/* 全局和基础样式 */
:root {
    --primary-color: #00e889;
    --primary-hover-color: #00c677;
    --background-color: #000503;
    --surface-color: #0a0f0d;
    --border-color: rgba(0, 232, 137, 0.15);
    --text-color: #e5e7eb;
    --text-muted-color: #9ca3af;
}

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

body {
    font-family: 'Inter', 'PingFang SC', 'Microsoft YaHei', sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    line-height: 1.7;
    font-size: 16px;
}

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

section {
    padding: 80px 0;
}

h2 {
    font-size: 2.5rem;
    text-align: center;
    margin-bottom: 1rem;
}

.section-subtitle {
    text-align: center;
    color: var(--text-muted-color);
    max-width: 600px;
    margin: 0 auto 60px auto;
    font-size: 1.1rem;
}

.btn {
    display: inline-block;
    padding: 12px 28px;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s ease;
    border: none;
    cursor: pointer;
}

.btn-primary {
    background: linear-gradient(90deg, var(--primary-color), var(--primary-hover-color));
    color: #000;
}

.btn-primary:hover {
    box-shadow: 0 0 20px rgba(0, 232, 137, 0.5);
}

.btn-secondary {
    background-color: transparent;
    color: var(--text-color);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover {
    background-color: var(--surface-color);
    border-color: var(--primary-color);
}

.main-header {
    padding: 20px 0;
    position: fixed;
    width: 100%;
    top: 0;
    left: 0;
    z-index: 1000;
    background: rgba(0, 5, 3, 0.8);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
}

.main-header .container,
.main-nav ul {
    display: flex;
    align-items: center;
}

.main-header .container {
    justify-content: space-between;
}

.logo img {
    height: 40px; /* Adjust height as needed */
    width: auto;
    display: block;
}

.main-nav ul {
    list-style: none;
}

.main-nav li {
    margin-left: 30px;
}

.main-nav a {
    color: var(--text-muted-color);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s ease;
}

.main-nav a:hover, .main-nav a.active {
    color: var(--text-color);
}

.hero-section {
    padding-top: 180px;
    padding-bottom: 120px;
    text-align: center;
    background: radial-gradient(circle at 50% 0%, rgba(0, 232, 137, 0.15), transparent 40%);
}

.hero-title {
    font-size: 3.8rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    line-height: 1.2;
}

.hero-subtitle {
    font-size: 1.2rem;
    color: var(--text-muted-color);
    margin-bottom: 2.5rem;
}

.hero-actions .btn {
    margin: 0 10px;
}

.btn-primary {
    background-color: var(--primary-color);
    color: #000;
    box-shadow: 0 0 15px var(--glow-color);
}

.btn-primary:hover {
    background-color: var(--primary-color-dark);
    transform: translateY(-3px);
    box-shadow: 0 0 25px var(--glow-color);
}

.btn-secondary {
    background-color: transparent;
    color: var(--primary-color);
    border-color: var(--primary-color);
}

.btn-secondary:hover {
    background-color: var(--primary-color);
    color: #000;
}

.stats-section {
    padding: 60px 0;
    background-color: var(--background-color);
}

.stats-grid {
    display: flex;
    justify-content: center;
    align-items: center;
    text-align: center;
}

.stat-item .stat-value {
    font-size: 64px;
    font-weight: 700;
    color: var(--primary-color);
    line-height: 1.2;
}

.stat-item .stat-label {
    font-size: 16px;
    color: var(--text-color-secondary);
    margin-top: 10px;
}

.features-section, .how-it-works-section, .faq-section, .cta-section {
    padding: 100px 0;
    text-align: center;
}

h2 {
    font-size: 40px;
    font-weight: 700;
    margin-bottom: 20px;
}

.section-subtitle {
    max-width: 600px;
    margin: 0 auto 50px auto;
    color: var(--text-color-secondary);
    font-size: 18px;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 30px;
    text-align: left;
    margin-top: 50px;
}

.feature-item {
    background-color: var(--surface-color);
    padding: 30px;
    border-radius: 12px;
    border: 1px solid var(--border-color);
    transition: transform 0.3s ease, box-shadow 0.3s ease, border-color 0.3s ease;
}

.feature-item:hover {
    transform: translateY(-5px);
    border-color: var(--primary-color);
    box-shadow: 0 10px 20px rgba(0,0,0,0.2);
}

.feature-item h3 {
    font-size: 22px;
    margin-top: 0;
    margin-bottom: 15px;
    color: var(--primary-color);
}

.steps-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
    margin-top: 50px;
    position: relative;
}

.step-item {
    text-align: center;
    position: relative;
}

.step-number {
    width: 60px;
    height: 60px;
    border-radius: 50%;
    border: 2px solid var(--primary-color);
    background-color: var(--surface-color);
    color: var(--primary-color);
    display: inline-flex;
    justify-content: center;
    align-items: center;
    font-size: 28px;
    font-weight: bold;
    margin-bottom: 20px;
    transition: all 0.3s ease;
}

.step-item:hover .step-number {
    background-color: var(--primary-color);
    color: #000;
    transform: scale(1.1);
}

.step-item h3 {
    font-size: 22px;
    margin-bottom: 10px;
}

.faq-item {
    max-width: 750px;
    margin: 0 auto 15px auto;
    text-align: left;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background-color: var(--surface-color);
    overflow: hidden;
    transition: background-color 0.3s ease;
}

.faq-item:hover {
    background-color: #1c222b;
}

.faq-question {
    padding: 20px;
    font-weight: bold;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.faq-question::after {
    content: '+';
    font-size: 24px;
    transition: transform 0.3s ease;
}

.faq-item.active .faq-question::after {
    transform: rotate(45deg);
}

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.4s ease-in-out;
}

.faq-answer p {
    padding: 0 20px 20px 20px;
    margin: 0;
    color: var(--text-color-secondary);
}

.faq-item.active .faq-answer {
    max-height: 200px;
}

.cta-section {
    background: linear-gradient(rgba(13, 17, 23, 0.8), rgba(13, 17, 23, 0.8)), url('https://www.transparenttextures.com/patterns/cubes.png');
}

.main-footer {
    background-color: #000;
    padding: 60px 0 30px 0;
    border-top: 1px solid var(--border-color);
    font-size: 15px;
}

.footer-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 40px;
    margin-bottom: 40px;
}

.footer-col h4 {
    font-size: 18px;
    margin-bottom: 20px;
    color: #fff;
    font-weight: 600;
}

.footer-col p,
.footer-col a {
    color: var(--text-muted-color);
    text-decoration: none;
    transition: color 0.3s ease;
    line-height: 1.8;
}

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

.footer-col ul {
    list-style: none;
    padding: 0;
}

.footer-col ul li {
    margin-bottom: 12px;
}

.footer-bottom {
    text-align: center;
    padding-top: 30px;
    border-top: 1px solid var(--border-color);
    font-size: 14px;
    color: var(--text-muted-color);
}

.footer-disclaimer {
    margin-bottom: 15px;
    line-height: 1.6;
}

.footer-copyright {
    color: #888;
}

/* 响应式设计 */
@media (max-width: 992px) {
    .footer-grid {
        grid-template-columns: 1fr 1fr;
    }
}

@media (max-width: 768px) {
    h2 { font-size: 2rem; }
    .hero-title { font-size: 2.8rem; }
    .main-nav { display: none; } /* Simple hiding for now, needs a mobile menu implementation */
    .steps-grid { grid-template-columns: 1fr; }
    .estimator-form { flex-direction: column; }
}

@media (max-width: 576px) {
    .footer-grid {
        grid-template-columns: 1fr;
    }
}