/* ===== Variables ===== */
  :root {
    --color-bg: #0f0f12;
    --color-surface: #18181d;
    --color-surface-elevated: #222228;
    --color-text: #e8e8ed;
    --color-text-muted: #9898a6;
    --color-accent: #f59e0b;
    --color-accent-hover: #fbbf24;
    --color-border: #2d2d35;
    --font-sans: 'Outfit', -apple-system, BlinkMacSystemFont, sans-serif;
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --header-height: 72px;
    --container-max: 1100px;
    --transition: 0.2s ease;
  }

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

  html {
    scroll-behavior: smooth;
  }

  body {
    font-family: var(--font-sans);
    background: var(--color-bg);
    color: var(--color-text);
    line-height: 1.6;
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
  }

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

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

  ul {
    list-style: none;
  }

  /* ===== Layout ===== */
  .container {
    width: 100%;
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 1.5rem;
  }

  /* ===== Header & Navigation ===== */
  .header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    height: var(--header-height);
    background: rgba(15, 15, 18, 0.85);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--color-border);
    transition: background var(--transition), border-color var(--transition);
  }

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

  .logo {
    font-weight: 700;
    font-size: 1.25rem;
    letter-spacing: -0.02em;
    color: var(--color-text);
  }

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

  .nav-toggle {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 6px;
    width: 40px;
    height: 40px;
    background: transparent;
    border: none;
    cursor: pointer;
    padding: 8px;
    color: var(--color-text);
  }

  .nav-toggle span {
    display: block;
    width: 100%;
    height: 2px;
    background: currentColor;
    border-radius: 2px;
    transition: transform var(--transition), opacity var(--transition);
  }

  .nav-toggle[aria-expanded="true"] span:nth-child(1) {
    transform: translateY(8px) rotate(45deg);
  }

  .nav-toggle[aria-expanded="true"] span:nth-child(2) {
    opacity: 0;
  }

  .nav-toggle[aria-expanded="true"] span:nth-child(3) {
    transform: translateY(-8px) rotate(-45deg);
  }

  .nav-list {
    display: flex;
    align-items: center;
    gap: 2rem;
  }

  .nav-link {
    font-weight: 500;
    font-size: 0.95rem;
    color: var(--color-text-muted);
    transition: color var(--transition);
  }

  .nav-link:hover,
  .nav-link:focus {
    color: var(--color-accent);
  }

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

  .hero-bg {
    position: absolute;
    inset: 0;
    background:
      radial-gradient(ellipse 80% 50% at 50% -20%, rgba(245, 158, 11, 0.15), transparent),
      radial-gradient(ellipse 60% 40% at 100% 50%, rgba(245, 158, 11, 0.08), transparent),
      url("https://images.pexels.com/photos/2739792/pexels-photo-2739792.jpeg?auto=compress&cs=tinysrgb&w=1920") center / cover no-repeat;
    z-index: -1;
  }

  .hero-bg::after {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(to bottom, rgba(15, 15, 18, 0.4) 0%, var(--color-bg) 85%);
  }

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

  .hero-title {
    font-size: clamp(2.25rem, 5vw, 3.5rem);
    font-weight: 700;
    line-height: 1.15;
    letter-spacing: -0.03em;
    margin-bottom: 1rem;
  }

  .hero-title-accent {
    color: var(--color-accent);
  }

  .hero-desc {
    font-size: 1.125rem;
    color: var(--color-text-muted);
    max-width: 480px;
    margin-bottom: 2rem;
  }

  .btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.875rem 1.75rem;
    font-family: var(--font-sans);
    font-size: 1rem;
    font-weight: 600;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: background var(--transition), transform var(--transition);
  }

  .btn-primary {
    background: var(--color-accent);
    color: #0f0f12;
  }

  .btn-primary:hover {
    background: var(--color-accent-hover);
    transform: translateY(-1px);
  }

  .btn-full {
    width: 100%;
  }

  /* ===== Section common ===== */
  .section-title {
    font-size: clamp(1.75rem, 4vw, 2.25rem);
    font-weight: 700;
    letter-spacing: -0.02em;
    margin-bottom: 0.5rem;
  }

  .section-desc {
    color: var(--color-text-muted);
    margin-bottom: 2.5rem;
  }

  /* ===== Projects ===== */
  .projects {
    padding: 5rem 0;
  }

  .project-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
  }

  .project-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    overflow: hidden;
    transition: border-color var(--transition), transform var(--transition), box-shadow 0.3s ease;
  }

  .project-card:hover {
    border-color: var(--color-accent);
    transform: translateY(-4px);
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.3);
  }

  .project-card-image {
    aspect-ratio: 3 / 2;
    overflow: hidden;
    background: var(--color-surface-elevated);
  }

  .project-card-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.4s ease;
  }

  .project-card:hover .project-card-image img {
    transform: scale(1.05);
  }

  .project-card-body {
    padding: 1.5rem;
  }

  .project-card-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
  }

  .project-card-desc {
    font-size: 0.95rem;
    color: var(--color-text-muted);
    margin-bottom: 1rem;
    line-height: 1.5;
  }

  .project-card-link {
    font-weight: 500;
    font-size: 0.9rem;
    color: var(--color-accent);
    transition: color var(--transition), gap var(--transition);
  }

  .project-card-link:hover {
    color: var(--color-accent-hover);
  }

  /* ===== Contact ===== */
  .contact {
    padding: 5rem 0;
    background: var(--color-surface);
  }

  .contact-form {
    max-width: 520px;
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
  }

  .form-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
  }

  .form-group label {
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--color-text-muted);
  }

  .form-group input,
  .form-group textarea {
    width: 100%;
    padding: 0.875rem 1rem;
    font-family: var(--font-sans);
    font-size: 1rem;
    color: var(--color-text);
    background: var(--color-bg);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    transition: border-color var(--transition), box-shadow var(--transition);
  }

  .form-group input::placeholder,
  .form-group textarea::placeholder {
    color: var(--color-text-muted);
    opacity: 0.8;
  }

  .form-group input:focus,
  .form-group textarea:focus {
    outline: none;
    border-color: var(--color-accent);
    box-shadow: 0 0 0 3px rgba(245, 158, 11, 0.2);
  }

  .form-group input.invalid,
  .form-group textarea.invalid {
    border-color: #ef4444;
  }

  .form-group .error-msg {
    font-size: 0.85rem;
    color: #ef4444;
  }

  /* ===== Footer ===== */
  .footer {
    padding: 1.5rem 0;
    border-top: 1px solid var(--color-border);
  }

  .footer-text {
    font-size: 0.9rem;
    color: var(--color-text-muted);
    text-align: center;
  }

  /* ===== Responsive ===== */
  @media (max-width: 768px) {
    .nav-toggle {
      display: flex;
    }

    .nav {
      position: fixed;
      top: var(--header-height);
      left: 0;
      right: 0;
      background: var(--color-surface);
      border-bottom: 1px solid var(--color-border);
      padding: 1rem;
      transform: translateY(-100%);
      opacity: 0;
      visibility: hidden;
      transition: transform var(--transition), opacity var(--transition), visibility var(--transition);
    }

    .nav.is-open {
      transform: translateY(0);
      opacity: 1;
      visibility: visible;
    }

    .nav-list {
      flex-direction: column;
      gap: 0;
    }

    .nav-list li {
      width: 100%;
      border-bottom: 1px solid var(--color-border);
    }

    .nav-list li:last-child {
      border-bottom: none;
    }

    .nav-link {
      display: block;
      padding: 1rem;
      font-size: 1rem;
    }

    .hero {
      min-height: 90vh;
    }

    .hero-desc {
      font-size: 1rem;
    }

    .projects,
    .contact {
      padding: 3.5rem 0;
    }

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

  @media (max-width: 480px) {
    .container {
      padding: 0 1rem;
    }

    .project-card-body {
      padding: 1.25rem;
    }
  }