/* ============================================================
   main.css — Raul Medeiros personal website
   Clean, minimal, framework-free.
   ============================================================ */

/* ── Custom properties ─────────────────────────────────────── */
:root {
  --bg:           #ffffff;
  --bg-alt:       #f8fafc;
  --bg-dark:      #0f172a;
  --text:         #111827;
  --text-muted:   #6b7280;
  --accent:       #b8936a;
  --accent-dark:  #9a7754;
  --border:       #e5e7eb;
  --radius:       8px;
  --font:         'Inter', system-ui, -apple-system, sans-serif;
  --nav-h:        64px;
  --section-pad:  96px;
  --inner-width:  960px;
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font);
  color: var(--text);
  background: var(--bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

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

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

a:hover {
  color: var(--accent-dark);
  text-decoration: underline;
}

p {
  margin-bottom: 1rem;
}

p:last-child {
  margin-bottom: 0;
}

h1, h2, h3, h4 {
  font-weight: 700;
  line-height: 1.2;
}

ul {
  list-style: none;
}

input,
textarea,
button {
  font-family: inherit;
  font-size: inherit;
}

/* ── Utility ────────────────────────────────────────────────── */
.section-inner {
  max-width: var(--inner-width);
  margin-inline: auto;
  padding-inline: 24px;
  padding-block: var(--section-pad);
}

.section-title {
  font-size: 2rem;
  margin-bottom: 0.5rem;
  padding-bottom: 0.5rem;
  border-bottom: 3px solid var(--accent);
  display: inline-block;
}

.section-title--light {
  color: #ffffff;
  border-bottom-color: var(--accent);
}

.section-sub {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-top: 3rem;
  margin-bottom: 1.5rem;
}

.section-desc {
  color: var(--text-muted);
  margin-top: 0.5rem;
  margin-bottom: 2.5rem;
}

.section-desc--light {
  color: #94a3b8;
}

/* ── Buttons ────────────────────────────────────────────────── */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.625rem 1.5rem;
  border-radius: var(--radius);
  font-weight: 600;
  font-size: 0.9rem;
  cursor: pointer;
  transition: background 0.2s, color 0.2s, border-color 0.2s, box-shadow 0.2s;
  border: 2px solid transparent;
  text-decoration: none;
}

.btn-primary {
  background: var(--accent);
  color: #ffffff;
  border-color: var(--accent);
}

.btn-primary:hover {
  background: var(--accent-dark);
  border-color: var(--accent-dark);
  color: #ffffff;
  text-decoration: none;
}

.btn-outline {
  background: transparent;
  color: #ffffff;
  border-color: rgba(255, 255, 255, 0.6);
}

.btn-outline:hover {
  background: rgba(255, 255, 255, 0.1);
  border-color: #ffffff;
  color: #ffffff;
  text-decoration: none;
}

.btn-submit {
  padding: 0.75rem 2rem;
  font-size: 1rem;
  background: var(--accent);
  color: #ffffff;
  border: none;
  border-radius: var(--radius);
  cursor: pointer;
  transition: background 0.2s, opacity 0.2s;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}

.btn-submit:hover:not(:disabled) {
  background: var(--accent-dark);
}

.btn-submit:disabled {
  opacity: 0.65;
  cursor: not-allowed;
}

.btn-loading {
  display: none;
}

/* ── Nav ────────────────────────────────────────────────────── */
#nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  height: var(--nav-h);
  transition: background 0.3s, box-shadow 0.3s;
}

#nav.scrolled {
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  box-shadow: 0 1px 12px rgba(0, 0, 0, 0.08);
}

.nav-inner {
  max-width: var(--inner-width);
  margin-inline: auto;
  padding-inline: 24px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-brand {
  color: #ffffff;
  text-decoration: none;
  transition: color 0.3s;
  display: flex;
  align-items: center;
  line-height: 1;
}

#nav.scrolled .nav-brand {
  color: var(--text);
}

#nav-links {
  display: flex;
  gap: 0.25rem;
  align-items: center;
}

.nav-link {
  color: rgba(255, 255, 255, 0.85);
  font-size: 0.85rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  padding: 0.4rem 0.75rem;
  border-radius: 4px;
  border-bottom: 2px solid transparent;
  transition: color 0.2s, border-color 0.2s;
  text-decoration: none;
}

.nav-link:hover,
.nav-link.active {
  color: var(--accent);
  border-bottom-color: var(--accent);
  text-decoration: none;
}

#nav.scrolled .nav-link {
  color: var(--text-muted);
}

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

/* hamburger */
#nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
  width: 36px;
  height: 36px;
}

#nav-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: #ffffff;
  border-radius: 2px;
  transition: transform 0.3s, opacity 0.3s, background 0.3s;
  transform-origin: center;
}

#nav.scrolled #nav-toggle span {
  background: var(--text);
}

#nav-toggle.open span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

#nav-toggle.open span:nth-child(2) {
  opacity: 0;
  transform: scaleX(0);
}

#nav-toggle.open span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ── Hero ───────────────────────────────────────────────────── */
#home {
  min-height: 100vh;
  background: var(--bg-dark);
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  position: relative;
  overflow: hidden;
}

/* subtle grid overlay */
#home::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(255,255,255,0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,0.03) 1px, transparent 1px);
  background-size: 60px 60px;
  pointer-events: none;
}

.hero-inner {
  position: relative;
  z-index: 1;
  padding: 120px 24px 80px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
}

.hero-label {
  font-size: 1rem;
  font-weight: 500;
  color: var(--accent);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 0;
}

#home h1 {
  font-size: clamp(2.5rem, 8vw, 4.5rem);
  color: #ffffff;
  letter-spacing: -0.02em;
  line-height: 1.1;
}

.hero-tagline {
  font-size: 1.1rem;
  color: #94a3b8;
  margin-bottom: 0;
}

.hero-tagline a {
  color: #cbd5e1;
  text-decoration: underline;
  text-underline-offset: 3px;
}

.hero-tagline a:hover {
  color: #ffffff;
}

.hero-sub {
  font-size: 1rem;
  color: #64748b;
  margin-bottom: 0.5rem;
}

.hero-actions {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
  justify-content: center;
  margin-top: 0.5rem;
}

.hero-social {
  display: flex;
  gap: 1.25rem;
  margin-top: 0.5rem;
}

.hero-social a {
  color: #475569;
  font-size: 1.4rem;
  transition: color 0.2s;
  text-decoration: none;
}

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

/* bouncing chevron */
@keyframes bounce {
  0%, 100% { transform: translateY(0); }
  50%       { transform: translateY(6px); }
}

.hero-scroll {
  margin-top: 2rem;
  color: #475569;
  font-size: 1.2rem;
  animation: bounce 1.6s ease-in-out infinite;
  display: inline-block;
  text-decoration: none;
  transition: color 0.2s;
}

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

/* ── About ──────────────────────────────────────────────────── */
#about {
  background: var(--bg-alt);
}

.about-content {
  display: flex;
  gap: 3.5rem;
  align-items: flex-start;
  margin-top: 2.5rem;
}

.about-photo {
  flex-shrink: 0;
}

.about-photo img {
  width: 200px;
  height: 200px;
  border-radius: 50%;
  object-fit: cover;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.14);
}

.about-text {
  flex: 1;
  min-width: 0;
}

.about-text p {
  color: var(--text);
}

.about-text a {
  color: var(--accent);
}

.about-contact {
  margin-top: 1.25rem;
  font-weight: 500;
  color: var(--text-muted);
}

.about-contact .fa {
  margin-right: 0.4rem;
  color: var(--accent);
}

/* ── Resume ─────────────────────────────────────────────────── */
#resume {
  background: var(--bg);
}

/* Timeline */
.timeline {
  display: flex;
  flex-direction: column;
}

.timeline-item {
  display: grid;
  grid-template-columns: 140px 1fr;
  gap: 1.5rem;
  padding-bottom: 1.75rem;
  margin-bottom: 1.75rem;
  border-bottom: 1px solid var(--border);
}

.timeline-item:last-child {
  border-bottom: none;
  margin-bottom: 0;
}

.timeline-date {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--accent);
  padding-top: 0.2rem;
  line-height: 1.4;
  text-align: right;
}

.timeline-body h4 {
  font-size: 1rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 0.2rem;
}

.timeline-org {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--accent);
  margin-bottom: 0.4rem;
}

.timeline-body p:not(.timeline-org) {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin-bottom: 0;
}

/* Publications */
.publications-list {
  list-style: none;
  counter-reset: pub-counter;
  padding: 0;
}

.pub-item {
  counter-increment: pub-counter;
  padding-bottom: 1.5rem;
  margin-bottom: 1.5rem;
  border-bottom: 1px solid var(--border);
  position: relative;
  padding-left: 2.5rem;
}

.pub-item:last-child {
  border-bottom: none;
  margin-bottom: 0;
}

.pub-item::before {
  content: counter(pub-counter);
  position: absolute;
  left: 0;
  top: 0.1rem;
  width: 1.75rem;
  height: 1.75rem;
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 50%;
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--text-muted);
  display: flex;
  align-items: center;
  justify-content: center;
}

.pub-title {
  font-weight: 600;
  color: var(--text);
  margin-bottom: 0.2rem;
  font-size: 0.95rem;
}

.pub-authors {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
}

.pub-meta {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.pub-venue {
  background: var(--accent);
  color: #ffffff;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  padding: 0.2rem 0.6rem;
  border-radius: 100px;
  text-transform: uppercase;
}

.pub-date {
  font-size: 0.8rem;
  color: var(--text-muted);
  font-weight: 500;
}

.pub-doi {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--accent);
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

.pub-doi:hover {
  color: var(--accent-dark);
  text-decoration: underline;
}

/* Skills */
.skills-list {
  display: flex;
  flex-direction: column;
  gap: 1.1rem;
}

.skill-item {
  list-style: none;
}

.skill-header {
  display: flex;
  justify-content: space-between;
  margin-bottom: 0.4rem;
}

.skill-name {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text);
}

.skill-pct {
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--text-muted);
}

.skill-track {
  height: 6px;
  background: var(--border);
  border-radius: 100px;
  overflow: hidden;
}

.skill-fill {
  height: 100%;
  width: 0;
  background: linear-gradient(90deg, var(--accent), var(--accent-dark));
  border-radius: 100px;
  transition: width 1s cubic-bezier(.4, 0, .2, 1);
}

/* ── Portfolio ──────────────────────────────────────────────── */
#portfolio {
  background: var(--bg-alt);
}

.portfolio-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.75rem;
  margin-top: 0;
}

.portfolio-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.75rem;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.05);
  transition: transform 0.2s, box-shadow 0.2s;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.portfolio-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.1);
}

.card-header {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.card-icon {
  width: 40px;
  height: 40px;
  border-radius: 6px;
  object-fit: contain;
  flex-shrink: 0;
}

.card-tag {
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--accent);
  background: rgba(8, 145, 178, 0.1);
  padding: 0.2rem 0.6rem;
  border-radius: 100px;
}

.portfolio-card h3 {
  font-size: 1.1rem;
  color: var(--text);
}

.portfolio-card p {
  font-size: 0.9rem;
  color: var(--text-muted);
  flex: 1;
  margin-bottom: 0;
}

.card-link {
  margin-top: auto;
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--accent);
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  text-decoration: none;
  transition: color 0.2s;
}

.card-link:hover {
  color: var(--accent-dark);
  text-decoration: underline;
}

/* ── Contact ────────────────────────────────────────────────── */
#contact {
  background: var(--bg-dark);
}

#contact .section-inner {
  max-width: 680px;
}

#contact-form {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  margin-top: 2rem;
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.25rem;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.form-group label {
  font-size: 0.85rem;
  font-weight: 600;
  color: #94a3b8;
  letter-spacing: 0.02em;
}

.form-group label .optional {
  font-weight: 400;
  color: #64748b;
}

.form-group input,
.form-group textarea {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.12);
  color: #f1f5f9;
  border-radius: var(--radius);
  padding: 0.65rem 0.9rem;
  width: 100%;
  outline: none;
  transition: border-color 0.2s, box-shadow 0.2s;
  resize: vertical;
}

.form-group input::placeholder,
.form-group textarea::placeholder {
  color: #475569;
}

.form-group input:focus,
.form-group textarea:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(8, 145, 178, 0.2);
}

#form-status {
  font-size: 0.9rem;
  border-radius: var(--radius);
  min-height: 0;
  transition: all 0.3s;
}

#form-status:not(:empty) {
  padding: 0.75rem 1rem;
}

#form-status.success {
  background: rgba(16, 185, 129, 0.15);
  border: 1px solid rgba(16, 185, 129, 0.4);
  color: #6ee7b7;
}

#form-status.error {
  background: rgba(239, 68, 68, 0.15);
  border: 1px solid rgba(239, 68, 68, 0.4);
  color: #fca5a5;
}

/* ── Footer ─────────────────────────────────────────────────── */
#footer {
  background: #070e1a;
  padding-block: 2rem;
}

.footer-inner {
  max-width: var(--inner-width);
  margin-inline: auto;
  padding-inline: 24px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 2rem;
  position: relative;
}

.footer-social {
  display: flex;
  gap: 1rem;
}

.footer-social a {
  color: #475569;
  font-size: 1.2rem;
  transition: color 0.2s;
  text-decoration: none;
}

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

.footer-copy {
  font-size: 0.85rem;
  color: #475569;
  margin-bottom: 0;
}

#back-to-top {
  position: absolute;
  right: 24px;
  top: 50%;
  transform: translateY(-50%);
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.06);
  border: 1px solid rgba(255, 255, 255, 0.1);
  color: #475569;
  font-size: 0.85rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.2s, color 0.2s;
}

#back-to-top:hover {
  background: var(--accent);
  color: #ffffff;
  border-color: var(--accent);
}

/* ── Responsive: 768px ──────────────────────────────────────── */
@media (max-width: 768px) {
  :root {
    --section-pad: 64px;
  }

  /* hamburger visible */
  #nav-toggle {
    display: flex;
    z-index: 1001;
  }

  /* nav dropdown */
  #nav-links {
    position: fixed;
    top: var(--nav-h);
    left: 0;
    right: 0;
    background: rgba(15, 23, 42, 0.97);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    flex-direction: column;
    align-items: stretch;
    padding: 1rem 0;
    gap: 0;
    transform: translateY(-110%);
    opacity: 0;
    transition: transform 0.3s, opacity 0.3s;
    pointer-events: none;
  }

  #nav-links.open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
  }

  #nav.scrolled #nav-links {
    background: rgba(255, 255, 255, 0.97);
  }

  .nav-link {
    display: block;
    padding: 0.75rem 1.5rem;
    color: #f1f5f9;
    border-bottom: none;
    border-radius: 0;
    font-size: 0.95rem;
  }

  #nav.scrolled .nav-link {
    color: var(--text);
  }

  .nav-link:hover,
  .nav-link.active {
    background: rgba(8, 145, 178, 0.1);
    color: var(--accent);
    border-bottom: none;
  }

  /* about stacks vertically */
  .about-content {
    flex-direction: column;
    align-items: center;
    text-align: center;
    gap: 2rem;
  }

  .about-contact {
    justify-content: center;
  }

  /* timeline single column */
  .timeline-item {
    grid-template-columns: 1fr;
    gap: 0.4rem;
  }

  .timeline-date {
    text-align: left;
    font-size: 0.78rem;
    padding-top: 0;
  }

  /* form single column */
  .form-row {
    grid-template-columns: 1fr;
  }

  /* footer back-to-top centers */
  .footer-inner {
    flex-wrap: wrap;
    justify-content: center;
  }

  #back-to-top {
    position: static;
    transform: none;
  }
}

/* ── Responsive: 480px ──────────────────────────────────────── */
@media (max-width: 480px) {
  /* hero buttons stack */
  .hero-actions {
    flex-direction: column;
    width: 100%;
    padding-inline: 1rem;
  }

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

  /* profile photo smaller */
  .about-photo img {
    width: 140px;
    height: 140px;
  }
}