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

    :root {
        --primary-red: #1a4dff;
        --primary-purple: #0d2b8c;
        --accent-pink: #0066ff;
        --bg-dark: #020202;
        --bg-card: rgba(12,12,14,0.85);
        --bg-card-hover: rgba(18,18,22,0.9);
        --text-white: #ffffff;
        --text-gray: #a0a0a0;
        --text-light: #d0d0d0;
        --border-color: rgba(255,255,255,0.06);
        --gradient-primary: linear-gradient(135deg, #1a4dff 0%, #0066ff 50%, #0d2b8c 100%);
        --gradient-text: linear-gradient(135deg, #1a4dff 0%, #0066ff 50%, #0d2b8c 100%);
        --glow-red: 0 0 50px rgba(26,77,255,0.25);
        --glow-purple: 0 0 50px rgba(13,43,140,0.25);
    }

    body {
        font-family: "Noto Sans SC", "HarmonyOS Sans", "HarmonyOS Sans SC", -apple-system, "PingFang SC", "Microsoft YaHei", "WenQuanYi Micro Hei", sans-serif;
        background: var(--bg-dark);
        color: var(--text-white);
        overflow-x: hidden;
    }

    a { text-decoration: none; }

    /* Form */
    .form-group { margin-bottom: 24px; }
    .form-group label {
        display: block; margin-bottom: 10px;
        color: var(--text-white); font-weight: 600; font-size: 14px;
    }
    .form-group input, .form-group textarea {
        width: 100%; padding: 14px 18px;
        background: rgba(255,255,255,0.03);
        border: 1px solid var(--border-color);
        border-radius: 12px; color: var(--text-white);
        font-size: 15px; font-family: inherit;
        transition: all 0.3s;
    }
    .form-group input:focus, .form-group textarea:focus {
        outline: none; border-color: rgba(26,77,255,0.4);
        background: rgba(26,77,255,0.05);
    }

    /* Button */
    .btn-primary {
        padding: 18px 44px;
        background: var(--gradient-primary);
        border: none; border-radius: 50px;
        color: #fff; font-size: 16px; font-weight: 700;
        cursor: pointer; transition: all 0.3s;
        text-decoration: none;
        display: inline-flex; align-items: center; gap: 8px;
        box-shadow: 0 8px 30px rgba(26,77,255,0.4);
    }
    .btn-primary:hover { transform: translateY(-3px); box-shadow: 0 15px 40px rgba(26,77,255,0.6); }

    /* Glow Animation */
    @keyframes float1 {
        0%, 100% { transform: translate(0, 0) scale(1); }
        50% { transform: translate(40px, -30px) scale(1.1); }
    }
    @keyframes float2 {
        0%, 100% { transform: translate(0, 0) scale(1); }
        50% { transform: translate(-30px, 20px) scale(1.15); }
    }



    /* SVG Icons */
    .ic { width: 20px; height: 20px; flex-shrink: 0; }
    .feature-item-icon .ic, .about-card-icon .ic { width: 24px; height: 24px; }
    .footer-social .ic { width: 18px; height: 18px; }
    .footer-contact-chip .ic { width: 20px; height: 20px; }
    .ai-node .ic { width: 18px; height: 18px; }
    .mobile-menu-btn .ic, .mobile-nav-close .ic { width: 22px; height: 22px; }
    .footer-newsletter button .ic { width: 18px; height: 18px; }
    h4 .ic { vertical-align: -3px; margin-right: 2px; }
    .ic-arrow { width: 14px; height: 14px; margin-left: 6px; vertical-align: -2px; }
    .ic-trend { width: 12px; height: 12px; margin-right: 4px; vertical-align: -1px; }
    .subscribe-ok .ic-trend { width: 14px; height: 14px; }

    /* Auth Pages (login / 404) */
    .contact-form .btn-primary { justify-content: center; }
    .auth-page { min-height: 100vh; display: flex; flex-direction: column; }
    .auth-bg {
        position: fixed; inset: 0; z-index: 0;
        background: linear-gradient(180deg, #0a0a0a 0%, #1a0a2e 50%, #0a0a0a 100%);
    }
    .auth-bg::before {
        content: ''; position: absolute;
        width: 700px; height: 700px;
        background: radial-gradient(circle, rgba(26,77,255,0.2) 0%, transparent 60%);
        top: 5%; left: 15%;
        animation: float1 6s ease-in-out infinite;
    }
    .auth-bg::after {
        content: ''; position: absolute;
        width: 600px; height: 600px;
        background: radial-gradient(circle, rgba(13,43,140,0.15) 0%, transparent 60%);
        bottom: 5%; right: 10%;
        animation: float2 8s ease-in-out infinite;
    }
    .auth-main {
        flex: 1; display: flex; align-items: center; justify-content: center;
        position: relative; z-index: 1; padding: 60px 24px;
    }
    .auth-card {
        width: 100%; max-width: 460px;
        background: var(--bg-card);
        border: 1px solid var(--border-color);
        border-radius: 28px; padding: 48px 44px;
        backdrop-filter: blur(20px);
        box-shadow: 0 30px 80px rgba(0,0,0,0.5);
        text-align: center;
    }
    .auth-logo img { height: 50px; width: auto; display: block; margin: 0 auto 16px; filter: brightness(1.2); }
    .auth-card h1 { font-size: 28px; font-weight: 800; margin-bottom: 10px; }
    .auth-desc { font-size: 14px; color: var(--text-gray); margin-bottom: 36px; line-height: 1.7; }
    .auth-form { text-align: left; }
    .auth-options {
        display: flex; align-items: center; justify-content: space-between;
        margin: -4px 0 28px; font-size: 13px;
    }
    .auth-remember { display: flex; align-items: center; gap: 8px; color: var(--text-gray); cursor: pointer; }
    .auth-remember input { accent-color: var(--primary-red); width: 15px; height: 15px; cursor: pointer; }
    .auth-options a { color: var(--primary-red); text-decoration: none; }
    .auth-options a:hover { text-decoration: underline; }
    .auth-submit { width: 100%; justify-content: center; font-size: 17px; letter-spacing: 8px; padding: 16px; }
    .auth-links { margin-top: 28px; font-size: 14px; color: var(--text-gray); }
    .auth-links a { color: var(--primary-red); text-decoration: none; font-weight: 700; margin-left: 4px; }
    .auth-links a:hover { text-decoration: underline; }

    .auth-notice {
        margin-top: 22px; padding: 14px 16px;
        background: rgba(26,77,255,0.06);
        border: 1px solid rgba(26,77,255,0.18);
        border-radius: 12px;
        font-size: 12px; color: var(--text-gray);
        line-height: 1.9; text-align: left;
    }
    .auth-home { margin-top: 16px; }
    .auth-home a {
        display: inline-flex; align-items: center; gap: 6px;
        font-size: 13px; color: var(--text-gray); text-decoration: none; transition: color 0.3s;
    }
    .auth-home a:hover { color: var(--primary-red); }
    .auth-home .ic-arrow { margin-left: 0; transform: rotate(180deg); }
    .error-code {
        font-size: 110px; font-weight: 900; line-height: 1; letter-spacing: -4px;
        background: var(--gradient-text);
        -webkit-background-clip: text; background-clip: text;
        -webkit-text-fill-color: transparent;
        margin: 6px 0 18px;
    }
    .error-buttons { display: flex; gap: 16px; justify-content: center; flex-wrap: wrap; }
    .error-buttons .btn-primary, .error-buttons .btn-secondary { padding: 15px 36px; font-size: 15px; }
    .auth-footer { position: relative; z-index: 1; text-align: center; padding: 24px 20px 30px; }
    .auth-footer .copyright-text { font-size: 13px; color: var(--text-gray); margin-bottom: 10px; }
    .auth-footer .copyright-text a { color: var(--text-gray); text-decoration: none; transition: color 0.3s; }
    .auth-footer .copyright-text a:hover { color: var(--primary-red); }
    .auth-footer .footer-beian { display: flex; align-items: center; justify-content: center; gap: 8px; }
    .auth-footer .footer-beian img { height: 14px; width: auto; }
    .auth-footer .footer-beian a { color: var(--text-gray); text-decoration: none; font-size: 13px; transition: color 0.3s; }
    .auth-footer .footer-beian a:hover { color: var(--primary-red); }
    @media (max-width: 480px) {
        .auth-card { padding: 36px 26px; }
        .error-code { font-size: 84px; }
    }

    /* Back to Top */
    .back-to-top {
        position: fixed; right: 28px; bottom: 28px; z-index: 999;
        width: 50px; height: 50px; border-radius: 14px;
        background: var(--gradient-primary); border: none; cursor: pointer;
        display: flex; align-items: center; justify-content: center;
        color: #fff; opacity: 0; visibility: hidden;
        transform: translateY(16px); transition: all 0.35s;
        box-shadow: 0 10px 30px rgba(26,77,255,0.35);
    }
    .back-to-top.show { opacity: 1; visibility: visible; transform: translateY(0); }
    .back-to-top:hover { transform: translateY(-4px); box-shadow: 0 14px 36px rgba(26,77,255,0.5); }
    .back-to-top svg { width: 22px; height: 22px; }