:root{--font-sans: -apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Text", "Helvetica Neue", Helvetica, "PingFang SC", "Microsoft YaHei", Arial, sans-serif;--font-mono: "SF Mono", "Fira Code", "Fira Mono", "Roboto Mono", monospace;--spacing-xs: 8px;--spacing-sm: 16px;--spacing-md: 24px;--spacing-lg: 48px;--spacing-xl: 80px;--spacing-2xl: 120px;--radius-sm: 8px;--radius-md: 16px;--radius-lg: 24px;--radius-full: 9999px;--transition-fast: .2s ease;--transition-normal: .35s ease;--color-accent: #0071e3;--color-accent-hover: #0077ed;--max-width: 1024px}:root{--color-bg: #ffffff;--color-bg-secondary: #f5f5f7;--color-bg-card: #ffffff;--color-text: #1d1d1f;--color-text-secondary: #86868b;--color-text-tertiary: #aeaeb2;--color-border: rgba(0, 0, 0, .08);--color-border-strong: rgba(0, 0, 0, .12);--color-shadow: rgba(0, 0, 0, .06);--color-nav-bg: rgba(255, 255, 255, .72)}@media(prefers-color-scheme:dark){:root{--color-bg: #000000;--color-bg-secondary: #111111;--color-bg-card: #1c1c1e;--color-text: #f5f5f7;--color-text-secondary: #86868b;--color-text-tertiary: #636366;--color-border: rgba(255, 255, 255, .1);--color-border-strong: rgba(255, 255, 255, .15);--color-shadow: rgba(0, 0, 0, .3);--color-nav-bg: rgba(0, 0, 0, .72);--color-accent: #2997ff;--color-accent-hover: #40a9ff}}*,*:before,*:after{margin:0;padding:0;box-sizing:border-box}html{scroll-behavior:smooth;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale}body{font-family:var(--font-sans);font-size:17px;line-height:1.6;color:var(--color-text);background-color:var(--color-bg);transition:background-color var(--transition-normal),color var(--transition-normal)}a{color:var(--color-accent);text-decoration:none;transition:color var(--transition-fast)}a:hover{color:var(--color-accent-hover)}.section{max-width:var(--max-width);margin:0 auto;padding:var(--spacing-2xl) var(--spacing-md)}.section-label{font-size:14px;font-weight:600;letter-spacing:.05em;text-transform:uppercase;color:var(--color-text-secondary);margin-bottom:var(--spacing-sm)}.section-title{font-size:48px;font-weight:700;line-height:1.15;letter-spacing:-.015em;margin-bottom:var(--spacing-lg)}@media(max-width:768px){.section{padding:var(--spacing-xl) var(--spacing-sm)}.section-title{font-size:36px}}.fade-in{opacity:0;transform:translateY(24px);transition:opacity .7s ease,transform .7s ease}.fade-in.visible{opacity:1;transform:translateY(0)}.btn{display:inline-flex;align-items:center;gap:var(--spacing-xs);padding:12px 28px;font-size:17px;font-weight:500;font-family:var(--font-sans);border:none;border-radius:var(--radius-full);cursor:pointer;transition:all var(--transition-fast);background:var(--color-text);color:var(--color-bg)}.btn:hover{opacity:.85;transform:scale(1.02)}.btn-outline{background:transparent;color:var(--color-accent);border:1.5px solid var(--color-accent)}.btn-outline:hover{background:var(--color-accent);color:#fff}