:root {
    --win-blue: #0078D7;
    --win-hover: #005A9E;
    --win-dark: #1E1E1E;
    --win-gray: #2D2D30;
    --bg-light: #F3F3F3;
    --text-main: #333333;
    --text-muted: #666666;
    --card-bg: #FFFFFF;
}
* { margin: 0; padding: 0; box-sizing: border-box; font-family: "Segoe UI", "Microsoft YaHei", sans-serif; }
body { background: var(--bg-light); color: var(--text-main); line-height: 1.6; }
a { text-decoration: none; color: inherit; }

/* Nav */
.nav { background: var(--win-dark); color: white; display: flex; justify-content: space-between; align-items: center; padding: 15px 5%; position: sticky; top: 0; z-index: 100; box-shadow: 0 4px 10px rgba(0,0,0,0.2); }
.nav-brand { font-size: 24px; font-weight: 600; display: flex; align-items: center; gap: 10px; }
.nav-brand::before { content: ""; display: inline-block; width: 20px; height: 20px; background: linear-gradient(45deg, #f09433, #e6683c, #dc2743, #cc2366, #bc1888); border-radius: 4px; }
.nav-links a { margin-left: 20px; font-size: 15px; transition: 0.2s; padding: 5px 10px; border-radius: 4px; }
.nav-links a:hover, .nav-links a.active { background: rgba(255,255,255,0.1); }

/* Hero (Poster Style) */
.hero { background: linear-gradient(135deg, var(--win-gray) 0%, var(--win-dark) 100%); color: white; padding: 100px 20px; text-align: center; border-bottom: 4px solid var(--win-blue); position: relative; overflow: hidden; }
.hero::after { content: ""; position: absolute; right: -10%; top: -10%; width: 400px; height: 400px; background: radial-gradient(circle, rgba(0,120,215,0.2) 0%, transparent 70%); }
.hero h1 { font-size: 56px; font-weight: 300; margin-bottom: 20px; letter-spacing: -1px; }
.hero p { font-size: 20px; color: #CCCCCC; max-width: 800px; margin: 0 auto 40px; }
.btn-group { display: flex; justify-content: center; gap: 20px; position: relative; z-index: 2; }
.btn { padding: 12px 30px; font-size: 18px; border-radius: 2px; font-weight: 600; display: inline-flex; align-items: center; gap: 8px; transition: 0.2s; border: 2px solid transparent; }
.btn-primary { background: var(--win-blue); color: white; }
.btn-primary:hover { background: var(--win-hover); }
.btn-secondary { background: transparent; color: white; border-color: rgba(255,255,255,0.3); }
.btn-secondary:hover { background: rgba(255,255,255,0.1); border-color: white; }

/* Data Bar */
.data-bar { display: flex; justify-content: center; flex-wrap: wrap; background: var(--win-blue); color: white; padding: 20px 0; }
.data-item { padding: 15px 40px; text-align: center; }
.data-item h3 { font-size: 32px; font-weight: 400; margin-bottom: 5px; }
.data-item p { font-size: 14px; text-transform: uppercase; letter-spacing: 1px; opacity: 0.9; }

/* Sections */
.container { max-width: 1200px; margin: 0 auto; padding: 60px 20px; }
.section-title { font-size: 32px; font-weight: 300; margin-bottom: 40px; color: var(--win-dark); text-align: center; }
.text-center { text-align: center; }

/* Grid Cards (Windows Fluent feel) */
.grid-3 { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 20px; }
.card { background: var(--card-bg); padding: 30px; border-radius: 4px; box-shadow: 0 2px 5px rgba(0,0,0,0.05); transition: 0.2s; border-top: 4px solid transparent; }
.card:hover { transform: translateY(-3px); box-shadow: 0 8px 20px rgba(0,0,0,0.1); border-top-color: var(--win-blue); }
.card h3 { font-size: 20px; font-weight: 600; margin-bottom: 12px; color: var(--win-dark); }
.card p { font-size: 15px; color: var(--text-muted); }

/* FAQ & Guide */
.faq-list { background: var(--card-bg); padding: 30px; border-radius: 4px; box-shadow: 0 2px 5px rgba(0,0,0,0.05); }
.faq-item { margin-bottom: 25px; padding-bottom: 20px; border-bottom: 1px solid #EEEEEE; }
.faq-item:last-child { margin-bottom: 0; padding-bottom: 0; border-bottom: none; }
.faq-item h3 { font-size: 18px; color: var(--win-blue); margin-bottom: 8px; }

.guide-step { background: var(--card-bg); padding: 30px 20px; text-align: center; border-radius: 4px; box-shadow: 0 2px 5px rgba(0,0,0,0.05); border-bottom: 4px solid var(--win-blue); }
.guide-step .step-num { font-size: 48px; font-weight: 300; color: var(--win-blue); margin-bottom: 10px; opacity: 0.5; line-height: 1; }
.guide-step h3 { font-size: 18px; margin-bottom: 10px; }

/* Images */
.img-fluid { max-width: 100%; border-radius: 4px; box-shadow: 0 10px 30px rgba(0,0,0,0.15); display: block; margin: 30px auto 0; border: 1px solid #DDD; }

/* Footer */
.footer { background: var(--win-gray); color: #AAAAAA; padding: 40px 20px; text-align: center; margin-top: 40px; }
.footer-links { margin-bottom: 20px; }
.footer-links a { color: white; margin: 0 15px; font-size: 14px; }
.footer-links a:hover { text-decoration: underline; }