/* ───────────────────────────────────────
   Design Tokens
   ─────────────────────────────────────── */
:root {
  --font-display: 'Space Grotesk', system-ui, sans-serif;
  --font-body: 'Inter', system-ui, sans-serif;

  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  --ease-in-out: cubic-bezier(0.65, 0, 0.35, 1);

  --nav-h: 64px;
  --container: 1120px;
  --container-narrow: 760px;
  --radius: 12px;
  --radius-sm: 8px;
}

[data-theme="dark"] {
  --bg-primary: #0a0a0f;
  --bg-secondary: #111118;
  --bg-card: #16161e;
  --bg-card-hover: #1e1e28;
  --text-primary: #e8e8ed;
  --text-secondary: #9494a3;
  --text-muted: #5c5c6e;
  --accent: #6c63ff;
  --accent-glow: rgba(108, 99, 255, 0.25);
  --accent-hover: #7b73ff;
  --border: rgba(255, 255, 255, 0.06);
  --border-hover: rgba(255, 255, 255, 0.12);
  --tag-bg: rgba(108, 99, 255, 0.12);
  --tag-text: #9d96ff;
  --shadow: 0 4px 24px rgba(0, 0, 0, 0.4);
  --nav-bg: rgba(10, 10, 15, 0.85);
  --timeline-line: rgba(108, 99, 255, 0.2);
}

[data-theme="light"] {
  --bg-primary: #fafafa;
  --bg-secondary: #f0f0f3;
  --bg-card: #ffffff;
  --bg-card-hover: #f5f5fa;
  --text-primary: #1a1a2e;
  --text-secondary: #555566;
  --text-muted: #888899;
  --accent: #5a4fff;
  --accent-glow: rgba(90, 79, 255, 0.15);
  --accent-hover: #4a3fef;
  --border: rgba(0, 0, 0, 0.07);
  --border-hover: rgba(0, 0, 0, 0.14);
  --tag-bg: rgba(90, 79, 255, 0.08);
  --tag-text: #5a4fff;
  --shadow: 0 4px 24px rgba(0, 0, 0, 0.06);
  --nav-bg: rgba(250, 250, 250, 0.85);
  --timeline-line: rgba(90, 79, 255, 0.2);
}

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

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

body {
  font-family: var(--font-body);
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

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

ul { list-style: none; }

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

/* ───────────────────────────────────────
   Layout
   ─────────────────────────────────────── */
.container {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 24px;
}

.container--narrow {
  max-width: var(--container-narrow);
}

.section {
  padding: 100px 0;
}

.section--alt {
  background: var(--bg-secondary);
}

.section__title {
  font-family: var(--font-display);
  font-size: clamp(1.8rem, 4vw, 2.4rem);
  font-weight: 700;
  margin-bottom: 48px;
  position: relative;
  display: inline-block;
}

.section__title::after {
  content: '';
  display: block;
  width: 48px;
  height: 3px;
  background: var(--accent);
  border-radius: 2px;
  margin-top: 12px;
}

/* ───────────────────────────────────────
   Navigation
   ─────────────────────────────────────── */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-h);
  background: var(--nav-bg);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border);
  z-index: 1000;
  transition: box-shadow 0.3s var(--ease-out);
}

.nav--scrolled {
  box-shadow: var(--shadow);
}

.nav__inner {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  height: 100%;
  gap: 32px;
}

.nav__logo {
  font-family: var(--font-display);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--accent);
  flex-shrink: 0;
}

.nav__links {
  display: flex;
  gap: 8px;
  margin-left: auto;
}

.nav__links a {
  padding: 6px 14px;
  border-radius: 6px;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: color 0.2s, background 0.2s;
}

.nav__links a:hover,
.nav__links a.active {
  color: var(--text-primary);
  background: var(--border);
}

.nav__toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
  margin-left: auto;
}

.nav__toggle span {
  width: 24px;
  height: 2px;
  background: var(--text-primary);
  border-radius: 2px;
  transition: transform 0.3s, opacity 0.3s;
}

.theme-toggle {
  background: none;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 8px;
  cursor: pointer;
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: color 0.2s, border-color 0.2s;
  flex-shrink: 0;
}

.theme-toggle:hover {
  color: var(--accent);
  border-color: var(--accent);
}

[data-theme="dark"] .icon-sun { display: block; }
[data-theme="dark"] .icon-moon { display: none; }
[data-theme="light"] .icon-sun { display: none; }
[data-theme="light"] .icon-moon { display: block; }

/* ───────────────────────────────────────
   Hero
   ─────────────────────────────────────── */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 48px;
  position: relative;
  padding: calc(var(--nav-h) + 40px) 24px 80px;
  max-width: var(--container);
  margin: 0 auto;
}

.hero__content {
  max-width: 580px;
  flex: 1;
}

.hero__photo {
  flex-shrink: 0;
}

.hero__photo img {
  width: 280px;
  height: 280px;
  border-radius: 50%;
  object-fit: cover;
  border: 4px solid var(--accent);
  box-shadow: 0 0 40px var(--accent-glow), 0 8px 32px rgba(0, 0, 0, 0.3);
  transition: transform 0.4s var(--ease-out), box-shadow 0.4s var(--ease-out);
}

.hero__photo img:hover {
  transform: scale(1.04);
  box-shadow: 0 0 60px var(--accent-glow), 0 12px 40px rgba(0, 0, 0, 0.4);
}

.hero__greeting {
  font-size: 1rem;
  color: var(--accent);
  font-weight: 500;
  letter-spacing: 0.05em;
  margin-bottom: 8px;
}

.hero__name {
  font-family: var(--font-display);
  font-size: clamp(2.4rem, 6vw, 3.8rem);
  font-weight: 700;
  line-height: 1.1;
  margin-bottom: 12px;
  background: linear-gradient(135deg, var(--text-primary) 0%, var(--accent) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero__title {
  font-family: var(--font-display);
  font-size: clamp(1.2rem, 3vw, 1.6rem);
  font-weight: 500;
  color: var(--text-secondary);
  margin-bottom: 20px;
}

.hero__subtitle {
  font-size: 1.05rem;
  color: var(--text-secondary);
  max-width: 540px;
  line-height: 1.7;
  margin-bottom: 32px;
}

.hero__subtitle strong {
  color: var(--text-primary);
}

.hero__actions {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 40px;
}

.hero__socials {
  display: flex;
  gap: 16px;
}

.hero__socials a {
  color: var(--text-muted);
  transition: color 0.2s, transform 0.2s;
}

.hero__socials a:hover {
  color: var(--accent);
  transform: translateY(-2px);
}

.hero__scroll {
  position: absolute;
  bottom: 32px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  color: var(--text-muted);
  font-size: 0.75rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.hero__scroll-line {
  width: 1px;
  height: 40px;
  background: linear-gradient(to bottom, var(--accent), transparent);
  animation: scroll-pulse 2s ease-in-out infinite;
}

@keyframes scroll-pulse {
  0%, 100% { opacity: 0.3; }
  50% { opacity: 1; }
}

/* ───────────────────────────────────────
   Buttons
   ─────────────────────────────────────── */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 28px;
  font-family: var(--font-display);
  font-size: 0.9rem;
  font-weight: 600;
  border-radius: var(--radius-sm);
  border: none;
  cursor: pointer;
  transition: all 0.25s var(--ease-out);
}

.btn--primary {
  background: var(--accent);
  color: #fff;
  box-shadow: 0 4px 16px var(--accent-glow);
}

.btn--primary:hover {
  background: var(--accent-hover);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px var(--accent-glow);
}

.btn--outline {
  background: transparent;
  color: var(--text-primary);
  border: 1px solid var(--border-hover);
}

.btn--outline:hover {
  border-color: var(--accent);
  color: var(--accent);
  transform: translateY(-2px);
}

.btn--lg {
  padding: 16px 36px;
  font-size: 1rem;
}

/* ───────────────────────────────────────
   About
   ─────────────────────────────────────── */
.about__grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  align-items: start;
}

.about__text p {
  color: var(--text-secondary);
  margin-bottom: 16px;
  font-size: 1rem;
  line-height: 1.75;
}

.about__text strong {
  color: var(--text-primary);
}

.about__stats {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
}

.stat-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  text-align: center;
  transition: border-color 0.3s, transform 0.3s;
}

.stat-card:hover {
  border-color: var(--accent);
  transform: translateY(-4px);
}

.stat-card__number {
  font-family: var(--font-display);
  font-size: 2.4rem;
  font-weight: 700;
  color: var(--accent);
  display: inline;
}

.stat-card__plus {
  font-family: var(--font-display);
  font-size: 1.8rem;
  font-weight: 700;
  color: var(--accent);
}

.stat-card__label {
  display: block;
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-top: 4px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* ───────────────────────────────────────
   Timeline (Experience)
   ─────────────────────────────────────── */
.timeline {
  position: relative;
  padding-left: 40px;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 8px;
  top: 8px;
  bottom: 8px;
  width: 2px;
  background: var(--timeline-line);
}

.timeline__item {
  position: relative;
  margin-bottom: 40px;
}

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

.timeline__dot {
  position: absolute;
  left: -36px;
  top: 6px;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--bg-primary);
  border: 3px solid var(--accent);
  z-index: 1;
}

.timeline__item:first-child .timeline__dot {
  background: var(--accent);
  box-shadow: 0 0 12px var(--accent-glow);
}

.timeline__content {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  transition: border-color 0.3s, transform 0.3s;
}

.timeline__content:hover {
  border-color: var(--border-hover);
  transform: translateX(4px);
}

.timeline__date {
  font-size: 0.8rem;
  color: var(--accent);
  font-weight: 600;
  letter-spacing: 0.02em;
}

.timeline__role {
  font-family: var(--font-display);
  font-size: 1.2rem;
  font-weight: 600;
  margin: 6px 0 2px;
}

.timeline__company {
  font-size: 0.9rem;
  color: var(--text-secondary);
  font-weight: 400;
  margin-bottom: 12px;
}

.timeline__content p {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

.timeline__tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 14px;
}

.timeline__tags span {
  background: var(--tag-bg);
  color: var(--tag-text);
  font-size: 0.75rem;
  font-weight: 500;
  padding: 4px 10px;
  border-radius: 20px;
}

/* ───────────────────────────────────────
   Projects
   ─────────────────────────────────────── */
.projects__filters {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 32px;
}

.filter-btn {
  background: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text-secondary);
  font-family: var(--font-display);
  font-size: 0.85rem;
  font-weight: 500;
  padding: 8px 20px;
  border-radius: 20px;
  cursor: pointer;
  transition: all 0.25s var(--ease-out);
}

.filter-btn:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.filter-btn.active {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

.project-card__badge {
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  padding: 4px 10px;
  border-radius: 4px;
  margin-bottom: 14px;
  display: inline-block;
}

.project-card__badge--thesis {
  background: rgba(255, 183, 77, 0.15);
  color: #ffb74d;
}

.project-card__badge--university {
  background: rgba(79, 195, 247, 0.15);
  color: #4fc3f7;
}

.project-card__badge--side {
  background: rgba(129, 199, 132, 0.15);
  color: #81c784;
}

.project-card.hidden {
  display: none;
}

.projects__grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 24px;
}

.project-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  display: flex;
  flex-direction: column;
  transition: border-color 0.3s, transform 0.3s, box-shadow 0.3s;
}

.project-card:hover {
  border-color: var(--accent);
  transform: translateY(-6px);
  box-shadow: 0 12px 40px rgba(0, 0, 0, 0.15);
}

.project-card__header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 20px;
  color: var(--accent);
}

.project-card__links {
  display: flex;
  gap: 12px;
}

.project-card__links a {
  color: var(--text-muted);
  transition: color 0.2s;
}

.project-card__links a:hover {
  color: var(--accent);
}

.project-card__title {
  font-family: var(--font-display);
  font-size: 1.15rem;
  font-weight: 600;
  margin-bottom: 10px;
}

.project-card__desc {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.65;
  flex: 1;
}

.project-card__tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 18px;
}

.project-card__tags span {
  background: var(--tag-bg);
  color: var(--tag-text);
  font-size: 0.75rem;
  font-weight: 500;
  padding: 4px 10px;
  border-radius: 20px;
}

/* ───────────────────────────────────────
   Skills
   ─────────────────────────────────────── */
.skills__grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 32px;
}

.skill-group {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
}

.skill-group__title {
  font-family: var(--font-display);
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--accent);
  margin-bottom: 16px;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.skill-group__items {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.skill-tag {
  background: var(--tag-bg);
  color: var(--tag-text);
  font-size: 0.82rem;
  font-weight: 500;
  padding: 6px 14px;
  border-radius: 20px;
  transition: background 0.2s, transform 0.2s;
}

.skill-tag:hover {
  background: var(--accent);
  color: #fff;
  transform: scale(1.05);
}

/* ───────────────────────────────────────
   Education
   ─────────────────────────────────────── */
.education__grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: 24px;
  margin-bottom: 48px;
}

.edu-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px;
  transition: border-color 0.3s, transform 0.3s;
}

.edu-card:hover {
  border-color: var(--accent);
  transform: translateY(-4px);
}

.edu-card__icon {
  color: var(--accent);
  margin-bottom: 16px;
}

.edu-card__date {
  font-size: 0.8rem;
  color: var(--accent);
  font-weight: 600;
}

.edu-card__degree {
  font-family: var(--font-display);
  font-size: 1.15rem;
  font-weight: 600;
  margin: 8px 0 4px;
}

.edu-card__school {
  font-size: 0.95rem;
  color: var(--text-secondary);
  font-weight: 400;
}

.edu-card__location {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-top: 4px;
}

.edu-card__badge {
  display: inline-block;
  margin-top: 12px;
  background: var(--tag-bg);
  color: var(--tag-text);
  font-size: 0.78rem;
  font-weight: 600;
  padding: 4px 12px;
  border-radius: 20px;
}

/* Certifications */
.certs__title {
  font-family: var(--font-display);
  font-size: 1.2rem;
  font-weight: 600;
  margin-bottom: 20px;
}

.certs__list {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.cert-tag {
  background: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text-secondary);
  font-size: 0.82rem;
  font-weight: 500;
  padding: 8px 16px;
  border-radius: 20px;
  transition: border-color 0.2s, color 0.2s;
}

.cert-tag:hover {
  border-color: var(--accent);
  color: var(--accent);
}

/* ───────────────────────────────────────
   Recommendations
   ─────────────────────────────────────── */
.recs__grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(400px, 1fr));
  gap: 24px;
}

.rec-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px;
  position: relative;
}

.rec-card::before {
  content: '\201C';
  font-family: Georgia, serif;
  font-size: 4rem;
  color: var(--accent);
  opacity: 0.3;
  position: absolute;
  top: 12px;
  left: 20px;
  line-height: 1;
}

.rec-card p {
  font-size: 0.95rem;
  color: var(--text-secondary);
  line-height: 1.7;
  font-style: italic;
  margin-bottom: 20px;
  position: relative;
  z-index: 1;
}

.rec-card footer {
  display: flex;
  flex-direction: column;
}

.rec-card footer strong {
  font-size: 0.9rem;
  color: var(--text-primary);
}

.rec-card footer span {
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* ───────────────────────────────────────
   Contact
   ─────────────────────────────────────── */
.contact__intro {
  font-size: 1.05rem;
  color: var(--text-secondary);
  margin-bottom: 36px;
  line-height: 1.7;
}

.contact__grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-bottom: 36px;
}

.contact-card {
  display: flex;
  align-items: center;
  gap: 14px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 18px 20px;
  color: var(--text-secondary);
  font-size: 0.88rem;
  transition: border-color 0.2s, color 0.2s, transform 0.2s;
}

.contact-card:hover {
  border-color: var(--accent);
  color: var(--accent);
  transform: translateY(-2px);
}

.contact-card svg {
  flex-shrink: 0;
  color: var(--accent);
}

.contact__cv {
  text-align: center;
  margin-top: 24px;
}

.contact__cv-label {
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-bottom: 14px;
}

.contact__cv-buttons {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-items: center;
  gap: 12px;
}

.contact__cv-buttons .btn {
  min-width: 200px;
}

/* ───────────────────────────────────────
   Footer
   ─────────────────────────────────────── */
.footer {
  border-top: 1px solid var(--border);
  padding: 32px 0;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.85rem;
}

/* ───────────────────────────────────────
   Animations
   ─────────────────────────────────────── */
.animate-in {
  opacity: 0;
  transform: translateY(24px);
  animation: fadeInUp 0.6s var(--ease-out) forwards;
}

.animate-in:nth-child(1) { animation-delay: 0.1s; }
.animate-in:nth-child(2) { animation-delay: 0.2s; }
.animate-in:nth-child(3) { animation-delay: 0.35s; }
.animate-in:nth-child(4) { animation-delay: 0.5s; }
.animate-in:nth-child(5) { animation-delay: 0.65s; }
.animate-in:nth-child(6) { animation-delay: 0.8s; }

@keyframes fadeInUp {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.reveal {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s var(--ease-out), transform 0.6s var(--ease-out);
}

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

/* ───────────────────────────────────────
   Mobile
   ─────────────────────────────────────── */
@media (max-width: 768px) {
  .nav__links {
    position: fixed;
    top: var(--nav-h);
    left: 0;
    right: 0;
    background: var(--nav-bg);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    flex-direction: column;
    padding: 16px 24px;
    border-bottom: 1px solid var(--border);
    transform: translateY(-100%);
    opacity: 0;
    pointer-events: none;
    transition: transform 0.3s var(--ease-out), opacity 0.3s;
  }

  .nav__links.open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: all;
  }

  .nav__toggle {
    display: flex;
  }

  .nav__toggle.open span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
  }

  .nav__toggle.open span:nth-child(2) {
    opacity: 0;
  }

  .nav__toggle.open span:nth-child(3) {
    transform: rotate(-45deg) translate(5px, -5px);
  }

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

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

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

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

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

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

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

  .hero {
    flex-direction: column-reverse;
    text-align: center;
  }

  .hero__photo img {
    width: 200px;
    height: 200px;
  }

  .hero__subtitle {
    margin-left: auto;
    margin-right: auto;
  }

  .hero__actions {
    justify-content: center;
  }

  .hero__socials {
    justify-content: center;
  }

  .hero__scroll {
    display: none;
  }

  .section {
    padding: 64px 0;
  }
}

@media (max-width: 480px) {
  .hero__name {
    font-size: 2rem;
  }

  .hero__actions {
    flex-direction: column;
  }

  .btn {
    justify-content: center;
    width: 100%;
  }
}