:root {
    --primary: #0ea5e9;
    --primary-dark: #0284c7;
    --accent: #06b6d4;
    --bg-dark: #0b1120;
    --bg-card: #111827;
    --bg-light: #f0f9ff;
    --text: #1e293b;
    --text-muted: #64748b;
    --text-light: #94a3b8;
    --white: #ffffff;
    --gradient: linear-gradient(135deg, #0ea5e9 0%, #06b6d4 50%, #22d3ee 100%);
    --shadow: 0 4px 24px rgba(14, 165, 233, 0.15);
    --radius: 16px;
    --nav-height: 72px;
}

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

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

body {
    font-family: "PingFang SC", "SF Pro SC", "Microsoft YaHei", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    color: var(--text);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    overflow-x: hidden;
}

a {
    color: inherit;
    text-decoration: none;
    transition: color 0.2s, opacity 0.2s;
}

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

.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

/* Navigation */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    height: var(--nav-height);
    background: rgba(11, 17, 32, 0.85);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid rgba(255, 255, 255, 0.06);
    transition: background 0.3s;
}

.navbar .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 100%;
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.15rem;
    font-weight: 700;
    color: var(--white);
    letter-spacing: 0.5px;
}

.logo-icon {
    width: 36px;
    height: 36px;
    background: var(--gradient);
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.logo-icon svg {
    width: 22px;
    height: 22px;
    fill: white;
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 32px;
    list-style: none;
}

.nav-links a {
    color: var(--text-light);
    font-size: 0.9rem;
    font-weight: 500;
}

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

.nav-cta {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 10px 22px;
    background: var(--gradient);
    color: var(--white) !important;
    border-radius: 50px;
    font-size: 0.875rem;
    font-weight: 600;
    box-shadow: 0 4px 16px rgba(14, 165, 233, 0.35);
}

.nav-cta:hover {
    opacity: 0.9;
    transform: translateY(-1px);
}

.nav-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
}

.nav-toggle span {
    display: block;
    width: 22px;
    height: 2px;
    background: var(--white);
    margin: 5px 0;
    transition: 0.3s;
}

/* Hero */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    background: var(--bg-dark);
    padding-top: var(--nav-height);
    overflow: hidden;
}

.hero-bg {
    position: absolute;
    inset: 0;
    background:
        radial-gradient(ellipse 80% 60% at 70% 40%, rgba(14, 165, 233, 0.18) 0%, transparent 60%),
        radial-gradient(ellipse 50% 50% at 20% 80%, rgba(6, 182, 212, 0.12) 0%, transparent 50%),
        var(--bg-dark);
}

.hero-grid {
    position: absolute;
    inset: 0;
    background-image:
        linear-gradient(rgba(255, 255, 255, 0.03) 1px, transparent 1px),
        linear-gradient(90deg, rgba(255, 255, 255, 0.03) 1px, transparent 1px);
    background-size: 60px 60px;
    mask-image: radial-gradient(ellipse 70% 70% at 50% 50%, black 20%, transparent 80%);
}

.hero .container {
    position: relative;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
    padding-top: 60px;
    padding-bottom: 80px;
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 6px 16px;
    background: rgba(14, 165, 233, 0.12);
    border: 1px solid rgba(14, 165, 233, 0.3);
    border-radius: 50px;
    color: var(--accent);
    font-size: 0.8rem;
    font-weight: 600;
    margin-bottom: 24px;
    letter-spacing: 1px;
}

.hero-badge::before {
    content: '';
    width: 6px;
    height: 6px;
    background: var(--accent);
    border-radius: 50%;
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0%, 100% { opacity: 1; transform: scale(1); }
    50% { opacity: 0.5; transform: scale(1.3); }
}

.hero h1 {
    font-size: clamp(2.2rem, 5vw, 3.5rem);
    font-weight: 800;
    color: var(--white);
    line-height: 1.2;
    margin-bottom: 20px;
    letter-spacing: -0.5px;
}

.hero h1 span {
    background: var(--gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-desc {
    font-size: 1.1rem;
    color: var(--text-light);
    margin-bottom: 36px;
    max-width: 480px;
    line-height: 1.8;
}

.hero-actions {
    display: flex;
    gap: 16px;
    flex-wrap: wrap;
    margin-bottom: 48px;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 14px 28px;
    border-radius: 50px;
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    border: none;
    transition: all 0.2s;
}

.btn-primary {
    background: var(--gradient);
    color: var(--white);
    box-shadow: 0 4px 20px rgba(14, 165, 233, 0.4);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 28px rgba(14, 165, 233, 0.5);
}

.btn-outline {
    background: transparent;
    color: var(--white);
    border: 1px solid rgba(255, 255, 255, 0.25);
}

.btn-outline:hover {
    border-color: rgba(255, 255, 255, 0.5);
    background: rgba(255, 255, 255, 0.05);
}

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

.stat-item strong {
    display: block;
    font-size: 1.8rem;
    font-weight: 800;
    color: var(--white);
    line-height: 1;
    margin-bottom: 4px;
}

.stat-item span {
    font-size: 0.8rem;
    color: var(--text-light);
}

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

.drone-scene {
    position: relative;
    width: 100%;
    max-width: 480px;
    aspect-ratio: 1;
}

.drone-ring {
    position: absolute;
    border-radius: 50%;
    border: 1px solid rgba(14, 165, 233, 0.2);
    animation: rotate 20s linear infinite;
}

.drone-ring:nth-child(1) {
    inset: 5%;
    animation-duration: 25s;
}

.drone-ring:nth-child(2) {
    inset: 15%;
    animation-duration: 18s;
    animation-direction: reverse;
    border-color: rgba(6, 182, 212, 0.15);
}

.drone-ring:nth-child(3) {
    inset: 25%;
    animation-duration: 12s;
    border-color: rgba(34, 211, 238, 0.1);
}

@keyframes rotate {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

.drone-center {
    position: absolute;
    inset: 30%;
    background: rgba(14, 165, 233, 0.08);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 1px solid rgba(14, 165, 233, 0.2);
}

.drone-center svg {
    width: 60%;
    height: 60%;
}

.floating-card {
    position: absolute;
    background: rgba(17, 24, 39, 0.9);
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: 12px;
    padding: 12px 16px;
    backdrop-filter: blur(8px);
    animation: float 4s ease-in-out infinite;
}

.floating-card:nth-child(5) {
    top: 10%;
    right: 0;
    animation-delay: 0s;
}

.floating-card:nth-child(6) {
    bottom: 15%;
    left: -5%;
    animation-delay: 1.5s;
}

.floating-card:nth-child(7) {
    top: 50%;
    right: -8%;
    animation-delay: 3s;
}

@keyframes float {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-10px); }
}

.floating-card .card-label {
    font-size: 0.7rem;
    color: var(--text-light);
    margin-bottom: 2px;
}

.floating-card .card-value {
    font-size: 0.95rem;
    font-weight: 700;
    color: var(--white);
}

.floating-card .card-value.green { color: #34d399; }

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

.section-header {
    text-align: center;
    margin-bottom: 64px;
}

.section-tag {
    display: inline-block;
    padding: 4px 14px;
    background: rgba(14, 165, 233, 0.1);
    color: var(--primary);
    border-radius: 50px;
    font-size: 0.8rem;
    font-weight: 600;
    letter-spacing: 1px;
    margin-bottom: 16px;
}

.section-header h2 {
    font-size: clamp(1.8rem, 3.5vw, 2.5rem);
    font-weight: 800;
    color: var(--text);
    margin-bottom: 16px;
    letter-spacing: -0.3px;
}

.section-header p {
    font-size: 1.05rem;
    color: var(--text-muted);
    max-width: 560px;
    margin: 0 auto;
}

/* Features */
.features {
    background: var(--bg-light);
}

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

.feature-card {
    background: var(--white);
    border-radius: var(--radius);
    padding: 32px 24px;
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.04);
    border: 1px solid rgba(0, 0, 0, 0.04);
    transition: transform 0.2s, box-shadow 0.2s;
}

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

.feature-icon {
    width: 52px;
    height: 52px;
    background: rgba(14, 165, 233, 0.1);
    border-radius: 14px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 20px;
    font-size: 1.5rem;
}

.feature-card h3 {
    font-size: 1.05rem;
    font-weight: 700;
    margin-bottom: 10px;
    color: var(--text);
}

.feature-card p {
    font-size: 0.875rem;
    color: var(--text-muted);
    line-height: 1.7;
    margin: 0;
}

/* Courses */
.courses-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.course-card {
    position: relative;
    border-radius: var(--radius);
    overflow: hidden;
    background: var(--bg-card);
    aspect-ratio: 4/3;
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
    padding: 28px;
    cursor: default;
    transition: transform 0.3s;
}

.course-card::before {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(to top, rgba(11, 17, 32, 0.95) 0%, rgba(11, 17, 32, 0.3) 60%, transparent 100%);
    z-index: 1;
}

.course-card:hover {
    transform: scale(1.02);
}

.course-card-bg {
    position: absolute;
    inset: 0;
    z-index: 0;
}

.course-card-bg.c1 { background: linear-gradient(135deg, #0c4a6e, #0369a1); }
.course-card-bg.c2 { background: linear-gradient(135deg, #164e63, #0891b2); }
.course-card-bg.c3 { background: linear-gradient(135deg, #1e3a5f, #1d4ed8); }
.course-card-bg.c4 { background: linear-gradient(135deg, #134e4a, #0d9488); }
.course-card-bg.c5 { background: linear-gradient(135deg, #312e81, #4f46e5); }
.course-card-bg.c6 { background: linear-gradient(135deg, #4a044e, #a21caf); }

.course-card-content {
    position: relative;
    z-index: 2;
}

.course-tag {
    display: inline-block;
    padding: 3px 10px;
    background: rgba(14, 165, 233, 0.3);
    border-radius: 4px;
    font-size: 0.7rem;
    color: #7dd3fc;
    font-weight: 600;
    margin-bottom: 10px;
}

.course-card h3 {
    font-size: 1.15rem;
    font-weight: 700;
    color: var(--white);
    margin-bottom: 6px;
}

.course-card p {
    font-size: 0.8rem;
    color: var(--text-light);
    margin: 0;
}

/* Steps */
.steps {
    background: var(--bg-dark);
}

.steps .section-header h2,
.steps .section-header p {
    color: var(--white);
}

.steps .section-header p {
    color: var(--text-light);
}

.steps .section-tag {
    background: rgba(14, 165, 233, 0.15);
    color: var(--accent);
}

.steps-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 0;
    position: relative;
}

.steps-grid::before {
    content: '';
    position: absolute;
    top: 40px;
    left: calc(16.67% + 24px);
    right: calc(16.67% + 24px);
    height: 2px;
    background: linear-gradient(90deg, var(--primary), var(--accent), var(--primary));
    opacity: 0.3;
}

.step-item {
    text-align: center;
    padding: 0 24px;
}

.step-num {
    width: 80px;
    height: 80px;
    background: rgba(14, 165, 233, 0.1);
    border: 2px solid rgba(14, 165, 233, 0.3);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 24px;
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--accent);
    position: relative;
    z-index: 1;
}

.step-item h3 {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--white);
    margin-bottom: 10px;
}

.step-item p {
    font-size: 0.875rem;
    color: var(--text-light);
    line-height: 1.7;
    margin: 0;
}

/* CTA */
.cta {
    background: var(--bg-light);
}

.cta-box {
    background: var(--gradient);
    border-radius: 24px;
    padding: 64px;
    display: grid;
    grid-template-columns: 1fr auto;
    gap: 40px;
    align-items: center;
    position: relative;
    overflow: hidden;
}

.cta-box::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -10%;
    width: 400px;
    height: 400px;
    background: rgba(255, 255, 255, 0.08);
    border-radius: 50%;
}

.cta-content {
    position: relative;
    z-index: 1;
}

.cta-content h2 {
    font-size: 2rem;
    font-weight: 800;
    color: var(--white);
    margin-bottom: 12px;
}

.cta-content p {
    font-size: 1rem;
    color: rgba(255, 255, 255, 0.85);
    margin: 0;
}

.cta-qr {
    position: relative;
    z-index: 1;
    background: var(--white);
    border-radius: 16px;
    padding: 20px;
    text-align: center;
    min-width: 160px;
}

.qr-placeholder {
    width: 120px;
    height: 120px;
    background: #f1f5f9;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 10px;
    font-size: 0.75rem;
    color: var(--text-muted);
    border: 2px dashed #cbd5e1;
}

.cta-qr p {
    font-size: 0.8rem;
    color: var(--text-muted);
    margin: 0;
}

/* Footer */
.footer {
    background: var(--bg-dark);
    padding: 48px 0 32px;
    border-top: 1px solid rgba(255, 255, 255, 0.06);
}

.footer .container {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 16px;
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1rem;
    font-weight: 700;
    color: var(--white);
}

.footer p {
    font-size: 0.85rem;
    color: var(--text-light);
    margin: 0;
    text-align: center;
}

.footer a {
    color: var(--text-light);
}

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

.footer-links {
    display: flex;
    gap: 24px;
    list-style: none;
    margin-bottom: 8px;
}

.footer-links a {
    font-size: 0.85rem;
}

/* Responsive */
@media (max-width: 1024px) {
    .features-grid {
        grid-template-columns: repeat(2, 1fr);
    }

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

@media (max-width: 768px) {
    .nav-links {
        display: none;
        position: absolute;
        top: var(--nav-height);
        left: 0;
        right: 0;
        background: rgba(11, 17, 32, 0.97);
        flex-direction: column;
        padding: 24px;
        gap: 20px;
        border-bottom: 1px solid rgba(255, 255, 255, 0.06);
    }

    .nav-links.open {
        display: flex;
    }

    .nav-toggle {
        display: block;
    }

    .hero .container {
        grid-template-columns: 1fr;
        gap: 40px;
        text-align: center;
    }

    .hero-desc {
        margin-left: auto;
        margin-right: auto;
    }

    .hero-actions {
        justify-content: center;
    }

    .hero-stats {
        justify-content: center;
    }

    .hero-visual {
        order: -1;
    }

    .drone-scene {
        max-width: 300px;
    }

    .floating-card:nth-child(6),
    .floating-card:nth-child(7) {
        display: none;
    }

    .features-grid,
    .courses-grid,
    .steps-grid {
        grid-template-columns: 1fr;
    }

    .steps-grid::before {
        display: none;
    }

    .cta-box {
        grid-template-columns: 1fr;
        padding: 40px 28px;
        text-align: center;
    }

    .cta-qr {
        margin: 0 auto;
    }

    section {
        padding: 72px 0;
    }
}