/* ===================================
   91助手官网 - 极简主义风格样式表
   黑白灰为主色调，大量留白，精致优雅
   =================================== */

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --black: #0a0a0a;
    --dark: #1a1a1a;
    --gray-900: #212121;
    --gray-800: #2d2d2d;
    --gray-600: #555555;
    --gray-400: #999999;
    --gray-300: #b0b0b0;
    --gray-200: #d1d1d1;
    --gray-100: #e8e8e8;
    --gray-50: #f7f7f7;
    --white: #ffffff;
    --accent: #0066ff;
    --transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
    line-height: 1.8;
    color: var(--black);
    background-color: var(--white);
    font-weight: 300;
}

a {
    text-decoration: none;
    color: inherit;
    transition: var(--transition);
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 40px;
}

/* Header - Minimalist */
header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    z-index: 1000;
    border-bottom: 1px solid var(--gray-100);
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px 0;
}

.logo {
    font-size: 1.5rem;
    font-weight: 600;
    letter-spacing: -0.5px;
}

.nav-links {
    display: flex;
    gap: 40px;
}

.nav-links a {
    font-size: 0.875rem;
    font-weight: 400;
    color: var(--gray-600);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.nav-links a:hover,
.nav-links a.active {
    color: var(--black);
}

.mobile-menu-btn {
    display: none;
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--black);
}

/* Hero - Clean & Bold */
.hero {
    padding: 180px 0 120px;
    text-align: center;
    background: var(--white);
}

.hero h1 {
    font-size: 4rem;
    font-weight: 700;
    letter-spacing: -2px;
    line-height: 1.1;
    margin-bottom: 2rem;
    color: var(--black);
}

.hero p {
    font-size: 1.25rem;
    color: var(--gray-600);
    max-width: 600px;
    margin: 0 auto 3rem;
    font-weight: 300;
}

.btn {
    display: inline-block;
    padding: 16px 40px;
    border-radius: 0;
    font-weight: 500;
    font-size: 0.875rem;
    letter-spacing: 1px;
    text-transform: uppercase;
    transition: var(--transition);
    cursor: pointer;
    border: 2px solid var(--black);
}

.btn-primary {
    background-color: var(--black);
    color: var(--white);
}

.btn-primary:hover {
    background-color: var(--white);
    color: var(--black);
}

.btn-outline {
    background-color: transparent;
    color: var(--black);
}

.btn-outline:hover {
    background-color: var(--black);
    color: var(--white);
}

/* Section - Spacious */
section {
    padding: 120px 0;
}

.section-title {
    text-align: center;
    margin-bottom: 80px;
}

.section-title h2 {
    font-size: 2.5rem;
    font-weight: 600;
    letter-spacing: -1px;
    margin-bottom: 1rem;
}

.section-title p {
    color: var(--gray-600);
    font-size: 1.125rem;
}

/* Minimal Cards */
.features-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 60px;
}

.feature-card {
    padding: 40px;
    background-color: var(--gray-50);
    border: 1px solid var(--gray-100);
    transition: var(--transition);
}

.feature-card:hover {
    background-color: var(--white);
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.08);
    transform: translateY(-10px);
}

.feature-card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    font-weight: 600;
}

.feature-card p {
    color: var(--gray-600);
    line-height: 1.8;
}

/* Split Layout */
.content-wrapper {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 80px;
    align-items: center;
}

.content-text h2 {
    font-size: 2.5rem;
    margin-bottom: 2rem;
    font-weight: 600;
    letter-spacing: -1px;
}

.content-text p {
    color: var(--gray-600);
    margin-bottom: 1.5rem;
    font-size: 1.0625rem;
}

.content-image {
    background: linear-gradient(135deg, var(--gray-50), var(--gray-100));
    border-radius: 0;
    padding: 80px;
    text-align: center;
    min-height: 400px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--gray-400);
}

/* Stats Section */
.stats-section {
    background-color: var(--black);
    color: var(--white);
    padding: 100px 0;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 40px;
    text-align: center;
}

.stat-item h3 {
    font-size: 3.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}

.stat-item p {
    color: var(--gray-400);
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 2px;
}

/* Testimonials */
.testimonial-card {
    padding: 60px;
    background-color: var(--white);
    border: 1px solid var(--gray-100);
    text-align: center;
}

.testimonial-card blockquote {
    font-size: 1.25rem;
    font-style: italic;
    color: var(--gray-600);
    margin-bottom: 2rem;
    line-height: 1.8;
}

.testimonial-card cite {
    color: var(--black);
    font-weight: 500;
    font-style: normal;
}

/* Contact Form - Minimal */
.contact-wrapper {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 80px;
}

.form-group {
    margin-bottom: 2rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.75rem;
    font-weight: 500;
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--gray-600);
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 16px 0;
    border: none;
    border-bottom: 2px solid var(--gray-200);
    font-size: 1rem;
    font-family: inherit;
    background: transparent;
    transition: var(--transition);
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-bottom-color: var(--black);
}

.form-group textarea {
    resize: vertical;
    min-height: 150px;
}

/* Footer - Clean */
footer {
    background-color: var(--gray-50);
    padding: 80px 0 40px;
    border-top: 1px solid var(--gray-100);
}

.footer-content {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr;
    gap: 60px;
    margin-bottom: 60px;
}

.footer-section h4 {
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 2px;
    margin-bottom: 1.5rem;
    color: var(--gray-600);
}

.footer-section ul li {
    margin-bottom: 0.75rem;
}

.footer-section a {
    color: var(--gray-600);
}

.footer-section a:hover {
    color: var(--black);
}

.footer-bottom {
    text-align: center;
    padding-top: 40px;
    border-top: 1px solid var(--gray-200);
    color: var(--gray-400);
    font-size: 0.875rem;
}

/* Breadcrumb */
.breadcrumb {
    background-color: var(--gray-50);
    padding: 20px 0;
    border-bottom: 1px solid var(--gray-100);
}

.breadcrumb nav {
    font-size: 0.875rem;
    color: var(--gray-400);
}

.breadcrumb a {
    color: var(--gray-600);
}

.breadcrumb a:hover {
    color: var(--black);
}

/* Page Header */
.page-header {
    background-color: var(--black);
    color: var(--white);
    padding: 200px 0 120px;
    text-align: center;
}

.page-header h1 {
    font-size: 3.5rem;
    margin-bottom: 1.5rem;
    font-weight: 700;
    letter-spacing: -2px;
}

.page-header p {
    font-size: 1.25rem;
    color: var(--gray-400);
}

/* Responsive */
@media (max-width: 1024px) {
    .features-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    .container {
        padding: 0 20px;
    }
    
    .hero {
        padding: 140px 0 80px;
    }
    
    .hero h1 {
        font-size: 2.5rem;
    }
    
    section {
        padding: 80px 0;
    }
    
    .nav-links {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: var(--white);
        flex-direction: column;
        padding: 20px;
        gap: 15px;
        border-bottom: 1px solid var(--gray-100);
    }
    
    .nav-links.active {
        display: flex;
    }
    
    .mobile-menu-btn {
        display: block;
    }
    
    .content-wrapper,
    .contact-wrapper {
        grid-template-columns: 1fr;
        gap: 40px;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
        gap: 30px;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
    }
    
    .page-header h1 {
        font-size: 2rem;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
    }
}
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