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

        :root {
            --bg-primary: #ffffff;
            --bg-secondary: #f5f5f5;
            --text-primary: #1a202c;
            --text-secondary: #718096;
            --border-color: #e2e8f0;
            --primary: #667eea;
            --primary-hover: #5a67d8;
            --error-bg: #fed7d7;
            --error-text: #c53030;
            --shadow: rgba(0, 0, 0, 0.1);
        }

        [data-theme="dark"] {
            --bg-primary: #1a202c;
            --bg-secondary: #2d3748;
            --text-primary: #f7fafc;
            --text-secondary: #a0aec0;
            --border-color: #4a5568;
            --primary: #667eea;
            --primary-hover: #5a67d8;
            --error-bg: #742a2a;
            --error-text: #fc8181;
            --shadow: rgba(0, 0, 0, 0.3);
        }

        body {
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
            background: var(--bg-secondary);
            min-height: 100vh;
            display: flex;
            align-items: center;
            justify-content: center;
            padding: 20px;
            transition: background 0.3s ease;
        }

        .login-container {
            background: var(--bg-primary);
            border-radius: 12px;
            box-shadow: 0 2px 10px var(--shadow);
            padding: 48px 40px;
            width: 100%;
            max-width: 420px;
            transition: background 0.3s ease, box-shadow 0.3s ease;
        }

        .theme-toggle svg {
            color: var(--text-secondary);
            transition: color 0.2s;
        }

        .theme-toggle:hover svg {
            color: var(--text-primary);
        }

        .top-controls {
            position: fixed;
            top: 20px;
            left: 20px;
            display: flex;
            gap: 12px;
            z-index: 1000;
        }

        .control-btn {
            background: var(--bg-primary);
            border: 1px solid var(--border-color);
            border-radius: 8px;
            width: 44px;
            height: 44px;
            display: flex;
            align-items: center;
            justify-content: center;
            cursor: pointer;
            transition: all 0.2s;
            box-shadow: 0 2px 8px var(--shadow);
        }

        .control-btn:hover {
            background: var(--bg-secondary);
            transform: translateY(-1px);
        }

        .control-btn svg {
            color: var(--text-secondary);
            transition: color 0.2s;
        }

        .control-btn:hover svg {
            color: var(--text-primary);
        }

        .control-btn i {
            color: var(--text-secondary);
            transition: color 0.2s;
            font-size: 18px;
        }

        .control-btn:hover i {
            color: var(--text-primary);
        }

        .language-selector {
            background: var(--bg-primary);
            border: 1px solid var(--border-color);
            border-radius: 8px;
            padding: 0 12px;
            height: 44px;
            font-size: 14px;
            color: var(--text-primary);
            cursor: pointer;
            transition: all 0.2s;
            box-shadow: 0 2px 8px var(--shadow);
            font-weight: 500;
            min-width: 140px;
        }

        .language-selector:hover {
            background: var(--bg-secondary);
            transform: translateY(-1px);
        }

        .language-selector:focus {
            outline: none;
            border-color: var(--primary);
        }

        .logo-container {
            text-align: center;
            margin-bottom: 32px;
        }

        .logo-container img {
            max-width: 200px;
            height: auto;
        }

        h1 {
            text-align: center;
            color: var(--text-primary);
            font-size: 28px;
            margin-bottom: 8px;
        }

        .subtitle {
            text-align: center;
            color: var(--text-secondary);
            font-size: 14px;
            margin-bottom: 32px;
        }

        .form-group {
            margin-bottom: 24px;
        }

        label {
            display: block;
            color: var(--text-primary);
            font-size: 14px;
            font-weight: 500;
            margin-bottom: 8px;
        }

        input {
            width: 100%;
            padding: 12px 16px;
            border: 2px solid var(--border-color);
            border-radius: 8px;
            font-size: 16px;
            transition: all 0.3s;
            background: var(--bg-primary);
            color: var(--text-primary);
        }

        input:focus {
            outline: none;
            border-color: var(--primary);
            box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
        }

        .error-message {
            background: var(--error-bg);
            color: var(--error-text);
            padding: 12px 16px;
            border-radius: 8px;
            font-size: 14px;
            margin-bottom: 20px;
            display: none;
        }

        .error-message.show {
            display: block;
        }

        button {
            width: 100%;
            padding: 14px;
            background: var(--primary);
            color: white;
            border: none;
            border-radius: 8px;
            font-size: 16px;
            font-weight: 600;
            cursor: pointer;
            transition: background 0.2s;
        }

        button:hover:not(:disabled) {
            background: var(--primary-hover);
        }

        button:disabled {
            opacity: 0.6;
            cursor: not-allowed;
        }

        .loading {
            display: none;
            text-align: center;
            margin-top: 16px;
            color: var(--text-secondary);
            font-size: 14px;
        }

        .loading.show {
            display: block;
        }

        @media (max-width: 480px) {
            .login-container {
                padding: 32px 24px;
            }

            h1 {
                font-size: 24px;
            }
        }