:root {
            --primary-color: #2563eb;
            --primary-hover: #1d4ed8;
            --primary-light: rgba(37, 99, 235, 0.08);
            --secondary-color: #64748b;
            --background-start: #f8fafc;
            --background-mid: #e2e8f0;
            --background-end: #f1f5f9;
            --card-bg: #ffffff;
            --card-border: rgba(0, 0, 0, 0.08);
            --text-primary: #1e293b;
            --text-secondary: #64748b;
            --text-light: #94a3b8;
            --shadow-color: rgba(0, 0, 0, 0.08);
            --shadow-lg: rgba(0, 0, 0, 0.1);
            --success-color: #10b981;
            --tab-inactive-bg: #f8fafc;
            --tab-hover-bg: #f1f5f9;
        }

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

        body {
            font-family: 'Inter', 'Segoe UI', -apple-system, BlinkMacSystemFont, Roboto, sans-serif;
            min-height: 100vh;
            display: flex;
            justify-content: center;
            align-items: center;
            background: linear-gradient(135deg, var(--background-start) 0%, var(--background-mid) 50%, var(--background-end) 100%);
            background-attachment: fixed;
            padding: 20px;
            position: relative;
            overflow-x: hidden;
        }

        body::before {
            content: '';
            position: fixed;
            top: -50%;
            left: -50%;
            width: 200%;
            height: 200%;
            background: radial-gradient(circle at 20% 80%, rgba(37, 99, 235, 0.06) 0%, transparent 40%),
                        radial-gradient(circle at 80% 20%, rgba(99, 102, 241, 0.05) 0%, transparent 40%),
                        radial-gradient(circle at 50% 50%, rgba(14, 165, 233, 0.04) 0%, transparent 50%);
            animation: gradientShift 20s ease-in-out infinite;
            pointer-events: none;
            z-index: 0;
        }

        @keyframes gradientShift {
            0%, 100% { transform: translate(0, 0) rotate(0deg); }
            50% { transform: translate(-3%, 3%) rotate(1deg); }
        }

        @keyframes fadeInUp {
            from {
                opacity: 0;
                transform: translateY(20px);
            }
            to {
                opacity: 1;
                transform: translateY(0);
            }
        }

        @keyframes slideIn {
            from {
                opacity: 0;
                transform: translateX(-10px);
            }
            to {
                opacity: 1;
                transform: translateX(0);
            }
        }

        .container {
            background: var(--card-bg);
            width: 100%;
            max-width: 440px;
            border-radius: 20px;
            box-shadow: 0 4px 6px -1px var(--shadow-color),
                        0 10px 15px -3px var(--shadow-lg),
                        0 20px 25px -5px rgba(0, 0, 0, 0.05),
                        0 0 0 1px var(--card-border);
            display: flex;
            flex-direction: column;
            position: relative;
            z-index: 1;
            overflow: hidden;
            animation: fadeInUp 0.5s ease-out;
        }

        .header {
            background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-hover) 100%);
            color: white;
            padding: 26px 24px;
            font-size: 19px;
            font-weight: 600;
            text-align: center;
            letter-spacing: 0.3px;
            position: relative;
            overflow: hidden;
        }

        .header::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            background: linear-gradient(135deg, rgba(255,255,255,0.12) 0%, transparent 60%);
            pointer-events: none;
        }

        .tabs {
            display: flex;
            padding: 16px 16px 0;
            background: var(--tab-inactive-bg);
            gap: 8px;
            border-bottom: 1px solid var(--card-border);
        }

        .tab {
            flex: 1;
            text-align: center;
            padding: 12px 16px;
            font-weight: 600;
            font-size: 13px;
            cursor: pointer;
            border: none;
            background: transparent;
            color: var(--text-secondary);
            border-radius: 10px 10px 0 0;
            transition: all 0.25s ease;
            position: relative;
            white-space: nowrap;
            overflow: hidden;
            text-overflow: ellipsis;
        }

        .tab:hover {
            color: var(--primary-color);
            background: var(--tab-hover-bg);
        }

        .tab.active {
            background: var(--card-bg);
            color: var(--primary-color);
            box-shadow: 0 -2px 8px -2px var(--shadow-color);
        }

        .tab.active::after {
            content: '';
            position: absolute;
            bottom: 0;
            left: 50%;
            transform: translateX(-50%);
            width: 36px;
            height: 3px;
            background: var(--primary-color);
            border-radius: 3px 3px 0 0;
        }

        .tab-content {
            display: none;
            padding: 24px;
            background: var(--card-bg);
            min-height: 180px;
        }

        .tab-content.active {
            display: block;
            animation: slideIn 0.25s ease-out;
        }

        .login-button {
            display: flex;
            flex-direction: row;
            align-items: center;
            justify-content: flex-start;
            padding: 14px 18px;
            margin: 10px 0;
            background: var(--primary-color);
            color: white;
            border: none;
            width: 100%;
            border-radius: 12px;
            cursor: pointer;
            transition: all 0.25s ease;
            position: relative;
            overflow: hidden;
            box-shadow: 0 2px 8px -2px rgba(37, 99, 235, 0.35);
        }

        .login-button::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            background: linear-gradient(135deg, rgba(255,255,255,0.1) 0%, transparent 50%);
            opacity: 0;
            transition: opacity 0.25s ease;
        }

        .login-button:hover {
            transform: translateY(-1px);
            box-shadow: 0 4px 12px -2px rgba(37, 99, 235, 0.4);
        }

        .login-button:hover::before {
            opacity: 1;
        }

        .login-button:active {
            transform: translateY(0);
            box-shadow: 0 2px 8px -2px rgba(37, 99, 235, 0.35);
        }

        .login-button img {
            width: 26px;
            height: 26px;
            margin-right: 14px;
            border-radius: 6px;
            background: white;
            padding: 4px;
            flex-shrink: 0;
        }

        .login-text {
            display: flex;
            flex-direction: column;
            line-height: 1.4;
            text-align: left;
        }

        .login-text span:first-child {
            font-size: 14px;
            font-weight: 600;
            letter-spacing: 0.2px;
        }

        .login-text .login-description {
            font-size: 12px;
            opacity: 0.9;
            margin-top: 2px;
            font-weight: 400;
        }

        .no-providers {
            padding: 40px 24px;
            text-align: center;
            color: var(--text-secondary);
            font-size: 14px;
            display: flex;
            flex-direction: column;
            align-items: center;
            gap: 12px;
        }

        .no-providers::before {
            content: '';
            width: 48px;
            height: 48px;
            background: var(--primary-light);
            border-radius: 12px;
            display: flex;
            align-items: center;
            justify-content: center;
        }

        /* Provider-specific button colors */
        .login-button[data-provider='azure'],
        .login-button[data-provider='microsoft'] {
            background: #0078d4;
            box-shadow: 0 2px 8px -2px rgba(0, 120, 212, 0.35);
        }

        .login-button[data-provider='azure']:hover,
        .login-button[data-provider='microsoft']:hover {
            background: #006cbe;
            box-shadow: 0 4px 12px -2px rgba(0, 120, 212, 0.45);
        }

        .login-button[data-provider='google'] {
            background: #4285f4;
            box-shadow: 0 2px 8px -2px rgba(66, 133, 244, 0.35);
        }

        .login-button[data-provider='google']:hover {
            background: #3b78e7;
            box-shadow: 0 4px 12px -2px rgba(66, 133, 244, 0.45);
        }

        .login-button[data-provider='github'] {
            background: #24292e;
            box-shadow: 0 2px 8px -2px rgba(36, 41, 46, 0.35);
        }

        .login-button[data-provider='github']:hover {
            background: #1b1f23;
            box-shadow: 0 4px 12px -2px rgba(36, 41, 46, 0.45);
        }

        /* Footer branding */
        .container::after {
            content: 'Powered by AdminDroid';
            display: block;
            text-align: center;
            padding: 14px;
            font-size: 11px;
            color: var(--text-light);
            background: var(--tab-inactive-bg);
            letter-spacing: 0.4px;
            border-top: 1px solid var(--card-border);
        }

        /* Responsive Design */
        @media (max-width: 500px) {
            body {
                padding: 16px;
                align-items: flex-start;
                padding-top: 8vh;
            }

            .container {
                max-width: 100%;
                border-radius: 16px;
            }

            .header {
                padding: 22px 20px;
                font-size: 17px;
            }

            .tabs {
                padding: 12px 12px 0;
                gap: 6px;
            }

            .tab {
                padding: 10px 12px;
                font-size: 12px;
                border-radius: 8px 8px 0 0;
            }

            .tab-content {
                padding: 20px 16px;
            }

            .login-button {
                padding: 12px 14px;
                border-radius: 10px;
            }

            .login-button img {
                width: 22px;
                height: 22px;
                margin-right: 12px;
            }

            .login-text span:first-child {
                font-size: 13px;
            }

            .login-text .login-description {
                font-size: 11px;
            }
        }

        @media (max-width: 360px) {
            .tabs {
                flex-wrap: wrap;
            }

            .tab {
                flex: 1 1 45%;
                min-width: 45%;
            }
        }

        /* Reduced motion preference */
        @media (prefers-reduced-motion: reduce) {
            *, *::before, *::after {
                animation-duration: 0.01ms !important;
                animation-iteration-count: 1 !important;
                transition-duration: 0.01ms !important;
            }
        }