/* --- CSS 变量系统 --- */
:root {
    /* 亮色模式 */
    --primary-color: #2563eb; 
    --primary-gradient: linear-gradient(135deg, #2563eb 0%, #7c3aed 100%);
    --bg-body: #ffffff;
    --bg-glass: rgba(255, 255, 255, 0.95);
    --bg-section: #f8fafc;
    --bg-card: #ffffff;
    --text-main: #0f172a;
    --text-sub: #475569;
    --border-color: rgba(0,0,0,0.06);
    --shadow-card: 0 10px 40px -10px rgba(37, 99, 235, 0.1);
    --icon-bg: linear-gradient(135deg, rgba(37, 99, 235, 0.08) 0%, rgba(124, 58, 237, 0.08) 100%);
    --btn-text: #ffffff;
    --hero-overlay-1: rgba(37, 99, 235, 0.05);
    --hero-overlay-2: rgba(124, 58, 237, 0.05);
}

/* 暗色模式 */
[data-theme="dark"] {
    --primary-color: #38bdf8;
    --primary-gradient: linear-gradient(135deg, #0ea5e9 0%, #a855f7 100%);
    --bg-body: #020617;
    --bg-glass: rgba(2, 6, 23, 0.85);
    --bg-section: #0f172a;
    --bg-card: rgba(30, 41, 59, 0.6);
    --text-main: #f1f5f9;
    --text-sub: #94a3b8;
    --border-color: rgba(255,255,255,0.08);
    --shadow-card: 0 10px 40px -10px rgba(0, 0, 0, 0.5);
    --icon-bg: rgba(255, 255, 255, 0.05);
    --btn-text: #ffffff;
    --hero-overlay-1: rgba(14, 165, 233, 0.15);
    --hero-overlay-2: rgba(168, 85, 247, 0.15);
}

/* --- 基础样式 --- */
* { margin: 0; padding: 0; box-sizing: border-box; }

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-body);
    color: var(--text-main);
    overflow-x: hidden;
    line-height: 1.8;
    transition: background-color 0.4s ease, color 0.4s ease;
}

a { text-decoration: none; color: inherit; transition: 0.3s; }
ul { list-style: none; }

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

.gradient-text {
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    display: inline-block;
    font-weight: 800;
}

/* --- 导航栏 --- */
.navbar {
    display: flex;
    padding: 18px 0;
    position: fixed;
    width: 100%;
    top: 0;
    z-index: 1000;
    background: var(--bg-glass);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border-color);
}
.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 100%;
}

.logo {
    font-family: 'Orbitron', sans-serif;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-main);
    display: flex; 
    align-items: center; 
    gap: 8px;
}
.logo span { color: var(--primary-color); }

.nav-links { 
    display: flex; 
    gap: 40px; 
}
.nav-links a { 
    font-weight: 500; 
    font-size: 0.95rem; 
    position: relative; 
    color: var(--text-sub);
}
.nav-links a:hover, .nav-links a.active { 
    color: var(--text-main); 
}
.nav-links a::after {
    content: ''; 
    position: absolute; 
    bottom: -5px; 
    left: 0; 
    width: 0; 
    height: 2px;
    background: var(--primary-gradient); 
    transition: 0.3s;
}
.nav-links a:hover::after { 
    width: 100%; 
}

/* --- 按钮与控制 --- */
.controls { 
    display: flex; 
    gap: 12px; 
    align-items: center; 
}

.icon-btn {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-main);
    width: 38px; 
    height: 38px;
    border-radius: 50%;
    cursor: pointer;
    display: flex; 
    align-items: center; 
    justify-content: center;
    font-size: 1.1rem;
    transition: 0.3s;
}
.icon-btn:hover {
    background: var(--bg-section);
    border-color: var(--primary-color);
    color: var(--primary-color);
}

.lang-btn {
    font-size: 0.75rem;
    font-weight: 700;
    font-family: 'Orbitron', sans-serif;
    width: auto;
    padding: 0 14px;
    border-radius: 20px;
}

/* --- Hero 首屏 --- */
#hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    position: relative;
    background: radial-gradient(circle at 70% 30%, var(--hero-overlay-1) 0%, transparent 50%),
                radial-gradient(circle at 30% 70%, var(--hero-overlay-2) 0%, transparent 50%);
    padding-top: 80px;
}
#particles-js { 
    position: absolute; 
    top: 0; 
    left: 0; 
    width: 100%; 
    height: 100%; 
    z-index: 1; 
}

.hero-content { 
    position: relative; 
    z-index: 10; 
    max-width: 750px; 
}
.hero-tag {
    display: inline-block;
    padding: 6px 16px;
    background: rgba(37, 99, 235, 0.1);
    color: var(--primary-color);
    border-radius: 30px;
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 24px;
    border: 1px solid rgba(37, 99, 235, 0.2);
}
.hero-title {
    font-size: 4.2rem;
    line-height: 1.1;
    margin-bottom: 24px;
    font-weight: 800;
    letter-spacing: -1.5px;
}
.hero-subtitle {
    font-size: 1.25rem;
    color: var(--text-sub);
    margin-bottom: 48px;
    max-width: 600px;
}

.btn-tech {
    padding: 16px 40px;
    background: var(--primary-gradient);
    color: var(--btn-text);
    border: none; 
    border-radius: 50px;
    font-size: 1rem; 
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 20px 40px -10px rgba(37, 99, 235, 0.3);
    display: inline-flex; 
    align-items: center; 
    gap: 10px;
}
.btn-tech:hover {
    transform: translateY(-3px);
    box-shadow: 0 25px 50px -10px rgba(37, 99, 235, 0.4);
}

/* --- 通用 Section --- */
section { 
    padding: 120px 0; 
    position: relative; 
    z-index: 10; 
}

.section-header { 
    text-align: center; 
    margin-bottom: 80px; 
    max-width: 700px; 
    margin-left: auto; 
    margin-right: auto; 
}
.section-title { 
    font-size: 2.5rem; 
    font-weight: 800; 
    margin-bottom: 16px; 
    letter-spacing: -0.5px; 
}
.section-desc { 
    color: var(--text-sub); 
    font-size: 1.1rem; 
}

/* --- 产品网格 (Features) --- */
.bg-section { 
    background-color: var(--bg-section); 
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 40px;
}

.feature-card {
    background: var(--bg-card);
    padding: 48px 36px;
    border-radius: 24px;
    border: 1px solid var(--border-color);
    transition: 0.4s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    position: relative;
}
.feature-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-card);
    border-color: var(--primary-color);
}
.card-icon {
    font-size: 3rem; 
    color: var(--primary-color);
    margin-bottom: 24px;
    width: 72px; 
    height: 72px;
    display: flex; 
    align-items: center; 
    justify-content: center;
    background: var(--icon-bg);
    border-radius: 18px;
}
.card-title { 
    font-size: 1.4rem; 
    margin-bottom: 12px; 
    font-weight: 700; 
}
.card-desc { 
    color: var(--text-sub); 
    font-size: 1rem; 
}

/* --- 解决方案 (Solutions) --- */
.solutions-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 40px;
    margin-top: 60px;
}
.sol-card {
    display: flex;
    gap: 24px;
    padding: 30px;
    border-radius: 20px;
    border: 1px solid var(--border-color);
    background: var(--bg-body);
    transition: 0.3s;
}
.sol-card:hover { 
    border-color: var(--primary-color); 
}

.sol-icon { 
    font-size: 2rem; 
    color: var(--text-sub); 
    margin-top: 5px; 
    transition: 0.3s; 
}
.sol-card:hover .sol-icon { 
    color: var(--primary-color); 
}

.sol-info h4 { 
    font-size: 1.2rem; 
    font-weight: 700; 
    margin-bottom: 8px; 
}
.sol-info p { 
    font-size: 0.95rem; 
    color: var(--text-sub); 
}

/* --- Footer --- */
footer {
    background: var(--bg-body);
    padding: 80px 0 40px;
    border-top: 1px solid var(--border-color);
}
.footer-content {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: 60px;
    margin-bottom: 60px;
}
.footer-logo { 
    font-family: 'Orbitron'; 
    font-weight: 700; 
    font-size: 1.5rem; 
    margin-bottom: 20px; 
    display: block; 
}
.footer-desc { 
    color: var(--text-sub); 
    max-width: 300px; 
    font-size: 0.95rem; 
}

.footer-links { 
    display: flex; 
    justify-content: space-around; 
    width: 100%; 
}
.link-group h4 { 
    font-weight: 700; 
    margin-bottom: 20px; 
}
.link-group li { 
    margin-bottom: 12px; 
}
.link-group a { 
    color: var(--text-sub); 
    font-size: 0.9rem; 
}
.link-group a:hover { 
    color: var(--primary-color); 
}

.copyright { 
    text-align: center; 
    color: var(--text-sub); 
    font-size: 0.85rem; 
    border-top: 1px solid var(--border-color); 
    padding-top: 30px; 
}

/* --- 响应式设计 --- */
@media (max-width: 900px) {
    .hero-title { 
        font-size: 3rem; 
    }
    .solutions-grid { 
        grid-template-columns: 1fr; 
    }
    .footer-content { 
        grid-template-columns: 1fr; 
        text-align: center; 
    }
    .footer-links { 
        flex-direction: column; 
        gap: 30px; 
    }
    .nav-links { 
        display: none; 
    }
}

/* --- 弹窗样式 --- */
.modal {
    display: none;
    position: fixed;
    z-index: 2000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.modal.show {
    display: flex;
    align-items: center;
    justify-content: center;
}

.modal-content {
    background-color: var(--bg-card);
    padding: 40px;
    border-radius: 24px;
    max-width: 500px;
    width: 90%;
    position: relative;
    border: 1px solid var(--border-color);
    animation: slideDown 0.3s ease;
}

@keyframes slideDown {
    from {
        transform: translateY(-50px);
        opacity: 0;
    }
    to {
        transform: translateY(0);
        opacity: 1;
    }
}

.modal-content h2 {
    font-size: 1.8rem;
    margin-bottom: 16px;
    color: var(--text-main);
    font-weight: 700;
}

.modal-content p {
    color: var(--text-sub);
    margin-bottom: 20px;
}

.close {
    color: var(--text-sub);
    float: right;
    font-size: 28px;
    font-weight: bold;
    cursor: pointer;
    transition: 0.3s;
}

.close:hover,
.close:focus {
    color: var(--primary-color);
}

.contact-info {
    background: var(--bg-section);
    padding: 20px;
    border-radius: 12px;
    margin-bottom: 24px;
}

.contact-info p {
    margin-bottom: 8px;
}

.contact-info a {
    color: var(--primary-color);
    font-weight: 600;
}

#demoForm {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

#demoForm input,
#demoForm textarea {
    padding: 12px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background-color: var(--bg-body);
    color: var(--text-main);
    font-family: inherit;
    font-size: 0.95rem;
    transition: 0.3s;
}

#demoForm input:focus,
#demoForm textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.submit-btn {
    padding: 12px 24px;
    background: var(--primary-gradient);
    color: var(--btn-text);
    border: none;
    border-radius: 8px;
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: 0.3s;
    margin-top: 10px;
}

.submit-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 25px -5px rgba(37, 99, 235, 0.3);
}