/* Base styles */
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        /*dark mode toggle*/
        .theme-toggle {
            background: transparent;
            border: 2px solid var(--toggle-border);
            border-radius: 50%;
            width: 40px;
            height: 40px;
            display: flex;
            align-items: center;
            justify-content: center;
            cursor: pointer;
            transition: background 0.3s ease, transform 0.3s ease;
            font-size: 1.2rem;
            color: var(--toggle-icon);
            box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
        }

        .theme-toggle:hover {
            background: var(--toggle-hover);
            transform: scale(1.1);
        }

        .theme-toggle span {
            transition: transform 0.3s ease, opacity 0.3s ease;
        }

        :root {
            --toggle-border: #ddd;
            --toggle-icon: #333;
            --toggle-hover: #f0f0f0;
            --bg-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            --text-color: #333;
            --bg-card: rgba(255, 255, 255, 0.95);
            --text-card: #333;
            --box-shadow: 0 8px 32px rgba(31, 38, 135, 0.37);
            --bg-header: rgba(255, 255, 255, 0.95);
            --header-border: rgba(255, 255, 255, 0.18);
            --card-bg: rgba(255, 255, 255, 0.95);
            --card-border: rgba(255, 255, 255, 0.18);
            --card-shadow: 0 8px 32px rgba(31, 38, 135, 0.37);
            --card-hover-shadow: 0 20px 40px rgba(31, 38, 135, 0.5);
            --nav-link-color: #333; 
            --nav-link-hover-bg: rgba(102, 126, 234, 0.1);
            --project-title-color: #333;
            --placeholder-bg: linear-gradient(135deg, #f5f7fa, #c3cfe2);
            --placeholder-text: #666;
        }

        .dark-theme {
            --toggle-border: #888;
            --toggle-icon: #f9f9f9;
            --toggle-hover: #333;
            --bg-gradient: linear-gradient(135deg, #1a1445 0%, #2c1d5c 100%);
            --text-color: #e4e4f0;
            --bg-card: rgba(30, 25, 60, 0.9); 
            --text-card: #eee;
            --box-shadow: 0 8px 32px rgba(0, 0, 0, 0.4);
            --bg-header: rgba(30, 25, 60, 0.9); 
            --header-border: rgba(255, 255, 255, 0.05);
            --card-bg: rgba(30, 25, 60, 0.9);
            --card-border: rgba(255, 255, 255, 0.05);
            --card-shadow: 0 8px 24px rgba(0, 0, 0, 0.4);
            --card-hover-shadow: 0 20px 40px rgba(0, 0, 0, 0.6);
            --nav-link-color: #f1f1f1;
            --nav-link-hover-bg: rgba(255, 255, 255, 0.1);
            --project-title-color: #ffffff;
            --placeholder-bg: linear-gradient(135deg, #2a2d3e, #3b3f59);  /* deep bluish-purple tone */
            --placeholder-text: #ddd;
        }

        body {
            font-family: 'Inter', sans-serif;
            background: var(--bg-gradient);
            color: var(--text-color);
            min-height: 100vh;
            transition: background 0.3s ease, color 0.3s ease;
        }


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

        /* Header styles */
        .header {
            background: var(--bg-header);
            backdrop-filter: blur(10px);
            box-shadow: var(--box-shadow);
            border-bottom: 1px solid var(--header-border);
            padding: 1rem 0;
            position: sticky;
            top: 0;
            z-index: 100;
            transition: background 0.3s, border-bottom 0.3s, box-shadow 0.3s;
        }


        .header-content {
            display: flex;
            justify-content: space-between;
            align-items: center;
            flex-wrap: wrap;
            gap: 1rem;
        }

        .logo {
            font-size: 2rem;
            font-weight: 700;
            background: linear-gradient(135deg, #667eea, #764ba2);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            background-clip: text;
        }

        .nav {
            display: flex;
            gap: 2rem;
            align-items: center;
            flex-wrap: wrap;
        }

        .nav-link {
            color: var(--nav-link-color);
            text-decoration: none;
            font-weight: 500;
            padding: 0.5rem 1rem;
            border-radius: 8px;
            transition: all 0.3s ease;
            position: relative;
        }

        .nav-link:hover {
            background: var(--nav-link-hover-bg);
            transform: translateY(-2px);
        }


        .btn-primary {
            background: linear-gradient(135deg, #667eea, #764ba2);
            color: white;
            padding: 0.75rem 1.5rem;
            border: none;
            border-radius: 12px;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s ease;
            text-decoration: none;
            display: inline-block;
        }

        .btn-primary:hover {
            transform: translateY(-2px);
            box-shadow: 0 10px 25px rgba(102, 126, 234, 0.3);
        }

        /* Hero section */
        .hero {
            text-align: center;
            padding: 4rem 0;
            color: white;
        }

        .hero h1 {
            font-size: 3.5rem;
            font-weight: 700;
            margin-bottom: 1rem;
            text-shadow: 0 4px 8px rgba(0, 0, 0, 0.3);
        }

        .hero p {
            font-size: 1.2rem;
            margin-bottom: 2rem;
            opacity: 0.9;
            max-width: 600px;
            margin-left: auto;
            margin-right: auto;
        }

        /* Filter section */
        .filters {
            background: var(--bg-card);
            color: var(--text-card);
            backdrop-filter: blur(10px);
            border-radius: 16px;
            padding: 2rem;
            margin: 2rem 0;
            box-shadow: var(--box-shadow);
            transition: background 0.3s, color 0.3s, box-shadow 0.3s;
        }


        .filters h2 {
            font-size: 1.5rem;
            margin-bottom: 1.5rem;
            color: var(--project-title-color);
        }

        .filter-controls {
            display: flex;
            gap: 2rem;
            align-items: center;
            flex-wrap: wrap;
        }

        .filter-group {
            display: flex;
            align-items: center;
            gap: 0.5rem;
        }

        .filter-group label {
            font-weight: 500;
            color: #555;
        }

        .filter-group select {
            padding: 0.5rem;
            border: 2px solid #e1e5e9;
            border-radius: 8px;
            background: white;
            font-family: inherit;
            transition: border-color 0.3s ease;
        }

        .filter-group select:focus {
            outline: none;
            border-color: #667eea;
        }

        .filter-group input[type="checkbox"] {
            width: 20px;
            height: 20px;
            accent-color: #667eea;
        }

        /* Search styles */
        .search-group {
            flex: 1;
            min-width: 300px;
        }

        .search-container {
            position: relative;
            display: flex;
            align-items: center;
        }

        .search-icon {
            position: absolute;
            left: 12px;
            color: #666;
            z-index: 1;
        }

        .search-container input[type="text"] {
            width: 100%;
            padding: 12px 40px 12px 40px;
            border: 2px solid #ddd;
            border-radius: 8px;
            font-size: 1rem;
            background: var(--card-bg);
            color: var(--text-card);
            transition: border-color 0.3s ease, box-shadow 0.3s ease;
        }

        .search-container input[type="text"]:focus {
            outline: none;
            border-color: #667eea;
            box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
        }

        .clear-search {
            position: absolute;
            right: 8px;
            background: none;
            border: none;
            color: #666;
            cursor: pointer;
            padding: 4px;
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            transition: background-color 0.3s ease, color 0.3s ease;
        }

        .clear-search:hover {
            background-color: #f0f0f0;
            color: #333;
        }

        .dark-theme .search-container input[type="text"] {
            border-color: #444;
            background: var(--card-bg);
            color: var(--text-card);
        }

        .dark-theme .search-container input[type="text"]:focus {
            border-color: #667eea;
        }

        .dark-theme .clear-search:hover {
            background-color: #444;
            color: #fff;
        }

        .btn-secondary {
            background: white;
            color: #667eea;
            border: 2px solid #667eea;
            padding: 0.75rem 1.5rem;
            border-radius: 12px;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s ease;
        }

        .btn-secondary:hover {
            background: #667eea;
            color: white;
            transform: translateY(-2px);
        }

        /* Projects section */
        .projects-section {
            padding: 2rem 0;
        }

        .section-title {
            font-size: 2rem;
            font-weight: 700;
            color: white;
            margin-bottom: 2rem;
            text-align: center;
            text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
        }

        .projects-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
            gap: 2rem;
            margin-bottom: 3rem;
        }

        .project-card {
            background: var(--card-bg);
            backdrop-filter: blur(10px);
            border-radius: 16px;
            padding: 1.5rem;
            box-shadow: var(--card-shadow);
            border: 1px solid var(--card-border);
            transition: all 0.3s ease;
            display: flex;
            flex-direction: column;
        }

        .project-card:hover {
            transform: translateY(-5px);
            box-shadow: var(--card-hover-shadow);
        }


        .project-image {
            width: 100%;
            height: 200px;
            object-fit: cover;
            border-radius: 12px;
            margin-bottom: 1rem;
        }

        .project-placeholder {
                width: 100%;
                height: 200px;
                background: var(--placeholder-bg);
                border-radius: 12px;
                display: flex;
                align-items: center;
                justify-content: center;
                margin-bottom: 1rem;
                color: var(--placeholder-text);
                font-weight: 500;
        }


        .project-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 1rem;
        }

        .project-title {
            font-size: 1.25rem;
            font-weight: 700;
            color: var(--project-title-color);
        }


        .repo-link {
            color: #667eea;
            font-size: 1.5rem;
            transition: all 0.3s ease;
        }

        .repo-link:hover {
            color: #764ba2;
            transform: scale(1.1);
        }

        .difficulty-badge {
            display: inline-block;
            padding: 0.25rem 0.75rem;
            border-radius: 20px;
            font-size: 0.875rem;
            font-weight: 600;
            margin-bottom: 1rem;
        }

        .difficulty-beginner {
            background: rgba(34, 197, 94, 0.1);
            color: #22c55e;
        }

        .difficulty-intermediate {
            background: rgba(251, 191, 36, 0.1);
            color: #fbbf24;
        }

        .difficulty-advanced {
            background: rgba(239, 68, 68, 0.1);
            color: #ef4444;
        }

        .project-description {
            color: #666;
            margin-bottom: 1rem;
            line-height: 1.6;
            flex-grow: 1;
        }

        .project-meta {
            display: flex;
            align-items: center;
            gap: 0.5rem;
            font-size: 0.875rem;
            color: #888;
            margin-bottom: 1rem;
        }

        .meta-icon {
            color: #667eea;
        }

        .upvote-section {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-top: auto;
            padding-top: 1rem;
            border-top: 1px solid #eee;
        }

        .upvote-btn {
            background: linear-gradient(135deg, #667eea, #764ba2);
            color: white;
            border: none;
            padding: 0.5rem 1rem;
            border-radius: 8px;
            font-weight: 600;
            cursor: pointer;
            display: flex;
            align-items: center;
            gap: 0.5rem;
            transition: all 0.3s ease;
        }

        .upvote-btn:hover {
            transform: translateY(-1px);
            box-shadow: 0 4px 12px rgba(102, 126, 234, 0.3);
        }

        /* Footer */
        .footer {
            background: rgba(0, 0, 0, 0.8);
            color: white;
            text-align: center;
            padding: 2rem 0;
            margin-top: 3rem;
        }

        /* Responsive design */
        @media (max-width: 768px) {
            .hero h1 {
                font-size: 2.5rem;
            }
            
            .nav {
                gap: 1rem;
            }
            
            .filter-controls {
                flex-direction: column;
                align-items: stretch;
            }
            
            .search-group {
                min-width: 100%;
            }
            
            .projects-grid {
                grid-template-columns: 1fr;
            }
            
            .header-content {
                flex-direction: column;
                text-align: center;
            }
        }

        /* Loading animation */
        .loading {
            display: flex;
            justify-content: center;
            align-items: center;
            height: 200px;
            color: white;
        }

        .spinner {
            width: 40px;
            height: 40px;
            border: 4px solid rgba(255, 255, 255, 0.3);
            border-top: 4px solid white;
            border-radius: 50%;
            animation: spin 1s linear infinite;
        }

        @keyframes spin {
            0% { transform: rotate(0deg); }
            100% { transform: rotate(360deg); }
        }

        /* Empty state */
        .empty-state {
            text-align: center;
            color: white;
            padding: 3rem 0;
        }

        .empty-state i {
            font-size: 4rem;
            margin-bottom: 1rem;
            opacity: 0.5;
        }

        .empty-state h3 {
            font-size: 1.5rem;
            margin-bottom: 0.5rem;
        }

        .empty-state p {
            opacity: 0.8;
        }

    @keyframes bounce {
      0%, 100% { transform: translateY(0); }
      50% { transform: translateY(-5px); }
    }