:root {
            --primary-color: #4285f4;
            --primary-hover: #3367d6;
            --gradient-start: #667eea;
            --gradient-end: #764ba2;
            --text-primary: #1a1a1a;
            --text-secondary: #6b7280;
            --border-color: #e5e7eb;
            --white: #ffffff;
            --light-bg: #f8f9fa;
            --error-color: #ef4444;
        }

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

        body {
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
            background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
            min-height: 100vh;
            display: flex;
            align-items: center;
            justify-content: center;
            padding: 20px;
            position: relative;
            overflow-x: hidden;
        }

        /* Subtle background animation */
        body::before {
            content: '';
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: 
                radial-gradient(circle at 20% 80%, rgba(120, 119, 198, 0.1) 0%, transparent 50%),
                radial-gradient(circle at 80% 20%, rgba(255, 255, 255, 0.1) 0%, transparent 50%);
            animation: subtleFloat 15s ease-in-out infinite alternate;
            pointer-events: none;
            z-index: 1;
        }

        @keyframes subtleFloat {
            0% { transform: translateY(0px) scale(1); }
            100% { transform: translateY(-10px) scale(1.02); }
        }

        .login-container {
            position: relative;
            z-index: 10;
            display: flex;
            max-width: 1100px;
            width: 100%;
            min-height: 650px;
            background: #ffffff;
            border-radius: 20px;
            box-shadow: 
                0 25px 50px rgba(0, 0, 0, 0.08),
                0 0 0 1px rgba(255, 255, 255, 0.8);
            overflow: hidden;
            animation: containerEntry 1.2s cubic-bezier(0.16, 1, 0.3, 1) forwards;
            transform: translateY(30px);
            opacity: 0;
        }

        @keyframes containerEntry {
            to {
                transform: translateY(0);
                opacity: 1;
            }
        }

        /* Enhanced Visual Section */
        .login-visual {
            flex: 1;
            background: linear-gradient(135deg, var(--gradient-start) 0%, var(--gradient-end) 100%);
            display: flex;
            flex-direction: column;
            align-items: center;
            justify-content: center;
            position: relative;
            overflow: hidden;
            padding: 40px;
        }

        /* Geometric background pattern */
        .login-visual::before {
            content: '';
            position: absolute;
            width: 100%;
            height: 100%;
            background-image: 
                radial-gradient(circle at 25% 25%, rgba(255, 255, 255, 0.1) 2px, transparent 2px),
                radial-gradient(circle at 75% 75%, rgba(255, 255, 255, 0.05) 1px, transparent 1px);
            background-size: 60px 60px, 40px 40px;
            animation: patternShift 20s linear infinite;
            opacity: 0.4;
        }

        @keyframes patternShift {
            0% { transform: translate(0, 0); }
            100% { transform: translate(60px, 60px); }
        }

        /* Floating geometric shapes */
        .floating-shape {
            position: absolute;
            border-radius: 50%;
            background: rgba(255, 255, 255, 0.1);
            animation: floatUp 8s ease-in-out infinite;
        }

        .floating-shape:nth-child(1) {
            width: 80px;
            height: 80px;
            top: 80%;
            left: 20%;
            animation-delay: 0s;
        }

        .floating-shape:nth-child(2) {
            width: 60px;
            height: 60px;
            top: 60%;
            right: 20%;
            animation-delay: 2s;
        }

        .floating-shape:nth-child(3) {
            width: 40px;
            height: 40px;
            top: 30%;
            left: 15%;
            animation-delay: 4s;
        }

        @keyframes floatUp {
            0%, 100% {
                transform: translateY(0) scale(1);
                opacity: 0.3;
            }
            50% {
                transform: translateY(-20px) scale(1.1);
                opacity: 0.6;
            }
        }

        /* Main title styling */
        .brand-title {
            font-family: 'Noto Sans KR', sans-serif;
            font-size: 3.5rem;
            font-weight: 800;
            color: var(--white);
            text-align: center;
            margin: 0;
            position: relative;
            z-index: 5;
            animation: titleReveal 1.5s cubic-bezier(0.16, 1, 0.3, 1) 0.5s both;
            text-shadow: 0 4px 20px rgba(0, 0, 0, 0.2);
            line-height: 1.1;
        }

        @keyframes titleReveal {
            0% {
                transform: translateY(30px);
                opacity: 0;
                filter: blur(10px);
            }
            100% {
                transform: translateY(0);
                opacity: 1;
                filter: blur(0);
            }
        }

        /* Elegant underline animation */
        .brand-title::after {
            content: '';
            position: absolute;
            bottom: -10px;
            left: 50%;
            width: 0;
            height: 3px;
            background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.8), transparent);
            border-radius: 2px;
            animation: underlineGrow 2s ease-out 1.2s both;
            transform: translateX(-50%);
        }

        @keyframes underlineGrow {
            to {
                width: 80%;
            }
        }

        /* Subtle tagline */
        .brand-tagline {
            color: rgba(255, 255, 255, 0.8);
            font-size: 1.1rem;
            font-weight: 500;
            margin-top: 30px;
            animation: taglineReveal 1.5s cubic-bezier(0.16, 1, 0.3, 1) 1s both;
            text-align: center;
        }

        @keyframes taglineReveal {
            0% {
                transform: translateY(20px);
                opacity: 0;
            }
            100% {
                transform: translateY(0);
                opacity: 1;
            }
        }

        /* Decorative elements */
        .deco-circle {
            position: absolute;
            border: 2px solid rgba(255, 255, 255, 0.1);
            border-radius: 50%;
            animation: rotate 20s linear infinite;
        }

        .deco-circle.large {
            width: 300px;
            height: 300px;
            top: 50%;
            left: 50%;
            transform: translate(-50%, -50%);
        }

        .deco-circle.medium {
            width: 200px;
            height: 200px;
            top: 50%;
            left: 50%;
            transform: translate(-50%, -50%);
            animation-direction: reverse;
            animation-duration: 15s;
        }

        @keyframes rotate {
            from { transform: translate(-50%, -50%) rotate(0deg); }
            to { transform: translate(-50%, -50%) rotate(360deg); }
        }

        .login-form-section {
            flex: 0 0 480px;
            padding: 60px 50px;
            display: flex;
            flex-direction: column;
            justify-content: center;
            background: #ffffff;
        }

        .logo-section {
            display: flex;
            align-items: center;
            margin-bottom: 50px;
        }

        @keyframes logoEntry {
            to {
                transform: translateX(0);
                opacity: 1;
            }
        }

        .logo-icon {
            width: 48px;
            height: 48px;
            background: linear-gradient(135deg, #4285f4, #3367d6);
            border-radius: 14px;
            display: flex;
            align-items: center;
            justify-content: center;
            margin-right: 16px;
            box-shadow: 0 6px 20px rgba(66, 133, 244, 0.25);
            transition: transform 0.3s ease;
        }

        .logo-icon:hover {
            transform: scale(1.05);
        }

        .logo-icon::before {
            content: 'AI';
            color: #ffffff;
            font-weight: 700;
            font-size: 16px;
        }

        .logo-text {
            font-size: 22px;
            font-weight: 700;
            color: #1a1a1a;
            margin: 0;
        }

        .form-title {
            font-size: 36px;
            font-weight: 700;
            color: #1a1a1a;
            margin-bottom: 12px;
            line-height: 1.2;
        }

        @keyframes formEntry {
            to {
                transform: translateY(0);
                opacity: 1;
            }
        }

        .form-subtitle {
            color: #6b7280;
            margin-bottom: 40px;
            font-size: 16px;
            line-height: 1.6;
        }

        .form-group {
            margin-bottom: 28px;
        }

        .form-label {
            display: block;
            margin-bottom: 10px;
            font-weight: 600;
            color: #1a1a1a;
            font-size: 15px;
        }

        .required {
            color: #ef4444;
        }

        .form-control {
            width: 100%;
            height: 52px;
            padding: 16px 20px;
            border: 2px solid #e5e7eb;
            border-radius: 14px;
            font-size: 16px;
            font-weight: 500;
            transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
            background: #ffffff;
            color: #1a1a1a;
        }

        .form-control:focus {
            outline: none;
            border-color: #4285f4;
            box-shadow: 0 0 0 4px rgba(66, 133, 244, 0.1);
            transform: translateY(-1px);
        }

        .input-group {
            position: relative;
        }

        .input-group .form-control {
            padding-right: 55px;
        }

        .input-group-append {
            position: absolute;
            right: 18px;
            top: 50%;
            transform: translateY(-50%);
            cursor: pointer;
            color: #6b7280;
            transition: all 0.3s ease;
            font-size: 18px;
        }

        .input-group-append:hover {
            color: #4285f4;
            transform: translateY(-50%) scale(1.1);
        }

        .remember-id {
            display: flex;
            align-items: center;
            margin-bottom: 20px;
        }

        .remember-id input[type="checkbox"] {
            margin-right: 8px;
            width: 16px;
            height: 16px;
            cursor: pointer;
        }

        .remember-id label {
            font-size: 14px;
            color: #6b7280;
            cursor: pointer;
        }

        .forgot-password {
            text-align: right;
            margin-bottom: 36px;
        }

        .forgot-password a {
            color: #4285f4;
            text-decoration: none;
            font-size: 15px;
            font-weight: 600;
            transition: all 0.3s ease;
        }

        .forgot-password a:hover {
            color: #3367d6;
            text-decoration: underline;
        }

        .btn-danger {
            width: 100%;
            height: 54px;
            background: linear-gradient(135deg, #dc3545, #c82333);
            border: none;
            border-radius: 14px;
            color: #ffffff;
            font-size: 16px;
            font-weight: 600;
            transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
            margin-bottom: 20px;
            box-shadow: 0 4px 16px rgba(220, 53, 69, 0.3);
            cursor: pointer;
        }

        .btn-danger:hover:not(:disabled) {
            transform: translateY(-2px);
            box-shadow: 0 8px 25px rgba(220, 53, 69, 0.4);
            background: linear-gradient(135deg, #e04758, #d32535);
        }

        .btn-danger:active:not(:disabled) {
            transform: translateY(0);
            box-shadow: 0 4px 16px rgba(220, 53, 69, 0.3);
        }

        .btn-danger:disabled {
            background: linear-gradient(135deg, #e69da3, #d57a82);
            box-shadow: none;
            cursor: not-allowed;
            opacity: 0.7;
        }

        .btn-secondary {
            width: 100%;
            height: 54px;
            background: #f8f9fa;
            border: 2px solid #e5e7eb;
            border-radius: 14px;
            color: #1a1a1a;
            font-size: 16px;
            font-weight: 600;
            transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
            text-decoration: none;
            display: flex;
            align-items: center;
            justify-content: center;
        }

        .btn-secondary:hover {
            background: #f3f4f6;
            border-color: #d1d5db;
            color: #1a1a1a;
            text-decoration: none;
            transform: translateY(-1px);
        }

        .error {
            color: var(--error-color);
            font-size: 13px;
            margin-top: 8px;
            display: block;
            font-weight: 500;
            text-align: center;
        }

        @media (max-width: 1024px) {
            .login-visual {
                min-width: 320px;
            }
            
            .login-form-section {
                flex: 0 0 420px;
                padding: 50px 40px;
            }
            
            .brand-title {
                font-size: 3rem;
            }
        }

        @media (max-width: 768px) {
            .login-container {
                flex-direction: column;
                margin: 15px;
                min-height: auto;
                max-width: 500px;
            }

            .login-visual {
                min-height: 280px;
                min-width: auto;
                order: 1;
                padding: 30px;
            }

            .login-form-section {
                flex: none;
                padding: 40px 30px;
                order: 2;
            }

            .brand-title {
                font-size: 2.5rem;
            }

            .brand-tagline {
                font-size: 1rem;
            }

            .deco-circle.large {
                width: 200px;
                height: 200px;
            }

            .deco-circle.medium {
                width: 120px;
                height: 120px;
            }

            body {
                padding: 15px;
            }
        }

        @media (max-width: 480px) {
            .brand-title {
                font-size: 2rem;
            }
            
            .login-form-section {
                padding: 30px 25px;
            }

            .form-title {
                font-size: 28px;
            }
        }

        /* Micro-interactions */
        .form-control:hover {
            border-color: #d1d5db;
        }

        .logo-section:hover .logo-icon {
            transform: scale(1.05) rotate(5deg);
        }

        /* Focus states for accessibility */
        .btn-danger:focus,
        .btn-secondary:focus,
        .form-control:focus {
            outline: 2px solid #dc3545;
            outline-offset: 2px;
        }