/* === Site Theme Variables === */
:root {
  --primary-color: #1f78c1;        /* main site color */
  --background-left: #ffffff;      /* left column background */
  --background-card: #ffffff;      /* research card background */
  --font-body: "Inter", sans-serif; /* body font */
  --font-heading: "Merriweather", serif; /* headings font */
}

/* === Custom Text Selection === */
::selection {
  background-color: var(--primary-color);
  color: white;
}

/* === Base Styles === */
body {
  font-family: var(--font-body);
  margin: 0;
  padding: 0;
  color: #222;
}

.container {
  display: flex;
  min-height: 100vh;
  flex-direction: row;
}

/* === Left Column === */
.left-col {
  width: 320px; /* Increased from 250px */
  background-color: var(--background-left);
  padding: 3rem 2.5rem; /* Increased vertical padding */
  flex-shrink: 0;
  position: sticky; 
  top: 0;
  height: 100vh;
  text-align: center;
  box-sizing: border-box;
}

.left-col img {
  width: 100%;
  max-width: 280px; /* Prevent image from being too large */
  border-radius: 8px;
  margin-bottom: 1rem;
}

/* === Right Column === */
.right-col {
  flex: 1;
  padding: 3rem 4rem; /* Significantly increased padding */
  overflow: visible; /* prevents independent scroll */
  max-width: calc(100vw - 320px); /* Prevent overflow on smaller screens */
  box-sizing: border-box;
}

/* === Section Divider === */
.crimson-line {
  border: 0;
  height: 2px;
  background-color: var(--primary-color);
  margin: 30px 0; /* Increased spacing */
}

/* === Research Cards === */

/* Make research items stack vertically */
.research-grid {
  display: flex;
  flex-direction: column;
  gap: 2rem; /* Increased gap */
}

.research-card {
  background-color: var(--background-card); 
  padding: 2rem; /* Increased padding */
  display: flex;
  flex-direction: column;
  transition: none; /* remove hover translate to keep flat */
  margin-bottom: 1rem;
}

/* === Toggle Links === */
.toggle-link {
  color: var(--primary-color);
  cursor: pointer;
  text-decoration: none;
  font-weight: normal;
  margin-top: 0.75rem; /* Slightly increased */
}

.toggle-link:hover {
  text-decoration: underline;
}

/* === Abstract Toggle === */
.abstract {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.5s ease, padding 0.5s ease;
  padding-top: 0;
  padding-bottom: 0;
  margin-top: 0.5rem; /* Increased margin */
  text-align: justify;
}

.abstract.open {
  max-height: 1000px;
  padding-top: 0.75rem; /* Increased padding */
  padding-bottom: 0.75rem;
}

/* === Link Styling === */
a {
  color: var(--primary-color);
  text-decoration: none;
}

a:hover {
  color: #155a8a;
}

/* === Headings === */
h1, h2, h3 {
  font-family: var(--font-heading);
  color: #222;
}

/* === Mobile-Responsive Styles === */

/* Tablet styles */
@media (max-width: 1200px) {
  .left-col {
    width: 280px; /* Slightly smaller on tablets */
    padding: 2.5rem 2rem;
  }
  
  .right-col {
    padding: 2.5rem 3rem;
    max-width: calc(100vw - 280px);
  }
}

@media (max-width: 1024px) {
  .left-col {
    width: 260px;
    padding: 2rem 1.5rem;
  }
  
  .right-col {
    padding: 2rem 2.5rem;
    max-width: calc(100vw - 260px);
  }
  
  .research-grid {
    gap: 1.5rem;
  }
  
  .research-card {
    padding: 1.5rem;
  }
}

@media (max-width: 768px) {
  .container {
    flex-direction: column; /* stack left and right columns */
  }

  .left-col {
    width: 100%;
    height: auto;
    position: static;
    padding: 2rem 1.5rem; /* Maintained broader padding */
    text-align: center;
    border-right: none;
    border-bottom: 1px solid #e0e0e0;
  }

  .left-col h1 {
    font-size: 1.8rem; /* Slightly larger */
    margin-bottom: 1.5rem;
  }

  .left-col img {
    max-width: 200px; /* Slightly larger on mobile */
    margin-bottom: 1.5rem;
  }

  .right-col {
    width: 100%;
    padding: 2rem 1.5rem; /* Maintained broader padding */
    overflow: visible;
    max-width: 100%;
  }

  .research-card {
    padding: 1.5rem; /* Maintained broader padding */
    margin-bottom: 1.5rem;
  }

  .research-grid {
    gap: 1.5rem;
  }

  .paper-title {
    font-size: 1.2rem; /* Slightly larger */
  }

  .paper-links {
    gap: 0.5rem; /* Increased gap */
  }

  .paper-links a {
    font-size: 0.9rem; /* Slightly larger */
    padding: 0.4rem 0.8rem; /* More padding */
  }

  h2 {
    font-size: 1.6rem; /* Larger headings */
  }
  
  .crimson-line {
    margin: 25px 0;
  }
}

@media (max-width: 480px) {
  .left-col {
    padding: 1.5rem 1rem; /* Still broader than original */
  }

  .right-col {
    padding: 1.5rem 1rem; /* Still broader than original */
  }

  .left-col h1 {
    font-size: 1.6rem;
  }

  .research-card {
    padding: 1.25rem; /* Still broader than original */
  }

  .research-grid {
    gap: 1.25rem;
  }

  h2 {
    font-size: 1.4rem;
  }
  
  .crimson-line {
    margin: 20px 0;
  }
}

/* === Very small screens === */
@media (max-width: 360px) {
  .left-col {
    padding: 1rem 0.75rem;
  }

  .right-col {
    padding: 1rem 0.75rem;
  }
  
  .research-card {
    padding: 1rem;
  }
}

/* === Print Styles === */
@media print {
  .container {
    flex-direction: column;
  }
  
  .left-col {
    width: 100%;
    position: static;
    height: auto;
    border: none;
    padding: 2rem;
  }
  
  .right-col {
    padding: 2rem;
  }
  
  .research-card {
    break-inside: avoid;
    border: 1px solid #e0e0e0;
    padding: 1.5rem;
    margin-bottom: 1rem;
  }
  
  .toggle-link {
    display: none;
  }
  
  .abstract {
    max-height: none;
    padding: 1rem;
    background-color: #f5f5f5;
  }
  
  .crimson-line {
    background: #222;
  }
}