.3s ease, box-shadow 0.3s ease;
            padding: 40px 30px; text-align: center; border-radius: var(--border-radius);
        }
        .card:hover, .testimonial-card:hover { transform: translateY(-8px) perspective(1000px); box-shadow: 0 12px 35px rgba(0, 0, 0, 0.2); }
        .card i { color: var(--accent-color); font-size: 2.8rem; margin-bottom: 20px; }
        .card h3, .workflow-step h3 { font-size: 1.25rem; margin-bottom: 10px; }
        .testimonial-card .author { color: var(--accent-color); }
        .service-cards, .testimonial-cards, .freelancing-cards { display: grid; gap: 30px; }
        .service-cards { grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); }
        .testimonial-cards { grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); }
        .freelancing-cards { grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); }

        /* Portfolio Section */
        .portfolio-grid {
            display: grid;
            grid-template-columns: repeat(2, 1fr);
            gap: 30px;
        }
        .portfolio-item {
            border-radius: var(--border-radius); overflow: hidden; position: relative; cursor: pointer;
            background: var(--card-bg-color); border: 1px solid var(--card-border-color);
            backdrop-filter: blur(5px); -webkit-backdrop-filter: blur(5px);
            transform-style: preserve-3d; transition: transform 0.3s ease, box-shadow 0.3s ease;
        }
        .portfolio-item.featured { grid-column: span 2; }
        .portfolio-item img { width: 100%; height: 100%; object-fit: cover; display: block; transition: transform 0.4s ease; }
        .portfolio-item:hover img { transform: scale(1.05); }
        .portfolio-item .overlay { position: absolute; bottom: 0; left: 0; right: 0; background: linear-gradient(to top, rgba(0,0,0,0.85), transparent); padding: 40px 20px 20px; color: var(--light-color); opacity: 0; transition: opacity 0.4s ease; }
        .portfolio-item:hover .overlay { opacity: 1; }
        .overlay h3 { color: var(--light-color); margin-bottom: 5px; }
        .overlay p { color: #ccc; margin-bottom: 0; }

        /* Gallery Section */
        .gallery-grid {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
            gap: 20px;
        }
        .gallery-item {
            border-radius: var(--border-radius);
            overflow: hidden;
            cursor: pointer;
            position: relative;
        }
        .gallery-item img {
            width: 100%;
            height: 100%;
            object-fit: cover;
            display: block;
            transition: transform 0.3s ease;
        }
        .gallery-item:hover img {
            transform: scale(1.1);
        }
        .gallery-item::after {
            content: '\f00e'; /* Font Awesome search-plus icon */
            font-family: 'Font Awesome 6 Free';
            font-weight: 900;
            position: absolute;
            top: 50%;
            left: 50%;
            transform: translate(-50%, -50%) scale(0.8);
            color: white;
            font-size: 2rem;
            background: rgba(0,0,0,0.5);
            width: 60px;
            height: 60px;
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            opacity: 0;
            transition: opacity 0.3s ease, transform 0.3s ease;
        }
        .gallery-item:hover::after {
            opacity: 1;
            transform: translate(-50%, -50%) scale(1);
        }

        /* Lightbox */
        .lightbox {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: rgba(0, 0, 0, 0.9);
            z-index: 1001;
            display: flex;
            align-items: center;
            justify-content: center;
            opacity: 0;
            visibility: hidden;
            transition: opacity 0.3s ease, visibility 0.3s ease;
        }
        .lightbox.show {
            opacity: 1;
            visibility: visible;
        }
        .lightbox-content {
            max-width: 90%;
            max-height: 80%;
            position: relative;
        }
        .lightbox-content img {
            width: 100%;
            height: 100%;
            object-fit: contain;
        }
        .lightbox-close, .lightbox-prev, .lightbox-next {
            position: absolute;
            background: none;
            border: none;
            color: white;
            font-size: 2rem;
            cursor: pointer;
        }
        .lightbox-close { top: -40px; right: 0; }
        .lightbox-prev { left: -50px; top: 50%; transform: translateY(-50%); }
        .lightbox-next { right: -50px; top: 50%; transform: translateY(-50%); }

        /* Contact Section */
        .contact-form { max-width: 700px; margin: 0 auto; text-align: left; }
        .form-group { margin-bottom: 20px; }
        .form-group input, .form-group textarea {
            background-color: var(--card-bg-color); border: 1px solid var(--card-border-color);
            color: var(--light-color); width: 100%; padding: 15px; border-radius: var(--border-radius);
            font-family: 'Poppins', sans-serif; font-size: 1rem;
        }
        .form-group input::placeholder, .form-group textarea::placeholder { color: var(--text-color-dark); }
        .form-group input:focus, .form-group textarea:focus { border-color: var(--accent-color); box-shadow: 0 0 0 3px rgba(100, 255, 218, 0.1); outline: none; }
        body.light-mode .form-group input:focus, body.light-mode .form-group textarea:focus { box-shadow: 0 0 0 3px rgba(0, 123, 255, 0.1); }
        .form-group textarea { resize: vertical; min-height: 150px; }
        .form-submit-btn { text-align: center; }

        /* 5. UTILITIES */
        footer { background: #020c1b; color: var(--text-color-dark); text-align: center; padding: 30px 0; }
        #back-to-top {
            position: fixed; bottom: 30px; right: 30px; width: 50px; height: 50px;
            background-color: var(--accent-color); color: var(--bg-color);
            border: none; border-radius: 50%; font-size: 1.5rem; cursor: pointer;
            box-shadow: var(--shadow-soft); opacity: 0; visibility: hidden;
            transition: opacity 0.3s, visibility 0.3s, transform 0.3s; z-index: 999;
        }
        #back-to-top.show { opacity: 1; visibility: visible; }
        #back-to-top:hover { filter: brightness(1.2); transform: scale(1.1); }
        .cursor-dot { width: 8px; height: 8px; background-color: var(--accent-color); border-radius: 50%; position: fixed; z-index: 1001; pointer-events: none; transition: transform 0.2s ease-out; }

        /* 6. RESPONSIVE DESIGN */
        @media (max-width: 992px) {
            h1 { font-size: 2.8rem; } h2 { font-size: 2.2rem; }
            section:not(.hero) { max-width: 95%; }
            .alternating-grid { grid-template-columns: 1fr; text-align: center; }
            .alternating-grid > div:last-child { grid-row: 1; } /* Image appears first on mobile */
            .profile-image { margin-bottom: 30px; }
            .portfolio-grid { grid-template-columns: 1fr; }
            .portfolio-item.featured { grid-column: span 1; }
        }
        @media (max-width: 768px) {
            nav ul { display: none; }
            .hero { text-align: center; }
            h1 { font-size: 2.2rem; }
            section { padding: 80px 20px; }
            section:not(.hero) { padding: 60px 20px; }
            .cursor-dot { display: none; }
            body { cursor: auto; }
            .lightbox-prev, .lightbox-next { display: none; } /* Hide side arrows on small screens */
        }

        /* Preloader Styles */
.preloader {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: var(--bg-color);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 9999;
    transition: opacity 0.75s ease, visibility 0.75s ease;
}

.preloader-hidden {
    opacity: 0;
    visibility: hidden;
}

.preloader-logo {
    font-size: 2rem;
    font-weight: 700;
    color: var(--accent-color);
    animation: pulse 1.5s infinite ease-in-out;
}

@keyframes pulse {
    0% {
        transform: scale(1);
        opacity: 1;
    }
    50% {
        transform: scale(1.1);
        opacity: 0.7;
    }
    100% {
        transform: scale(1);
        opacity: 1;
    }
}