/* ===== CSS Variables ===== */
:root {
    --color-bg: #FFFFFF;
    --color-text: #1A1A1A;
    --color-text-secondary: #666666;
    --color-accent: #0A2540;
    --color-bg-alt: #F5F7FA;
    --color-border: #E5E8ED;
    --font-stack: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
    --transition: all 0.3s ease;
    --shadow-card: 0 4px 20px rgba(0, 0, 0, 0.06);
    --shadow-hover: 0 8px 30px rgba(0, 0, 0, 0.12);
}

/* ===== Reset ===== */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-stack);
    color: var(--color-text);
    background-color: var(--color-bg);
    line-height: 1.75;
    -webkit-font-smoothing: antialiased;
}

a {
    text-decoration: none;
    color: inherit;
}

ul {
    list-style: none;
}

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

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

/* ===== Buttons ===== */
.btn {
    display: inline-block;
    padding: 14px 32px;
    border-radius: 6px;
    font-size: 16px;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    border: none;
}

.btn-primary {
    background-color: var(--color-accent);
    color: #FFFFFF;
}

.btn-primary:hover {
    background-color: #0d3054;
    transform: translateY(-2px);
}

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

.btn-secondary:hover {
    background-color: var(--color-accent);
    color: #FFFFFF;
}

/* ===== Section Common ===== */
section {
    padding: 100px 0;
}

.section-title {
    font-size: 32px;
    font-weight: 600;
    margin-bottom: 16px;
    color: var(--color-text);
}

.section-subtitle {
    font-size: 16px;
    color: var(--color-text-secondary);
    margin-bottom: 48px;
}

/* ===== Navbar ===== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    transition: var(--transition);
    padding: 20px 0;
}

.navbar.scrolled {
    background-color: var(--color-bg);
    box-shadow: 0 2px 20px rgba(0, 0, 0, 0.08);
    padding: 14px 0;
}

.nav-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo {
    font-size: 22px;
    font-weight: 700;
    color: var(--color-accent);
    letter-spacing: 1px;
}

.nav-links {
    display: flex;
    gap: 36px;
}

.nav-links a {
    font-size: 15px;
    font-weight: 500;
    color: var(--color-text);
    transition: var(--transition);
    position: relative;
}

.nav-links a:hover {
    color: var(--color-accent);
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--color-accent);
    transition: var(--transition);
}

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

.nav-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    color: var(--color-text);
}

/* ===== Hero ===== */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    padding-top: 80px;
}

.hero-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
}

.hero-content {
    max-width: 560px;
}

.hero-tag {
    display: inline-block;
    font-size: 14px;
    color: var(--color-text-secondary);
    margin-bottom: 16px;
    letter-spacing: 1px;
}

.hero-title {
    font-size: 52px;
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: 24px;
    color: var(--color-text);
}

.hero-desc {
    font-size: 18px;
    color: var(--color-text-secondary);
    margin-bottom: 36px;
    line-height: 1.8;
}

.hero-visual {
    display: flex;
    justify-content: center;
    align-items: center;
    position: relative;
}

.hero-visual::after {
    content: '';
    position: absolute;
    inset: 0;
    max-width: 480px;
    margin: 0 auto;
    background: linear-gradient(135deg, rgba(10, 37, 64, 0.15) 0%, rgba(10, 37, 64, 0.4) 100%);
    border-radius: 12px;
    pointer-events: none;
}

.hero-image {
    width: 100%;
    max-width: 480px;
    aspect-ratio: 4 / 3;
    object-fit: cover;
    border-radius: 12px;
    box-shadow: var(--shadow-hover);
    filter: saturate(0.8);
}

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

.about-image {
    position: relative;
}

.about-image::after {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(135deg, rgba(10, 37, 64, 0.1) 0%, rgba(10, 37, 64, 0.3) 100%);
    border-radius: 12px;
    pointer-events: none;
}

.about-img {
    width: 100%;
    aspect-ratio: 4 / 3;
    object-fit: cover;
    border-radius: 12px;
    box-shadow: var(--shadow-card);
    filter: saturate(0.8);
}

.about-text {
    font-size: 16px;
    color: var(--color-text-secondary);
    line-height: 1.8;
    margin-bottom: 36px;
}

.about-stats {
    display: flex;
    gap: 40px;
}

.stat-item {
    display: flex;
    flex-direction: column;
}

.stat-number {
    font-size: 32px;
    font-weight: 700;
    color: var(--color-accent);
    line-height: 1.2;
}

.stat-label {
    font-size: 14px;
    color: var(--color-text-secondary);
    margin-top: 4px;
}

/* ===== Services ===== */
.services {
    background-color: var(--color-bg-alt);
}

.services-header {
    margin-bottom: 48px;
}

.services-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
}

.service-card {
    background-color: var(--color-bg);
    border-radius: 8px;
    padding: 36px 28px;
    box-shadow: var(--shadow-card);
    transition: var(--transition);
}

.service-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-hover);
}

.service-icon {
    width: 64px;
    height: 64px;
    background-color: var(--color-bg-alt);
    border-radius: 12px;
    display: flex;
    justify-content: center;
    align-items: center;
    color: var(--color-accent);
    margin-bottom: 20px;
}

.service-title {
    font-size: 20px;
    font-weight: 600;
    margin-bottom: 12px;
}

.service-desc {
    font-size: 15px;
    color: var(--color-text-secondary);
    line-height: 1.6;
}

/* ===== Cases ===== */
.cases-header {
    margin-bottom: 48px;
}

.cases-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 24px;
}

.case-card {
    background-color: var(--color-bg);
    border: 1px solid var(--color-border);
    border-radius: 8px;
    overflow: hidden;
    transition: var(--transition);
    position: relative;
}

.case-img {
    width: 100%;
    height: 180px;
    object-fit: cover;
    display: block;
    background-color: var(--color-bg-alt);
}

.case-card:hover {
    border-color: var(--color-accent);
    box-shadow: var(--shadow-card);
}

.case-card:hover .case-img {
    transform: scale(1.03);
}

.case-img {
    transition: var(--transition);
}

.case-tag {
    display: inline-block;
    font-size: 13px;
    font-weight: 500;
    color: var(--color-accent);
    background-color: rgba(10, 37, 64, 0.06);
    padding: 4px 12px;
    border-radius: 4px;
    margin: 24px 32px 16px;
}

.case-title {
    font-size: 20px;
    font-weight: 600;
    margin: 0 32px 12px;
    color: var(--color-text);
}

.case-desc {
    font-size: 15px;
    color: var(--color-text-secondary);
    line-height: 1.7;
    margin: 0 32px 20px;
}

.case-year {
    font-size: 14px;
    color: var(--color-text-secondary);
    font-weight: 500;
    margin: 0 32px 32px;
    display: block;
}

.case-year::before {
    content: '';
    display: inline-block;
    width: 8px;
    height: 8px;
    background-color: var(--color-accent);
    border-radius: 50%;
    margin-right: 8px;
}

/* ===== Contact ===== */
.contact-container {
    display: grid;
    grid-template-columns: 2fr 3fr;
    gap: 60px;
    align-items: start;
}

.info-item {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 16px;
    font-size: 15px;
    color: var(--color-text-secondary);
}

.info-item i {
    color: var(--color-accent);
    flex-shrink: 0;
}

.map-placeholder {
    width: 100%;
    aspect-ratio: 16 / 9;
    background-color: var(--color-bg-alt);
    border-radius: 8px;
    display: flex;
    justify-content: center;
    align-items: center;
    margin-top: 24px;
}

.contact-form .form-row {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 16px;
    margin-bottom: 16px;
}

.form-group {
    margin-bottom: 16px;
}

.form-input,
.form-textarea {
    width: 100%;
    padding: 14px 16px;
    border: 1px solid var(--color-border);
    border-radius: 6px;
    font-size: 15px;
    font-family: var(--font-stack);
    transition: var(--transition);
    background-color: var(--color-bg);
}

.form-input:focus,
.form-textarea:focus {
    outline: none;
    border-color: var(--color-accent);
    box-shadow: 0 0 0 3px rgba(10, 37, 64, 0.08);
}

.form-textarea {
    resize: vertical;
    min-height: 140px;
}

/* ===== Footer ===== */
.footer {
    background-color: var(--color-accent);
    color: #FFFFFF;
    padding: 32px 0;
}

.footer-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.footer-logo {
    font-size: 18px;
    font-weight: 700;
    margin-right: 12px;
}

.footer-slogan {
    font-size: 14px;
    opacity: 0.8;
}

.footer-copy {
    font-size: 14px;
    opacity: 0.7;
}

/* ===== Responsive ===== */
@media (max-width: 1023px) {
    .hero-container {
        grid-template-columns: 1fr;
        text-align: center;
        gap: 40px;
    }

    .hero-content {
        max-width: 100%;
    }

    .hero-title {
        font-size: 40px;
    }

    .about-container {
        grid-template-columns: 1fr;
        gap: 40px;
    }

    .services-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .cases-grid {
        grid-template-columns: 1fr;
    }

    .contact-container {
        grid-template-columns: 1fr;
        gap: 40px;
    }
}

@media (max-width: 767px) {
    section {
        padding: 60px 0;
    }

    .hero-title {
        font-size: 32px;
    }

    .hero-desc {
        font-size: 16px;
    }

    .nav-links {
        position: fixed;
        top: 0;
        left: 0;
        right: 0;
        bottom: 0;
        background-color: var(--color-bg);
        flex-direction: column;
        justify-content: center;
        align-items: center;
        gap: 32px;
        transform: translateX(100%);
        transition: var(--transition);
        z-index: 999;
    }

    .nav-links.active {
        transform: translateX(0);
    }

    .nav-links a {
        font-size: 20px;
    }

    .nav-toggle {
        display: block;
        z-index: 1001;
    }

    .services-grid {
        grid-template-columns: 1fr;
    }

    .about-stats {
        justify-content: space-around;
        gap: 20px;
    }

    .stat-number {
        font-size: 26px;
    }

    .contact-form .form-row {
        grid-template-columns: 1fr;
    }

    .footer-container {
        flex-direction: column;
        gap: 12px;
        text-align: center;
    }
}