/* ===== Variables (WCAG AA contrast: 4.5:1 normal text, 3:1 large) ===== */
:root {
  --bg: #0f0f12;
  --bg-elevated: #1a1a20;
  --text: #e8e8ed;
  --text-muted: #b2b2c0;
  --accent: #7cabff;
  --accent-hover: #9ac2ff;
  --border: #2a2a32;
  --focus-ring: #9ac2ff;
  --header-bg: rgba(15, 15, 18, 0.85);
  --header-bg-scrolled: rgba(15, 15, 18, 0.95);
  --transition-fast: 0.2s;
  --transition-mid: 0.3s;
  --transition-slow: 0.5s;
  --font-sans: "DM Sans", system-ui, sans-serif;
  --font-mono: "JetBrains Mono", monospace;
}

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

html {
  scroll-behavior: smooth;
}

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

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

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

a:focus-visible {
  outline: 2px solid var(--focus-ring);
  outline-offset: 3px;
  border-radius: 2px;
}

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


/* ===== Sticky Header ===== */
.header {
  position: -webkit-sticky;
  position: sticky;
  top: 0;
  z-index: 1001;
  background: var(--header-bg);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid transparent;
  transition: background-color var(--transition-mid), border-color var(--transition-mid);
}

.header.scrolled {
  background: var(--header-bg-scrolled);
  border-bottom-color: var(--border);
}

.header-inner {
  max-width: 1500px;
  margin: 0 auto;
  padding: 2.25rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  font-weight: 700;
  font-size: 1.75rem;
  color: var(--text);
}

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

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

/* Hamburger menu button */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 4px;
  background: transparent;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
  z-index: 1002;
  position: relative;
}

.hamburger span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--text);
  border-radius: 2px;
  transition: transform var(--transition-mid), opacity var(--transition-mid);
}

.hamburger[aria-expanded="true"] span:nth-child(1) {
  transform: rotate(45deg) translate(6px, 6px);
}

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

.hamburger[aria-expanded="true"] span:nth-child(3) {
  transform: rotate(-45deg) translate(6px, -6px);
}

/* Mobile menu styles */
@media (max-width: 767px) {
  .header {
    position: -webkit-sticky !important;
    position: sticky !important;
    top: 0 !important;
    left: 0;
    right: 0;
    width: 100%;
    background: var(--bg) !important;
    backdrop-filter: none;
    -webkit-backdrop-filter: none;
    border-bottom: 1px solid var(--border);
    will-change: transform;
  }

  .header.scrolled {
    background: var(--bg) !important;
    border-bottom-color: var(--border);
  }

  .hamburger {
    display: flex;
  }

  .nav {
    position: fixed;
    top: 0;
    right: -100%;
    width: 280px;
    height: 100vh;
    background: var(--bg-elevated);
    border-left: 1px solid var(--border);
    flex-direction: column;
    gap: 0;
    padding: 4rem 1.5rem 2rem;
    padding-top: calc(4rem + 60px);
    transition: right var(--transition-mid);
    z-index: 1002;
    overflow-y: auto;
    box-shadow: -4px 0 24px rgba(0, 0, 0, 0.3);
  }

  .nav.open {
    right: 0;
  }

  body.menu-open::before {
    content: "";
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background: rgba(0, 0, 0, 0.5);
    z-index: 998;
    pointer-events: all;
  }

  .nav-link {
    padding: 1rem 0;
    border-bottom: 1px solid var(--border);
    width: 100%;
    font-size: 1.1rem;
  }

  .nav-link::after {
    display: none;
  }

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

.nav-link {
  color: var(--text-muted);
  font-weight: 500;
  font-size: 1.1rem;
  position: relative;
  padding-bottom: 0.25rem;
}

.nav-link::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 0;
  height: 2px;
  background: var(--accent);
  border-radius: 1px;
  transition: width var(--transition-mid);
}

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

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

/* ===== Hero ===== */
.hero {
  min-height: 85vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 4rem 1.5rem;
  scroll-margin-top: 100px;
  background:
    radial-gradient(ellipse 80% 50% at 50% -20%, rgba(124, 171, 255, 0.12), transparent),
    linear-gradient(180deg, var(--bg) 0%, var(--bg-elevated) 100%);
}

.hero-content {
  opacity: 0;
  animation: heroFadeIn var(--transition-slow) ease-out forwards;
}

@keyframes heroFadeIn {
  to {
    opacity: 1;
  }
}

.hero-title {
  font-size: clamp(2rem, 5vw, 3.5rem);
  font-weight: 700;
  margin-bottom: 0.5rem;
  letter-spacing: -0.03em;
  line-height: 1.15;
}

.hero-tagline {
  font-size: 1.15rem;
  color: var(--text-muted);
  margin-bottom: 2rem;
}

.hero-cta {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  justify-content: center;
}

/* Buttons ===== */
.btn {
  display: inline-block;
  padding: 0.75rem 1.5rem;
  font-family: var(--font-sans);
  font-weight: 600;
  font-size: 1rem;
  border-radius: 8px;
  border: none;
  cursor: pointer;
  transition: transform var(--transition-fast), background-color var(--transition-mid), color var(--transition-mid);
}

.btn:hover {
  transform: scale(1.03);
}

.btn:focus-visible {
  outline: 2px solid var(--focus-ring);
  outline-offset: 3px;
}

.btn-primary {
  background: var(--accent);
  color: var(--bg);
}

.btn-primary:hover {
  background: var(--accent-hover);
  color: var(--bg);
}

.btn-secondary {
  background: transparent;
  color: var(--accent);
  border: 2px solid var(--accent);
}

.btn-secondary:hover {
  background: var(--accent);
  color: var(--bg);
}

/* ===== Sections ===== */
.section {
  padding: 4rem 1.5rem;
  max-width: 1500px;
  margin: 0 auto;
  scroll-margin-top: 100px;
}

.container {
  max-width: 1500px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.section-title {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 2.5rem;
  text-align: center;
  letter-spacing: -0.02em;
}

.section-title::after {
  content: "";
  display: block;
  width: 3rem;
  height: 3px;
  margin: 1rem auto 0;
  background: linear-gradient(90deg, var(--accent), var(--accent-hover));
  border-radius: 2px;
}

/* Section reveal (JS adds .visible) */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

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

/* ===== About ===== */
.about-grid {
  max-width: 1500px;
  margin: 0 auto;
}

.about-bio {
  font-size: 1.1rem;
  color: var(--text-muted);
  margin-bottom: 1.5rem;
}

/* ===== Education / Timeline ===== */
.timeline {
  display: flex;
  flex-wrap: wrap;
  gap: 1.5rem;
  max-width: 1500px;
  margin: 0 auto;
  justify-content: center;
}

.timeline::before {
  display: none;
}

.timeline-item {
  flex: 1 1 min(320px, 100%);
  margin: 0;
  padding: 0;
  display: flex;
}

#education .timeline + .timeline,
#experience .timeline + .timeline {
  margin-top: 2rem;
}

.timeline-card {
  flex: 1;
  display: flex;
  flex-direction: column;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.25rem 1.5rem;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.2);
  transition: border-color var(--transition-mid), box-shadow var(--transition-mid);
}

.timeline-card:hover {
  border-color: rgba(124, 171, 255, 0.4);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.3), 0 0 0 1px rgba(124, 171, 255, 0.08);
}

.timeline-card h3 {
  font-size: 1.1rem;
  margin-bottom: 0.25rem;
}

.timeline-meta {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
}

.timeline-card p:last-child {
  font-size: 0.95rem;
  color: var(--text-muted);
  margin-top: auto;
}

/* ===== Contact ===== */
.contact-wrap {
  max-width: 1500px;
  margin: 0 auto;
}

.contact-form label {
  display: block;
  font-weight: 500;
  margin-bottom: 0.35rem;
  font-size: 0.95rem;
}

.contact-form input,
.contact-form textarea {
  width: 100%;
  padding: 0.75rem 1rem;
  margin-bottom: 1.25rem;
  font-family: var(--font-sans);
  font-size: 1rem;
  background: var(--bg-elevated);
  border: 2px solid var(--border);
  border-radius: 8px;
  color: var(--text);
  transition: border-color var(--transition-mid);
}

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

.contact-form input:focus-visible,
.contact-form textarea:focus-visible {
  outline: 2px solid var(--focus-ring);
  outline-offset: 2px;
}

.contact-form input::placeholder,
.contact-form textarea::placeholder {
  color: var(--text-muted);
  opacity: 0.9;
}

.contact-form textarea {
  resize: vertical;
  min-height: 120px;
}

.contact-form button {
  margin-top: 0;
}

.contact-form button:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

@media (max-width: 767px) {
  .contact-form button {
    width: 100%;
  }
}

.form-status {
  margin-top: 1rem;
  padding: 0.75rem 1rem;
  border-radius: 8px;
  font-size: 0.95rem;
  font-weight: 500;
}

.form-status-success {
  background: rgba(76, 175, 80, 0.15);
  color: #4caf50;
  border: 1px solid rgba(76, 175, 80, 0.3);
}

.form-status-error {
  background: rgba(244, 67, 54, 0.15);
  color: #f44336;
  border: 1px solid rgba(244, 67, 54, 0.3);
}


/* ===== Footer ===== */
.footer {
  padding: 2rem 1.5rem;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.9rem;
  border-top: 1px solid var(--border);
}

.footer-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 1rem;
}

.footer-back {
  color: var(--accent);
  font-weight: 500;
  transition: color var(--transition-mid);
}

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

.linkedin-icon {
  display: block;
  width: fit-content;
  margin: 2rem auto 0;
  padding-top: 2rem;
  border-top: 1px solid var(--border);
  line-height: 0;
}

.linkedin-icon svg {
  display: block;
}

.linkedin-icon svg path {
  fill: var(--accent);
  transition: fill var(--transition-mid);
}

.linkedin-icon:hover svg path {
  fill: var(--accent-hover);
}

/* ===== Focus visible (Lighthouse accessibility) ===== */
:focus {
  outline: none;
}

:focus-visible {
  outline: 2px solid var(--focus-ring);
  outline-offset: 2px;
}

/* ===== Reduced motion ===== */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }

  html {
    scroll-behavior: auto;
  }

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