/* 头部与导航 */
.site-header {
    position: sticky;
    top: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.92);
    box-shadow: 0 8px 30px rgba(15, 23, 42, 0.08);
    z-index: 1000;
    backdrop-filter: blur(16px);
}

.site-header.scrolled {
    background: rgba(8, 47, 73, 0.95);
    color: var(--color-surface);
}

.site-header .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem 0;
    gap: var(--space-md);
}

.brand {
    display: flex;
    align-items: center;
    gap: 0.35rem;
    font-family: var(--font-family-heading);
    font-weight: 700;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    line-height: 1.1;
    margin-left: -12px; /* pull brand further left without affecting nav layout */
}

.brand-text {
    display: flex;
    flex-direction: column;
    gap: 0.15rem;
}

.brand-logo {
    display: none;
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    font-weight: 500;
}

.nav-link {
    color: var(--color-text-main);
}

.site-header.scrolled .nav-link {
    color: rgba(255, 255, 255, 0.9);
}

.nav-item {
    position: relative;
}

.nav-item>a {
    padding: 0.45rem 0;
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
}

.nav-item>a::after {
    content: '';
    position: absolute;
    left: 0;
    bottom: -0.2rem;
    width: 100%;
    height: 2px;
    background: var(--color-gradient-ocean);
    transform: scaleX(0);
    transform-origin: left;
    transition: transform 0.3s ease;
}

.nav-item:hover>a::after,
.nav-item.active>a::after {
    transform: scaleX(1);
}

.nav-dropdown {
    position: absolute;
    left: 0;
    top: 100%;
    background: var(--color-surface);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-soft);
    padding: var(--space-sm);
    min-width: 220px;
    border: 1px solid rgba(14, 165, 233, 0.2);
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transform: translateY(10px);
    transition: opacity 0.2s ease, transform 0.2s ease, visibility 0.2s ease;
}

.nav-dropdown::before {
    content: '';
    position: absolute;
    top: -10px;
    left: 0;
    right: 0;
    height: 10px;
}

.nav-dropdown a {
    display: block;
    padding: 0.55rem 0.8rem;
    border-radius: var(--radius-sm);
    color: var(--color-text-muted);
}

.nav-dropdown a:hover {
    background: rgba(14, 165, 233, 0.08);
    color: var(--color-primary-dark);
}

.nav-item:hover .nav-dropdown,
.nav-item:focus-within .nav-dropdown {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
    transform: translateY(0);
}

.nav-toggle {
    display: none;
    width: 44px;
    height: 44px;
    border-radius: 12px;
    border: 1px solid var(--color-border);
    background: rgba(255, 255, 255, 0.8);
    align-items: center;
    justify-content: center;
    font-size: 1.4rem;
}

/* 页脚 */
.site-footer {
    background: #0B1120;
    color: rgba(255, 255, 255, 0.8);
    padding: var(--space-xl) 0 var(--space-lg);
}

.site-footer h4 {
    color: var(--color-surface);
    margin-bottom: var(--space-sm);
}

.footer-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--space-lg);
}

.footer-bottom {
    margin-top: var(--space-lg);
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    gap: var(--space-sm);
    font-size: 0.9rem;
}

/* 英雄区 */
.hero {
    padding: calc(var(--space-xxl) + 80px) 0 var(--space-xl);
    position: relative;
    overflow: hidden;
    color: var(--color-surface);
}

.hero::before {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(120deg, rgba(14, 165, 233, 0.85), rgba(8, 47, 73, 0.85));
    z-index: 1;
}

.hero::after {
    content: '';
    position: absolute;
    inset: 0;
    background: radial-gradient(circle at 20% 20%, rgba(255, 255, 255, 0.15), transparent 40%),
                radial-gradient(circle at 80% 30%, rgba(14, 165, 233, 0.25), transparent 45%),
                url('../images/skyscraper_night_17.png') center/cover;
    opacity: 0.35;
    z-index: 0;
}

.hero-content {
    position: relative;
    z-index: 2;
    display: grid;
    gap: var(--space-lg);
}

.hero-headline {
    font-size: var(--font-size-h1);
    font-family: var(--font-family-heading);
    line-height: 1.15;
    max-width: 700px;
}

.hero-subtitle {
    font-size: 1.2rem;
    color: rgba(255, 255, 255, 0.9);
    max-width: 560px;
}

.hero-actions {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-sm);
}

.hero-metrics {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: var(--space-md);
}

.metric-card {
    padding: var(--space-md);
    border-radius: var(--radius-md);
    background: rgba(255, 255, 255, 0.08);
    border: 1px solid rgba(255, 255, 255, 0.2);
    text-align: left;
}

.metric-value {
    font-size: 2.4rem;
    font-weight: 600;
}

.metric-label {
    color: rgba(255, 255, 255, 0.75);
}

/* 通用模块 */
.card {
    background: var(--color-surface);
    border-radius: var(--radius-md);
    padding: var(--space-md);
    box-shadow: var(--shadow-soft);
    border: 1px solid rgba(226, 232, 240, 0.8);
}

.system-card {
    padding: var(--space-lg) var(--space-md);
    background: radial-gradient(circle at top, rgba(14, 165, 233, 0.15), transparent 60%), var(--color-surface);
    border-radius: var(--radius-lg);
    border: 1px solid rgba(14, 165, 233, 0.2);
    position: relative;
    overflow: hidden;
    transform-style: preserve-3d;
    transition: transform 0.4s ease, box-shadow 0.4s ease;
}

.system-card:hover {
    transform: translateY(-6px) rotateX(5deg);
    box-shadow: var(--shadow-border-glow);
}

.system-card img {
    border-radius: var(--radius-md);
    margin-bottom: var(--space-md);
}

.data-board {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: var(--space-md);
}

.data-item {
    padding: var(--space-md);
    border-radius: var(--radius-md);
    background: var(--color-gradient-sky);
    border: 1px solid rgba(255, 255, 255, 0.6);
    box-shadow: var(--shadow-soft);
}

.data-value {
    font-size: 2.2rem;
    font-weight: 600;
    color: var(--color-primary-dark);
}

.data-label {
    color: var(--color-text-muted);
}

.case-gallery {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--space-md);
}

.case-card {
    border-radius: var(--radius-lg);
    overflow: hidden;
    position: relative;
    min-height: 320px;
}

.case-card img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.case-card .case-info {
    position: absolute;
    inset: 0;
    background: linear-gradient(180deg, rgba(15, 23, 42, 0.2), rgba(8, 47, 73, 0.85));
    color: var(--color-surface);
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
    padding: var(--space-md);
}

.tech-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: var(--space-md);
}

.tech-card {
    padding: var(--space-md);
    border-radius: var(--radius-md);
    border: 1px solid rgba(14, 165, 233, 0.2);
    background: rgba(255, 255, 255, 0.95);
    box-shadow: var(--shadow-soft);
}

.contact-panel {
    background: var(--color-primary-dark);
    color: var(--color-surface);
    border-radius: var(--radius-lg);
    padding: var(--space-lg);
    display: grid;
    gap: var(--space-md);
}

.contact-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: var(--space-md);
}

.form-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: var(--space-md);
}

form .form-field {
    display: flex;
    flex-direction: column;
    gap: 0.4rem;
}

input, textarea, select {
    padding: 0.9rem 1rem;
    border-radius: var(--radius-md);
    border: 1px solid rgba(148, 163, 184, 0.6);
    background: rgba(255, 255, 255, 0.9);
    transition: border 0.3s ease, box-shadow 0.3s ease;
}

input:focus, textarea:focus, select:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(14, 165, 233, 0.2);
}