:root {
  --text-color: #1a1c20;
  --link-color: #4a76ee;
  --background-color: #eeeff1;
}

@media (prefers-color-scheme: dark) {
  :root {
    --text-color: #ffffff;
    --link-color: #6b9aff;
    --background-color: #1a1a1a;
  }

  .timeline-icon:not([data-logo]) {
    background-color: #2d2d2d !important;
  }

  .timeline-item {
    border-bottom: 1px solid #404040 !important;
  }

  .timeline-content .period,
  .timeline-content .location {
    color: #cccccc !important;
  }

  .research-item {
    background-color: #2d2d2d !important;
    border-color: #404040 !important;
    color: #ffffff !important;
  }

  .research-item .description,
  .research-item .title,
  .research-item h3 {
    color: #ffffff !important;
  }

  .research-item .keywords,
  .cert-item p {
    color: #cccccc !important;
  }

  .skills-section .cells .cell {
    border-color: #404040 !important;
    background-color: #2d2d2d !important;
  }

  .skills-section .cells .cell:hover {
    border-color: var(--link-color) !important;
    background-color: #353535 !important;
  }

  .expandable-header {
    background-color: #2d2d2d !important;
    border-color: #404040 !important;
  }

  .expandable-header:hover {
    background-color: #353535 !important;
  }

  .project-item,
  .blog-item {
    background: #2d2d2d !important;
    border-color: #404040 !important;
    color: #ffffff !important;
  }

  .project-item .description,
  .blog-item .description,
  .project-item h3,
  .blog-item h3 {
    color: #ffffff !important;
  }

  .project-item .period,
  .blog-item .period {
    color: #cccccc !important;
  }

  .project-item:hover,
  .blog-item:hover {
    background: #353535 !important;
  }

  .section-overlay {
    background-color: rgba(0, 0, 0, 0.85) !important;
  }

  .section-overlay-content {
    background: #1a1a1a !important;
  }

  .modal-content {
    background: #2d2d2d !important;
  }

  .modal-close {
    color: #ffffff !important;
  }

  .modal-close:hover {
    background-color: #404040 !important;
  }

  .modal-header .meta {
    color: #cccccc !important;
  }

  .modal-body,
  .modal-header h2 {
    color: #ffffff !important;
  }

  .contact-section .group form input,
  .contact-section .group form textarea {
    background-color: #2d2d2d !important;
    color: #ffffff !important;
    border-color: var(--link-color) !important;
  }
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Poppins', sans-serif;
  color: var(--text-color);
  background-color: var(--background-color);
  max-width: 1400px;
  margin: 0 auto;
}

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

/* NAVBAR */
nav {
  display: flex;
  justify-content: space-between;
  align-items: center;

  padding: 0 50px;
  height: 80px;
}

nav .left a {
  color: var(--text-color);
  font-size: 22px;
  font-weight: 600;
}

nav .right a {
  color: var(--text-color);
  margin: 0 10px;
}

nav .right a:last-child {
  color: var(--background-color);
  background-color: var(--text-color);
  padding: 5px 15px;
  border-radius: 5px;
}

nav .right a span {
  margin-left: 5px;
}

/* SECTION 1: Hero */
.hero-section {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0 50px;
  margin: 50px 0;
  margin-bottom: 100px;
  gap: 40px;
}

.hero-section .text {
  flex: 5;
}

.hero-section .text h2 {
  font-size: 45px;
}

.hero-section .text .links {
  margin-top: 25px;
}

.hero-section .text .links a {
  display: inline-block;
  padding: 5px 10px;
  border: 2px solid var(--link-color);
  border-radius: 5px;
  margin-right: 10px;
  margin-bottom: 10px;
  transition: .1s;
}

.hero-section .text .links a:hover {
  color: var(--text-color);
  border: 2px solid var(--text-color);
}

.hero-section .headshot {
  flex: 2;
  display: flex;
  justify-content: right;
}

.hero-section .headshot img {
  width: 350px;
  border-radius: 50%;
}

/* SECTION 2: Education */
.education-section {
  padding: 0 50px;
  margin-bottom: 100px;
}

.education-section h2 {
  text-align: center;
  font-size: 35px;
  margin-bottom: 40px;
}

/* SECTION 3: Work Experience */
.experience-section {
  padding: 0 50px;
  margin-bottom: 100px;
}

.experience-section h2 {
  text-align: center;
  font-size: 35px;
  margin-bottom: 40px;
}

/* Timeline Styles (for Education & Experience) */
.timeline {
  max-width: 900px;
  margin: 0 auto;
}

.timeline-item {
  display: flex;
  gap: 30px;
  margin-bottom: 40px;
  padding-bottom: 40px;
  border-bottom: 1px solid #d3d3d3;
}

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

.timeline-icon {
  flex-shrink: 0;
  width: 80px;
  height: 80px;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: white;
  border-radius: 10px;
  overflow: hidden;
  padding: 8px;
}

.timeline-icon[data-logo="uni-hohenheim"] {
  background-color: #003D7A !important;
  padding: 10px !important;
}

.timeline-icon[data-logo="hilti"] {
  background-color: #E2001A !important;
  padding: 0;
}

.timeline-icon[data-logo="gymnasium"] {
  background-color: white !important;
}

.timeline-icon[data-logo="fim-research"] {
  background-color: white !important;
}

.timeline-icon img {
  width: 100%;
  height: 100%;
  object-fit: contain;
}

.timeline-content h3 {
  font-size: 22px;
  margin-bottom: 5px;
  color: var(--text-color);
}

.timeline-content .institution {
  font-size: 16px;
  color: var(--link-color);
  margin-bottom: 5px;
}

.timeline-content .institution a {
  color: var(--link-color);
  text-decoration: none;
  transition: .2s;
}

.timeline-content .institution a:hover {
  text-decoration: underline;
}

.timeline-content h3 a {
  color: var(--text-color);
  text-decoration: none;
  transition: .2s;
}

.timeline-content h3 a:hover {
  color: var(--link-color);
}

.timeline-content .period {
  font-size: 14px;
  color: #666;
  margin-bottom: 8px;
}

.timeline-content .location {
  font-size: 14px;
  color: #666;
  margin-bottom: 8px;
}

.timeline-content .grade {
  font-size: 15px;
  font-weight: 600;
  color: var(--text-color);
  margin-bottom: 8px;
}

.timeline-content .description {
  font-size: 15px;
  line-height: 1.6;
  margin-bottom: 8px;
}

.timeline-content .highlight {
  font-size: 14px;
  margin-bottom: 5px;
  padding-left: 10px;
}

/* SECTION 4: Research */
.research-section {
  padding: 0 50px;
  margin-bottom: 100px;
}

.research-section h2 {
  text-align: center;
  font-size: 35px;
  margin-bottom: 40px;
}

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

.research-item {
  margin-bottom: 40px;
  padding: 25px;
  background-color: white;
  border-radius: 10px;
  border: 1.5px solid #d3d3d3;
}

.research-item h3 {
  font-size: 24px;
  margin-bottom: 15px;
  color: var(--text-color);
}

.research-item .title,
.research-item .supervisor,
.research-item .period {
  margin-bottom: 10px;
  font-size: 15px;
}

.research-item .description {
  line-height: 1.6;
  margin-bottom: 15px;
}

.research-item .keywords {
  font-size: 14px;
  color: #666;
  font-style: italic;
}

.research-link {
  display: inline-block;
  padding: 8px 16px;
  background-color: var(--link-color);
  color: white !important;
  border-radius: 5px;
  transition: .1s;
  text-decoration: none;
}

.research-link:hover {
  filter: brightness(.9);
}

.research-link i {
  margin-right: 8px;
}

.research-interests {
  list-style-position: inside;
  line-height: 2;
}

.research-interests li {
  font-size: 15px;
}

.certificates {
  display: flex;
  flex-direction: column;
  gap: 15px;
}

.cert-item {
  display: flex;
  gap: 15px;
  align-items: start;
}

.cert-item i {
  font-size: 24px;
  color: var(--link-color);
  margin-top: 5px;
}

.cert-item strong {
  display: block;
  margin-bottom: 3px;
}

.cert-item p {
  font-size: 14px;
  color: #666;
}

/* SECTION 5: Skills */
.skills-section {
  padding: 0 50px;
  margin-bottom: 100px;
}

.skills-section h2 {
  text-align: center;
  font-size: 35px;
}

.skills-section .text {
  text-align: center;
  margin-bottom: 30px;
}

.skills-categories {
  max-width: 1000px;
  margin: 0 auto;
}

.skill-category {
  margin-bottom: 40px;
}

.skill-category h3 {
  font-size: 22px;
  margin-bottom: 15px;
  color: var(--text-color);
  text-align: center;
}

.skills-section .cells {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
}

.skills-section .cells .cell {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 10px;

  width: 200px;
  padding: 10px 20px;
  margin: 10px;
  border: 1.5px solid #d3d3d3;
  border-radius: 5px;
  transition: .2s;
}

.skills-section .cells .cell:hover {
  border-color: var(--link-color);
  transform: translateY(-2px);
  box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

.skills-section .cells .cell img {
  width: 30px;
  height: 30px;
  object-fit: contain;
  border-radius: 2px;
}

.skills-section .cells .cell span {
  font-size: 16px;
}

/* Language cells - center text between icon and right edge */
.skill-category:last-child .cells .cell {
  justify-content: flex-start;
}

.skill-category:last-child .cells .cell span {
  flex: 1;
  text-align: center;
}

/* SECTION 6: Contact */
.contact-section {
  padding: 0 50px;
  margin-bottom: 100px;
  margin-top: 80px;
}

.contact-section h2 {
  font-size: 35px;
}

.contact-section .group {
  display: flex;
  gap: 50px;
}

.contact-section .group .text {
  flex: 3;
  margin-top: 20px;
}

.contact-section .group form {
  flex: 3;
  display: flex;
  flex-direction: column;
}

.contact-section .group form input,
.contact-section .group form textarea {
  font-family: 'Poppins', sans-serif;
  border: 2px solid var(--link-color);
  background-color: transparent;
  padding: 10px;
  margin-bottom: 15px;
  outline: none;
  resize: none;
}

.contact-section .group form button {
  font-size: 16px;
  font-family: 'Poppins', sans-serif;
  color: #fff;
  background-color: var(--link-color);
  border: none;
  height: 50px;
  cursor: pointer;
  transition: .1s;
}

.contact-section .group form button:hover {
  filter: brightness(.9);
}

@media (max-width: 850px) {
  /* SECTION 1: Hero */
  .hero-section .text h2 {
    font-size: 35px;
  }
}

@media (max-width: 740px) {
  /* SECTION 1: Hero */
  .hero-section {
    flex-direction: column-reverse;
  }

  .hero-section .headshot img {
    width: 300px;
  }

  /* Timeline */
  .timeline-item {
    flex-direction: column;
    gap: 15px;
  }

  .timeline-icon {
    margin: 0 auto;
  }

  /* Research */
  .research-item {
    padding: 20px;
  }

  /* Contact */
  .contact-section .group {
    flex-direction: column;
  }
}

@media (max-width: 600px) {
  /* NAVBAR */
  nav {
    padding: 0 20px;
  }

  nav .right a {
    font-size: 22px;
  }

  nav .right a:last-child {
    color: var(--text-color);
    background-color: transparent;
    padding: 0;
  }

  nav .right a span {
    display: none;
  }

  /* SECTION 1: Hero */
  .hero-section {
    padding: 0 20px;
  }

  .hero-section .text h2 {
    font-size: 30px;
  }

  /* Education & Experience */
  .education-section,
  .experience-section {
    padding: 0 20px;
  }

  .timeline-icon {
    width: 60px;
    height: 60px;
  }

  .timeline-icon img {
    width: 45px;
    height: 45px;
  }

  .timeline-content h3 {
    font-size: 18px;
  }

  /* Research */
  .research-section {
    padding: 0 20px;
  }

  .research-item {
    padding: 15px;
  }

  /* Skills */
  .skills-section {
    padding: 0 20px;
  }

  .skills-section .cells .cell {
    width: 160px;
  }

  .skills-section .cells .cell span {
    font-size: 14px;
  }

  .skill-category h3 {
    font-size: 20px;
  }

  /* Contact */
  .contact-section {
    padding: 0 20px;
  }
}

/* EXPANDABLE SECTIONS (Projects & Blog) */
.expandable-section {
  padding: 0 50px;
  margin-bottom: 100px;
}

.expandable-section > h2 {
  text-align: center;
  font-size: 35px;
  margin-bottom: 40px;
}

.expandable-box-container {
  max-width: 900px;
  margin: 0 auto;
}

.expandable-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  cursor: pointer;
  user-select: none;
  transition: all 0.3s ease;
  padding: 25px;
  background-color: white;
  border-radius: 8px;
  border: 1.5px solid #d3d3d3;
}

.expandable-header:hover {
  border-color: var(--link-color);
  box-shadow: 0 2px 8px rgba(74, 118, 238, 0.1);
}

.expandable-header h3 {
  font-size: 24px;
  margin: 0;
  color: var(--text-color);
}

.expand-icon {
  font-size: 24px;
  color: var(--link-color);
  transition: transform 0.4s ease;
  margin-left: 20px;
  flex-shrink: 0;
}

.expandable-header.active .expand-icon {
  transform: rotate(180deg);
}

.expandable-content {
  display: none;
}

/* Projects Section */
.project-item {
  margin-bottom: 35px;
  padding: 25px;
  background: #fafafa;
  border-radius: 12px;
  border: 1px solid #f0f0f0;
  transition: all 0.3s ease;
}

.project-item:hover {
  background: #f5f5f5;
  border-color: var(--link-color);
  transform: translateY(-2px);
}

.project-item:last-child {
  margin-bottom: 0;
}

.project-item h3 {
  font-size: 24px;
  margin-bottom: 10px;
  color: var(--text-color);
}

.project-item .period {
  color: #666;
  font-size: 14px;
  margin-bottom: 15px;
}

.project-item .description {
  line-height: 1.8;
  margin-bottom: 20px;
  color: var(--text-color);
}

.tech-stack {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.tech-tag {
  background-color: var(--link-color);
  color: white;
  padding: 6px 14px;
  border-radius: 20px;
  font-size: 13px;
  font-weight: 500;
}

/* Blog Section */
.blog-item {
  margin-bottom: 35px;
  padding: 25px;
  background: #fafafa;
  border-radius: 12px;
  border: 1px solid #f0f0f0;
  transition: all 0.3s ease;
}

.blog-item:hover {
  background: #f5f5f5;
  border-color: var(--link-color);
  transform: translateY(-2px);
}

.blog-item:last-child {
  margin-bottom: 0;
}

.blog-item h3 {
  font-size: 24px;
  margin-bottom: 10px;
  color: var(--text-color);
}

.blog-item .period {
  color: #666;
  font-size: 14px;
  margin-bottom: 15px;
}

.blog-item .description {
  line-height: 1.8;
  margin-bottom: 15px;
  color: var(--text-color);
}

.read-more {
  color: var(--link-color);
  font-weight: 500;
  transition: opacity 0.3s ease;
}

.read-more:hover {
  opacity: 0.7;
}

/* Section Overlay for Projects & Blog */
.section-overlay {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(26, 28, 32, 0.7);
  z-index: 999;
  overflow-y: auto;
  padding: 60px 0;
  opacity: 0;
  transition: opacity 0.4s ease;
}

.section-overlay.active {
  display: block;
  opacity: 1;
}

.section-overlay-content {
  max-width: 1200px;
  margin: 0 auto;
  background: var(--background-color);
  padding: 60px 80px;
  position: relative;
  transform: translateY(20px);
  opacity: 0;
  transition: transform 0.4s ease, opacity 0.4s ease;
  border-radius: 8px;
}

.section-overlay.active .section-overlay-content {
  transform: translateY(0);
  opacity: 1;
}

.section-overlay-close {
  position: fixed;
  top: 20px;
  right: 20px;
  font-size: 36px;
  line-height: 1;
  color: white;
  cursor: pointer;
  background: rgba(0, 0, 0, 0.5);
  border: none;
  width: 50px;
  height: 50px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  transition: background-color 0.3s ease;
  z-index: 1001;
  padding: 0;
}

.section-overlay-close:hover {
  background-color: rgba(0, 0, 0, 0.8);
}

.section-overlay h2 {
  text-align: center;
  font-size: 42px;
  margin-bottom: 50px;
  color: var(--text-color);
}

/* Modal Overlay for Read More */
.modal-overlay {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.6);
  z-index: 1000;
  overflow-y: auto;
  padding: 40px 20px;
  opacity: 0;
  transition: opacity 0.3s ease;
}

.modal-overlay.active {
  display: flex;
  justify-content: center;
  align-items: flex-start;
  opacity: 1;
}

.modal-content {
  background: white;
  border-radius: 12px;
  max-width: 900px;
  width: 100%;
  padding: 50px;
  margin: 40px auto;
  box-shadow: 0 10px 40px rgba(0, 0, 0, 0.3);
  position: relative;
  transform: translateY(-20px);
  transition: transform 0.3s ease;
}

.modal-overlay.active .modal-content {
  transform: translateY(0);
}

.modal-close {
  position: absolute;
  top: 20px;
  right: 20px;
  font-size: 32px;
  color: #666;
  cursor: pointer;
  background: none;
  border: none;
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  transition: background-color 0.3s ease, color 0.3s ease;
}

.modal-close:hover {
  background-color: #f0f0f0;
  color: var(--text-color);
}

.modal-header {
  margin-bottom: 20px;
}

.modal-header h2 {
  font-size: 32px;
  margin-bottom: 10px;
  color: var(--text-color);
}

.modal-header .meta {
  color: #666;
  font-size: 14px;
  margin-bottom: 20px;
}

.modal-body {
  line-height: 1.8;
  color: var(--text-color);
  font-size: 16px;
}

.modal-body p {
  margin-bottom: 20px;
}

.modal-body h3 {
  font-size: 24px;
  margin-top: 30px;
  margin-bottom: 15px;
  color: var(--text-color);
}

.modal-body ul {
  margin-left: 25px;
  margin-bottom: 20px;
}

.modal-body li {
  margin-bottom: 10px;
}

/* Responsive for expandable sections */
@media (max-width: 850px) {
  .expandable-section {
    padding: 0 20px;
  }

  .expandable-section > h2 {
    font-size: 26px;
  }

  .expandable-header {
    padding: 20px;
  }

  .expandable-header h3 {
    font-size: 18px;
  }

  .project-item,
  .blog-item {
    padding: 20px;
  }

  .project-item h3,
  .blog-item h3 {
    font-size: 20px;
  }

  .modal-content {
    padding: 30px 20px;
    margin: 20px auto;
  }

  .modal-header h2 {
    font-size: 26px;
  }

  .modal-body {
    font-size: 15px;
  }

  .modal-close {
    top: 10px;
    right: 10px;
  }
}