:root {
     /* PRIMARY COLORS */
     --color-primary: #667eea;
     --color-primary-dark: #444444;
     --color-primary-light: #b4c0f0;

     /* NEUTRAL COLORS */
     --color-white: #ffffff;
     --color-black: #000000;
     --color-light-gray: #f8f8f8;
     --color-medium-gray: #f0f0f0;
     --color-dark-gray: #666666;
     --color-text-dark: #333333;
     --color-text-light: #999999;

     /* BACKGROUND COLORS */
     --color-bg-primary: #ffffff;
     --color-bg-secondary: #000000;
     --color-bg-overlay: #222222;

     /* ACCENT COLORS */
     --color-accent: #667eea;
     --color-accent-hover: #4b4b4b;

     /* BORDERS & SHADOWS */
     --color-border: #e0e0e0;
     --color-border-dark: #333333;
     --shadow-sm: 0 2px 10px rgba(0, 0, 0, 0.05);
     --shadow-md: 0 10px 40px rgba(0, 0, 0, 0.1);
     --shadow-lg: 0 20px 60px rgba(0, 0, 0, 0.15);

     /* GRADIENTS */
     --gradient-primary: linear-gradient(135deg, #667eea 0%, #575757 100%);
     --gradient-overlay: linear-gradient(135deg, rgba(102, 126, 234, 0.6) 0%, rgba(136, 136, 136, 0.6) 100%);
     --gradient-bg: linear-gradient(45deg, #f0f0f0, #e0e0e0);

     /* ANIMATION DURATIONS */
     --duration-fast: 0.3s;
     --duration-normal: 0.5s;
     --easing: cubic-bezier(0.4, 0, 0.2, 1);
 }

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

 body {
     font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
     background: var(--color-bg-primary);
     color: var(--color-black);
     line-height: 1.6;
     overflow-x: hidden;
 }

 /* NOVÉ STYLE PRO OBRÁZKY S FILL EFEKTY */
 .profile-image,
 .about-image,
 .project-image {
     position: relative;
     overflow: hidden;
     background-size: cover !important;
     background-position: center !important;
     transition: all 0.5s cubic-bezier(0.4, 0, 0.2, 1);
 }

 .profile-image::before,
 .about-image::before,
 .project-image::before {
     content: '';
     position: absolute;
     top: 0;
     left: 0;
     right: 0;
     bottom: 0;
     background: linear-gradient(135deg, rgba(102, 126, 234, 0.6) 0%, rgba(85, 85, 85, 0.6) 100%);
     opacity: 0;
     transition: opacity 0.4s ease;
     z-index: 1;
 }

 .profile-image:hover::before,
 .about-image:hover::before,
 .project-image:hover::before {
     opacity: 1;
 }

 .profile-image img,
 .about-image img,
 .project-image img {
     width: 100%;
     height: 100%;
     object-fit: cover;
     transition: all 0.6s cubic-bezier(0.4, 0, 0.2, 1);
     filter: grayscale(20%) brightness(0.9);
 }

 .profile-image:hover img,
 .about-image:hover img,
 .project-image:hover img {
     transform: scale(1.05);
     filter: grayscale(0%) brightness(1.1);
 }

 .profile-image .icon-overlay,
 .about-image .icon-overlay {
     position: absolute;
     top: 50%;
     left: 50%;
     transform: translate(-50%, -50%);
     font-size: 4rem;
     color: white;
     opacity: 0;
     z-index: 2;
     transition: opacity 0.3s ease;
     text-shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
 }

 .profile-image:hover .icon-overlay,
 .about-image:hover .icon-overlay {
     opacity: 1;
 }

 .project-image .icon-overlay {
     position: absolute;
     top: 50%;
     left: 50%;
     transform: translate(-50%, -50%);
     font-size: 3rem;
     color: white;
     opacity: 0;
     z-index: 2;
     transition: opacity 0.3s ease;
     text-shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
 }

 .project-image:hover .icon-overlay {
     opacity: 1;
 }

 /* Loading Screen */
 .loader {
     position: fixed;
     top: 0;
     left: 0;
     width: 100%;
     height: 100%;
     background: var(--color-bg-primary);
     display: flex;
     justify-content: center;
     align-items: center;
     z-index: 10000;
     transition: opacity 0.5s, visibility 0.5s;
 }

 .loader.hidden {
     opacity: 0;
     visibility: hidden;
 }

 .spinner {
     width: 50px;
     height: 50px;
     border: 3px solid var(--color-medium-gray);
     border-top: 3px solid var(--color-black);
     border-radius: 50%;
     animation: spin 1s linear infinite;
 }

 @keyframes spin {
     0% {
         transform: rotate(0deg);
     }

     100% {
         transform: rotate(360deg);
     }
 }

 .container {
     max-width: 1200px;
     margin: 0 auto;
     padding: 0 20px;
 }

 /* Hero Section */
 .hero {
     min-height: 100vh;
     display: flex;
     align-items: center;
     justify-content: center;
     text-align: center;
     position: relative;
     overflow: hidden;
 }

 .hero::before {
     content: '';
     position: absolute;
     width: 500px;
     height: 500px;
     background: linear-gradient(45deg, #f0f0f0, #e0e0e0);
     border-radius: 50%;
     top: -250px;
     right: -250px;
     opacity: 0.3;
 }

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

 .profile-image {
     width: 180px;
     height: 180px;
     border-radius: 50%;
     margin: 0 auto 30px;
     display: flex;
     align-items: center;
     justify-content: center;
     box-shadow: 0 20px 60px rgba(0, 0, 0, 0.1);
 }

 h1 {
     font-size: 4em;
     font-weight: 700;
     margin-bottom: 20px;
     letter-spacing: -2px;
     background: var(--color-bg-overlay);
     -webkit-background-clip: text;
     -webkit-text-fill-color: transparent;
     background-clip: text;
 }

 .hero-subtitle {
     font-size: 1.5em;
     color: var(--color-dark-gray);
     font-weight: 300;
     margin-bottom: 40px;
 }

 .cta-buttons {
     display: flex;
     gap: 20px;
     justify-content: center;
     flex-wrap: wrap;
 }

 .btn {
     padding: 15px 40px;
     border: 2px solid var(--color-black);
     background: var(--color-black);
     color: var(--color-white);
     text-decoration: none;
     border-radius: 50px;
     font-weight: 500;
     transition: all var(--duration-fast);
     cursor: pointer;
     font-size: 1em;
 }

 .btn:hover {
     background: var(--color-white);
     color: var(--color-black);
     transform: translateY(-3px);
     box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
 }

 .btn-outline {
     background: var(--color-white);
     color: var(--color-black);
 }

 .btn-outline:hover {
     background: var(--color-black);
     color: var(--color-white);
 }

 /* Navigation */
 nav {
     position: sticky;
     top: 0;
     background: rgba(255, 255, 255, 0.95);
     backdrop-filter: blur(10px);
     padding: 20px 0;
     border-bottom: 2px solid var(--color-border);
     z-index: 1000;
 }

 .nav-container {
     display: flex;
     justify-content: center;
     gap: 40px;
     flex-wrap: wrap;
 }

 nav button {
     background: none;
     border: none;
     font-size: 1.1em;
     color: var(--color-dark-gray);
     cursor: pointer;
     padding: 10px 20px;
     transition: all var(--duration-fast);
     font-weight: 500;
     position: relative;
 }

 nav button::after {
     content: '';
     position: absolute;
     bottom: 0;
     left: 50%;
     transform: translateX(-50%);
     width: 0;
     height: 2px;
     background: var(--color-black);
     transition: width var(--duration-fast);
 }

 nav button:hover::after,
 nav button.active::after {
     width: 100%;
 }

 nav button:hover,
 nav button.active {
     color: var(--color-black);
 }

 /* Sections */
 .section {
     padding: 100px 0;
     display: none;
 }

 .section.active {
     display: block;
 }

 h2 {
     font-size: 3em;
     font-weight: 700;
     margin-bottom: 20px;
     letter-spacing: -1px;
     text-align: center;
     color: var(--color-black);
 }

 .section-subtitle {
     text-align: center;
     font-size: 1.2em;
     color: var(--color-dark-gray);
     margin-bottom: 60px;
     max-width: 600px;
     margin-left: auto;
     margin-right: auto;
 }

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

 .about-image {
     width: 100%;
     height: 400px;
     border-radius: 20px;
     display: flex;
     align-items: center;
     justify-content: center;
     box-shadow: 0 20px 60px rgba(0, 0, 0, 0.15);
 }

 .about-text p {
     margin-bottom: 20px;
     color: var(--color-text-dark);
     font-size: 1.1em;
     line-height: 1.8;
 }

 .skills {
     display: grid;
     grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
     gap: 20px;
     margin-top: 40px;
 }

 .skill-card {
     padding: 30px;
     background: var(--color-light-gray);
     border-radius: 15px;
     text-align: center;
     transition: all var(--duration-fast);
     border: 2px solid transparent;
 }

 .skill-card:hover {
     transform: translateY(-10px);
     box-shadow: var(--shadow-md);
     border-color: var(--color-accent);
 }

 .skill-icon {
     font-size: 2.5em;
     margin-bottom: 15px;
 }

 .skill-name {
     font-weight: 600;
     font-size: 1.1em;
     color: var(--color-black);
 }

 /* Portfolio Section */
 .portfolio-grid {
     display: grid;
     grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
     gap: 40px;
     margin-top: 60px;
 }

 .project-card {
     background: var(--color-white);
     border-radius: 20px;
     overflow: hidden;
     box-shadow: var(--shadow-md);
     transition: all var(--duration-fast);
     border: 1px solid var(--color-medium-gray);
 }

 .project-card:hover {
     transform: translateY(-10px);
     box-shadow: var(--shadow-lg);
 }

 .project-image {
     width: 100%;
     height: 250px;
     display: flex;
     align-items: center;
     justify-content: center;
 }

 .project-content {
     padding: 30px;
 }

 .project-card h3 {
     font-size: 1.5em;
     font-weight: 600;
     margin-bottom: 15px;
     color: var(--color-black);
 }

 .project-desc {
     color: var(--color-dark-gray);
     margin-bottom: 20px;
     line-height: 1.6;
 }

 .tech-stack {
     display: flex;
     gap: 10px;
     flex-wrap: wrap;
     margin-bottom: 20px;
 }

 .tech {
     padding: 8px 16px;
     background: var(--color-medium-gray);
     border-radius: 20px;
     font-size: 0.85em;
     color: var(--color-dark-gray);
     font-weight: 500;
     display: flex;
     align-items: center;
     gap: 6px;
 }

 .tech img {
     width: 16px;
     height: 16px;
     object-fit: contain;
 }

 .project-link {
     display: inline-block;
     color: var(--color-accent);
     text-decoration: none;
     font-weight: 600;
     transition: all var(--duration-fast);
 }

 .project-link:hover {
     transform: translateX(5px);
 }

 /* Contact Section */
 .contact-container {
     max-width: 800px;
     margin: 0 auto;
 }

 .contact-grid {
     display: grid;
     grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
     gap: 30px;
     margin-top: 60px;
 }

 .contact-card {
     background: var(--color-light-gray);
     padding: 40px;
     border-radius: 20px;
     text-align: center;
     transition: all var(--duration-fast);
     border: 2px solid transparent;
 }

 .contact-card:hover {
     transform: translateY(-10px);
     box-shadow: var(--shadow-md);
     border-color: var(--color-accent);
     background: var(--color-white);
 }

 .contact-icon {
     font-size: 3em;
     margin-bottom: 20px;
 }

 .contact-card h3 {
     font-size: 1.2em;
     margin-bottom: 10px;
     font-weight: 600;
     color: var(--color-black);
 }

 .contact-card a {
     color: var(--color-dark-gray);
     text-decoration: none;
     transition: color var(--duration-fast);
 }

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

 /* Footer */
 footer {
     background: var(--color-bg-secondary);
     color: var(--color-white);
     padding: 60px 0 30px;
     margin-top: 100px;
 }

 .footer-content {
     display: grid;
     grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
     gap: 40px;
     margin-bottom: 40px;
 }

 .footer-section h3 {
     font-size: 1.3em;
     margin-bottom: 20px;
     font-weight: 600;
     color: var(--color-white);
 }

 .footer-section p {
     color: var(--color-text-light);
     line-height: 1.8;
 }

 .footer-links {
     list-style: none;
 }

 .footer-links li {
     margin-bottom: 12px;
 }

 .footer-links a {
     color: var(--color-text-light);
     text-decoration: none;
     transition: color var(--duration-fast);
 }

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

 .social-links {
     display: flex;
     gap: 15px;
 }

 .social-link {
     width: 40px;
     height: 40px;
     background: var(--color-bg-overlay);
     border-radius: 50%;
     display: flex;
     align-items: center;
     justify-content: center;
     color: var(--color-white);
     text-decoration: none;
     transition: all var(--duration-fast);
     font-size: 1.2em;
 }

 .social-link:hover {
     background: var(--color-accent);
     transform: translateY(-3px);
 }

 .footer-bottom {
     border-top: 1px solid var(--color-border-dark);
     padding-top: 30px;
     text-align: center;
     color: var(--color-text-light);
 }

 /* Scroll to top button */
 .scroll-top {
     position: fixed;
     bottom: 30px;
     right: 30px;
     width: 50px;
     height: 50px;
     background: var(--color-black);
     color: var(--color-white);
     border: none;
     border-radius: 50%;
     cursor: pointer;
     display: none;
     align-items: center;
     justify-content: center;
     font-size: 1.5em;
     transition: all var(--duration-fast);
     z-index: 1000;
 }

 .scroll-top.visible {
     display: flex;
 }

 .scroll-top:hover {
     background: var(--color-accent);
     transform: translateY(-5px);
 }

 @media (max-width: 768px) {
     h1 {
         font-size: 2.5em;
     }

     h2 {
         font-size: 2em;
     }

     .about-content {
         grid-template-columns: 1fr;
     }

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

     .nav-container {
         gap: 15px;
     }

     nav button {
         font-size: 0.95em;
         padding: 8px 15px;
     }

     .profile-image {
         width: 150px;
         height: 150px;
     }

     .project-image {
         height: 220px;
     }
 }