/* ============================================================
   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 CSS while keeping selectors and layout exactly, but changing visual properties like colors, shadows, radius, transitions, gradients. The file is a small media query block.

Let me analyze the original 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;
    }
}
```

Constraints:
- Selectors must remain exactly the same: `@media (max-width: 575.98px)`, `.app-hero-section .row .col-lg-7`, `.app-hero-section .badge.bg-warning`, `.contact-channels-section article`, `.contact-quick-section .contact-card`.
- Layout properties: `text-align: center` cannot change (it's a layout/typography property? Actually text-align is listed under layout: "text-align, vertical-align" — cannot change). So keep `text-align: center`.
- `font-size: 0.85rem` — typography, cannot change. Keep.
- `padding: var(--space-md) !important` — padding is layout, keep similar values ±20%. The padding uses a CSS variable `--space-md`. I can change the value of `--space-md`? The instructions say "CSS custom properties (--color-*, --shadow-*) values" can change — but `--space-md` is a spacing custom property. Changing it would affect layout more than 20% potentially. However, the padding value itself references a var. Strictly, I should keep padding as-is or within ±20%. Since it's `var(--space-md)`, I should keep it exactly. Actually, I'm allowed to change colors, shadows, radius, transitions, gradients, opacity, outline, caret-color, accent-color, CSS custom properties values (--color-*, --shadow-*). But `--space-md` is a spacing variable, not in the allowed list. So I should keep `padding: var(--space-md) !important`.

Hmm, but the task says "Refresh this CSS visually." The original has very little visual styling — no colors, shadows, etc. The only visual things I could add are colors, shadows, radius, transitions, etc. But I cannot add new selectors or change layout.

Wait — can I add new declarations inside existing rules? The instructions say I must change colors, shadows, etc. But also "ONLY the rewritten CSS, preserving ALL selectors and layout exactly." Adding new visual properties like `background`, `border-radius`, `box-shadow` to existing rules would change the visual identity without breaking layout. The rule list says I MUST change all color values, shadows, etc. — but the original has none. The task says "Refresh this CSS visually." So I should add visual properties that fit the target style "centered-stage" and variant "tight-rhythm".

But careful: the variant "tight-rhythm" says small border-radius (2-6px), subtle shadows or none, compact spacing. The target style says dark stage background #0f0f1a, premium gold or deep purple accent.

However, I must not change layout. Adding `background-color`, `border-radius`, `box-shadow`, `transition`, `color` are all visual changes allowed. Adding `padding` would be layout — avoid. Adding `text-align` — already there.

Also note: adding `background` to `.app-hero-section .row .col-lg-7` could affect layout? No, background doesn't affect layout. Border-radius doesn't affect layout unless border is added (border-width changes layout). I should avoid adding border-width. Adding `box-shadow` doesn't affect layout. Adding `color` doesn't affect layout. Adding `transition` doesn't affect layout.

But wait — there might be a concern: the media query is for max-width 575.98px (small screens). Adding visual flair there is fine.

Also, I could add declarations to the `@media` block as new rules? No — I must preserve selectors exactly. I can only add declarations inside existing rules.

Let me think about what visual changes to make for each rule:

1. `.app-hero-section .row .col-lg-7 { text-align: center; }`
   - Keep text-align: center. Add visual properties: maybe `color` for text, `background` radial-gradient? But this is a column that wraps hero content. Adding a background to a column could look odd but it's allowed visually.
   - Given "centered-stage" spotlight feel: dark stage background, bright content area. But the media query is mobile. Hmm.
   - For the hero column, I could add `background: radial-gradient(...)`, `border-radius: 6px`, `box-shadow: ...`, `color: #...`, `transition: ...`. But careful not to break layout — background and shadow don't change layout dimensions (box-shadow doesn't affect layout). Border-radius doesn't affect layout.
   - Actually, adding background to a text column may not be desirable, but the task is to refresh visual identity. It's fine.

2. `.app-hero-section .badge.bg-warning { font-size: 0.85rem; }`
   - Badge uses `bg-warning` Bootstrap class. We can add `background-color` to override? But `.bg-warning` is a Bootstrap utility with `background-color: #ffc107 !important`. Our rule has `font-size: 0.85rem` only. If I add `background-color`, it would need to compete with Bootstrap's `!important`. Since Bootstrap `.bg-warning` has `!important`, my added `background-color` without `!important` would lose. I could add `background: linear-gradient(...)` — also an author stylesheet without `!important` would lose to Bootstrap's `!important`? Actually CSS specificity: `.bg-warning` has one class; `.app-hero-section .badge.bg-warning` has three classes, so higher specificity. But Bootstrap also often ships with `!important`. In Bootstrap 5, `.bg-warning { background-color: #ffc107 !important; }`. So to override, I'd need `!important`. I can add `background-color: ... !important;`? The instruction says keep layout exactly; adding `!important` is fine. But I "must change all color values" — there are none in original. I can add.
   - Since original only has `font-size`, I'll add `background-color` with gradient and `!important`, plus `border-radius`, `box-shadow`, `color`, `transition`. Wait, `background` with gradient: `background: linear-gradient(...) !important;` would override `background-color` too. That's fine.
   - Also keep font-size: 0.85rem.

3. `.contact-channels-section article, .contact-quick-section .contact-card { padding: var(--space-md) !important; }`
   - Keep padding exactly. Add `background`, `border-radius`, `box-shadow`, `transition`, `color`? Careful: `.contact-quick-section .contact-card` might already have background from other CSS; adding new declarations in this media query will apply on mobile. That's fine.
   - But adding `background` to `article` and `.contact-card` could be a nice card refresh. Add `border-radius: 6px`, `box-shadow: 0 2px 8px rgba(...)`, `transition: ...`.
   - However, the variant "tight-rhythm" says "Subtle shadows or none" and "Small border-radius (2-6px)". So use radius 6px and subtle shadow.

Now palette: "Premium gold or deep purple accent" on "dark stage #0f0f1a". Since mobile, the body background is probably already set elsewhere. We can add accent colors: gold `#f5c542` or deep purple `#7b2ff7`. Let's use gold accent with dark purple tinted backgrounds.

Let me craft the new CSS:

```css
@media (max-width: 575.98px) {
    .app-hero-section .row .col-lg-7 {
        text-align: center;
        color: #f5f0ff;
        background: radial-gradient(ellipse at top, rgba(123, 47, 247, 0.18), transparent 60%);
        border-radius: 6px;
        box-shadow: 0 4px 24px rgba(15, 15, 26, 0.45), inset 0 1px 0 rgba(255, 255, 255, 0.06);
        transition: background 0.3s ease, box-shadow 0.3s ease;
    }

    .app-hero-section .badge.bg-warning {
        font-size: 0.85rem;
        background: linear-gradient(135deg, #ffd966, #f0b429) !important;
        color: #2a1a00 !important;
        border-radius: 4px;
        box-shadow: 0 2px 8px rgba(240, 180, 41, 0.35);
        transition: box-shadow 0.25s ease, transform 0.25s ease;
    }

    .contact-channels-section article,
    .contact-quick-section .contact-card {
        padding: var(--space-md) !important;
        background: linear-gradient(145deg, rgba(123, 47, 247, 0.12), rgba(255, 255, 255, 0.02));
        border-radius: 6px;
        box-shadow: 0 2px 12px rgba(15, 15, 26, 0.35), inset 0 1px 0 rgba(255, 255, 255, 0.04);
        transition: background 0.3s ease, box-shadow 0.3s ease;
    }
}
```

Wait — transition on `transform` but we don't change transform. Adding transition on transform is fine visually but the actual transform is not applied; it's harmless. But maybe better to keep transitions to properties we set.

Also, is adding `color` to `.app-hero-section .row .col-lg-7` okay? It's a visual property. It changes text color — allowed. But it might override existing text colors in the hero section, potentially harming readability if some elements already have their own colors. Since it's a mobile media query, it should be fine and fits the "bright content area" spot.

Hmm, but there's a risk: `.col-lg-7` contains the hero text, and adding a background radial-gradient to the column will create a tinted box. On mobile, columns are full width. A subtle radial gradient is fine.

Actually, let me reconsider. The target style "centered-stage" is aggressive-only guidance; the mode is conservative. The variant "tight-rhythm" applies. The instruction says "Refresh this CSS visually. Keep ALL selectors and layout exactly as-is. Only change colors, shadows, radius, transitions, gradients." Given the original has no colors/shadows/radius/transitions/gradients, the only way to refresh is to ADD these properties. That's within the spirit.

But I must be careful about one thing: adding `box-shadow` to `.app-hero-section .row .col-lg-7` — box-shadow doesn't affect layout. Fine.

I should also consider whether I could redefine CSS custom properties. The original CSS doesn't define any custom properties. The padding uses `var(--space-md)`. I could add a declaration like `--space-md: 16px;`? That would change padding values. But the instruction says custom properties values can change only for `--color-*` and `--shadow-*`. So I shouldn't touch `--space-md`. Also changing it could affect layout beyond 20%. Keep padding as-is.

Let me double-check the "must change" list: "All color values: background, color, border-color, fill, stroke, outline-color" — the original has no color values. So there are none to change. "box-shadow (offsets, blur, spread, color — fully redesign with multi-layer effects)" — none exists. "text-shadow" — none. "border-radius" — none. So I'm adding new ones, which is fine.

Also I should preserve the exact selectors and the media query condition. I'm not changing any layout properties. `font-size` stays. `text-align` stays. `padding` stays.

One concern: In the original, `.app-hero-section .row .col-lg-7 { text-align: center; }` — if I add `background` with a gradient, it might alter the visual in a way that looks like a card, which could be a big change. But "visual identity refresh" wants that. The variant "tight-rhythm" says subtle shadows or none. I'll keep shadows subtle.

Let me refine the colors. Palette:
- Dark stage: #0f0f1a
- Deep purple accent: #6d28d9 / #7c3aed
- Gold accent: #f5c542, #fbbf24
- Bright content: #fdf8ff / #f5f0ff

For the hero column: use a very subtle dark stage background to create spotlight contrast: `background: radial-gradient(circle at 50% 0%, rgba(124, 58, 237, 0.25), transparent 65%);` and `color: #f5f0ff`. Maybe `border-radius: 6px` (tight-rhythm 2-6px).

For the badge: override bg-warning gold with premium gold gradient: `background: linear-gradient(135deg, #fcd34d, #f59e0b) !important;` and text dark `#1a1205 !important`. In Bootstrap, `.badge` has `color: #fff` and `background-color`. So I need `color: #2a1a00 !important;` to override. Also `border-radius: 4px` (Bootstrap badge already has 0.375rem radius; 4px is about 0.25rem, fits 2-6px). Add subtle shadow.

For contact cards: subtle purple-tinted gradient background, radius 6px, soft shadow. Keep `padding: var(--space-md) !important`.

Now transitions: The variant "tight-rhythm" has compact feel; transitions should be quick: `0.2s ease`. Use `0.2s` or `0.25s`.

Also I might add `-webkit-backdrop-filter`? Not needed.

Let me ensure no layout-affecting properties sneak in: `background`, `color`, `border-radius`, `box-shadow`, `transition` — all visual. Good.

One more thought: `box-shadow` on `.col-lg-7` might be too much on a full-width column. Maybe keep it subtle or omit. The variant says "Subtle shadows or none." I'll include a very subtle inset highlight rather than a big drop shadow. Actually a drop shadow on a column that has no background would be invisible; with a radial-gradient background, it may show slightly. But the column may not have a solid background, so a drop shadow wouldn't render visibly. It's safer to use inset highlight. Hmm, but the instruction says "box-shadow ... fully redesign with multi-layer effects" — I should add multi-layer shadows. So I'll add both outer and inset.

Let me write final CSS. Also no markdown fences, no preamble, no comments.

Final:

```css
@media (max-width: 575.98px) {
    .app-hero-section .row .col-lg-7 {
        text-align: center;
        color: #f5f0ff;
        background: radial-gradient(circle at 50% 0%, rgba(124, 58, 237, 0.22), transparent 68%);
        border-radius: 6px;
        box-shadow: 0 2px 16px rgba(15, 15, 26, 0.35), inset 0 1px 0 rgba(255, 255, 255, 0.06);
        transition: background 0.2s ease, box-shadow 0.2s ease, color 0.2s ease;
    }

    .app-hero-section .badge.bg-warning {
        font-size: 0.85rem;
        background: linear-gradient(135deg, #fcd34d, #f59e0b) !important;
        color: #2a1a00 !important;
        border-radius: 4px;
        box-shadow: 0 2px 8px rgba(245, 158, 11, 0.35), inset 0 1px 0 rgba(255, 255, 255, 0.25);
        transition: box-shadow 0.2s ease, background 0.2s ease;
    }

    .contact-channels-section article,
    .contact-quick-section .contact-card {
        padding: var(--space-md) !important;
        background: linear-gradient(145deg, rgba(124, 58, 237, 0.14), rgba(255, 255, 255, 0.02));
        border-radius: 6px;
        box-shadow: 0 2px 12px rgba(15, 15, 26, 0.3), inset 0 1px 0 rgba(255, 255, 255, 0.05);
        transition: background 0.2s ease, box-shadow 0.2s ease;
    }
}
```

Wait — I added `color` to the hero column. Is `color` a "color value" I'm allowed to change? Yes: "All color values: background, color, border-color, fill, stroke, outline-color". Adding color is fine.

But hold on: The original `.app-hero-section .badge.bg-warning` — Bootstrap's `.bg-warning` sets `background-color` with `!important`. My gradient with `!important` will override. Good. Also `.badge` in Bootstrap 5 has `color: #fff` (non-important?). Actually in Bootstrap 5, `.badge` doesn't set color by default unless using