/* ============================================
   Beijing Longweitengda Property Management Co., Ltd.
   Main Stylesheet
   ============================================ */

/* CSS Variables */
:root {
    --primary-color: #0066cc;
    --primary-dark: #0052a3;
    --secondary-color: #00a0e9;
    --accent-color: #ff6b35;
    --text-dark: #1a1a1a;
    --text-light: #666666;
    --text-lighter: #999999;
    --bg-light: #f5f7fa;
    --bg-white: #ffffff;
    --border-color: #e0e6ed;
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.12);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.16);
    --transition-fast: 0.3s ease;
    --transition-medium: 0.5s ease;
    --transition-slow: 0.8s ease;
}

/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    color: var(--text-dark);
    line-height: 1.6;
    overflow-x: hidden;
}

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

ul, ol {
    list-style: none;
}

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

button {
    cursor: pointer;
    border: none;
    outline: none;
    font-family: inherit;
}

input, textarea, select {
    font-family: inherit;
    outline: none;
}

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Header Styles */
.header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-medium);
}

.header.scrolled {
    background: rgba(255, 255, 255, 0.98);
    box-shadow: var(--shadow-md);
}

.header-inner {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 0;
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
}

.logo svg {
    width: 50px;
    height: 50px;
}

.logo-text {
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--primary-color);
    line-height: 1.2;
}

.logo-text span {
    display: block;
    font-size: 0.7rem;
    font-weight: 400;
    color: var(--text-light);
}

/* Navigation */
.nav {
    display: flex;
    gap: 40px;
}

.nav-item {
    position: relative;
    padding: 10px 0;
    font-weight: 600;
    color: var(--text-dark);
    transition: color var(--transition-fast);
}

.nav-item:hover {
    color: var(--primary-color);
}

.nav-item::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-color);
    transition: width var(--transition-fast);
}

.nav-item:hover::after {
    width: 100%;
}

.nav-item.active {
    color: var(--primary-color);
}

.nav-item.active::after {
    width: 100%;
}

/* Mobile Menu Button */
.mobile-menu-btn {
    display: none;
    flex-direction: column;
    gap: 5px;
    padding: 5px;
    background: none;
}

.mobile-menu-btn span {
    width: 25px;
    height: 3px;
    background: var(--text-dark);
    transition: all var(--transition-fast);
}

.mobile-menu-btn.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
}

.mobile-menu-btn.active span:nth-child(2) {
    opacity: 0;
}

.mobile-menu-btn.active span:nth-child(3) {
    transform: rotate(-45deg) translate(7px, -6px);
}

/* Hero Section */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, var(--bg-light) 0%, var(--bg-white) 100%);
    overflow: hidden;
    padding-top: 80px;
}

.hero-bg-shapes {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
}

.hero-content {
    position: relative;
    z-index: 2;
    text-align: center;
    max-width: 900px;
    padding: 0 20px;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 800;
    color: var(--text-dark);
    margin-bottom: 20px;
    line-height: 1.2;
}

.hero-title span {
    color: var(--primary-color);
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--text-light);
    margin-bottom: 40px;
    line-height: 1.8;
}

.hero-buttons {
    display: flex;
    gap: 20px;
    justify-content: center;
    flex-wrap: wrap;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    padding: 15px 40px;
    border-radius: 50px;
    font-size: 1rem;
    font-weight: 600;
    transition: all var(--transition-fast);
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: white;
    box-shadow: 0 4px 15px rgba(0, 102, 204, 0.4);
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 25px rgba(0, 102, 204, 0.5);
}

.btn-secondary {
    background: white;
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
}

.btn-secondary:hover {
    background: var(--primary-color);
    color: white;
    transform: translateY(-3px);
}

.btn svg {
    width: 20px;
    height: 20px;
}

/* Sections */
.section {
    padding: 100px 0;
}

.section-dark {
    background: var(--text-dark);
    color: white;
}

.section-light {
    background: var(--bg-light);
}

.section-header {
    text-align: center;
    margin-bottom: 60px;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: 15px;
}

.section-dark .section-title {
    color: white;
}

.section-subtitle {
    font-size: 1.1rem;
    color: var(--text-light);
    max-width: 600px;
    margin: 0 auto;
}

.section-dark .section-subtitle {
    color: rgba(255, 255, 255, 0.8);
}

/* Services Grid */
.services-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 30px;
}

.service-card {
    background: white;
    padding: 40px 30px;
    border-radius: 20px;
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-medium);
    text-align: center;
    position: relative;
    overflow: hidden;
}

.service-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    transform: scaleX(0);
    transition: transform var(--transition-fast);
}

.service-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-lg);
}

.service-card:hover::before {
    transform: scaleX(1);
}

.service-icon {
    width: 80px;
    height: 80px;
    margin: 0 auto 25px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    border-radius: 20px;
    transition: transform var(--transition-fast);
}

.service-card:hover .service-icon {
    transform: scale(1.1) rotate(5deg);
}

.service-icon svg {
    width: 40px;
    height: 40px;
    fill: white;
}

.service-title {
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: 15px;
}

.service-description {
    font-size: 0.95rem;
    color: var(--text-light);
    line-height: 1.7;
}

/* App Features Section */
.app-features {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
}

.app-content h2 {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: 20px;
}

.app-content p {
    font-size: 1.1rem;
    color: var(--text-light);
    margin-bottom: 30px;
    line-height: 1.8;
}

.app-list {
    display: grid;
    gap: 15px;
}

.app-list-item {
    display: flex;
    align-items: center;
    gap: 15px;
    padding: 15px 20px;
    background: var(--bg-light);
    border-radius: 10px;
    transition: all var(--transition-fast);
}

.app-list-item:hover {
    background: var(--primary-color);
    color: white;
    transform: translateX(10px);
}

.app-list-item svg {
    width: 24px;
    height: 24px;
    flex-shrink: 0;
}

.app-image {
    position: relative;
}

.app-mockup {
    width: 100%;
    max-width: 400px;
    margin: 0 auto;
    display: block;
}

/* Stats Section */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 30px;
}

.stat-card {
    text-align: center;
    padding: 40px 20px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 20px;
    backdrop-filter: blur(10px);
    transition: transform var(--transition-fast);
}

.stat-card:hover {
    transform: translateY(-5px);
}

.stat-number {
    font-size: 3rem;
    font-weight: 800;
    color: var(--accent-color);
    margin-bottom: 10px;
}

.stat-label {
    font-size: 1rem;
    color: rgba(255, 255, 255, 0.9);
}

/* About Section */
.about-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
}

.about-content h2 {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: 20px;
}

.about-content p {
    font-size: 1.05rem;
    color: var(--text-light);
    margin-bottom: 20px;
    line-height: 1.8;
}

.about-image {
    position: relative;
}

.about-image img {
    border-radius: 20px;
    box-shadow: var(--shadow-lg);
}

/* Culture Section */
.culture-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 30px;
}

.culture-card {
    text-align: center;
    padding: 40px 30px;
    background: white;
    border-radius: 20px;
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-medium);
}

.culture-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-lg);
}

.culture-icon {
    width: 100px;
    height: 100px;
    margin: 0 auto 25px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    border-radius: 50%;
}

.culture-icon svg {
    width: 50px;
    height: 50px;
    fill: white;
}

.culture-title {
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: 15px;
}

.culture-description {
    font-size: 0.95rem;
    color: var(--text-light);
    line-height: 1.7;
}

/* News Grid */
.news-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 30px;
}

.news-card {
    background: white;
    border-radius: 20px;
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-medium);
}

.news-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-lg);
}

.news-image {
    position: relative;
    height: 200px;
    overflow: hidden;
}

.news-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform var(--transition-medium);
}

.news-card:hover .news-image img {
    transform: scale(1.1);
}

.news-date {
    position: absolute;
    top: 15px;
    left: 15px;
    padding: 8px 15px;
    background: var(--primary-color);
    color: white;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
}

.news-content {
    padding: 25px;
}

.news-category {
    display: inline-block;
    padding: 5px 12px;
    background: var(--bg-light);
    color: var(--primary-color);
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 600;
    margin-bottom: 15px;
}

.news-title {
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: 10px;
    line-height: 1.4;
    transition: color var(--transition-fast);
}

.news-card:hover .news-title {
    color: var(--primary-color);
}

.news-excerpt {
    font-size: 0.95rem;
    color: var(--text-light);
    line-height: 1.6;
}

/* Contact Section */
.contact-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
}

.contact-info h2 {
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: 30px;
}

.contact-item {
    display: flex;
    gap: 20px;
    margin-bottom: 30px;
    align-items: flex-start;
}

.contact-icon {
    width: 60px;
    height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    border-radius: 15px;
    flex-shrink: 0;
}

.contact-icon svg {
    width: 30px;
    height: 30px;
    fill: white;
}

.contact-text h4 {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: 5px;
}

.contact-text p {
    font-size: 0.95rem;
    color: var(--text-light);
    line-height: 1.6;
}

.contact-form {
    background: white;
    padding: 40px;
    border-radius: 20px;
    box-shadow: var(--shadow-md);
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--text-dark);
    margin-bottom: 8px;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 12px 15px;
    border: 2px solid var(--border-color);
    border-radius: 10px;
    font-size: 1rem;
    transition: all var(--transition-fast);
}

.form-group input:focus,
.form-group textarea:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(0, 102, 204, 0.1);
}

.form-group textarea {
    min-height: 120px;
    resize: vertical;
}

/* Footer */
.footer {
    background: var(--text-dark);
    color: white;
    padding: 60px 0 30px;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 40px;
    margin-bottom: 40px;
}

.footer-about h3 {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 20px;
}

.footer-about p {
    font-size: 0.95rem;
    color: rgba(255, 255, 255, 0.8);
    line-height: 1.7;
    margin-bottom: 20px;
}

.footer-social {
    display: flex;
    gap: 15px;
}

.social-link {
    width: 45px;
    height: 45px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 10px;
    transition: all var(--transition-fast);
}

.social-link:hover {
    background: var(--primary-color);
    transform: translateY(-3px);
}

.social-link svg {
    width: 24px;
    height: 24px;
    fill: white;
}

.footer-column h4 {
    font-size: 1.1rem;
    font-weight: 700;
    margin-bottom: 20px;
}

.footer-links {
    display: grid;
    gap: 12px;
}

.footer-links a {
    font-size: 0.95rem;
    color: rgba(255, 255, 255, 0.8);
    transition: all var(--transition-fast);
}

.footer-links a:hover {
    color: var(--primary-color);
    padding-left: 5px;
}

.footer-bottom {
    padding-top: 30px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 20px;
}

.footer-bottom p {
    font-size: 0.9rem;
    color: rgba(255, 255, 255, 0.7);
}

.footer-legal {
    display: flex;
    gap: 20px;
}

.footer-legal a {
    font-size: 0.9rem;
    color: rgba(255, 255, 255, 0.7);
    transition: color var(--transition-fast);
}

.footer-legal a:hover {
    color: var(--primary-color);
}

/* Back to Top Button */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-md);
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-fast);
    z-index: 999;
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
}

.back-to-top:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.back-to-top svg {
    width: 24px;
    height: 24px;
    fill: white;
}

/* Loading Animation */
.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: white;
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 9999;
    transition: opacity 0.5s ease;
}

.loading-overlay.hidden {
    opacity: 0;
    pointer-events: none;
}

.loader {
    width: 50px;
    height: 50px;
    border: 5px solid var(--bg-light);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}