:root {
    --bg-color: #ffffff;
    --text-color: #333333;
    --text-muted: #888888;
    --accent-primary: #000000;
    --border-color: #eaeaea;
    --font-main: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --border-radius: 8px;
}

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

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    font-family: var(--font-main);
    line-height: 1.6;
    overflow-x: hidden;
    scroll-behavior: smooth;
}

/* Navbar */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(5px);
    z-index: 1000;
    padding: 1.5rem 2rem;
    border-bottom: 1px solid var(--border-color);
}

.navbar ul {
    list-style: none;
    display: flex;
    justify-content: center;
    gap: 3rem;
}

.navbar a {
    color: var(--text-muted);
    text-decoration: none;
    font-weight: 500;
    font-size: 1rem;
    transition: color 0.3s ease;
}

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

/* Sections */
.section {
    padding: 8rem 2rem 4rem;
    min-height: 60vh;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.section-title {
    font-size: 2rem;
    font-weight: 600;
    margin-bottom: 3rem;
    color: var(--accent-primary);
}

.section-divider {
    border: none;
    border-top: 1px solid var(--border-color);
    width: 80%;
    max-width: 1000px;
    margin: 0 auto;
}

/* Hero Section */
.hero {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
}

.hero-content h1 {
    font-size: 4rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--accent-primary);
    letter-spacing: -1px;
}

.hero-avatar {
    width: 180px;
    height: 180px;
    object-fit: cover;
    border-radius: 24px;
    margin-bottom: 1.5rem;
    border: 3px solid var(--border-color);
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.05);
    background-color: #f5f5f5; /* 占位背景色 */
}

.hero-content p {
    font-size: 1.2rem;
    color: var(--text-muted);
}

/* Industrial Robotic Arm and Drone (Side View) */
.industrial-robot-container {
    position: relative;
    width: 650px;
    height: 300px;
    margin: 50px auto 0;
    display: flex;
    justify-content: flex-start;
    align-items: flex-end;
    /* Optional: scale down if needed */
    transform: scale(0.85);
    background: transparent;
}

.ind-arm-group {
    position: absolute;
    left: 120px;
    bottom: 0;
    width: 350px;
    height: 300px;
}

/* Industrial Drone */
.ind-drone {
    position: absolute;
    top: 60px;
    left: 10px;
    width: 100px;
    height: 60px;
    animation: droneFloat 3s ease-in-out infinite;
    z-index: 10;
}

@keyframes droneFloat {
    0%, 100% { transform: translateY(0) rotate(2deg); }
    50% { transform: translateY(-15px) rotate(-1deg); }
}

.drone-body {
    position: absolute;
    top: 20px;
    left: 20px;
    width: 60px;
    height: 16px;
    background: linear-gradient(to bottom, var(--ind-metal), var(--ind-trim));
    border-radius: 4px 8px 8px 4px;
    border: 2px solid var(--ind-dark);
    box-shadow: 0 5px 15px rgba(0,0,0,0.3);
    z-index: 2;
}

.drone-body::after {
    /* red recording indicator */
    content: '';
    position: absolute;
    top: 3px;
    left: 45px;
    width: 6px;
    height: 6px;
    background: var(--ind-accent);
    border-radius: 50%;
    box-shadow: 0 0 5px var(--ind-accent);
}

.drone-arm {
    position: absolute;
    top: 25px;
    width: 35px;
    height: 4px;
    background: var(--ind-trim);
    border: 1px solid var(--ind-dark);
    z-index: 1;
}
.drone-arm.front { left: -5px; transform: rotate(-20deg); transform-origin: right center;}
.drone-arm.back { right: -5px; transform: rotate(20deg); transform-origin: left center;}

.drone-motor {
    position: absolute;
    top: 10px;
    width: 10px;
    height: 12px;
    background: var(--ind-dark);
    border-radius: 2px;
    border-top: 2px solid var(--ind-light);
    z-index: 3;
}
.drone-motor.front-motor { left: -10px; }
.drone-motor.back-motor { right: -10px; }

.drone-blade {
    position: absolute;
    top: -6px;
    left: -15px;
    width: 40px;
    height: 4px;
    background: linear-gradient(to right, transparent, rgba(55, 65, 81, 0.85) 20%, rgba(55, 65, 81, 0.85) 80%, transparent);
    border-radius: 50%;
    animation: bladeSpin 0.08s linear infinite;
    box-shadow: 0 0 6px rgba(31, 41, 55, 0.5);
}

@keyframes bladeSpin {
    0% { transform: scaleX(1); opacity: 1; }
    50% { transform: scaleX(0.15); opacity: 0.5; }
    100% { transform: scaleX(1); opacity: 1; }
}

.drone-cam {
    position: absolute;
    bottom: 12px;
    left: 50%;
    transform: translateX(-50%);
    width: 14px;
    height: 10px;
    background: var(--ind-dark);
    border-radius: 4px 4px 8px 8px;
    border: 2px solid var(--ind-trim);
    z-index: 1;
}
.drone-cam::after {
    content: '';
    position: absolute;
    bottom: 1px;
    left: 3px;
    width: 4px;
    height: 4px;
    background: #3b82f6; /* camera lens reflex */
    border-radius: 50%;
}

.drone-leg {
    position: absolute;
    top: 36px;
    width: 2px;
    height: 16px;
    background: var(--ind-dark);
    z-index: 0;
}
.drone-leg.left { left: 30px; transform: rotate(20deg); }
.drone-leg.right { right: 30px; transform: rotate(-20deg); }

.drone-skid {
    position: absolute;
    bottom: -2px;
    left: -8px;
    width: 18px;
    height: 2px;
    background: var(--ind-trim);
    border-radius: 2px;
}

/* Industrial Smart Glasses (Front View) */
.ind-glasses {
    position: absolute;
    top: 100px;
    right: 20px;
    width: 100px;
    height: 45px;
    animation: glassesFloat 4s ease-in-out infinite reverse;
    z-index: 10;
}

@keyframes glassesFloat {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-8px); }
}

.glasses-bridge {
    position: absolute;
    top: 15px;
    left: 50%;
    transform: translateX(-50%);
    width: 24px;
    height: 6px;
    background: linear-gradient(to bottom, var(--ind-metal), var(--ind-trim));
    border-radius: 2px;
    border: 1px solid var(--ind-dark);
    z-index: 2;
}

.glasses-frame {
    position: absolute;
    top: 10px;
    width: 44px;
    height: 24px;
    background: var(--ind-dark);
    border: 2px solid var(--ind-metal);
    border-radius: 6px;
    box-shadow: 0 4px 10px rgba(0,0,0,0.3);
    z-index: 3;
}

.glasses-frame.left-frame {
    left: 0;
}

.glasses-frame.right-frame {
    right: 0;
}

.glasses-lens {
    position: absolute;
    top: 2px;
    left: 2px;
    width: calc(100% - 4px);
    height: calc(100% - 4px);
    background: rgba(59, 130, 246, 0.7);
    border-radius: 4px;
    box-shadow: inset 0 0 10px rgba(59, 130, 246, 0.5), 0 0 8px rgba(59, 130, 246, 0.4);
    overflow: hidden;
}

.glasses-lens::before {
    /* 反光特效 */
    content: '';
    position: absolute;
    top: -10px;
    left: -15px;
    width: 20px;
    height: 40px;
    background: rgba(255, 255, 255, 0.3);
    transform: rotate(30deg);
}

.glasses-temple {
    position: absolute;
    top: 10px;
    width: 20px;
    height: 4px;
    background: linear-gradient(to right, var(--ind-trim), rgba(31,41,55,0.2));
    z-index: 1;
}

.glasses-temple.left-temple {
    left: -8px;
    transform-origin: right center;
    transform: rotate(15deg);
    border-radius: 2px 0 0 2px;
}

.glasses-temple.right-temple {
    right: -8px;
    background: linear-gradient(to left, var(--ind-trim), rgba(31,41,55,0.2));
    transform-origin: left center;
    transform: rotate(-15deg);
    border-radius: 0 2px 2px 0;
}

.glasses-hub {
    position: absolute;
    top: -8px;
    right: -4px;
    width: 14px;
    height: 10px;
    background: var(--ind-dark);
    border: 1px solid var(--ind-light);
    border-radius: 2px;
}

.glasses-hub::after {
    /* 运行指示红灯 */
    content: '';
    position: absolute;
    top: 2px;
    left: 4px;
    width: 4px;
    height: 4px;
    background: var(--ind-accent);
    border-radius: 50%;
    box-shadow: 0 0 4px var(--ind-accent);
}

/* Colors for Industrial Theme */
:root {
    --ind-light: #e5e7eb;   /* Light metallic */
    --ind-dark: #1f2937;    /* Dark structure */
    --ind-metal: #9ca3af;   /* Base metal */
    --ind-accent: #ef4444;  /* Red indicator */
    --ind-trim: #4b5563;    /* Metallic borders */
}

.ind-base {
    position: absolute;
    bottom: 0;
    left: 40px;
    width: 140px;
    height: 30px;
    background: linear-gradient(to right, #374151, #1f2937);
    border-radius: 8px 8px 4px 4px;
    box-shadow: 0 10px 20px rgba(0,0,0,0.3);
    border-bottom: 4px solid #111827;
    z-index: 1;
}

.ind-base::before {
    content: '';
    position: absolute;
    top: 5px;
    left: 10px;
    width: calc(100% - 20px);
    height: 4px;
    background: rgba(255,255,255,0.1);
    border-radius: 2px;
}

.ind-base-mount {
    position: absolute;
    bottom: 30px;
    left: 80px;
    width: 60px;
    height: 50px;
    background: linear-gradient(to bottom, #d1d5db, #9ca3af);
    box-shadow: inset 0 0 10px rgba(0,0,0,0.5), -5px 0 15px rgba(0,0,0,0.2);
    border-radius: 6px 6px 0 0;
    border: 2px solid var(--ind-trim);
    z-index: 2;
}

.ind-shoulder {
    position: absolute;
    bottom: 60px;
    left: 110px;
    width: 70px;
    height: 70px;
    background: linear-gradient(135deg, #4b5563, #374151);
    border-radius: 50%;
    transform: translate(-50%, -50%);
    box-shadow: 2px 5px 15px rgba(0,0,0,0.4), inset 2px 2px 5px rgba(255,255,255,0.2);
    border: 4px solid var(--ind-light);
    z-index: 3;
    display: flex;
    justify-content: center;
    align-items: center;
}

.ind-joint-center {
    width: 25px;
    height: 25px;
    background: #111827;
    border-radius: 50%;
    box-shadow: inset 0 2px 4px rgba(0,0,0,0.8);
    position: relative;
}

.ind-joint-center::after {
    content: '';
    position: absolute;
    top: 50%; left: 50%;
    transform: translate(-50%, -50%);
    width: 10px; height: 10px;
    background: #4b5563;
    border-radius: 50%;
}

.ind-joint-center.small {
    width: 16px;
    height: 16px;
}

.ind-joint-center.small::after {
    width: 6px;
    height: 6px;
}

.ind-lower-arm {
    position: absolute;
    top: 50%;
    left: 50%;
    width: 140px;
    height: 35px;
    background: linear-gradient(to bottom, #e5e7eb, #9ca3af);
    border-radius: 20px;
    transform-origin: 35px center; /* left coordinate approx */
    transform: translate(-35px, -50%) rotate(-45deg);
    border: 2px solid var(--ind-trim);
    box-shadow: 0 8px 15px rgba(0,0,0,0.3);
    z-index: 4;
}

.ind-arm-detail {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 60px;
    height: 8px;
    background: #374151;
    border-radius: 4px;
    opacity: 0.8;
}

.ind-elbow {
    position: absolute;
    right: 0;
    top: 50%;
    width: 50px;
    height: 50px;
    background: linear-gradient(135deg, #6b7280, #374151);
    border-radius: 50%;
    transform: translate(50%, -50%); /* translate right to the edge */
    border: 3px solid var(--ind-light);
    box-shadow: 2px 5px 15px rgba(0,0,0,0.4);
    display: flex;
    justify-content: center;
    align-items: center;
}

.ind-upper-arm {
    position: absolute;
    top: 50%;
    left: 50%;
    width: 110px;
    height: 25px;
    background: linear-gradient(to bottom, #d1d5db, #6b7280);
    border-radius: 15px;
    transform-origin: 25px center;
    transform: translate(-25px, -50%) rotate(75deg);
    border: 2px solid var(--ind-dark);
    box-shadow: 0 5px 10px rgba(0,0,0,0.3);
}

.ind-wrist {
    position: absolute;
    right: -10px;
    top: 50%;
    width: 30px;
    height: 30px;
    background: #374151;
    border-radius: 50%;
    transform: translateY(-50%);
    border: 2px solid #9ca3af;
    display: flex;
    justify-content: center;
    align-items: center;
}

.ind-gripper-base {
    position: absolute;
    right: -40px;
    top: 50%;
    width: 40px;
    height: 35px;
    background: #4b5563;
    transform: translateY(-50%) rotate(0deg);
    border-radius: 4px 10px 10px 4px;
    border: 2px solid #1f2937;
    border-left: none;
}

.ind-finger {
    position: absolute;
    right: -30px;
    width: 35px;
    height: 8px;
    background: #6b7280;
    border-radius: 0 4px 4px 0;
    border: 2px solid #1f2937;
    border-left: none;
}

.top-finger {
    top: 4px;
    transform-origin: left center;
    transform: rotate(-10deg);
}

.bottom-finger {
    bottom: 4px;
    transform-origin: left center;
    transform: rotate(10deg);
}

/* Cards & Elements */
.card {
    max-width: 700px;
    text-align: center;
    font-size: 1.1rem;
    color: var(--text-color);
}

.about-card {
    text-align: left;
    padding: 3rem;
    background: #fff;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    box-shadow: 0 10px 30px rgba(0,0,0,0.03);
}

.intro-text {
    font-size: 1.2rem;
    line-height: 1.8;
    margin-bottom: 2.5rem;
    color: var(--accent-primary);
}

.intro-text strong {
    font-weight: 600;
}

.about-details {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
    border-top: 1px solid var(--border-color);
    padding-top: 2rem;
}

.detail-item h4 {
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--text-muted);
    margin-bottom: 0.5rem;
}

.detail-item p {
    font-size: 1.1rem;
    color: var(--text-color);
}

@media (max-width: 600px) {
    .about-details {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }
}

.project-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    width: 100%;
    max-width: 1000px;
}

.project-card {
    padding: 2rem;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    background: #fff;
}

.project-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 20px rgba(0,0,0,0.05);
}

.project-card h3 {
    margin-bottom: 0.5rem;
    font-size: 1.3rem;
    color: var(--accent-primary);
}

.project-card p {
    color: var(--text-muted);
}

.testimonial-slider {
    display: flex;
    gap: 2rem;
    flex-wrap: wrap;
    justify-content: center;
    max-width: 1000px;
}

.testimonial-item {
    border-left: 2px solid var(--border-color);
    padding: 1.5rem 2rem;
    max-width: 400px;
}

.testimonial-item p {
    font-style: italic;
    color: var(--text-muted);
}

.testimonial-item span {
    display: block;
    margin-top: 1rem;
    font-size: 0.9rem;
    font-weight: 600;
}

.contact-card {
    text-align: center;
}

.contact-card p {
    margin-bottom: 1.5rem;
}

.btn {
    display: inline-block;
    padding: 1rem 2rem;
    background: var(--accent-primary);
    color: #fff;
    text-decoration: none;
    border-radius: var(--border-radius);
    margin: 1.5rem 0 2rem;
    transition: background 0.3s ease;
}

.btn:hover {
    background: #555;
}

.social-links {
    display: flex;
    justify-content: center;
    gap: 1.5rem;
}

.social-links a {
    color: var(--text-muted);
    text-decoration: none;
    transition: color 0.3s ease;
}

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

footer {
    text-align: center;
    padding: 3rem;
    color: var(--text-muted);
    font-size: 0.9rem;
    border-top: 1px solid var(--border-color);
}

@media (max-width: 768px) {
    .navbar ul {
        gap: 1rem;
    }
    .hero-content h1 {
        font-size: 2.5rem;
    }
}