:root {
            --primary-color: #3182ce;
            --primary-hover: #2b6cb0;
            --background-color: #f7fafc;
            --card-bg: #ffffff;
            --text-color: #1a202c;
            --subtle-text: #718096;
            --input-bg: #edf2f7;
            --border-color: #e2e8f0;
            --error-color: #e53e3e;
            --success-color: #38a169;
        }

        * { margin: 0; padding: 0; box-sizing: border-box; }
        body {
            font-family: 'Poppins', sans-serif;
            background-color: var(--background-color);
            color: var(--text-color);
        }

        /* --- NAVBAR STYLES --- */
        .navbar {
            background-color: var(--card-bg);
            padding: 15px 30px;
            box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
            display: flex;
            justify-content: space-between;
            align-items: center;
            position: relative;
            z-index: 100;
        }
        .navbar-logo {
            font-size: 1.5rem;
            font-weight: 700;
            color: var(--primary-color);
            text-decoration: none;
        }
        .navbar-links {
            list-style: none;
            display: flex;
            align-items: center;
            gap: 25px;
        }
        .navbar-links a {
            text-decoration: none;
            color: var(--text-color);
            font-weight: 500;
            transition: color 0.3s ease;
        }
        .navbar-links a:hover { color: var(--primary-color); }
        .navbar-links .btn {
            background-color: var(--primary-color);
            color: white;
            padding: 10px 15px;
            border-radius: 8px;
            transition: background-color 0.3s ease;
        }
        .navbar-links .btn:hover {
            background-color: var(--primary-hover);
            color: white;
        }

        /* --- HAMBURGER MENU STYLES --- */
        .navbar-toggle { display: none; }
        .navbar-toggle .bar {
            width: 100%;
            height: 3px;
            background-color: var(--text-color);
            border-radius: 10px;
            transition: all 0.3s ease-in-out;
        }
        
        /* --- RESPONSIVE STYLES --- */
        @media (max-width: 768px) {
            .navbar-toggle {
                display: flex;
                flex-direction: column;
                justify-content: space-around;
                width: 30px;
                height: 25px;
                background: transparent;
                border: none;
                cursor: pointer;
                padding: 0;
                z-index: 10;
            }
            .navbar-links {
                display: none;
                flex-direction: column;
                justify-content: center;
                align-items: center;
                gap: 40px;
                background-color: var(--card-bg);
                position: absolute;
                top: 100%;
                left: 0;
                width: 100%;
                padding: 30px 0;
                box-shadow: 0 4px 6px rgba(0,0,0,0.1);
            }
            .navbar-links.active { display: flex; }
            .navbar-links a { font-size: 1.2rem; }
        }

        .container {
            display: flex;
            justify-content: center;
            align-items: center;
            padding: 40px 20px;
        }

        .shortener-container {
            width: 100%;
            max-width: 500px;
            background: var(--card-bg);
            border-radius: 16px;
            padding: 40px;
            box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.05), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
            text-align: center;
        }

        h1 { font-size: 2rem; font-weight: 700; margin-bottom: 30px; }

        .input-wrapper { position: relative; margin-bottom: 20px; }
        .input-wrapper svg.icon-left {
            position: absolute;
            left: 15px;
            top: 50%;
            transform: translateY(-50%);
            width: 20px;
            height: 20px;
            color: var(--subtle-text);
        }
        
        .input-wrapper svg.icon-right {
            position: absolute;
            right: 15px;
            top: 50%;
            transform: translateY(-50%);
            width: 22px;
            height: 22px;
            color: var(--subtle-text);
            cursor: pointer;
            transition: color 0.3s ease;
        }
        .input-wrapper svg.icon-right:hover {
            color: var(--primary-color);
        }

        #linkinput, #sluginput {
            width: 100%;
            padding: 15px;
            font-size: 1rem;
            background: var(--input-bg);
            border: 2px solid transparent;
            border-radius: 12px;
            color: var(--text-color);
            transition: all 0.3s ease;
        }
        #linkinput { padding-left: 50px; padding-right: 50px; }
        #sluginput { padding-right: 50px; }
        #linkinput::placeholder, #sluginput::placeholder { color: var(--subtle-text); }
        #linkinput:focus, #sluginput:focus {
            outline: none;
            background-color: var(--card-bg);
            border-color: var(--primary-color);
        }

        #shorten-btn {
            width: 100%;
            padding: 15px;
            font-size: 1.1rem;
            font-weight: 600;
            color: white;
            background-color: var(--primary-color);
            border: none;
            border-radius: 12px;
            cursor: pointer;
            transition: all 0.3s ease;
            margin-top: 10px;
            position: relative;
            overflow: hidden;
            height: 54px;
        }
        #shorten-btn:hover:not(:disabled) {
            background-color: var(--primary-hover);
            transform: translateY(-2px);
            box-shadow: 0 4px 10px rgba(49, 130, 206, 0.3);
        }
        #shorten-btn:disabled {
            cursor: not-allowed;
            background-color: #a0aec0;
        }

        .btn-text { transition: opacity 0.2s ease; }
        .spinner {
            position: absolute;
            top: 50%; left: 50%;
            width: 24px; height: 24px;
            border: 3px solid rgba(255, 255, 255, 0.3);
            border-top-color: #fff;
            border-radius: 50%;
            transform: translate(-50%, -50%);
            opacity: 0;
            transition: opacity 0.2s ease;
            animation: spin 1s linear infinite;
        }
        #shorten-btn.loading .btn-text { opacity: 0; }
        #shorten-btn.loading .spinner { opacity: 1; }
        @keyframes spin { to { transform: translate(-50%, -50%) rotate(360deg); } }

        .popup-overlay {
            position: fixed;
            top: 0; left: 0;
            width: 100%; height: 100%;
            background-color: rgba(0, 0, 0, 0.3); /* Slightly less dark */
            display: flex;
            justify-content: center;
            align-items: center;
            opacity: 0;
            visibility: hidden;
            transition: opacity 0.3s ease, visibility 0.3s ease;
            z-index: 1000;
            /* [MODIFIED] Modern backdrop blur */
            -webkit-backdrop-filter: blur(4px);
            backdrop-filter: blur(4px);
        }
        .popup-overlay.show { opacity: 1; visibility: visible; }
        .popup-box {
            background-color: var(--card-bg);
            padding: 30px;
            border-radius: 16px;
            box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
            text-align: center;
            width: 90%;
            max-width: 450px;
            /* [MODIFIED] Smoother animation */
            transform: scale(0.95) translateY(10px);
            transition: transform 0.3s cubic-bezier(0.25, 0.46, 0.45, 0.94);
        }
        .popup-overlay.show .popup-box { 
            transform: scale(1) translateY(0); 
        }
        .popup-box h2 {
            margin-bottom: 10px;
            font-size: 1.6rem; /* Slightly larger */
            font-weight: 700; /* Bolder */
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 10px;
        }
        .popup-box .icon { width: 30px; height: 30px; }
        #success-popup h2 { color: var(--success-color); }
        #error-popup h2 { color: var(--error-color); }
        #error-message { margin-top: 10px; color: var(--subtle-text); }

        .popup-link-container { display: flex; margin: 20px 0; }
        #popup-link {
            flex-grow: 1; padding: 10px; font-size: 1rem;
            border: 1px solid var(--border-color);
            border-radius: 8px 0 0 8px;
            background-color: var(--background-color);
            color: var(--text-color); border-right: none;
        }
        #popup-link:focus { outline: none; }
        #copy-btn {
            padding: 0 20px; border: 1px solid var(--primary-color);
            background-color: var(--primary-color);
            color: white; border-radius: 0 8px 8px 0;
            cursor: pointer; font-weight: 500;
        }
        .close-btn {
            margin-top: 10px; padding: 10px 20px;
            background: var(--border-color);
            border: none; border-radius: 8px;
            cursor: pointer; font-weight: 500;
            transition: background-color 0.3s ease;
        }
        .close-btn:hover {
            background-color: #cbd5e0;
        }
        
        /* --- [MODIFIED] MODERN SLUG ALERT STYLES --- */
        .help-popup p {
            color: var(--subtle-text);
            margin: 15px 0 25px 0; /* More bottom margin */
            line-height: 1.7;
            text-align: center;
            max-width: 350px;
            margin-left: auto;
            margin-right: auto;
        }
        .example-box {
            background-color: var(--background-color);
            border: 1px solid var(--border-color);
            border-radius: 12px;
            padding: 20px;
            margin: 25px 0;
            display: flex;
            flex-direction: column;
            gap: 20px;
        }
        .example-item {
            text-align: left;
        }
        .example-header {
            display: flex;
            align-items: center;
            gap: 10px;
            margin-bottom: 8px;
            font-size: 0.9rem;
            color: var(--text-color);
        }
        .example-header svg {
            width: 18px;
            height: 18px;
            color: var(--primary-color);
        }
        .example-box code {
            display: block;
            width: 100%;
            background-color: var(--card-bg);
            border: 1px solid var(--border-color);
            padding: 10px 12px;
            border-radius: 8px;
            font-family: 'Courier New', Courier, monospace;
            color: var(--primary-hover);
            font-weight: 600;
            word-break: break-all;
        }
        
        .btn-primary {
            background-color: var(--primary-color);
            color: white;
            font-weight: 600;
            border-radius: 12px;
            padding: 12px 25px;
            transition: all 0.3s ease;
            margin-top: 20px;
        }
        .btn-primary:hover {
            background-color: var(--primary-hover);
            transform: translateY(-2px);
            box-shadow: 0 4px 10px rgba(49, 130, 206, 0.3);
        }