/* ============================================
   George Mouratidis — Personal Site
   Minimal & Modern Design System
   ============================================ */

:root {
  --color-black: #0a0a0a;
  --color-dark: #1a1a1a;
  --color-gray-900: #262626;
  --color-gray-700: #525252;
  --color-gray-500: #737373;
  --color-gray-400: #a3a3a3;
  --color-gray-200: #e5e5e5;
  --color-gray-100: #f5f5f5;
  --color-white: #fafafa;
  --color-accent: #2563eb;
  --color-accent-light: #3b82f6;

  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'SF Mono', 'Fira Code', monospace;

  --max-width: 1120px;
  --header-height: 72px;
}

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

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  color: var(--color-gray-700);
  background: var(--color-white);
}

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

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

/* ============================================
   Typography
   ============================================ */

h1, h2, h3, h4 {
  color: var(--color-black);
  font-weight: 600;
  line-height: 1.2;
  letter-spacing: -0.02em;
}

h1 { font-size: clamp(2.5rem, 5vw, 3.75rem); }
h2 { font-size: clamp(1.75rem, 3vw, 2.5rem); }
h3 { font-size: 1.25rem; }
h4 { font-size: 1rem; }

p {
  max-width: 640px;
}

.text-sm { font-size: 0.875rem; }
.text-xs { font-size: 0.75rem; letter-spacing: 0.05em; text-transform: uppercase; }
.text-muted { color: var(--color-gray-500); }
.text-accent { color: var(--color-accent); }

/* ============================================
   Layout
   ============================================ */

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 2rem;
}

.section {
  padding: 6rem 0;
}

.section-lg {
  padding: 8rem 0;
}

/* ============================================
   Header / Navigation
   ============================================ */

.header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(250, 250, 250, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-gray-200);
  height: var(--header-height);
  display: flex;
  align-items: center;
}

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

.header__logo {
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--color-black);
  letter-spacing: -0.01em;
}

.header__nav {
  display: flex;
  align-items: center;
  gap: 2rem;
  list-style: none;
}

.header__nav a {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-gray-500);
  transition: color 0.2s ease;
}

.header__nav a:hover,
.header__nav a.active {
  color: var(--color-black);
}

.header__cta {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-white) !important;
  background: var(--color-black);
  padding: 0.5rem 1.25rem;
  border-radius: 6px;
  transition: opacity 0.2s ease;
}

.header__cta:hover {
  opacity: 0.8;
}

/* Mobile nav */
.mobile-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
}

.mobile-toggle span {
  display: block;
  width: 20px;
  height: 2px;
  background: var(--color-black);
  margin: 4px 0;
  transition: 0.2s;
}

/* ============================================
   Hero
   ============================================ */

.hero {
  padding: 8rem 0 6rem;
}

.hero__label {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: 1.5rem;
}

.hero h1 {
  margin-bottom: 1.5rem;
}

.hero p {
  font-size: 1.125rem;
  color: var(--color-gray-500);
  line-height: 1.7;
  margin-bottom: 2.5rem;
}

.hero__actions {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  flex-wrap: wrap;
}

/* ============================================
   Buttons
   ============================================ */

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.9375rem;
  font-weight: 500;
  padding: 0.75rem 1.5rem;
  border-radius: 8px;
  transition: all 0.2s ease;
  cursor: pointer;
  border: none;
  font-family: inherit;
}

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

.btn-primary:hover {
  opacity: 0.85;
}

.btn-secondary {
  background: transparent;
  color: var(--color-gray-700);
  border: 1px solid var(--color-gray-200);
}

.btn-secondary:hover {
  border-color: var(--color-gray-400);
}

.btn-text {
  background: none;
  padding: 0;
  color: var(--color-gray-700);
  font-weight: 500;
}

.btn-text:hover {
  color: var(--color-black);
}

.btn-text .arrow {
  transition: transform 0.2s ease;
}

.btn-text:hover .arrow {
  transform: translateX(3px);
}

/* ============================================
   Metrics Row
   ============================================ */

.metrics {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 2rem;
  padding: 3rem 0;
  border-top: 1px solid var(--color-gray-200);
  border-bottom: 1px solid var(--color-gray-200);
}

.metric {
  text-align: center;
}

.metric__value {
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--color-black);
  letter-spacing: -0.03em;
  line-height: 1;
  margin-bottom: 0.5rem;
}

.metric__label {
  font-size: 0.8125rem;
  color: var(--color-gray-500);
}

/* ============================================
   Cards
   ============================================ */

.card-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.5rem;
}

.card {
  padding: 2rem;
  border: 1px solid var(--color-gray-200);
  border-radius: 12px;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.card:hover {
  border-color: var(--color-gray-400);
  box-shadow: 0 4px 24px rgba(0,0,0,0.04);
}

.card__company {
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: 0.75rem;
}

.card h3 {
  margin-bottom: 0.75rem;
}

.card p {
  font-size: 0.9375rem;
  color: var(--color-gray-500);
  line-height: 1.6;
}

.card__stats {
  display: flex;
  gap: 2rem;
  margin-top: 1.5rem;
  padding-top: 1.25rem;
  border-top: 1px solid var(--color-gray-200);
}

.card__stat-value {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-black);
  letter-spacing: -0.02em;
}

.card__stat-label {
  font-size: 0.75rem;
  color: var(--color-gray-500);
  margin-top: 0.125rem;
}

/* Featured card (full-width) */
.card-featured {
  grid-column: 1 / -1;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: center;
}

/* ============================================
   Publication Logos
   ============================================ */

.logos-row {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 3rem;
  padding: 2rem 0;
  flex-wrap: wrap;
}

.logos-row span {
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-gray-400);
  white-space: nowrap;
}

/* ============================================
   Section Headers
   ============================================ */

.section-header {
  margin-bottom: 3rem;
}

.section-header h2 {
  margin-bottom: 0.75rem;
}

.section-header p {
  color: var(--color-gray-500);
  font-size: 1.0625rem;
}

/* ============================================
   About Page
   ============================================ */

.about-intro {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
  align-items: start;
}

.about-intro__text p {
  font-size: 1.0625rem;
  line-height: 1.8;
  color: var(--color-gray-700);
  margin-bottom: 1.5rem;
}

.about-photo {
  width: 100%;
  border-radius: 12px;
  aspect-ratio: 4/5;
  object-fit: cover;
}

.timeline {
  position: relative;
  padding-left: 2rem;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0.5rem;
  bottom: 0.5rem;
  width: 1px;
  background: var(--color-gray-200);
}

.timeline__item {
  position: relative;
  padding-bottom: 2.5rem;
}

.timeline__item:last-child {
  padding-bottom: 0;
}

.timeline__item::before {
  content: '';
  position: absolute;
  left: -2rem;
  top: 0.375rem;
  width: 7px;
  height: 7px;
  background: var(--color-accent);
  border-radius: 50%;
  transform: translateX(-3px);
}

.timeline__date {
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--color-gray-400);
  margin-bottom: 0.375rem;
}

.timeline__item h3 {
  margin-bottom: 0.25rem;
}

.timeline__item h4 {
  color: var(--color-gray-500);
  font-weight: 500;
  margin-bottom: 0.5rem;
}

.timeline__item p {
  font-size: 0.9375rem;
  color: var(--color-gray-500);
}

/* ============================================
   Credentials
   ============================================ */

.credentials-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
}

.credential {
  padding: 1.5rem;
  border: 1px solid var(--color-gray-200);
  border-radius: 10px;
}

.credential__type {
  font-size: 0.6875rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: 0.5rem;
}

.credential h4 {
  font-size: 0.9375rem;
  margin-bottom: 0.25rem;
}

.credential p {
  font-size: 0.8125rem;
  color: var(--color-gray-500);
}

/* ============================================
   Portfolio Page
   ============================================ */

.portfolio-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.5rem;
}

.portfolio-item {
  padding: 2rem;
  border: 1px solid var(--color-gray-200);
  border-radius: 12px;
  transition: border-color 0.2s ease;
}

.portfolio-item:hover {
  border-color: var(--color-gray-400);
}

.portfolio-item__pub {
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: 0.5rem;
}

.portfolio-item h3 {
  margin-bottom: 0.5rem;
}

.portfolio-item p {
  font-size: 0.9375rem;
  color: var(--color-gray-500);
  margin-bottom: 1.25rem;
}

.portfolio-item__link {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-black);
  display: inline-flex;
  align-items: center;
  gap: 0.375rem;
}

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

/* Ventures */
.ventures-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
}

.venture {
  padding: 2rem;
  background: var(--color-gray-100);
  border-radius: 12px;
}

.venture h3 {
  margin-bottom: 0.5rem;
}

.venture p {
  font-size: 0.9375rem;
  color: var(--color-gray-500);
  margin-bottom: 1rem;
}

.venture__badge {
  display: inline-block;
  font-size: 0.6875rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  padding: 0.25rem 0.75rem;
  border-radius: 100px;
  background: var(--color-gray-200);
  color: var(--color-gray-700);
}

/* ============================================
   Contact Page
   ============================================ */

.contact-layout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
  align-items: start;
}

.contact-info {
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

.contact-item {
  display: flex;
  align-items: flex-start;
  gap: 1rem;
}

.contact-item__icon {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-gray-100);
  border-radius: 8px;
  flex-shrink: 0;
}

.contact-item h4 {
  font-size: 0.875rem;
  margin-bottom: 0.125rem;
}

.contact-item p,
.contact-item a {
  font-size: 0.9375rem;
  color: var(--color-gray-500);
}

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

.contact-form {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.form-group label {
  display: block;
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--color-gray-700);
  margin-bottom: 0.375rem;
}

.form-group input,
.form-group textarea {
  width: 100%;
  padding: 0.75rem 1rem;
  border: 1px solid var(--color-gray-200);
  border-radius: 8px;
  font-family: inherit;
  font-size: 0.9375rem;
  color: var(--color-dark);
  background: var(--color-white);
  transition: border-color 0.2s ease;
  outline: none;
}

.form-group input:focus,
.form-group textarea:focus {
  border-color: var(--color-accent);
}

.form-group textarea {
  min-height: 140px;
  resize: vertical;
}

/* ============================================
   Footer
   ============================================ */

.footer {
  border-top: 1px solid var(--color-gray-200);
  padding: 2.5rem 0;
}

.footer .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.footer p {
  font-size: 0.8125rem;
  color: var(--color-gray-400);
}

.footer__links {
  display: flex;
  gap: 1.5rem;
}

.footer__links a {
  font-size: 0.8125rem;
  color: var(--color-gray-400);
  transition: color 0.2s ease;
}

.footer__links a:hover {
  color: var(--color-black);
}

/* ============================================
   Responsive
   ============================================ */

@media (max-width: 768px) {
  .header__nav {
    display: none;
  }

  .mobile-toggle {
    display: block;
  }

  /* Mobile nav overlay */
  .header__nav.open {
    display: flex;
    flex-direction: column;
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--color-white);
    padding: 2rem;
    gap: 1.5rem;
    z-index: 99;
  }

  .header__nav.open a {
    font-size: 1.125rem;
  }

  .hero {
    padding: 4rem 0 3rem;
  }

  .metrics {
    grid-template-columns: repeat(2, 1fr);
    gap: 1.5rem;
  }

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

  .card-featured {
    grid-template-columns: 1fr;
  }

  .about-intro {
    grid-template-columns: 1fr;
    gap: 2rem;
  }

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

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

  .contact-layout {
    grid-template-columns: 1fr;
    gap: 3rem;
  }

  .footer .container {
    flex-direction: column;
    gap: 1rem;
    text-align: center;
  }

  .logos-row {
    gap: 1.5rem;
  }

  .section {
    padding: 4rem 0;
  }

  .section-lg {
    padding: 5rem 0;
  }
}