/* ============================================================
   SAISHI.CSS v3.0 - 赛事/文章/APP 页面专属样式
   ============================================================
   匹配 Section 模板:
   - ArticleSection (单文章详情)
   - AppHeroSection / AppQrSection / AppInstallSection / AppShowcaseSection
   - ContactChannelsSection / ContactFormSection / ContactQuickSection / ContactCommitmentsSection
   - LoginFormSection / SignupFormSection
   - SearchBoxSection (extends)
   - 滚动条 / 打印样式 / 图标
   ============================================================ */

/* ============================================
   1. Single Post (ArticleSection)
   ============================================ */
.single-post {
    overflow: hidden;
}

.single-post .post-meta {
    font-size: 0.9rem;
}

.single-post .post-meta i {
    color: var(--color-primary);
}

/* Post content typography */
.post-content {
    line-height: 1.8;
    font-size: 1.05rem;
    color: var(--color-text);
}

.post-content :is(h2, h3, h4) {
    margin-block: 2rem 1rem;
    font-weight: 700;
    color: var(--color-primary-darker);
    line-height: 1.4;
}

.post-content h2 {
    font-size: 1.75rem;
    padding-bottom: var(--space-xs);
    border-bottom: 2px solid var(--color-border);
}

.post-content h3 {
    font-size: 1.35rem;
}

.post-content :is(p, li) {
    margin-bottom: var(--space-sm);
}

.post-content blockquote {
    border-inline-start: 4px solid var(--color-primary);
    padding: var(--space-sm) var(--space-md);
    background: var(--color-bg-soft);
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
    margin-block: var(--space-md);
    color: var(--color-text-muted);
    font-style: italic;
}

.post-content img {
    max-width: 100%;
    height: auto;
    border-radius: var(--radius-md);
    margin-block: var(--space-sm);
    box-shadow: var(--shadow-sm);
}

.post-content a {
    color: var(--color-primary);
    text-decoration: underline;
    transition: color var(--transition-fast);
}

.post-content a:hover {
    color: var(--color-primary-dark);
}

.post-content ul,
.post-content ol {
    padding-inline-start: 1.5rem;
}

.post-content code {
    background: var(--color-bg-muted);
    padding: 2px 6px;
    border-radius: 4px;
    font-size: 0.9em;
    color: var(--color-danger);
}

.post-content pre {
    background: var(--color-primary-darker);
    color: #fff;
    padding: var(--space-md);
    border-radius: var(--radius-md);
    overflow-x: auto;
    margin-block: var(--space-md);
}

.post-content pre code {
    background: transparent;
    color: inherit;
    padding: 0;
}

.post-content table {
    width: 100%;
    border-collapse: collapse;
    margin-block: var(--space-md);
}

.post-content table th,
.post-content table td {
    padding: var(--space-xs) var(--space-sm);
    border: 1px solid var(--color-border);
    text-align: start;
}

.post-content table th {
    background: var(--color-bg-muted);
    font-weight: 600;
}

/* TOC */
.toc-box {
    border-inline-start: 3px solid var(--color-primary);
}

.toc-box ol {
    padding-inline-start: 1.2rem;
}

.toc-box ol li {
    margin: 0.4rem 0;
}

.toc-box ol li a {
    transition: all var(--transition-fast);
}

.toc-box ol li a:hover {
    color: var(--color-primary-dark);
    text-decoration: underline !important;
    padding-inline-start: 4px;
}

/* Tags */
.post-tags .badge {
    background: var(--color-bg-muted) !important;
    color: #475569 !important;
    padding: 6px 12px;
    font-weight: 500;
    transition: all var(--transition-fast);
}

.post-tags .badge:hover {
    background: var(--color-primary) !important;
    color: #fff !important;
    transform: translateY(-1px);
}

/* Post nav */
.post-nav {
    flex-wrap: wrap;
    gap: var(--space-sm);
}

.post-nav .btn {
    max-width: 100%;
    overflow: hidden;
    text-overflow: ellipsis;
}

/* ============================================
   2. App Hero (AppHeroSection)
   ============================================ */
.app-hero-section {
    background: var(--gradient-hero);
    color: #fff;
    position: relative;
    overflow: hidden;
}

.app-hero-section::before {
    content: '';
    position: absolute;
    inset: 0;
    background: rgba(0, 0, 0, 0.2);
    z-index: 0;
}

.app-hero-section > .container {
    position: relative;
    z-index: 1;
}

.app-hero-section h1 {
    font-size: clamp(2rem, 4vw, 3rem);
    line-height: 1.2;
}

.app-hero-section img {
    transition: transform var(--transition-slow);
    filter: drop-shadow(0 20px 40px rgba(0, 0, 0, 0.3));
}

.app-hero-section img:hover {
    transform: translateY(-10px);
}

.text-white-50 {
    color: rgba(255, 255, 255, 0.65) !important;
}

/* ============================================
   3. App QR (AppQrSection)
   ============================================ */
.app-qr-section {
    background: var(--color-bg-soft);
}

.qr-card {
    transition: all var(--transition-base);
    border: 2px solid transparent;
}

.qr-card:hover {
    transform: scale(1.03);
    border-color: var(--color-accent);
    box-shadow: 0 15px 40px rgba(0, 0, 0, 0.15);
}

.qr-card img {
    image-rendering: pixelated;
    image-rendering: -moz-crisp-edges;
    image-rendering: crisp-edges;
}

/* ============================================
   4. App Install Steps (AppInstallSection)
   ============================================ */
.app-install-section {
    background: var(--color-bg-soft);
}

.app-install-section .badge.rounded-circle {
    width: 50px;
    height: 50px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    font-weight: 700;
}

.app-install-section .bg-white {
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
}

.app-install-section .bg-white:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.app-install-section .bg-white::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 100%;
    background: var(--gradient-icon);
    transform: scaleY(0);
    transform-origin: top;
    transition: transform var(--transition-base);
}

.app-install-section .bg-white:hover::before {
    transform: scaleY(1);
}

/* ============================================
   5. App Showcase (AppShowcaseSection)
   ============================================ */
.app-showcase-section {
    background: var(--color-bg);
}

.app-showcase-section img {
    transition: transform var(--transition-slow);
    filter: drop-shadow(0 15px 30px rgba(0, 0, 0, 0.15));
}

.app-showcase-section img:hover {
    transform: translateY(-5px) rotate(-1deg);
}

.app-showcase-section .bg-white {
    transition: all var(--transition-base);
    border-inline-start: 3px solid transparent;
}

.app-showcase-section .bg-white:hover {
    border-inline-start-color: var(--color-primary);
    transform: translateX(5px);
    box-shadow: var(--shadow-md);
}

/* ============================================
   6. Contact Sections
   ============================================ */
.contact-channels-section {
    background: var(--color-bg);
}

.contact-channels-section article {
    transition: all var(--transition-base);
    border: 1px solid var(--color-border-soft);
}

.contact-channels-section article:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
    border-color: var(--color-primary);
}

.contact-channels-section article ul li {
    transition: padding var(--transition-fast);
}

.contact-channels-section article ul li:hover {
    padding-inline-start: 4px;
}

/* Contact Quick */
.contact-quick-section {
    background: var(--color-bg-soft);
}

.contact-quick-section .contact-card {
    transition: all var(--transition-base);
}

.contact-quick-section .contact-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.contact-quick-section .contact-card i {
    transition: transform var(--transition-base);
}

.contact-quick-section .contact-card:hover i {
    transform: scale(1.1) rotate(-5deg);
}

/* Contact Form */
.contact-form-section {
    background: var(--color-bg-soft);
}

.contact-form-section .form-control,
.contact-form-section .form-select {
    border: 2px solid var(--color-border);
    transition: all var(--transition-fast);
}

.contact-form-section .form-control:focus,
.contact-form-section .form-select:focus {
    border-color: var(--color-primary);
    box-shadow: 0 0 0 0.2rem rgba(59, 130, 246, 0.1);
}

.contact-form-section button[type="submit"] {
    transition: all var(--transition-base);
}

.contact-form-section button[type="submit"]:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-primary);
}

/* Contact Commitments */
.contact-commitments-section {
    background: var(--color-bg-soft);
}

.contact-commitments-section .bg-white {
    transition: all var(--transition-base);
    text-align: center;
}

.contact-commitments-section .bg-white:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.contact-commitments-section .bg-white i {
    transition: transform var(--transition-base);
}

.contact-commitments-section .bg-white:hover i {
    transform: scale(1.15);
}

/* ============================================
   7. Login / Signup Forms
   ============================================ */
main:has(> .container > .bg-white > form) .input-group-text {
    background-color: var(--color-bg-muted);
    border-color: var(--color-border);
    border-inline-end: none;
}

main:has(> .container > .bg-white > form) .input-group .form-control {
    border-inline-start: none;
}

main:has(> .container > .bg-white > form) .input-group:focus-within .input-group-text {
    border-color: var(--color-primary);
    background-color: #eff6ff;
}

main:has(> .container > .bg-white > form) .input-group:focus-within .form-control {
    border-color: var(--color-primary);
}

main:has(> .container > .bg-white > form) .form-check-input:checked {
    background-color: var(--color-primary);
    border-color: var(--color-primary);
}

main:has(> .container > .bg-white > form) button[type="submit"] {
    transition: all var(--transition-base);
    font-weight: 600;
}

main:has(> .container > .bg-white > form) button[type="submit"]:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-primary);
}

/* ============================================
   8. Icons
   ============================================ */
.icon-img {
    max-width: 32px;
    max-height: 32px;
    object-fit: contain;
}

.icon-emoji {
    display: inline-block;
    line-height: 1;
}

/* ============================================
   9. Hero Buttons (đã có ở theme.css nhưng bổ sung thêm)
   ============================================ */
.hero-buttons .btn {
    transition: all var(--transition-base);
}

.hero-buttons .btn:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
}

.hero-buttons .btn-warning {
    background-color: var(--color-accent);
    border-color: var(--color-accent);
    color: var(--color-primary-darker);
    font-weight: 600;
}

.hero-buttons .btn-warning:hover {
    background-color: var(--color-accent-dark);
    border-color: var(--color-accent-dark);
}

.hero-buttons .btn-outline-light:hover {
    background-color: rgba(255, 255, 255, 0.15);
    color: #fff;
}

/* ============================================
   10. 自定义滚动条
   ============================================ */
::-webkit-scrollbar {
    width: 10px;
    height: 10px;
}

::-webkit-scrollbar-track {
    background: var(--color-bg-muted);
}

::-webkit-scrollbar-thumb {
    background: #94a3b8;
    border-radius: 5px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--color-text
-muted);
}

/* Firefox */
* {
    scrollbar-width: thin;
    scrollbar-color: #94a3b8 var(--color-bg-muted);
}

/* ============================================
   11. Print Styles
   ============================================ */
@media print {
    :is(.header,
        .footer,
        .sidebar-widgets,
        .social-share,
        #back-to-top,
        .breadcrumb-nav,
        .notice-bar,
        .cta-banner-section,
        .post-nav,
        .related-posts,
        .author-box,
        .pagination,
        .navbar-toggler,
        .nav-item) {
        display: none !important;
    }

    body {
        background: #fff !important;
        color: #000 !important;
        font-size: 12pt;
    }

    .single-post {
        box-shadow: none !important;
        border: none !important;
        padding: 0 !important;
        max-width: 100% !important;
    }

    .post-content {
        font-size: 11pt;
        line-height: 1.6;
    }

    a {
        text-decoration: underline;
        color: #000 !important;
    }

    a[href^="http"]::after {
        content: " (" attr(href) ")";
        font-size: 9pt;
        color: #555;
    }

    a[href^="#"]::after,
    a[href^="javascript:"]::after,
    a[href^="mailto:"]::after,
    a[href^="tel:"]::after {
        content: "";
    }

    .post-content img {
        max-width: 100% !important;
        page-break-inside: avoid;
    }

    :is(h1, h2, h3, h4) {
        page-break-after: avoid;
        color: #000 !important;
    }

    p, li {
        orphans: 3;
        widows: 3;
    }
}

/* ============================================
   12. Animations bổ sung
   ============================================ */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes pulse {
    0%, 100% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.05);
    }
}

.animate-fade-in {
    animation: fadeInUp 0.6s ease-out;
}

.animate-pulse {
    animation: pulse 2s infinite;
}

/* ============================================
   13. Responsive
   ============================================ */
@media (max-width: 991.98px) {
    .post-content {
        font-size: 1rem;
    }

    .post-content h2 {
        font-size: 1.5rem;
    }

    .post-content h3 {
        font-size: 1.2rem;
    }
}

@media (max-width: 767.98px) {
    .single-post {
        padding: var(--space-md) !important;
    }

    .post-content {
        font-size: 0.95rem;
    }

    .post-content h2 {
        font-size: 1.35rem;
    }

    .post-nav {
        flex-direction: column;
    }

    .post-nav .btn {
        width: 100%;
    }

    .post-tags .badge {
        font-size: 0.8rem;
        padding: 4px 8px;
    }

    .app-hero-section h1 {
        font-size: 1.75rem;
    }

    .app-install-section .badge.rounded-circle {
        width: 40px;
        height: 40px;
        font-size: 1rem;
    }

    .toc-box {
        padding: var(--space-sm) !important;
    }

    .qr-card img {
        max-width: 140px !important;
    }
}

We need to rewrite the CSS visually, but the given CSS snippet is very small, media query at max-width 575.98px. It includes three rules. The instructions say to keep layout, selectors, etc., and change only colors, shadows, radius, transitions, gradients, etc. But the original CSS has no colors, shadows, etc. It only sets text-align and padding (padding is layout, can vary ±20%? Actually "padding, margin (keep similar values, ±20% maximum)" — padding is layout, but they say keep similar values, but we can slightly adjust? The original padding: var(--space-md) !important; we can't change the var? Actually we can change custom property values? It says CSS custom properties (--color-*, --shadow-*) values can change. But --space-md is a spacing variable, not color/shadow. So we shouldn't change it. We can only change visual properties. But there are no visual properties here. However, the task is to refresh the CSS visually, but the snippet only contains a media query with responsive layout tweaks. Perhaps we need to output the same CSS with any possible visual changes? But there are no colors/shadows. The rules are about center text and padding. We cannot change padding except within ±20%? "padding, margin (keep similar values, ±20% maximum)" means we could change padding by up to 20% but that's layout-ish. However, the instruction says "ONLY change colors, shadows, radius, transitions, gradients" — if none exist, we might keep it unchanged. But the user expects a rewritten CSS. The target style "flat-solid" says box-shadow: none everywhere and minimal radius. But the original has no shadows. We need to ensure no shadows are added? Actually we can't add new selectors? We must preserve selectors exactly. Could we add box-shadow: none to existing rules? That would change visual? No, it's none. Not necessary.

Maybe we need to interpret this as: the provided CSS is a small fragment, and we should apply a visual refresh to the elements involved. The only mutable properties are text-align? No, text-align is typography? Actually text-align is in the "never change" list? It says text-align, vertical-align are never change under Typography. Wait, in the NEVER CHANGE list: "text-align, vertical-align" are listed under Typography? Actually in the prompt: "📐 LAYOUT ... text-align, vertical-align" — yes it's in that list. So text-align must not change. Padding can change within ±20%, but we should avoid. The only thing we can change is font-size? No, font-size never change. The original has font-size: 0.85rem in the second rule. We can't change font-size. So essentially nothing to change. But maybe we can add visual properties that don't affect layout: e.g., color, background-color, border-radius, etc. But the selectors are for hero section, badge, contact cards. We could add colors, backgrounds, borders, etc. to those existing rules without changing layout properties. The instruction says "Refresh the visual identity WITHOUT changing layout structure or class names." So we can add color, background, border-radius to these existing rules. But we must preserve all existing declarations? The output must contain the same selectors and presumably the same declarations? Actually the task is to rewrite the CSS, not necessarily preserve every line? It says "ONLY the rewritten CSS, preserving ALL selectors and layout exactly". So we can add new declarations to existing rules, as long as selectors remain. But we need to be careful: we cannot add new selectors, but we can add new properties within existing rule blocks. That's allowed because it's visual only. The "original CSS" here is just a media query. We need to output a refreshed version that includes all original declarations plus new visual ones? Or just refresh the original declarations if they were visual. Since there are no visual declarations, we should add flat-solid style properties: no box-shadow (doesn't matter), solid colors, minimal radius.

But the element types: .app-hero-section .row .col-lg-7 is a column, .badge.bg-warning is a badge, .contact-card is a card. We can set color, background-color, border, etc. However, we must avoid breaking layout. Adding border changes box sizing? If box-sizing is border-box globally, borders won't affect layout. But we don't know. We could use box-shadow: none explicitly? That's silly.

Maybe the user expects a complete CSS file? But the file fingerprint and "块2/2" (block 2/2) means this is block 2 of 2. The file might contain more CSS, but we only see this block. The instructions say "File: assets/css/saishi.css#块2/2" — perhaps the file is split into two blocks, and this is the second block. We need to rewrite this block. It's a media query with three rules. We should output a refreshed version that maintains all original declarations and adds a new visual identity, but the original has no colors. The target style "flat-solid" means minimal shadows, solid colors, minimal radius. Perhaps we can add color/background to these elements.

Let's analyze the selectors:

1. .app-hero-section .row .col-lg-7 — a column inside hero. Currently text-align: center. We can add color? It might inherit. We could set color to a new palette primary, but that might override global styles. Betternot to overdo. Maybe set a background for hero? But the selector is too specific to the column. Adding background to a column might be weird. The flat-solid style could mean no shadows, solid background for cards. The contact cards selector already has padding; we could add background-color, border-radius, border.

But we have constraints: "Minimal radius (0-6px)" and "box-shadow: none everywhere" — so we can add border-radius: 6px to contact-card, and maybe border: 1px solid a color. But border adds to layout unless box-sizing border-box. We should avoid adding border because width/height must remain? Actually border-width is not in the never-change list? Wait, "border-color and border-style (NOT border-width)" — border-width is not listed as never-change? Actually it says "border-color and border-style (NOT border-width)" under the can-change list? Let's check: Under "✅ YOU MUST CHANGE" there is: "All color values: background, color, border-color, fill, stroke, outline-color" and "border-color and border-style (NOT border-width)" — so border-width is not allowed to change? Actually the instruction says "border-color and border-style (NOT border-width)" in the MUST CHANGE list? It's ambiguous. It says "border-color and border-style (NOT border-width)" — meaning only border-color and border-style can change, border-width cannot. So border-width remains as originally specified. If no border-width originally, adding border-width 1px might be a change to border-width, which is prohibited. So don't add borders. Similarly, we can add border-radius because radius is visual. Good.

We can add background-color to the contact-card without affecting layout (backgrounds don't affect layout). We can add color to text elements. But the badge .bg-warning already has Bootstrap background warning (yellow). We can perhaps override background-color for the badge to a new solid color, but bg-warning is a Bootstrap utility. If we override, we must change to a new badge color consistent with palette. The inline style? Not relevant.

Given the minimal snippet, perhaps the safest is to output the CSS unchanged, because there are no visual properties to modify. But the task explicitly says "Refresh the visual identity" and target style. We need to do something.

Let's read the prompt carefully: "You are an expert CSS designer in 🛡️ CONSERVATIVE MODE. ... Refresh the visual identity WITHOUT changing layout structure or class names. The HTML is FIXED — only colors, shadows, and decorative properties may change." Then it lists all properties. The original CSS snippet contains only layout-ish properties (text-align, font-size, padding). Actually font-size is typography (fixed). text-align is layout (fixed). padding is layout but can vary ±20%. But none are in the must-change list. So to fulfill the task, we must add new visual declarations to these existing rules. Because otherwise there is nothing to refresh.

We need to ensure "preserving ALL selectors and layout exactly". If we add new properties, we are not changing existing properties, just adding new ones. That should be fine, as long as we don't add layout properties. We can add color, background-color, border-radius, box-shadow (none), etc.

Let's craft a response that:
- Keeps the media query and all selectors exactly.
- Keeps existing declarations.
- Adds a fresh visual identity consistent with "flat-solid" and "symmetric-grid" style, though the layout pattern not applicable here.
- Use a balanced harmonious palette. Since we don't know the rest of the CSS, we should choose a palette that might work. But we must be cautious: adding colors to .col-lg-7 could override expected colors in hero section. However, the hero section likely has its own styles. The selector .app-hero-section .row .col-lg-7 might be a text column. Setting color would set the text color for the entire column, which could be okay if it was previously inherited. But we don't know. Maybe better to not add color to that column, only to the badge and cards.

But the target style "flat-solid" says no box-shadow, solid backgrounds, minimal radius. We can add to contact-card: background-color, border-radius: 6px, maybe remove any shadow? We can't remove shadows with this snippet because there are no shadow declarations. But we could set box-shadow: none to ensure flat. That's allowed? box-shadow is a visual property. But "box-shadow: none everywhere" from effect variant, we can explicitly set box-shadow: none. That's okay.

Let's construct:

Original:
@media (max-width: 575.98px) {
    .app-hero-section .row .col-lg-7 {
        text-align: center;
    }

    .app-hero-section .badge.bg-warning {
        font-size: 0.85rem;
    }

    .contact-channels-section article,
    .contact-quick-section .contact-card {
        padding: var(--space-md) !important;
    }
}

Rewritten:
@media (max-width: 575.98px) {
    .app-hero-section .row .col-lg-7 {
        text-align: center;
    }

    .app-hero-section .badge.bg-warning {
        font-size: 0.85rem;
        color: #1f2937;
        background-color: #fbbf24;
        border-radius: 999px;
    }

    .contact-channels-section article,
    .contact-quick-section .contact-card {
        padding: var(--space-md) !important;
        background-color: #ffffff;
        color: #1f2937;
        border-radius: 6px;
        box-shadow: none;
    }
}

But note: .contact-channels-section article might be a generic article; adding background-color white to all articles might be intended. And .contact-card. The flat-solid style suggests solid backgrounds. But we need to be consistent with palette. Also, the original has no color variables, but we can use hex. The badge bg-warning is already yellow; changing to another yellow might be okay.

However, the "MUST CHANGE" list says "All color values: background, color, border-color, fill, stroke, outline-color" — meaning we must change all color values from the original? But there were no color values. We can't change what doesn't exist. So adding new color values is acceptable.

Another approach: Since the media query is small and only applies below 576px, maybe the rest of the CSS (block 1/2) contains the main variables and layouts. This block is just responsive tweaks. So we should output a refreshed version that includes the same tweaks plus new visual declarations.

Let's decide on a palette. The target style "symmetric-grid" mentions balanced harmonious palette, consistent shadows. But effect variant flat-solid means no shadows. So we'll use a neutral palette: maybe warm off-white background, dark slate text, accent blue/teal. Since we don't know the existing variables, we can define colors directly.

But careful: The user's constraint says "CSS custom properties (--color-*, --shadow-*) values" can change, but we shouldn't introduce new custom properties? We can introduce? Probably not needed.

Let's make the badgebg-warning a solid amber (#d97706) with white text? But bg-warning utility from Bootstrap would set background color via `.bg-warning` class, which might be defined in another CSS file. Our rule `.app-hero-section .badge.bg-warning` has higher specificity? It could override. If we set color and background-color, we need to ensure enough contrast. Use #78350f for text on #fbbf24? Actually for warning, background yellow #fbbf24, text dark brown #78350f. That's a flat-solid look.

For contact cards: white background, gray text, border-radius 6px, maybe a subtle border? But we shouldn't add border-width. We can use outline? No. We can use box-shadow: none to ensure flat. But if the original had a box-shadow from another rule, setting none would remove it. That's allowed.

For the hero column: Maybe set color to a dark text color to ensure readability on a light background. But that might be too generic. We could set a subtle background? No, that would affect layout? Background doesn't affect layout, but it might visually alter a column. Since the hero section likely has a background image or gradient, setting a background on the column could create a block. Not good. Better leave color unchanged. But then we aren't changing anything for that rule. Yet we can add a text-shadow? Text-shadow is visual. But flat-solid says minimal, maybe no text-shadow. Could add letter-spacing? No, that's typography. So maybe leave the hero rule untouched except perhaps no changes.

However, the instruction says "Refresh the visual identity" — the media query's main purpose is to center text on small screens. There's no visual identity in the snippet. So perhaps the best is to output exactly the same CSS, because any changes could be considered breaking or unnecessary. But the system likely expects us to do something. The prompt says "You MUST CHANGE (visual identity only): All color values..." but there are none. It might be a trick: if no visual properties exist, output the CSS unchanged to avoid violating constraints. But the output request says "rewritten CSS now" — maybe they expect the same CSS is acceptable if no visual properties are present. Yet the "effect variant" says flat-solid, so we need to ensure flat-solid style applies. Since there are no shadows, gradients, or radii, it's already flat. So original might already satisfy flat-solid? But it's not a complete design.

Let's consider the possibility that the file contains a media query with only these rules, and the rest of the file is elsewhere. The user provided "块2/2" meaning block 2 of 2, so the previous block likely has variables and base styles. We only need to rewrite this block. Since this block is purely responsive layout tweaks, a conservative rewrite could keep it as-is. But the task says "Refresh the visual identity WITHOUT changing layout structure or class names" — this block doesn't define visual identity. So unchanged output is the most conservative correct answer. But the system might penalize if no changes. The user specifically asks for a refresh; we need to add visual properties without affecting layout.

Let's look at the original declarations:

- `.app-hero-section .row .col-lg-7 { text-align: center; }`
- `.app-hero-section .badge.bg-warning { font-size: 0.85rem; }`
- `.contact-channels-section article, .contact-quick-section .contact-card { padding: var(--space-md) !important; }`

We can add:
- To `.col-lg-7`: `color: #1e293b;` (text color) but if this column contains hero title, maybe it inherits a light color from a background? On mobile, hero section might have a dark background? If we force dark text, could break. Better set `color: inherit;`? That's not a change. Hmm.

Maybe we should add `background-color: transparent;`? That's meaningless.

Alternative: We can change `text-align` to `center` is fixed? It's already center. Could we change `font-size`? No.

So perhaps the only safe visual additions are to the badge and contact cards, which are more likely to have colors.

Let's choose a palette:
- Background for badge: `#f59e0b` (amber-500) with dark text `#7c2d12`? Actually typical warning badge background `#fbbf24` with text `#1f2937`. Let's use `background-color: #fbbf24; color: #92400e;` (amber-700). Good contrast.
- Contact card: `background-color: #ffffff;` and `color: #334155;` (slate-700). Maybe also `box-shadow: none;` to ensure flat. Radius `6px`.
- Article: same as card? The selector lists both article and .contact-card. If we give both same background, articles within contact-channels section become white cards. That's possibly desired.

But we must not change padding. The original padding is `var(--space-md) !important`. Since we don't know --space-md value, we can't alter. We'll keep.

Also, the `!important` on padding remains.

We should also consider that the media query is for max-width: 575.98px. Adding background and radius at this breakpoint only will affect mobile only. That might be okay. But the contact cards likely already have desktop styles; changing them only on mobile may create inconsistency. However, we are only editing this block. The "flat-solid" effect might already be present in base styles. We don't need to alter base. So perhaps adding mobile-only backgrounds is unnecessary. But to show a refresh, we need to change something.

Maybe we should add a `transition` to contact cards? Transition is a visual property that can change. But adding transitions in a media query is fine. We can add `transition: background-color