/* ==================== FONTS & VARIABLES ==================== */
@font-face {
    font-family: 'MiSans';
    src: local('MiSans'), local('MiSans-Regular');
    font-weight: normal;
    font-style: normal;
}

:root {
    --primary-color: #FF5927;
    --text-white: #ffffff;
    --text-muted: rgba(255, 255, 255, 0.65);
    --bg-dark: #080808;
    --transition-smooth: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ==================== GLOBAL RESET ==================== */
[v-cloak] {
    display: none !important;
}

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

html {
    scroll-behavior: smooth;
    font-family: 'PingFang SC', 'MiSans', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    background-color: var(--bg-dark);
    color: var(--text-white);
    -webkit-font-smoothing: antialiased;
}

body.dark-theme,
body {
    width: 100%;
    min-height: 100vh;
    background-color: #080808;
    background-image: radial-gradient(rgba(255, 255, 255, 0.12) 1px, transparent 1px);
    background-size: 20px 20px;
    background-attachment: fixed;
    color: var(--text-white);
    overflow-x: hidden;
    position: relative;
    display: flex;
    flex-direction: column;
}

#app {
    width: 100%;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    position: relative;
}

/* ==================== HEADER FLOATING OVERRIDE ==================== */
header.nav-header.upgrade-nav-header,
nav-header.upgrade-nav-header {
    background: transparent !important;
    border-bottom: none !important;
    box-shadow: none !important;
}

header.nav-header.upgrade-nav-header .stepx-nav-card {
    background: #111111 !important;
    border: 1px solid rgba(255, 255, 255, 0.12) !important;
    border-top: none !important;
    border-radius: 0 0 10px 10px !important;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.5) !important;
}

/* ==================== MAIN UPGRADE SECTION ==================== */
.upgrade-container {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 80px 24px 60px;
    text-align: center;
    box-sizing: border-box;
    position: relative;
    z-index: 1;
}

.upgrade-image-wrapper {
    margin-bottom: 28px;
    display: flex;
    align-items: center;
    justify-content: center;
    user-select: none;
    -webkit-user-drag: none;
}

.upgrade-image {
    width: 320px;
    max-width: 85vw;
    height: auto;
    object-fit: contain;
    display: block;
    animation: floatAnimation 4s ease-in-out infinite;
}

@keyframes floatAnimation {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-6px);
    }
}

.upgrade-title {
    font-size: 26px;
    font-weight: 600;
    color: #FFFFFF;
    margin: 0 0 14px 0;
    letter-spacing: 0.5px;
    line-height: 1.4;
}

.upgrade-desc {
    font-size: 14px;
    font-weight: 400;
    color: rgba(255, 255, 255, 0.65);
    margin: 0;
    line-height: 1.6;
    letter-spacing: 0.3px;
    max-width: 600px;
}

/* ==================== BACK TO TOP FLOATING WIDGET (复刻 community.html) ==================== */
.back-to-top-widget {
    position: fixed;
    right: 36px;
    bottom: 36px;
    z-index: 998;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    user-select: none;
    opacity: 0;
    visibility: hidden;
    transform: translateY(12px);
    transition: opacity 0.25s cubic-bezier(0.16, 1, 0.3, 1),
        transform 0.25s cubic-bezier(0.16, 1, 0.3, 1),
        visibility 0.25s ease;
}

.back-to-top-widget.is-visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.back-to-top-widget:hover {
    transform: translateY(-3px);
}

.back-to-top-widget:active {
    transform: translateY(0) scale(0.95);
}

.back-to-top-icon {
    width: 36px;
    height: 36px;
    object-fit: contain;
    display: block;
    border-radius: 4px;
    transition: transform 0.2s ease, filter 0.2s ease;
}

.back-to-top-widget:hover .back-to-top-icon {
    filter: brightness(1.2);
}

.back-to-top-text {
    margin-top: 5px;
    font-size: 12px;
    font-weight: 500;
    color: rgba(255, 255, 255, 0.85);
    text-align: center;
    line-height: 1.2;
    white-space: nowrap;
    letter-spacing: 0.5px;
    transition: color 0.2s ease;
}

.back-to-top-widget:hover .back-to-top-text {
    color: #ffffff;
}

/* ==================== RESPONSIVE ==================== */
@media (max-width: 768px) {
    .upgrade-container {
        padding: 60px 20px 40px;
    }

    .upgrade-image {
        width: 220px;
    }

    .upgrade-title {
        font-size: 20px;
        margin-bottom: 10px;
    }

    .upgrade-desc {
        font-size: 13px;
    }

    .back-to-top-widget {
        right: 16px;
        bottom: 24px;
    }
}