:root {
    --color-primary: #2563eb;
    --color-primary-dark: #1e40af;
    --color-accent: #f59e0b;
    --color-surface: #fef3c7;
    --color-text: #1f2937;
    --rgb-primary: 37,99,235;
    --rgb-accent: 245,158,11;
    --radius-sm: 2px;
    --radius-md: 3px;
    --radius-lg: 4px;
    --radius-xl: 4px;
    --shadow-sm: 3px 3px 0px rgba(37,99,235,.25);
    --shadow-md: 4px 4px 0px rgba(37,99,235,.35);
    --shadow-lg: 6px 6px 0px rgba(37,99,235,.45);
    --space-section: 2rem;
    --space-card: 1rem;
    --space-gap: 0.75rem;
    --transition: 0.15s ease-in-out;
    --heading-weight: 700;
    --body-line-height: 1.65;
}

/* 基础覆盖 */
body { color: var(--color-text); line-height: var(--body-line-height); background-color: #f8fafc; }
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); border: 2px solid #d1d5db; }
.card:nth-child(3n+1) { border-color: #2563eb; box-shadow: 4px 4px 0px rgba(37,99,235,.4); }
.card:nth-child(3n+2) { border-color: #f59e0b; box-shadow: 4px 4px 0px rgba(245,158,11,.4); }
.card:nth-child(3n+3) { border-color: #10b981; box-shadow: 4px 4px 0px rgba(16,185,129,.4); }
.btn, button[class*="btn"], a[class*="btn"] { border-radius: var(--radius-md); transition: var(--transition); border: 2px solid var(--color-primary); box-shadow: 3px 3px 0px rgba(37,99,235,.3); }
.btn:hover, button[class*="btn"]:hover, a[class*="btn"]:hover { box-shadow: 1px 1px 0px rgba(37,99,235,.3); transform: translate(2px, 2px); }
a:not([class]) { color: var(--color-primary); transition: var(--transition); }

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

/* news: grid-4 */
/* 四列紧凑网格 */
                .news-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: calc(var(--space-gap) * 0.8); }
                .news-grid .card:nth-child(1) { grid-column: span 2; grid-row: span 2; }
                .news-grid .card:nth-child(4) { grid-column: span 2; }

/* features: horizontal */
/* 水平滚动 */
                .feature-list { display: flex; gap: var(--space-gap); overflow-x: auto; scroll-snap-type: x mandatory; }
                .feature-list > * { flex: 0 0 300px; scroll-snap-align: start; }

/* hero: left-aligned */
.hero-content { text-align: left; max-width: 600px; }

/* 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-6 */
.partner-grid { display: grid; grid-template-columns: repeat(6, 1fr); gap: var(--space-gap); align-items: center; }
.partner-grid > * { border: 2px solid #e5e7eb; border-radius: 2px; box-shadow: 2px 2px 0px rgba(0,0,0,.05); transition: var(--transition); }
.partner-grid > *:hover { box-shadow: 4px 4px 0px rgba(37,99,235,.15); }

/* faq: two-column */
.faq-list { display: grid; grid-template-columns: 1fr 1fr; gap: var(--space-gap); }

/* stats: grid-4 */
.stats-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: var(--space-gap); text-align: center; }
.stats-grid > * { border: 2px solid #d1d5db; border-radius: 2px; }
.stats-grid > *:nth-child(odd) { border-color: #2563eb; }
.stats-grid > *:nth-child(even) { border-color: #f59e0b; }

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

/* Page Layout: narrow-centered */
/* 窄版居中 */
            .page-main { max-width: 860px; margin: 0 auto; }

/* 条件性装饰 */
a:not([class]):hover { color: var(--color-accent); }
header, .header, .navbar { box-shadow: 4px 4px 0px rgba(37,99,235,.1); border-bottom: 2px solid #e5e7eb; }

/* 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; }
}