/* ============================================================
   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;
    }
}

The user wants me to rewrite the CSS in "assets/css/saishi.css#块2/2" (block 2/2) with a conservative mode, visual changes only. Let me analyze the input CSS:

```css
@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;
    }
}
```

This is a small media query block. The instructions say:
- Keep all selectors and layout exactly as-is
- Only change colors, shadows, radius, transitions, gradients
- Keep typography (font-size, font-weight) unchanged
- Keep padding/margin within ±20%

Wait, let me check what can be changed:
- text-align is in the "never change" list? Let me check... The instructions say:
  - text-align, vertical-align are in the NEVER change list (layout/layout-related typography)

So `text-align: center;` must stay the same.

- `font-size: 0.85rem;` — font-size is in the NEVER change list (typography fixed). So must stay.

- `padding: var(--space-md) !important;` — padding can change within ±20% but I should keep it similar. Actually the instruction says "padding, margin (keep similar values, ±20% maximum)". So I could adjust padding slightly. But since it's `var(--space-md)`, I could potentially keep it or change it slightly. However, changing `var(--space-md)` to some other value might be risky. Actually, since it's a CSS variable reference, I could keep the variable but maybe the variable value is defined elsewhere. Hmm.

The task: "Refresh this CSS visually. Keep ALL selectors and layout exactly as-is. Only change colors, shadows, radius, transitions, gradients."

In this small block, there are no colors, shadows, radius, transitions, or gradients explicitly. But I can add decorative properties without breaking layout. However, I must keep all existing properties? Actually the instruction says "Only change colors, shadows, radius, transitions, gradients" — but there are none to change here.

Wait, maybe I should add some decorative properties to meet the target style? The target style is "masonry-flow" with "gradient-rich" effects. But the selectors are about hero section, badge, contact cards.

Let me think about what I can do:

1. `.app-hero-section .row .col-lg-7` — text-align: center must stay. I could add color, background, etc.? But adding background to a column might change layout... Actually adding background doesn't change layout structure per se. But it might be visually disruptive. The instruction says "Only change colors, shadows, radius, transitions, gradients" — so adding these properties is allowed.

2. `.app-hero-section .badge.bg-warning` — font-size stays. I can change background gradient, add box-shadow, border-radius, transition.

3. `.contact-channels-section article, .contact-quick-section .contact-card` — padding stays (var(--space-md) !important). I can add background gradients, border-radius, box-shadow, transitions.

Given the "gradient-rich" variant, I should use linear-gradient/radial-gradient on most backgrounds, gradient borders via border-image, multiple stops, smooth long transitions (0.4-0.6s cubic-bezier).

Also "masonry-flow" target style suggests Pinterest-like: white cards, soft shadows on light gray bg, each card may have its own accent strip.

Let me write a rewrite that preserves all selectors and existing properties, but adds/changes visual properties.

Since the original block has no colors, I'll add some. But wait — should I be careful about adding properties that could affect layout? background, color, box-shadow, border-radius, transition, border-image don't affect layout (border-image doesn't affect layout, border-radius doesn't, box-shadow doesn't). color doesn't affect layout. So it's safe.

Let me construct the rewritten CSS:

```css
@media (max-width: 575.98px) {
    .app-hero-section .row .col-lg-7 {
        text-align: center;
        background: linear-gradient(135deg, rgba(255, 255, 255, 0.08) 0%, rgba(255, 255, 255, 0) 40%, rgba(255, 255, 255, 0.04) 100%);
        border-radius: 1.25rem;
    }

    .app-hero-section .badge.bg-warning {
        font-size: 0.85rem;
        background: linear-gradient(120deg, #f6d365 0%, #fda085 50%, #f6d365 100%);
        box-shadow: 0 0.375rem 0.875rem -0.25rem rgba(253, 160, 133, 0.55), 0 0.125rem 0.25rem rgba(246, 211, 101, 0.35);
        border-radius: 999px;
        transition: transform 0.5s cubic-bezier(0.22, 1, 0.36, 1), box-shadow 0.5s cubic-bezier(0.22, 1, 0.36, 1);
    }

    .app-hero-section .badge.bg-warning:hover {
        transform: translateY(-2px);
        box-shadow: 0 0.5rem 1.25rem -0.25rem rgba(253, 160, 133, 0.7), 0 0.25rem 0.375rem rgba(246, 211, 101, 0.45);
    }

    .contact-channels-section article,
    .contact-quick-section .contact-card {
        padding: var(--space-md) !important;
        background: linear-gradient(145deg, #ffffff 0%, #f8fafc 55%, #eef2f7 100%);
        border: 1px solid transparent;
        border-image: linear-gradient(135deg, rgba(255, 255, 255, 0.9), rgba(203, 213, 225, 0.6)) 1;
        border-radius: 1rem;
        box-shadow: 0 0.25rem 0.75rem -0.375rem rgba(15, 23, 42, 0.12), 0 0.125rem 0.25rem rgba(15, 23, 42, 0.06);
        transition: box-shadow 0.5s cubic-bezier(0.22, 1, 0.36, 1), border-color 0.5s cubic-bezier(0.22, 1, 0.36, 1);
    }

    .contact-channels-section article:hover,
    .contact-quick-section .contact-card:hover {
        box-shadow: 0 0.75rem 1.75rem -0.5rem rgba(15, 23, 42, 0.18), 0 0.25rem 0.5rem rgba(15, 23, 42, 0.08);
        border-image: linear-gradient(135deg, #f6d365, #fda085) 1;
    }
}
```

Wait — I need to be careful about a few things:

1. `border-image` with `border: 1px solid transparent` — border-width stays the same (it's not changing border-width, just border-color). But adding a border where there was none might be considered a layout change? Border-width wasn't specified in the original, so default is 0. If I add `border: 1px solid transparent`, I'm changing border-width from 0 to 1px, which could affect layout. The instructions say "border-color and border-style (NOT border-width)" can change. So I should NOT change border-width. If the original had no border, I shouldn't add one with width. But `border-image` doesn't work without border-width/ border-style. Hmm.

Let me reconsider: the instruction says border-color and border-style can change, NOT border-width. If original has no border, adding border-width is a layout change? It could slightly affect the box size. To be safe, I should avoid adding borders where none existed. Or use `outline` instead? Outline can be changed (outline styles). Adding an outline doesn't affect layout. Actually outline can change — "outline styles (color, type)" can change. Adding outline-width... well, outline is generally not part of layout. But to be safe, I'll avoid adding borders.

Alternatively, I can use `background` gradients, `box-shadow` (which doesn't affect layout), `border-radius` (which doesn't affect layout), and `transition`.

For "gradient borders via border-image" — I could skip that since border-width must not change. Actually, I could use a background gradient with padding trick, but that requires changing background-clip and padding... no, padding is fixed.

Let me keep it simple and safe: no new border. Use box-shadow for depth, background gradients for richness.

2. Adding a `:hover` pseudo-class — the instructions say pseudo-classes must be kept exactly. "Pseudo-classes (:hover, :focus, ::before, ::after)" are in the NEVER change list, meaning I should keep them as they are. If the original doesn't have a `:hover`, adding one might be "changing selectors." The rules: "Selectors: keep EXACTLY" — adding new selectors would violate. So I should NOT add new `:hover` rules.

So I cannot add a `:hover` rule. I'll only modify existing rules and add visual properties within them.

3. For `.app-hero-section .row .col-lg-7`, adding a background might be odd but allowed. Let me add a subtle gradient and maybe border-radius. But careful: this is a column layout; adding background to it might be visually fine.

Actually, adding these visual flourishes makes sense given the task wants a visual refresh. The target style is "masonry-flow" and "gradient-rich." Let me apply gradient backgrounds and shadows to the selectors.

Let me also consider: the instructions say "transition timing, easing, duration" can change. So adding transitions is fine.

Let me also check "text-shadow" — can change. I could add text-shadow to the badge or headings, but the selectors don't include headings.

Let me finalize:

```css
@media (max-width: 575.98px) {
    .app-hero-section .row .col-lg-7 {
        text-align: center;
        background: radial-gradient(circle at 50% 0%, rgba(255, 255, 255, 0.12) 0%, rgba(255, 255, 255, 0) 60%);
        border-radius: 1.5rem;
        box-shadow: inset 0 0 0 rgba(255, 255, 255, 0.4);
    }

    .app-hero-section .badge.bg-warning {
        font-size: 0.85rem;
        background: linear-gradient(120deg, #f6d365 0%, #fda085 45%, #f6a08c 55%, #f6d365 100%);
        background-size: 200% 100%;
        box-shadow: 0 0.375rem 1rem -0.375rem rgba(253, 160, 133, 0.6), 0 0.125rem 0.25rem rgba(246, 211, 101, 0.4);
        border-radius: 999px;
        transition: background-position 0.6s cubic-bezier(0.22, 1, 0.36, 1), box-shadow 0.6s cubic-bezier(0.22, 1, 0.36, 1);
    }

    .contact-channels-section article,
    .contact-quick-section .contact-card {
        padding: var(--space-md) !important;
        background: linear-gradient(145deg, #ffffff 0%, #f8fafc 50%, #eef2f7 100%);
        border-radius: 1.125rem;
        box-shadow: 0 0.25rem 0.875rem -0.375rem rgba(15, 23, 42, 0.1), 0 0.125rem 0.375rem rgba(15, 23, 42, 0.06);
        transition: box-shadow 0.55s cubic-bezier(0.22, 1, 0.36, 1), transform 0.55s cubic-bezier(0.22, 1, 0.36, 1), background 0.55s cubic-bezier(0.22, 1, 0.36, 1);
    }
}
```

Wait, transitioning transform without a hover state won't do anything, but it's harmless. Actually, if there is already a hover rule elsewhere in the file (outside this block), the transition on the base rule will apply. That's fine — I'm allowed to change transition timing/duration.

Now, let me double-check the constraints:

- Selectors: preserved exactly — yes.
- `text-align: center` — kept as-is (layout/typography fixed). Yes.
- `font-size: 0.85rem` — kept as-is. Yes.
- `padding: var(--space-md) !important` — kept as-is. Yes.
- I'm adding `background`, `box-shadow`, `border-radius`, `transition`, `background-size`. These are visual properties. None affect layout.
- No new selectors, no new pseudo-classes. Good.

Let me also consider whether `background-size` is okay — it's a decorative property affecting gradients. Fine.

Actually, for the badge, the original likely had `background-color: #ffc107` (bootstrap warning). Using `background` shorthand with a gradient will override the background-color. That's a visual change, allowed.

One concern: `.badge.bg-warning` — Bootstrap's `.bg-warning` sets `background-color`. Using `background: linear-gradient(...)` sets background-image and background-color (to transparent by default if not specified). The gradient will render. Good.

For the contact cards, adding a background gradient might override existing background-color. That's a visual change, allowed.

Let me also consider using `backdrop-filter` — allowed but might be heavy. Not needed.

Let me make the gradient-rich variant more pronounced. Also the masonry-flow style wants "white cards, soft shadows on light gray bg." So for contact cards, I'll use white-to-light-gray gradient with soft shadows.

I'll keep the final output minimal and exactly matching the requested format — no markdown fences, no comments.

Let me also think about whether I should add `accent-color` or `caret-color` — not applicable to these selectors.

Let me write the final answer:

```css
@media (max-width: 575.98px) {
    .app-hero-section .row .col-lg-7 {
        text-align: center;
        background: radial-gradient(ellipse at 50% 20%, rgba(255, 255, 255, 0.14) 0%, rgba(255, 255, 255, 0) 65%);
        border-radius: 1.5rem;
        box-shadow: inset 0 0 2rem rgba(255, 255, 255, 0.06);
    }

    .app-hero-section .badge.bg-warning {
        font-size: 0.85rem;
        background: linear-gradient(120deg, #f6d365 0%, #fda085 40%, #f7b733 60%, #f6d365 100%);
        background-size: 180% 100%;
        box-shadow: 0 0.375rem 1rem -0.375rem rgba(253, 160, 133, 0.55), 0 0.125rem 0.375rem rgba(247, 183, 51, 0.35);
        border-radius: 999px;
        transition: background-position 0.5s cubic-bezier(0.22, 1, 0.36, 1), box-shadow 0.5s cubic-bezier(0.22, 1, 0.36, 1);
    }

    .contact-channels-section article,
    .contact-quick-section .contact-card {
        padding: var(--space-md) !important;
        background: linear-gradient(150deg, #ffffff 0%, #f8fafc 48%, #eef2f7 100%);
        border-radius: 1.125rem;
        box-shadow: 0 0.25rem 0.875rem -0.375rem rgba(15, 23, 42, 0.1), 0 0.125rem 0.375rem rgba(15, 23, 42, 0.05), 0 0 0 0.0625rem rgba(255, 255, 255, 0.7) inset;
        transition: box-shadow 0.55s cubic-bezier(0.22, 1, 0.36, 1), background 0.55s cubic-bezier(0.22, 1, 0.36, 1);
    }
}
```

Hmm, the inset box-shadow with a spread of 0.0625rem — box-shadow can be changed freely, doesn't affect layout. That's fine.

Let me verify the self-check:
- Every selector character-for-character preserved? Yes.
- display, position, grid-template-*, flex-direction unchanged? They weren't present. Yes.
- width, height, padding, margin within ±20%? padding var(--space-md) unchanged. Yes.
- font-family, font-size, font-weight, line-height unchanged? font-size 0.85rem unchanged. Yes.
- Colors throughout replaced