:root{--primary-color:#2c3e50;--secondary-color:#2270a0;--accent-color:#e74c3c;--text-color:#333;--light-bg:#f8f9fa;--white:#fff;--dark-bg:#2c3e50;--dark-text:#ecf0f1;--shadow:0 2px 10px rgba(0,0,0,0.1);--border-radius:8px;--transition:all .3s ease;--menu-width:5px}*{margin:0;padding:0;box-sizing:border-box}html{scroll-behavior:smooth;overflow-x:hidden}body{font-family:'Segoe UI',Tahoma,Geneva,Verdana,sans-serif;line-height:1.6;color:var(--text-color);background-color:var(--light-bg);overflow-x:hidden}.visually-hidden{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}header{background:var(--white);box-shadow:var(--shadow);position:sticky;top:0;z-index:100}.nav-container{max-width:1200px;margin:0 auto;padding:0 1rem;display:flex;justify-content:space-between;align-items:center;height:70px}.logo{color:var(--primary-color);font-size:1.5rem;font-weight:bold}.nav-menu{display:flex;list-style:none;gap:2rem}.nav-menu a{text-decoration:none;color:var(--text-color);font-weight:500;padding:.5rem 1rem;border-radius:var(--border-radius);transition:var(--transition)}.nav-menu a:hover,.nav-menu a:focus,.nav-menu a[aria-current="page"]{background:var(--secondary-color);color:var(--white)}.mobile-menu-toggle{display:none;flex-direction:column;background:0;border:0;cursor:pointer;padding:.5rem;gap:4px}.hamburger-line{width:25px;height:3px;background:var(--primary-color);transition:var(--transition)}.hero{background:linear-gradient(135deg,var(--primary-color),var(--secondary-color));color:var(--white);padding:4rem 1rem}.hero-content{max-width:1200px;margin:0 auto;display:flex;align-items:center;justify-content:space-between;gap:3rem}.hero-text{flex:1;text-align:left}.hero-text h1{font-size:2.5rem;margin-bottom:1rem}.hero-text p{font-size:1.2rem;margin-bottom:2rem;opacity:.9}.hero-image{flex-shrink:0}.cta-button{display:inline-block;background:var(--accent-color);color:black;padding:.75rem 2rem;text-decoration:none;border-radius:var(--border-radius);font-weight:bold;transition:var(--transition)}.cta-button:hover,.cta-button:focus{background:#c0392b;transform:translateY(-2px)}.content-section{padding:4rem 1rem}.dark-section{background:var(--dark-bg);color:var(--dark-text)}.container{max-width:1200px;margin:0 auto}.section-title{text-align:center;margin-bottom:3rem;font-size:2rem;color:var(--primary-color)}.dark-section .section-title{color:var(--dark-text)}.image-container{width:100%;margin-bottom:1.5rem}.image-container img{width:100%;height:auto;border-radius:calc(var(--border-radius) - 2px);transition:var(--transition)}.image-container img:hover{transform:scale(1.1)}.section-image{width:100%;margin:2rem 0 3rem 0;text-align:center}.section-image img{max-width:100%;overflow:hidden;transition:var(--transition)}.section-image img:hover{transform:scale(1.15);filter:brightness(1.2)}.hero-image img{max-width:800px;border-radius:var(--border-radius);animation:spin 10s linear infinite}@keyframes spin{from{transform:rotate(0)}to{transform:rotate(360deg)}}.shape-image-item img{width:auto;height:267px;max-width:100%;object-fit:cover}.card{background:var(--white);padding:2rem;border-radius:var(--border-radius);box-shadow:var(--shadow);text-align:center}.card-small{padding:1.5rem !important}.card-small>h3{padding-bottom:.75rem}.dark-section .card{background:#34495e}.card-grid{display:grid;gap:2rem;margin:2rem 0}.text-content{max-width:800px;margin:0 auto}.text-content p{margin-bottom:1.5rem}.conclusion{font-style:italic;border-left:4px solid var(--secondary-color);padding-left:1rem;margin-top:2rem}.contrast-grid{grid-template-columns:repeat(auto-fit,minmax(300px,1fr))}.contrast-item{padding:2rem;border-radius:var(--border-radius);color:white;text-align:center;min-height:200px;display:flex;flex-direction:column;justify-content:center}.bw-contrast{background:linear-gradient(135deg,#000,#fff);color:#333;text-shadow:1px 1px 1px #fff,1px 1px 5px #ccc}.bw-contrast h3{color:#333}.complementary{background:linear-gradient(135deg,#f00,#0f0,#00f,#ff0)}.gray-scale-demo{max-width:800px;margin:0 auto;text-align:center}.gray-bar{display:flex;height:80px;margin:1.5rem 0;border-radius:var(--border-radius);overflow:hidden;box-shadow:0 3px 10px rgba(0,0,0,0.1)}.gray-step{flex:1;display:flex;align-items:center;justify-content:center;font-weight:bold;color:white;text-shadow:0 1px 2px rgba(0,0,0,0.5);transition:var(--transition)}.gray-step:hover{transform:scale(1.05);z-index:1;position:relative}.step-1{background:#fff;color:#222}.step-2{background:#ccc;color:#2c2c2c}.step-3{background:#999;color:#2c2c2c}.step-4{background:#666}.step-5{background:#333}.list{list-style:none;margin-top:1rem;text-align:left}.list li{padding:.5rem 0;border-bottom:1px solid #eee}.dark-section .list li{border-bottom:1px solid #4a6572}footer{background:var(--primary-color);color:var(--white);text-align:center;padding:2rem 1rem;margin-top:4rem}