/* ================================================================
   ARJUN KUMAR SINGH - ACADEMIC WEBSITE
   Minimal, warm, academic design
   ================================================================ */

:root {
  --primary: #3d5a80;
  --primary-light: #5a7ba8;
  --text-dark: #1f1f1f;
  --text-light: #555;
  --bg-light: #f9fafb;
  --border: #ddd;
  --ff-serif: 'Georgia', serif;
  --ff-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Helvetica Neue', sans-serif;
  
  /* Home Page: Blue + Terracotta */
  --home-primary: #3d5a80;
  --home-accent: #B85C3C;
  
  /* Research Page: Golden-Amber + Sage Green */
  --research-primary: #C89968;
  --research-accent: #6B8E7F;
  
  /* Courses Page: Deep Plum + Rose */
  --courses-primary: #6B5A7A;
  --courses-accent: #D4A5B4;
  
  /* Op-Eds Page: Warm Rose + Burgundy */
  --opeds-primary: #A88699;
  --opeds-accent: #8B4A5B;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--ff-sans);
  color: var(--text-dark);
  background: #fff;
  line-height: 1.65;
  font-size: 16px;
}

h1, h2, h3 {
  font-family: var(--ff-sans);
  font-weight: 700;
  line-height: 1.3;
  color: var(--text-dark);
  letter-spacing: -0.01em;
}

h1 {
  font-size: 2.2rem;
  margin-bottom: 1rem;
}

h2 {
  font-size: 1.6rem;
  margin: 2.5rem 0 1.5rem 0;
  border-bottom: 1px solid var(--border);
  padding-bottom: 0.75rem;
}

h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-top: 1.5rem;
  margin-bottom: 0.5rem;
}

p {
  margin-bottom: 1rem;
  color: var(--text-dark);
  line-height: 1.75;
  font-size: 1.05rem;
}

a {
  color: var(--primary);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: 0.2s ease;
}

a:hover {
  border-bottom-color: var(--primary);
  opacity: 0.8;
}

/* ================================================================
   NAVIGATION
   ================================================================ */

nav {
  background: #fff;
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 1000;
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.03);
}

.nav-container {
  max-width: 900px;
  margin: 0 auto;
  padding: 1rem 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.nav-logo {
  font-family: var(--ff-sans);
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--text-dark);
  border: none;
}

.nav-logo:hover {
  border: none;
  opacity: 0.7;
}

.nav-links {
  display: flex;
  list-style: none;
  gap: 2rem;
}

.nav-links a {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text-light);
  padding: 0.25rem 0;
  border-bottom: 2px solid transparent;
  transition: 0.2s ease;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--primary);
  border-bottom-color: var(--primary);
}

/* ================================================================
   MAIN CONTAINER
   ================================================================ */

.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 3rem 2rem;
}

/* ================================================================
   HERO SECTION - Home
   ================================================================ */

.hero {
  text-align: center;
  margin-bottom: 1.5rem;
  padding-bottom: 1rem;
}

.hero-image {
  width: 100%;
  max-width: 800px;
  margin: 0 auto 2rem auto;
  border-radius: 6px;
  overflow: hidden;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
  height: 500px;
}

.hero-image img {
  width: 100%;
  height: 100%;
  display: block;
  object-fit: cover;
}

.hero h1 {
  font-family: var(--ff-sans);
  font-size: 2.8rem;
  margin-bottom: 0.6rem;
  margin-top: 0;
  letter-spacing: -0.01em;
  font-weight: 700;
  color: var(--text-dark);
}

.hero-subtitle {
  font-size: 1.2rem;
  color: var(--primary);
  line-height: 1.5;
  margin: 0;
  font-weight: 500;
  letter-spacing: 0.2px;
}

.body-content {
  max-width: 750px;
  margin: 0 auto;
  line-height: 1.85;
  text-align: justify;
}

.body-content p {
  margin-bottom: 1.5rem;
  font-size: 1.1rem;
  color: var(--text-dark);
  line-height: 1.8;
}

.body-content p:last-child {
  margin-bottom: 0;
}

/* ================================================================
   COURSES LIST
   ================================================================ */

.courses-list {
  max-width: 750px;
}

.course-item {
  margin-bottom: 2rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--border);
}

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

.course-item strong {
  color: var(--text-dark);
  font-weight: 600;
}

.course-description {
  display: block;
  font-size: 0.95rem;
  color: var(--text-light);
  line-height: 1.7;
  margin-top: 0.4rem;
}

/* ================================================================
   CONTENT SECTIONS
   ================================================================ */

.content-block {
  margin-bottom: 2.5rem;
  line-height: 1.8;
}

.content-block p {
  margin-bottom: 1.2rem;
}

.content-block p:last-child {
  margin-bottom: 0;
}

/* ================================================================
   RESEARCH ITEMS
   ================================================================ */

.research-item {
  margin-bottom: 2rem;
  padding: 1.5rem;
  background: var(--bg-light);
  border-radius: 4px;
  border-left: 3px solid var(--primary);
}

.research-title {
  font-family: var(--ff-sans);
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  color: var(--text-dark);
}

.research-meta {
  font-size: 0.9rem;
  color: var(--text-light);
  margin-bottom: 0.75rem;
  line-height: 1.6;
}

.research-note {
  font-size: 0.9rem;
  color: var(--text-light);
  margin-top: 0.75rem;
  font-style: italic;
}

/* ================================================================
   OP-EDS
   ================================================================ */

.opeds-list {
  margin-top: 2rem;
}

.oped-item {
  margin-bottom: 1.75rem;
  padding-bottom: 1.75rem;
  border-bottom: 1px solid var(--border);
}

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

.oped-item a {
  display: block;
  font-size: 1rem;
  font-weight: 500;
  color: var(--primary);
  margin-bottom: 0.5rem;
}

.oped-item a:hover {
  opacity: 0.7;
}

/* ================================================================
   CV PAGE
   ================================================================ */

.cv-intro {
  background: var(--bg-light);
  padding: 1.5rem;
  border-radius: 4px;
  margin-bottom: 2rem;
  text-align: center;
}

.cv-buttons {
  display: flex;
  gap: 1rem;
  justify-content: center;
  margin-bottom: 3rem;
}

.btn {
  padding: 0.7rem 1.4rem;
  background: var(--primary);
  color: #fff;
  border: 2px solid var(--primary);
  border-radius: 4px;
  font-weight: 500;
  cursor: pointer;
  transition: 0.2s ease;
  text-decoration: none;
  display: inline-block;
  font-size: 0.95rem;
}

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

.btn-secondary {
  background: transparent;
  color: var(--primary);
}

.btn-secondary:hover {
  background: var(--primary);
  color: #fff;
}

.cv-viewer {
  background: var(--bg-light);
  border-radius: 4px;
  overflow: hidden;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.06);
}

.cv-viewer iframe {
  width: 100%;
  height: 800px;
  border: none;
}

/* ================================================================
   FOOTER
   ================================================================ */

footer {
  background: var(--bg-light);
  border-top: 1px solid var(--border);
  padding: 2.5rem;
  text-align: center;
  margin-top: 4rem;
}

.footer-content {
  max-width: 900px;
  margin: 0 auto;
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: 2rem;
  margin-bottom: 1.5rem;
  flex-wrap: wrap;
}

.footer-links a {
  font-size: 0.95rem;
  color: var(--text-dark);
}

.footer-credit {
  font-size: 0.85rem;
  color: var(--text-light);
  margin-top: 1.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
}

/* ================================================================
   PAGE-SPECIFIC COLORS
   ================================================================ */

/* HOME PAGE - Blue + Terracotta - Side by side layout */
body.home-page .container {
  display: flex;
  align-items: flex-start;
  gap: 4rem;
}

body.home-page .hero {
  flex-shrink: 0;
  margin-bottom: 0;
  padding-bottom: 0;
}

body.home-page .hero-image {
  width: 300px;
  height: 400px;
  margin: 0;
}

body.home-page .body-content {
  flex: 1;
  max-width: none;
  margin: 0;
  padding-top: 0;
}

body.home-page a {
  color: var(--home-primary);
}

body.home-page a:hover {
  border-bottom-color: var(--home-accent);
  color: var(--home-accent);
}

body.home-page .nav-links a.active {
  color: var(--home-primary);
  border-bottom-color: var(--home-primary);
}

body.home-page .research-item {
  border-left-color: var(--home-accent);
}

/* RESEARCH PAGE - Golden-Amber + Sage Green */
body.research-page {
  background: #f1ebe2;
}

body.research-page a {
  color: var(--research-primary);
}

body.research-page a:hover {
  border-bottom-color: var(--research-accent);
  color: var(--research-accent);
}

body.research-page .nav-links a.active {
  color: var(--research-primary);
  border-bottom-color: var(--research-primary);
}

body.research-page .research-item {
  border-left-color: var(--research-accent);
  background: rgba(200, 153, 104, 0.05);
}

/* COURSES PAGE - Deep Plum + Rose */
body.courses-page {
  background: #f0eaf4;
}

body.courses-page a {
  color: var(--courses-primary);
}

body.courses-page a:hover {
  border-bottom-color: var(--courses-accent);
  color: var(--courses-accent);
}

body.courses-page .nav-links a.active {
  color: var(--courses-primary);
  border-bottom-color: var(--courses-primary);
}

body.courses-page .course-item {
  border-bottom-color: rgba(107, 90, 122, 0.2);
}

/* OP-EDS PAGE - Warm Rose + Burgundy */
body.opeds-page {
  background: #faf5f7;
}

body.opeds-page a {
  color: var(--opeds-primary);
}

body.opeds-page a:hover {
  border-bottom-color: var(--opeds-accent);
  color: var(--opeds-accent);
}

body.opeds-page .nav-links a.active {
  color: var(--opeds-primary);
  border-bottom-color: var(--opeds-primary);
}

/* ================================================================
   RESPONSIVE
   ================================================================ */

@media (max-width: 768px) {
  .container {
    padding: 2rem 1.5rem;
  }

  body.home-page .container {
    flex-direction: column;
    gap: 2rem;
  }

  body.home-page .hero {
    margin-bottom: 0;
  }

  body.home-page .hero-image {
    width: 100%;
    height: 350px;
  }

  h1 {
    font-size: 1.75rem;
  }

  h2 {
    font-size: 1.4rem;
  }

  .nav-container {
    padding: 1rem;
  }

  .nav-links {
    gap: 1rem;
  }

  .nav-links a {
    font-size: 0.85rem;
  }

  .hero {
    margin-bottom: 2rem;
    padding-bottom: 1.5rem;
  }

  .hero-image {
    max-width: 100%;
    height: 300px;
    margin-bottom: 1.5rem;
  }

  .hero h1 {
    font-size: 2.2rem;
  }

  .hero-subtitle {
    font-size: 1rem;
  }

  .body-content p {
    font-size: 0.95rem;
    margin-bottom: 1.25rem;
  }

  .cv-buttons {
    flex-direction: column;
  }

  .btn {
    width: 100%;
    text-align: center;
  }

  .cv-viewer iframe {
    height: 600px;
  }

  .footer-links {
    gap: 1rem;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 1.5rem 1rem;
  }

  h1 {
    font-size: 1.4rem;
  }

  h2 {
    font-size: 1.2rem;
  }

  .nav-container {
    padding: 0.75rem;
  }

  .nav-links {
    gap: 0.75rem;
  }

  .nav-links a {
    font-size: 0.75rem;
  }

  .hero {
    margin-bottom: 1.5rem;
    padding-bottom: 1rem;
  }

  .hero-image {
    max-width: 100%;
    height: 220px;
    margin-bottom: 1.2rem;
  }

  .hero h1 {
    font-size: 1.6rem;
    margin-bottom: 0.4rem;
  }

  .hero-subtitle {
    font-size: 0.95rem;
    letter-spacing: 0;
  }

  .body-content p {
    font-size: 0.9rem;
    line-height: 1.75;
    margin-bottom: 1rem;
  }

  .cv-viewer iframe {
    height: 400px;
  }

  .oped-item {
    margin-bottom: 1.5rem;
    padding-bottom: 1.5rem;
  }
}