/* ==========================================================================
   Ravi Ranjan Singh — Portfolio
   Design tokens + base + components + sections + responsive
   ========================================================================== */

:root {
  /* -------- Brand palette (dark theme = default) -------- */
  --bg: #0a0e27;
  --bg-alt: #0d1230;
  --surface: rgba(255, 255, 255, 0.04);
  --surface-strong: rgba(255, 255, 255, 0.07);
  --border: rgba(255, 255, 255, 0.1);
  --text: #eef1fb;
  --text-muted: #9aa3c7;
  --accent: #00d4ff;
  --accent-2: #7c5cff;
  --accent-gradient: linear-gradient(135deg, #00d4ff 0%, #7c5cff 100%);
  --success: #22d3a5;
  --shadow: 0 20px 60px rgba(0, 0, 0, 0.45);
  --radius: 16px;
  --radius-sm: 10px;
  --font-display: "Syne", "Manrope", sans-serif;
  --font-body: "Manrope", system-ui, sans-serif;
  --header-h: 76px;
  --transition: 0.35s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="light"] {
  --bg: #f7f8fc;
  --bg-alt: #ffffff;
  --surface: rgba(10, 14, 39, 0.035);
  --surface-strong: rgba(10, 14, 39, 0.06);
  --border: rgba(10, 14, 39, 0.09);
  --text: #12162e;
  --text-muted: #565f83;
  --shadow: 0 20px 50px rgba(20, 25, 60, 0.1);
}

* , *::before, *::after { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-body);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  transition: background var(--transition), color var(--transition);
  overflow-x: hidden;
}

h1, h2, h3, h4 { font-family: var(--font-display); line-height: 1.2; margin: 0; }
p { margin: 0 0 1rem; color: var(--text-muted); }
a { color: inherit; text-decoration: none; }
ul { list-style: none; margin: 0; padding: 0; }
img { max-width: 100%; display: block; }
button { font-family: inherit; cursor: pointer; }

.container { width: min(1140px, 92%); margin-inline: auto; }

.placeholder-note {
  color: var(--accent-2);
  font-style: italic;
  opacity: 0.85;
}
[data-theme="light"] .placeholder-note { color: #6a3fd6; }

.center-note { text-align: center; margin-top: 1.5rem; }

/* -------------------------------- Preloader -------------------------------- */
#preloader {
  position: fixed; inset: 0; z-index: 9999;
  background: var(--bg);
  display: flex; align-items: center; justify-content: center;
  transition: opacity 0.6s ease, visibility 0.6s ease;
}
#preloader.hidden { opacity: 0; visibility: hidden; pointer-events: none; }
.loader-mark {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 2rem;
  letter-spacing: 0.1em;
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  animation: pulse 1.1s ease-in-out infinite;
}
@keyframes pulse { 0%, 100% { transform: scale(1); opacity: 1; } 50% { transform: scale(1.12); opacity: 0.6; } }

/* -------------------------------- Skip link -------------------------------- */
.skip-link {
  position: absolute; left: -999px; top: 0; z-index: 10000;
  background: var(--accent); color: #05070f; padding: 0.75rem 1.25rem; border-radius: 0 0 8px 0;
}
.skip-link:focus { left: 0; }

/* -------------------------------- Navbar -------------------------------- */
.navbar {
  position: fixed; top: 0; left: 0; right: 0; z-index: 1000;
  height: var(--header-h);
  display: flex; align-items: center;
  backdrop-filter: blur(14px) saturate(140%);
  -webkit-backdrop-filter: blur(14px) saturate(140%);
  background: rgba(10, 14, 39, 0.55);
  border-bottom: 1px solid transparent;
  transition: background var(--transition), border-color var(--transition), box-shadow var(--transition);
}
[data-theme="light"] .navbar { background: rgba(255, 255, 255, 0.7); }
.navbar.scrolled { border-bottom-color: var(--border); box-shadow: 0 8px 30px rgba(0,0,0,0.25); }

.nav-container {
  width: min(1240px, 94%); margin-inline: auto;
  display: flex; align-items: center; justify-content: space-between;
  gap: 1.5rem;
}

.logo {
  font-family: var(--font-display); font-weight: 700; font-size: 1.3rem; letter-spacing: -0.02em;
}
.logo span { color: var(--accent); }

.nav-links { display: flex; gap: 2rem; }
.nav-link {
  position: relative; font-size: 0.94rem; font-weight: 500; color: var(--text-muted);
  padding: 0.4rem 0; transition: color var(--transition);
}
.nav-link::after {
  content: ""; position: absolute; left: 0; bottom: -2px; width: 0; height: 2px;
  background: var(--accent-gradient); transition: width var(--transition);
}
.nav-link:hover, .nav-link.active-link { color: var(--text); }
.nav-link:hover::after, .nav-link.active-link::after { width: 100%; }

.nav-actions { display: flex; align-items: center; gap: 0.85rem; }

.icon-btn {
  background: var(--surface); border: 1px solid var(--border); color: var(--text);
  width: 40px; height: 40px; border-radius: 50%;
  display: grid; place-items: center; transition: transform var(--transition), background var(--transition);
}
.icon-btn:hover { transform: translateY(-2px) rotate(8deg); background: var(--surface-strong); }
.icon-moon { display: none; }
[data-theme="light"] .icon-sun { display: none; }
[data-theme="light"] .icon-moon { display: block; }

.hamburger {
  display: none; flex-direction: column; gap: 5px; background: none; border: none; padding: 8px;
}
.hamburger span { width: 24px; height: 2px; background: var(--text); border-radius: 2px; transition: var(--transition); }
.hamburger.active span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.hamburger.active span:nth-child(2) { opacity: 0; }
.hamburger.active span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* -------------------------------- Buttons -------------------------------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 0.5rem;
  padding: 0.85rem 1.7rem; border-radius: 999px; font-weight: 600; font-size: 0.95rem;
  border: 1px solid transparent; transition: transform var(--transition), box-shadow var(--transition), background var(--transition), color var(--transition);
  white-space: nowrap;
}
.btn-primary { background: var(--accent-gradient); color: #06070f; box-shadow: 0 10px 30px rgba(0, 212, 255, 0.25); }
.btn-primary:hover { transform: translateY(-3px); box-shadow: 0 16px 40px rgba(124, 92, 255, 0.35); }
.btn-outline { background: transparent; border-color: var(--border); color: var(--text); }
.btn-outline:hover { background: var(--surface); border-color: var(--accent); transform: translateY(-3px); }
.btn-small { padding: 0.55rem 1.1rem; font-size: 0.85rem; }

/* -------------------------------- Hero -------------------------------- */
.hero {
  position: relative; min-height: 100vh; display: flex; align-items: center;
  padding-top: var(--header-h);
  overflow: hidden;
}
#particles { position: absolute; inset: 0; z-index: 0; opacity: 0.55; }

.hero-inner { position: relative; z-index: 1; max-width: 780px; }

.eyebrow {
  font-family: var(--font-display); color: var(--accent); letter-spacing: 0.08em; text-transform: uppercase;
  font-size: 0.9rem; margin-bottom: 0.75rem; font-weight: 600;
}
.hero-name {
  font-size: clamp(2.4rem, 6vw, 4.2rem); font-weight: 700; letter-spacing: -0.03em; margin-bottom: 0.5rem;
}
.hero-role {
  font-size: clamp(1.2rem, 3vw, 1.8rem); font-weight: 600; color: var(--text-muted); margin-bottom: 1.5rem;
  min-height: 2.2rem;
}
.hero-role .cursor { color: var(--accent); animation: blink 1s step-end infinite; margin-left: 2px; }
@keyframes blink { 50% { opacity: 0; } }

.hero-summary { font-size: 1.08rem; max-width: 620px; margin-bottom: 2rem; }
.hero-summary strong { color: var(--text); }

.hero-cta { display: flex; gap: 1rem; flex-wrap: wrap; margin-bottom: 2rem; }

.hero-socials { display: flex; gap: 0.9rem; margin-bottom: 3rem; }
.hero-socials a {
  width: 42px; height: 42px; border-radius: 50%; border: 1px solid var(--border); background: var(--surface);
  display: grid; place-items: center; transition: var(--transition);
}
.hero-socials a:hover { background: var(--accent-gradient); color: #06070f; transform: translateY(-3px); }

.scroll-cue {
  position: absolute; bottom: 2.5rem; left: 50%; transform: translateX(-50%);
  width: 26px; height: 42px; border: 2px solid var(--border); border-radius: 20px;
  display: none;
}
.scroll-cue span {
  position: absolute; top: 6px; left: 50%; transform: translateX(-50%);
  width: 4px; height: 8px; border-radius: 3px; background: var(--accent);
  animation: scrollcue 1.6s ease infinite;
}
@keyframes scrollcue { 0% { top: 6px; opacity: 1; } 70% { top: 22px; opacity: 0; } 100% { opacity: 0; } }

/* -------------------------------- Reveal animation -------------------------------- */
.reveal { opacity: 0; transform: translateY(28px); transition: opacity 0.7s ease, transform 0.7s ease; }
.reveal.in-view { opacity: 1; transform: translateY(0); }
.reveal:nth-child(2) { transition-delay: 0.06s; }
.reveal:nth-child(3) { transition-delay: 0.12s; }
.reveal:nth-child(4) { transition-delay: 0.18s; }

/* -------------------------------- Sections -------------------------------- */
.section { padding: 7rem 0; }
.section-alt { background: var(--bg-alt); }

.section-tag {
  font-family: var(--font-display); color: var(--accent); text-transform: uppercase;
  letter-spacing: 0.1em; font-size: 0.85rem; font-weight: 600; margin-bottom: 0.6rem;
}
.section-title { font-size: clamp(1.8rem, 4vw, 2.6rem); margin-bottom: 1rem; max-width: 720px; }
.section-subtitle { max-width: 620px; font-size: 1.05rem; margin-bottom: 3rem; }

/* -------------------------------- About -------------------------------- */
.about-grid { display: grid; grid-template-columns: 1.3fr 1fr; gap: 3.5rem; margin-top: 3rem; align-items: start; }
.about-text p { font-size: 1.02rem; }
.about-text strong { color: var(--text); }

.about-stats { display: grid; grid-template-columns: 1fr 1fr; gap: 1.2rem; }
.stat-card {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 1.5rem; text-align: center; transition: transform var(--transition), border-color var(--transition);
}
.stat-card:hover { transform: translateY(-6px); border-color: var(--accent); }
.stat-number {
  font-family: var(--font-display); font-size: 2.4rem; font-weight: 700;
  background: var(--accent-gradient); -webkit-background-clip: text; background-clip: text; color: transparent;
}
.stat-suffix { font-size: 1.6rem; font-weight: 700; color: var(--accent-2); }
.stat-label { display: block; margin-top: 0.4rem; font-size: 0.85rem; color: var(--text-muted); }

/* -------------------------------- Skills -------------------------------- */
.skills-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); gap: 1.5rem; margin-top: 3rem; }
.skill-card {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 1.75rem; transition: transform var(--transition), border-color var(--transition);
}
.skill-card:hover { transform: translateY(-6px); border-color: var(--accent-2); }
.skill-card h3 { font-size: 1.1rem; margin-bottom: 1.25rem; }
.skill-bars li { margin-bottom: 1rem; }
.skill-bars li:last-child { margin-bottom: 0; }
.skill-bars span { display: block; font-size: 0.88rem; margin-bottom: 0.4rem; color: var(--text-muted); }
.bar { height: 6px; border-radius: 4px; background: var(--surface-strong); overflow: hidden; }
.bar i {
  display: block; height: 100%; width: 0; border-radius: 4px; background: var(--accent-gradient);
  transition: width 1.1s cubic-bezier(0.4,0,0.2,1);
}
.skill-card.in-view .bar i, .reveal.in-view .bar i { width: var(--w); }

/* -------------------------------- Timeline -------------------------------- */
.timeline { position: relative; margin-top: 3rem; padding-left: 2rem; border-left: 2px solid var(--border); }
.timeline-item { position: relative; padding-bottom: 3rem; padding-left: 2rem; }
.timeline-item:last-child { padding-bottom: 0; }
.timeline-dot {
  position: absolute; left: -2.55rem; top: 0.3rem; width: 14px; height: 14px; border-radius: 50%;
  background: var(--accent-gradient); box-shadow: 0 0 0 5px var(--surface);
}
.timeline-date { font-size: 0.85rem; color: var(--accent); font-weight: 600; letter-spacing: 0.03em; }
.timeline-content h3 { font-size: 1.3rem; margin-top: 0.4rem; }
.timeline-content h4 { font-size: 1rem; color: var(--text-muted); font-weight: 500; margin-bottom: 0.75rem; }
.timeline-content p { max-width: 680px; }
.placeholder-block { opacity: 0.85; }

.tags { display: flex; flex-wrap: wrap; gap: 0.5rem; margin-top: 1rem; }
.tags span {
  font-size: 0.78rem; padding: 0.35rem 0.8rem; border-radius: 999px; background: var(--surface-strong);
  border: 1px solid var(--border); color: var(--text-muted);
}

/* -------------------------------- Projects -------------------------------- */
.project-card {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 2.5rem; margin-top: 3rem; position: relative; overflow: hidden;
}
.project-card::before {
  content: ""; position: absolute; top: -60%; right: -20%; width: 60%; height: 220%;
  background: var(--accent-gradient); opacity: 0.08; transform: rotate(20deg);
}
.project-tag { font-size: 0.8rem; color: var(--accent-2); font-weight: 600; text-transform: uppercase; letter-spacing: 0.05em; }
.project-info h3 { font-size: 1.6rem; margin: 0.5rem 0 1rem; }
.project-points { margin: 1rem 0; }
.project-points li { position: relative; padding-left: 1.4rem; margin-bottom: 0.6rem; color: var(--text-muted); }
.project-points li::before { content: "→"; position: absolute; left: 0; color: var(--accent); }

/* -------------------------------- Education -------------------------------- */
.edu-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 1.5rem; margin-top: 3rem; }
.edu-card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 1.75rem; }
.edu-card h3 { font-size: 1.05rem; margin-bottom: 0.5rem; }

/* -------------------------------- Contact -------------------------------- */
.contact-grid { display: grid; grid-template-columns: 0.9fr 1.1fr; gap: 3rem; margin-top: 1rem; }
.contact-info { display: flex; flex-direction: column; gap: 1rem; }
.contact-item {
  display: flex; align-items: center; gap: 1rem; background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius-sm); padding: 1.1rem 1.25rem; transition: var(--transition);
}
a.contact-item:hover { border-color: var(--accent); transform: translateX(6px); }
.contact-item strong { display: block; color: var(--text); font-size: 0.95rem; }
.contact-item em { font-style: normal; color: var(--text-muted); font-size: 0.85rem; }
.contact-icon {
  width: 40px; height: 40px; border-radius: 50%; background: var(--surface-strong); display: grid; place-items: center;
  font-weight: 700; color: var(--accent); flex-shrink: 0;
}

.contact-form { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 2rem; }
.form-row { margin-bottom: 1.2rem; display: flex; flex-direction: column; gap: 0.5rem; }
.form-row label { font-size: 0.85rem; color: var(--text-muted); font-weight: 600; }
.form-row input, .form-row textarea {
  background: var(--bg); border: 1px solid var(--border); border-radius: var(--radius-sm); color: var(--text);
  padding: 0.75rem 1rem; font-family: inherit; font-size: 0.95rem; resize: vertical; transition: border-color var(--transition);
}
.form-row input:focus, .form-row textarea:focus { outline: none; border-color: var(--accent); }
.form-note { font-size: 0.8rem; margin-top: 0.75rem; margin-bottom: 0; }

/* -------------------------------- Footer -------------------------------- */
.footer { border-top: 1px solid var(--border); padding: 2.5rem 0; }
.footer-inner { display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: 1rem; }
.footer-inner p { margin: 0; font-size: 0.85rem; }
.footer-inner a[aria-label] { width: 38px; height: 38px; border-radius: 50%; border: 1px solid var(--border); display: grid; place-items: center; transition: var(--transition); }
.footer-inner a[aria-label]:hover { background: var(--accent-gradient); color: #06070f; }

/* -------------------------------- Back to top -------------------------------- */
.back-to-top {
  position: fixed; bottom: 2rem; right: 2rem; width: 46px; height: 46px; border-radius: 50%;
  background: var(--accent-gradient); color: #06070f; border: none; font-size: 1.1rem; font-weight: 700;
  display: grid; place-items: center; box-shadow: var(--shadow); opacity: 0; visibility: hidden; transform: translateY(10px);
  transition: var(--transition); z-index: 900;
}
.back-to-top.visible { opacity: 1; visibility: visible; transform: translateY(0); }

/* -------------------------------- Responsive -------------------------------- */
@media (max-width: 900px) {
  .about-grid, .contact-grid { grid-template-columns: 1fr; }
  .scroll-cue { display: block; }
}

@media (max-width: 780px) {
  .nav-links {
    position: fixed; top: var(--header-h); left: 0; right: 0; flex-direction: column; gap: 0;
    background: var(--bg-alt); border-bottom: 1px solid var(--border);
    max-height: 0; overflow: hidden; transition: max-height var(--transition);
  }
  .nav-links.open { max-height: 420px; }
  .nav-links li { width: 100%; }
  .nav-link { display: block; padding: 1rem 6%; }
  .hamburger { display: flex; }
  .about-stats { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 520px) {
  .section { padding: 5rem 0; }
  .hero-cta { flex-direction: column; align-items: stretch; }
  .btn { width: 100%; }
  .about-stats { grid-template-columns: 1fr; }
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal, .bar i, * { transition-duration: 0.01ms !important; animation-duration: 0.01ms !important; }
}