:root {
  --color-bg: #ffffff;
  --color-text: #0a0a0a;
  --color-accent: #0033ff;
  --font-heading: 'Space Grotesk', sans-serif;
  --font-body: 'IBM Plex Sans', sans-serif;
  --nav-height: 72px;
  --space-1: 8px;
  --space-2: 16px;
  --space-3: 24px;
  --space-4: 40px;
  --space-5: 64px;
  --space-6: 96px;
}

*, *::before, *::after {
  box-sizing: border-box;
  border-radius: 0 !important;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--nav-height);
}

body {
  margin: 0;
  background: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.6;
}

h1, h2, h3 {
  font-family: var(--font-heading);
  font-weight: 700;
  line-height: 1.15;
  margin: 0 0 var(--space-2) 0;
}

h1 { font-size: 48px; }
h2 { font-size: 32px; }
h3 { font-size: 20px; }

p { margin: 0 0 var(--space-2) 0; }

a {
  color: var(--color-accent);
  text-decoration: none;
}

a:hover { text-decoration: underline; }

.container {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 var(--space-3);
}

section {
  padding: var(--space-6) 0;
}

.btn {
  display: inline-block;
  background: var(--color-accent);
  color: #ffffff;
  font-family: var(--font-heading);
  font-weight: 700;
  padding: var(--space-2) var(--space-3);
  border: 2px solid var(--color-accent);
  cursor: pointer;
  transition: transform 0.15s ease, background-color 0.15s ease, color 0.15s ease;
}

.btn:hover {
  background: #ffffff;
  color: var(--color-accent);
  text-decoration: none;
  transform: translateY(-2px);
}

.btn:active {
  transform: translateY(0);
}

.btn-outline {
  background: #ffffff;
  color: var(--color-text);
  border: 2px solid var(--color-text);
}

.btn-outline:hover {
  background: var(--color-text);
  color: #ffffff;
}

#site-nav {
  position: sticky;
  top: 0;
  min-height: var(--nav-height);
  background: var(--color-bg);
  border-bottom: 2px solid var(--color-text);
  z-index: 100;
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: var(--nav-height);
  padding-top: var(--space-2);
  padding-bottom: var(--space-2);
}

.nav-name {
  font-family: var(--font-heading);
  font-weight: 700;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

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

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

.nav-resume {
  font-size: 14px;
  opacity: 0.7;
}

#nav-toggle {
  display: none;
  background: none;
  border: 2px solid var(--color-text);
  font-size: 20px;
  padding: 4px 10px;
  cursor: pointer;
}

@media (max-width: 720px) {
  #nav-toggle { display: block; }

  .nav-links {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--color-bg);
    border-bottom: 2px solid var(--color-text);
    flex-direction: column;
    align-items: flex-start;
    gap: 0;
    padding: var(--space-2) var(--space-3);
  }

  .nav-links a {
    padding: var(--space-1) 0;
    width: 100%;
  }

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

#hero {
  padding-top: var(--space-6);
  padding-bottom: var(--space-6);
}

.hero-inner {
  max-width: 700px;
}

.hero-subline {
  font-size: 18px;
  max-width: 560px;
}

#about {
  border-top: 2px solid var(--color-text);
}

#about .container p {
  max-width: 640px;
}

#case-studies {
  border-top: 2px solid var(--color-text);
  background: #fafafa;
}

.case-study {
  padding: var(--space-4) 0;
  border-bottom: 1px solid #ddd;
  transition: padding-left 0.2s ease, border-left-color 0.2s ease;
  border-left: 4px solid transparent;
}

.case-study:hover {
  padding-left: var(--space-2);
  border-left-color: var(--color-accent);
}

.case-study:last-child { border-bottom: none; }

.case-study h4 {
  font-family: var(--font-heading);
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-accent);
  margin-bottom: 4px;
}

.case-study > div { margin-bottom: var(--space-2); }

.cs-metric {
  font-family: var(--font-heading);
  font-size: 24px;
  font-weight: 700;
}

#skills {
  border-top: 2px solid var(--color-text);
}

.skills-grid {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
}

.skill-tag {
  border: 2px solid var(--color-text);
  padding: var(--space-1) var(--space-2);
  font-family: var(--font-heading);
  font-size: 14px;
  transition: background-color 0.15s ease, color 0.15s ease;
}

.skill-tag:hover {
  background: var(--color-text);
  color: #ffffff;
}

#testimonials {
  border-top: 2px solid var(--color-text);
  background: #fafafa;
}

.testimonial-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-3);
}

.testimonial {
  margin: 0;
  padding: var(--space-3);
  border-left: 4px solid var(--color-accent);
  background: var(--color-bg);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.testimonial:hover {
  transform: translateY(-4px);
  box-shadow: 4px 4px 0 var(--color-text);
}

.testimonial cite {
  display: block;
  margin-top: var(--space-1);
  font-style: normal;
  font-weight: 500;
  opacity: 0.7;
}

@media (max-width: 720px) {
  .testimonial-grid { grid-template-columns: 1fr; }
}

#contact {
  border-top: 2px solid var(--color-text);
  text-align: center;
}

#contact p {
  max-width: 480px;
  margin-left: auto;
  margin-right: auto;
}

.contact-links {
  display: flex;
  gap: var(--space-2);
  justify-content: center;
  margin-top: var(--space-3);
}

footer {
  border-top: 2px solid var(--color-text);
  padding: var(--space-3) 0;
  font-size: 14px;
  opacity: 0.6;
}

.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}

.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

@keyframes hero-fade-up {
  from { opacity: 0; transform: translateY(16px); }
  to { opacity: 1; transform: translateY(0); }
}

.hero-inner h1 {
  animation: hero-fade-up 0.6s ease both;
}

.hero-inner .hero-subline {
  animation: hero-fade-up 0.6s ease 0.1s both;
}

.hero-inner .btn {
  animation: hero-fade-up 0.6s ease 0.2s both;
}

.cs-diagram {
  margin-bottom: var(--space-3);
}

.cs-diagram svg {
  display: block;
  width: 100%;
  height: auto;
  max-width: 480px;
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

  .reveal {
    opacity: 1;
    transform: none;
    transition: none;
  }

  .hero-inner h1,
  .hero-inner .hero-subline,
  .hero-inner .btn {
    animation: none;
  }

  .btn:hover,
  .testimonial:hover,
  .case-study:hover {
    transform: none;
  }
}