We need respond with rewritten CSS. Need follow instructions. Need output only CSS no markdown. Need preserve selectors and layout, no layout changes. Need change colors/shadows/radius/transitions/gradients maybe. Need target centered-stage with dark stage #0f0f1a, bright content, premium gold/deep purple. Need airy-rhythm generous spacing? But spacing constrained ±20%, cannot huge padding changes except variables changed? Wait instructions say keep padding/margin similar ±20% max. But target style says aggressive only? Actually output mode conservative. Need visual identity only. But given original CSS variables --space-section: 4rem etc. Could adjust slightly maybe within ±20? 4rem -> 3.5rem? But target airy "generous spacing" maybe padding top/bottom 60-100px. Original 4rem=64px. Could change to 5rem? That's +25%, outside. Max 20% so 4.8rem max. Use 4.5rem maybe. --space-card 1.5rem -> 1.75rem? +16.7% ok. --space-gap 1.25rem -> 1.5rem? +20% okay. Need maintain media query override maybe 2rem -> 2.25rem? +12.5, 1rem -> 1.125? hmm. But need maybe keep. Need change colors all. Need preserve exact selectors and structure. Need change border-radius large (16-28px). Need shadow soft pillowy. Need palette dark stage #0f0f1a, bright content, gold/purple. Should selectors same. Need ensure not alter case. Need perhaps change section position? Cannot change layout. "Page Layout: wide" max-width 1400; target centered max width 720-960 but original max-width 1400. Cannot change max-width? It's layout property under width/max-width. Must not change. So leave. But perhaps visual centered? Actually "Target style centered-stage" but conservative constraints says don't change max-width. Need keep .page-main max-width 1400. Could maybe not? It says NEVER CHANGE width, max-width. preserve. So keep max-width 1400. Need maybe center. Already margin 0 auto. Fine. Need use accent. 

Need decide fresh palette. Original olives. Need replace. Original dark? Need dark stage #0f0f1a, bright content area. But background is transparent on header etc. We can set root colors. Need be careful with backgrounds. Variables: --color-primary, primary-dark, accent, surface, text. Need choose premium gold/deep purple with dark stage. Maybe:
--color-primary: #c9a24b (gold) or #a855f7? We need main links/primary. Since dark stage (deep purple/black) content bright. If surface is #f8f7ff, text #1f1b2e. Primary purple #7c3aed, preferred accent gold #eab308. But target premium gold or deep purple accent. Let's choose gold primary? Original primary is green (action). Need links. If dark stage, a link maybe #7c3aed? But gold accent for highlights. Let's craft:
--color-primary: #7c3aed; (deep purple)
--color-primary-dark: #4c1d95;
--color-accent: #d4a72c or #f5c542; (gold)
--color-surface: #faf9ff (bright content)
--color-text: #1e1b2e;
--rgb-primary: 124,58,237;
--rgb-accent: 212,167,44;
Need maybe dark background for body? body only color; no background specified. Could add? Cannot change selectors? We can add `background` to body? Selector body already exists; can add background property, since visual property allowed. Need maybe original has no body background. We can add background to body. But output must maybe set stage. Since body selector exists: `body { color: var(--color-text); line-height: var(--body-line-height); }` can add `background-color: var(--color-bg);` but new variable? Need define --color-bg: #0f0f1a in :root. That's okay. But careful visual: If body dark, cards/text maybe. Original cards no background property! It has box-shadow. Cards rely on background? Maybe global styles elsewhere. In original, .card has no background. So if body dark and surface not applied to card, text would be... Actually card subclass may have backgrounds from base CSS? The variant only overrides. If no background, dark body with dark text -> poor. Could set `.card, [class*="card"] { background: var(--color-surface); }` But is that allowed? It changes visual property, not layout. Need ensure all cards bright. However if card class has more specific backgrounds elsewhere? Variant takes precedence? It's linked maybe after. Could set background-color. But if cards are on dark stage, need bright content area. We can add background to body maybe. Need ensure `.btn` background? Original no background for button. Could set primary background? But maybe base CSS has. Could set background-color: var(--color-primary); color: #fff? Wait cannot set `color`? We can set color. `.btn, button[class*="btn"], a[class*="btn"]` original only border-radius and transition. We can add background and color? Visual allowed. But would this break? No layout. Need maybe not if buttons have existing background. But can refresh identity. Yet must be careful: `a[class*="btn"]` if anchor text maybe. Setting `color:#fff` okay. But if base button styles from base CSS override? This variant maybe after, so okay. Need perhaps not add too many properties. We can.

Need preserve comments? We can change comments? Comments okay. Need maybe write exact selectors. Need keep all layout declarations. Need adjust values for colors etc. Need use hex codes. For shadows: "soft pillowy", multi-layer. Need design unique from original. Original shadow has 0 2px 4px, 0 8 16, 0 20 40. Need redesign with different offsets/colors, e.g. `0 1px 2px rgba(15,15,26,.04), 0 8px 24px rgba(15,15,26,.08), 0 16px 48px rgba(124,58,237,.08)`. Need maybe use color. Need ensure names same? --shadow-sm/md/lg. Values can change. --radius.
Need transition change timing/easing. Original `--transition: 0.4s cubic-bezier(0.4, 0, 0.2, 1);` Need change maybe `0.3s cubic-bezier(0.22, 1, 0.36, 1)` (easeOutQuint) "airy". okay.
Need line-height/font-weight preserved? We cannot change line-height/letter spacing etc. Original `body { line-height: var(--body-line-height); }` `--body-line-height: 1.65;` listed typography fixed. Do not change font-size/weight/line-height. Need preserve variables? `--heading-weight: 700; --body-line-height: 1.65;` Keep same. Since font system fixed. Need not alter.
Need maybe keep `--space-section` etc within ±20. Original values: 4rem, 1.5rem, 1.25rem. We can change to 4.75rem? +18.75%, 1.75rem +16.67, 1.5 +20. And media override 2rem, 1rem, 0.75rem maybe change to 2.25rem +12.5, 1.125rem +12.5, 0.875rem +16.7. But original media perhaps "comfortable", airy. Need maybe set `--space-section: 4.5rem; --space-card: 1.75rem; --space-gap: 1.5rem;` Max +20. But "generous spacing (Aggressive: padding 32-56px, gap 32-48px)" For gap 1.5rem=24px, below 32. But conservative cannot change gap much? Actually gap is layout property, original allowed "gap similar ±20% max." So max 1.5rem. Could set --space-gap: 1.5rem exactly +20%. Fine. 32px would +60% not allowed. Need not fully aggressive. The prompt says "Target style (Aggressive only)" conflicting; but "other files already used" maybe from aggressive mode? Actually user asks conservative, in this interface maybe target style from a template but says "Layout pattern (Aggressive only)" in prompt. However our mode is conservative. Need respect allowed. The system says output refresh visual identity without changing layout, padding/margin similar ±20%. So use within. Good.

Need handle border-radius: --radius-sm 6px -> 10px, --radius-md 12px -> 18px, --radius-lg 16px -> 24px, --radius-xl 24px -> 32px? large 16-28? 32 maybe too high. Could use sm 10, md 18, lg 26, xl 32. Need "Large border-radius (16-28px)". Use lg 24, xl 32. For cards 26 maybe. But consistent. Maybe:
--radius-sm: 10px;
--radius-md: 18px;
--radius-lg: 24px;
--radius-xl: 32px;
Need perhaps --radius-lg used cards 24. Good.

Need maybe use `outline`? No outline currently. Could add? Not necessary.

Need revise comments? Could keep section comments maybe. Need ensure all selectors character-for-character. There are weird indentations for news-grid etc. We can preserve spacing? Doesn't matter. Need ensure selectors exact. Let's parse original:

:root { ... }

/* 基础覆盖 */
body { color: var(--color-text); line-height: var(--body-line-height); }
h1, h2, h3, h4 { font-weight: var(--heading-weight); }
section, .section { padding-top: var(--space-section); padding-bottom: var(--space-section); }
.card, [class*="card"] { border-radius: var(--radius-lg); box-shadow: var(--shadow-md); padding: var(--space-card); transition: var(--transition); }
.btn, button[class*="btn"], a[class*="btn"] { border-radius: var(--radius-md); transition: var(--transition); }
a:not([class]) { color: var(--color-primary); transition: var(--transition); }

/* ========== Section Layout Variants ========== */

/* news: featured-top */
/* 首篇横跨全宽 */
                .news-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--space-gap); }
                .news-grid > *:first-child { grid-column: span 3; }

/* features: grid-2 */
.feature-list { display: grid; grid-template-columns: repeat(2, 1fr); gap: calc(var(--space-gap) * 1.5); }

/* hero: overlay */
/* 全屏背景+文字覆盖 */
                .hero { position: relative; min-height: 70vh; display: flex; align-items: center; }
                .hero-content { position: relative; z-index: 1; }

/* testimonials: stacked */
/* 垂直堆叠 */
                .testimonial-list { display: flex; flex-direction: column; gap: var(--space-gap); max-width: 720px; margin: 0 auto; }

/* partners: grid-4 */
.partner-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: calc(var(--space-gap) * 1.5); align-items: center; }

/* faq: with-sidebar */
/* FAQ 左 + 联系信息右 */
                .faq-wrapper { display: grid; grid-template-columns: 2fr 1fr; gap: 2rem; }

/* stats: big-number */
/* 大数字居中 */
                .stats-grid { display: flex; flex-wrap: wrap; justify-content: center; gap: 2rem; }
                .stats-grid .stat-value { font-size: 3rem; }

/* cta: split */
.cta-inner { display: grid; grid-template-columns: 1fr auto; align-items: center; gap: 2rem; }

/* Page Layout: wide */
/* 超宽 */
            .page-main { max-width: 1400px; margin: 0 auto; }

/* 条件性装饰 */
a:not([class]):hover { color: var(--color-accent); }
.card { border: 1px solid rgba(var(--rgb-primary), .08); }
header, .header, .navbar { background: transparent; }

/* Responsive */
@media (max-width: 1024px) {
    .news-grid { grid-template-columns: repeat(2, 1fr) !important; }
    .feature-list { grid-template-columns: repeat(2, 1fr) !important; }
    .partner-grid { grid-template-columns: repeat(3, 1fr) !important; }
    .stats-grid { grid-template-columns: repeat(2, 1fr) !important; }
    .hero-inner { grid-template-columns: 1fr !important; }
}
@media (max-width: 640px) {
    :root { --space-section: 2rem; --space-card: 1rem; --space-gap: 0.75rem; }
    .news-grid { grid-template-columns: 1fr !important; }
    .feature-list { grid-template-columns: 1fr !important; }
    .faq-list { grid-template-columns: 1fr !important; }
    .testimonial-list { column-count: 1 !important; }
    .partner-grid { grid-template-columns: repeat(2, 1fr) !important; }
    .stats-grid { grid-template-columns: repeat(2, 1fr) !important; }
    .cta-inner { grid-template-columns: 1fr !important; }
}

Need perhaps maintain `column-count: 1` in media? Original has. Selector same.
Need maybe `gap: 2rem` in .faq-wrapper/stats/cta. Since fixed gap allowed similar ±20? 2rem could change to 2.25rem (+12.5). But these are gap layout property, allowed similar. But if we want airy, could set to 2.25rem. However gap uses fixed units not var. We can change to 2.25rem maybe. But target original gap maybe 32px; airy 32-48? 2.25rem=36. Good. In original 2rem = 32. Change to 2.25rem. But if "gap" allowed similar ±20, okay. Need `grid-template-columns` unchanged. `column-count`? It is layout? not in listed? Actually white-space? Could keep.
Need `.stats-grid .stat-value { font-size: 3rem; }` cannot change font-size. Keep.
Need maybe `min-height:70vh` keep. display. `.hero-content z-index` keep.
Need maybe `max-width: 720px` in testimonial-list keep.

Need maybe "Page Layout: wide" max-width 1400. Target "centered stage" maybe would want smaller but can't. Keep.

Need perhaps create new variable `--color-bg` and `--color-on-accent`? Need output maybe use in `body`, `.card`, `.btn`. Could define variables in root. That's allowed: update CSS custom properties values can include new variables? The instructions say "CSS custom properties (--color-*, --shadow-*) values" but not necessarily names; but HTML fixed. Adding custom properties is okay. Need maintain existing var names. Could add or replace. Better to use existing names plus one or two new. But if we add new var, selector values use. Need maybe `--color-gold`, `--color-bg`. Could. But to keep simple.

Need decide exact color palette.

Let's design "Centered stage" premium: dark stage #0f0f1a, bright content area #fafaf9? "Premium gold or deep purple accent." Need maybe deep purple primary with gold accent. Body dark. Cards bright.

Potential palette:
:root {
    --color-primary: #7c3aed; /* deep violet */
    --color-primary-dark: #3b0764; /* dark purple */
    --color-accent: #eab308; /* gold */
    --color-surface: #fdfcff; /* bright content */
    --color-text: #17151f; /* near black plum */
    --rgb-primary: 124,58,237;
    --rgb-accent: 234,179,8;
    --color-bg: #0f0f1a;
}
Need maybe `--color-primary` for a tags. On dark body, links/violet text might be low contrast on dark? But links likely in text on bright cards? Some links maybe. The body is dark, but links not in cards? Could still be violet on dark, low contrast. Maybe better primary = gold, accent = purple? Let's think. In dark stage, links in main content maybe usually on light sections? Body dark if set. If body dark and content surfaces not set on entire page, link color should be light gold for contrast. But then buttons? Hmm. But original primary is green (center), accent lime. On dark background maybe primary should be gold. But "premium gold or deep purple accent" could choose primary gold (#d4a72c), accent purple (#8b5cf6). `--color-primary` then gold, `--color-accent` violet. That gives links gold on dark and hover purple. But `.btn` if we set background primary gold, with white text. Could be okay. However target accent specifically maybe gold. We can choose primary as gold, accent as violet. OR primary deep purple with accent gold. Need use in link. Typically links on dark background should be gold. But