/* ================================== */
/*          NEW LIGHT THEME           */
/* ================================== */

/* --- 1. NEW Color Palette Variables --- */
:root {
    --bg-primary: #E0EFF1;     /* Your chosen light blue background */
    --bg-secondary: #FFFFFF;  /* White for header and cards */
    --text-primary: #2c3e50;  /* Dark slate for main text */
    --text-secondary: #555e6f; /* Medium gray for secondary text */
    --accent: #007BFF;        /* Professional blue for accents */
    --card-bg: #E0EFF1 ;       /* Card background is now white */
    --card-shadow: 0 5px 20px rgba(44, 62, 80, 0.1); /* Subtle shadow for depth */
    --card-border: #dce7e9;   /* A very light border */
}

/* --- 2. Base & Body Styles --- */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    background-color: var(--bg-primary);
    color: var(--text-primary);
    margin: 0;
    padding: 0;
    /* font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;*/
    font-family: 'Lato', Tahoma, Geneva, Verdana, sans-serif;
}

p {
    font-size: 1.125rem;
    line-height: 1.6;
    color: var(--text-secondary);
}

li {
    margin-bottom: 0.5rem;
}

/* --- 3. Header & Top Navigation --- */
header {
    background-color: var(--bg-secondary);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 999; /* Lower than sidebar */
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
}

header nav {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    color: var(--text-primary);
    font-weight: 700;
    font-size: 1.2rem;
}

header nav ul {
    display: flex;
    list-style: none;
    gap: 2rem;
}

header nav a {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 600;
    transition: color 0.3s ease;
    padding: 5px 10px;
    border-radius: 5px;
}

header nav a:hover {
    color: var(--accent);
    background-color: #f0f0f0;
}

/* --- 4. General Section Styling --- */
section {
    padding: 100px 20px;
    max-width: 1200px;
    margin: 0 auto;
}

h2 {
    font-size: 2.5rem;
    color: var(--text-primary);
    text-align: left;
    margin-bottom: 3rem;
    position: relative;
}
h3 {
    font-size: 2rem;
    color: var(--text-primary);
    text-align: center;
    margin-bottom: 3rem;
    position: relative;
}

h3:after {
    content: '';
    display: block;
    width: 80px;
    height: 4px;
    background: var(--accent);
    margin: 15px auto 0;
    border-radius: 2px;
}

h4 { color: var(--text-primary); }

/* --- 5. Hero Section --- */
.hero {
    background-color: transparent;
    padding: 4rem 2rem;
}
.hero-content { display: flex; align-items: center; gap: 4rem; }
.profile-image {
    width: 300px; height: 300px;
    border-radius: 50%; object-fit: cover;
    border: 5px solid var(--accent);
    box-shadow: var(--card-shadow);
}
.hero-image {
    display: flex;
    justify-content: center;
    align-items: center;
}
.hero-text h1 {
    font-size: 3.5rem; color: var(--text-primary);
    background: none; -webkit-text-fill-color: initial;
}
.hero-text h2 { font-size: 2rem; margin: 0.5rem 0; color: var(--text-secondary); font-weight: normal; }
.brief-intro { font-size: 1.2rem; color: var(--text-secondary); margin: 1rem 0; }
.social-links { margin-top: 2rem; }
.social-links a { color: var(--text-secondary); font-size: 1.5rem; margin-right: 1.5rem; transition: color 0.3s ease; }
.social-links a:hover { color: var(--accent); }

/* --- 6. Areas of Expertise Section --- */
.interests-section { padding-top: 50px; }
.interests-section h4 { text-align: center; font-size: 1.5rem; color: var(--text-primary); margin-bottom: 2.5rem; position: relative; }
.interests-section h4::after { content: ""; display: block; width: 80px; height: 3px; background: var(--accent); margin: 0.5rem auto 0; }
.interests-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 1.5rem; }
.interest-item {
    background: var(--card-bg); border-radius: 10px; padding: 2rem 1.5rem; text-align: center;
    box-shadow: var(--card-shadow); transition: all 0.3s ease; border: 1px solid var(--card-border);
}
.interest-item:hover { transform: translateY(-5px); border-color: var(--accent); }
.interest-item h4 { color: var(--text-primary); }
.interest-item p { color: var(--text-secondary); }
.interest-item i { font-size: 2.5rem; margin-bottom: 1.5rem; }
.interest-item[data-category="analysis"] i { color: #3498db; }
.interest-item[data-category="3d"] i { color: #9b59b6; }
.interest-item[data-category="modeling"] i { color: #e74c3c; }
.interest-item[data-category="data"] i { color: #2ecc71; }
.interest-item[data-category="ai"] i { color: #f39c12; }
.interest-item[data-category="cartography"] i { color: #1abc9c; }

/* --- 7. Generic Card Styling (Experience, Education, etc.) --- */
.experience, .education, .publications, .skills, .about, .contact { background-color: transparent; }
.experience-grid, .education-grid, .skills-container, .pub-category { display: grid; gap: 2rem; }
.experience-grid { grid-template-columns: repeat(auto-fit, minmax(350px, 1fr)); }
.education-grid { grid-template-columns: repeat(auto-fit, minmax(350px, 1fr)); }
.skills-container { grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); }
.experience-card, .education-card, .pub-card, .skill-card, .about-content {
    background: var(--card-bg); 
    border-radius: 16px; 
    padding: 2rem;
    border: 1px solid var(--card-border); 
    box-shadow: var(--card-shadow);
    transition: transform 0.3s ease, box-shadow 0.3s ease, border-color 0.3s ease;
}
.experience-card:hover, .education-card:hover, .pub-card:hover, .skill-card:hover {
    transform: translateY(-5px); box-shadow: 0 10px 25px rgba(44, 62, 80, 0.15); border-color: var(--accent);
}
.about-content p {  margin-bottom: 1rem; line-height: 1.7; }

.skill-header i{color: var(--accent);}
.skill-header h3 { color: var(--text-primary); } /* Your HTML uses h4, but your CSS targets h3. Let's make a rule that works for both. */
.skill-header h3, .skill-header h4 {
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: 0.75rem; /* Space between icon and text */
}

/* --- ADD THIS RULE HERE --- */
.skill-header {
    margin-bottom: 1rem; /* The space between the header and the list */
}
/* -------------------------- */


.skill-content li:before { content: '▸'; position: absolute; left: 0; color: var(--accent); }

/* --- 8. Contact Section --- */
.contact-info { display: flex; flex-direction: column; align-items: center; gap: 1.5rem; }
.contact-item a { color: var(--text-secondary); text-decoration: none; font-size: 1.1rem; transition: color 0.3s ease; }
.contact-item a:hover { color: var(--accent); }
.contact-item i { color: var(--accent); font-size: 1.3rem; margin-right: 0.5rem; }
.contact-item {
    display: flex;
    align-items: center;
    gap: 10px;
}
/* --- 9. Footer --- */
footer {
    background-color: var(--bg-secondary); color: var(--text-secondary);
    text-align: center; padding: 2rem; border-top: 1px solid var(--card-border);
}

/* --- 10. VERTICAL SIDEBAR NAVIGATION --- */
.sidebar-nav {
    position: fixed; top: 50%; transform: translateY(-50%);
    left: 20px; background-color: rgba(255, 255, 255, 0.8);
    backdrop-filter: blur(8px); border-radius: 30px;
    padding: 15px 10px; z-index: 1000;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
    border: 1px solid rgba(0, 0, 0, 0.05);
}
.sidebar-nav ul { list-style: none; padding: 0; margin: 0; display: flex; flex-direction: column; gap: 15px; }
.sidebar-nav a {
    display: flex; justify-content: center; align-items: center;
    width: 45px; height: 45px; border-radius: 50%;
    background-color: #f8f9fa; color: var(--text-secondary);
    font-size: 18px; text-decoration: none;
    transition: all 0.3s ease; position: relative;
}
.sidebar-nav a:hover, .sidebar-nav a.active {
    background-color: var(--accent); color: #ffffff; transform: scale(1.1);
}
.sidebar-nav a:hover::after {
    content: attr(data-tooltip); position: absolute; left: 60px; top: 50%;
    transform: translateY(-50%); background-color: var(--text-primary);
    color: var(--bg-secondary); padding: 5px 10px; border-radius: 5px;
    font-size: 14px; font-weight: 500; white-space: nowrap;
    box-shadow: 0 2px 5px rgba(0,0,0,0.2);
}

/* --- 11. Responsive Adjustments --- */
@media (max-width: 768px) {
    .sidebar-nav { display: none; }
    .hero-content { flex-direction: column; text-align: center; gap: 2rem; }
    .profile-image { width: 200px; height: 200px; }
    .hero-text h1 { font-size: 2.5rem; }
    .hero-text h2 { font-size: 1.5rem; }
    .hero-text h3 { font-size: 1.2rem; }
    .experience-grid, .education-grid, .skills-container { grid-template-columns: 1fr; }
}

/* --- Timeline Experience Layout --- */
.timeline {
  position: relative;
  margin: 2rem 0;
  padding-left: 40px;
  border-left: 3px solid var(--accent);
}

.timeline-item {
  position: relative;
  margin-bottom: 3rem;
  padding-left: 30px;
}

.timeline-icon {
  position: absolute;
  left: -27px;
  top: 0;
  width: 30px;
  height: 30px;
  background: var(--accent);
  color: #fff;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 0 0 4px var(--bg-primary);
}

.timeline-content {
  background: var(--card-bg);
  padding: 1.5rem;
  border-radius: 12px;
  box-shadow: var(--card-shadow);
  border: 1px solid var(--card-border);
  transition: transform 0.3s ease;
}

.timeline-content:hover {
  transform: translateY(-3px);
  border-color: var(--accent);
}

.timeline-content h4 {
  font-size: 1.3rem;
  margin-bottom: 0.3rem;
}

.timeline-content h4 span {
  font-weight: normal;
  color: var(--text-secondary);
}

.timeline-content ul {
  margin-top: 0.8rem;
  padding-left: 1.25rem;
}

.timeline-content ul li {
  margin-bottom: 0.5rem;
  line-height: 1.5;
  color: var(--text-secondary);
}

@media (max-width: 768px) {
  .timeline {
    padding-left: 20px;
  }
  .timeline-icon {
    left: -22px;
  }
  .timeline-content {
    padding: 1.2rem;
  }
}
.card-detail {
    font-size: 1rem;
    color: var(--text-secondary);
    margin-top: 0.5rem;
}
.thesis h4 {
    font-size: 1rem;
    color: var(--text-primary);
    margin-top: 1rem;
    margin-bottom: 0.25rem;
}
.thesis p {
    font-size: 1rem;
    color: var(--text-secondary);
}