/* ========================================
   Ultra Minimal Portfolio - B/W Design
   ======================================== */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600&display=swap');

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

:root {
  --black: #000000;
  --white: #ffffff;
  --gray: #666666;
  --light-gray: #f5f5f5;
  --border: #e0e0e0;
  
  /* Theme colors */
  --bg: var(--white);
  --text: var(--black);
  --text-secondary: var(--gray);
  --card-bg: var(--light-gray);
  --border-color: var(--border);
}

[data-theme="dark"] {
  --bg: #0a0a0a;
  --text: #ffffff;
  --text-secondary: #999999;
  --card-bg: #1a1a1a;
  --border-color: #333333;
  --light-gray: #1a1a1a;
  --gray: #999999;
  --black: #ffffff;
  --white: #0a0a0a;
  --border: #333333;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  transition: background 0.3s ease, color 0.3s ease;
}

::selection {
  background: var(--black);
  color: var(--white);
}

.container {
  max-width: 720px;
  margin: 0 auto;
  padding: 0 24px;
}

/* Navigation */
nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  z-index: 100;
  border-bottom: 1px solid var(--border);
  transition: background 0.3s ease;
}

[data-theme="dark"] nav {
  background: rgba(10, 10, 10, 0.95);
}

nav .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 60px;
}

.logo {
  font-weight: 600;
  font-size: 1rem;
  text-decoration: none;
  color: var(--black);
}

.nav-links {
  display: flex;
  gap: 32px;
  list-style: none;
}

.nav-links a {
  color: var(--gray);
  text-decoration: none;
  font-size: 0.875rem;
  transition: color 0.2s;
}

.nav-links a:hover {
  color: var(--black);
}

@media (max-width: 600px) {
  .nav-links {
    display: none;
  }
}

/* Sections */
section {
  padding: 80px 0;
}

section:first-of-type {
  padding-top: 140px;
}

/* Hero */
.hero h1 {
  font-size: clamp(2rem, 5vw, 3rem);
  font-weight: 600;
  letter-spacing: -0.02em;
  margin-bottom: 8px;
}

.hero .title-rotating {
  font-size: 1.125rem;
  color: var(--gray);
  margin-bottom: 24px;
  height: 28px;
}

.hero .title-rotating span {
  display: inline-block;
  transition: opacity 0.4s ease;
}

.hero p {
  color: var(--gray);
  font-size: 1rem;
  max-width: 520px;
  margin-bottom: 32px;
}

.hero-buttons {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 24px;
  font-size: 0.875rem;
  font-weight: 500;
  text-decoration: none;
  border-radius: 6px;
  transition: all 0.2s;
  cursor: pointer;
  font-family: inherit;
  border: none;
}

.btn-primary {
  background: var(--black);
  color: var(--white);
}

.btn-primary:hover {
  opacity: 0.8;
}

.btn-secondary {
  background: var(--white);
  color: var(--black);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  border-color: var(--black);
}

/* Dropdown */
.dropdown {
  position: relative;
}

.dropdown-menu {
  display: none;
  position: absolute;
  top: calc(100% + 8px);
  left: 0;
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: 8px;
  min-width: 200px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
  z-index: 50;
}

.dropdown.open .dropdown-menu {
  display: block;
}

.dropdown-menu button {
  display: block;
  width: 100%;
  padding: 12px 16px;
  text-align: left;
  background: none;
  border: none;
  font-size: 0.875rem;
  color: var(--gray);
  cursor: pointer;
  font-family: inherit;
  transition: all 0.15s;
}

.dropdown-menu button:hover {
  background: var(--light-gray);
  color: var(--black);
}

.dropdown-menu button:first-child {
  border-radius: 7px 7px 0 0;
}

.dropdown-menu button:last-child {
  border-radius: 0 0 7px 7px;
}

/* Section Titles */
h2 {
  font-size: 0.75rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--gray);
  margin-bottom: 32px;
}

/* Experience */
.experience-item {
  padding: 24px 0;
  border-bottom: 1px solid var(--border);
}

.experience-item:first-child {
  padding-top: 0;
}

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

.experience-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 8px;
  gap: 16px;
}

.experience-item h3 {
  font-size: 1rem;
  font-weight: 600;
}

.experience-item .company {
  color: var(--gray);
  font-size: 0.875rem;
}

.experience-item .date {
  color: var(--gray);
  font-size: 0.875rem;
  white-space: nowrap;
}

.experience-item p {
  color: var(--gray);
  font-size: 0.9375rem;
  margin-top: 8px;
}

/* Skills */
.skills-list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.skill-tag {
  padding: 6px 12px;
  background: var(--light-gray);
  border-radius: 4px;
  font-size: 0.8125rem;
  color: var(--black);
}

/* Projects */
.project-item {
  padding: 24px 0;
  border-bottom: 1px solid var(--border);
}

.project-item:first-child {
  padding-top: 0;
}

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

.project-item h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 4px;
}

.project-item .category {
  font-size: 0.75rem;
  color: var(--gray);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 8px;
}

.project-item p {
  color: var(--gray);
  font-size: 0.9375rem;
}

/* Education */
.education-item h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 4px;
}

.education-item p {
  color: var(--gray);
  font-size: 0.9375rem;
}

/* Contact */
.contact-links {
  display: flex;
  gap: 24px;
  flex-wrap: wrap;
}

.contact-links a {
  color: var(--black);
  text-decoration: none;
  font-size: 0.9375rem;
  border-bottom: 1px solid var(--border);
  padding-bottom: 2px;
  transition: border-color 0.2s;
}

.contact-links a:hover {
  border-color: var(--black);
}

/* Footer */
footer {
  padding: 40px 0;
  text-align: center;
  color: var(--gray);
  font-size: 0.8125rem;
  border-top: 1px solid var(--border);
}

/* Divider */
.divider {
  height: 1px;
  background: var(--border);
  margin: 0;
}

/* Additional Styles */
.availability {
  font-size: 0.875rem;
  color: var(--gray);
  margin-bottom: 24px;
  font-style: italic;
}

/* Focus Grid */
.focus-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 32px;
  margin-bottom: 24px;
}

.focus-column h3 {
  font-size: 0.875rem;
  font-weight: 600;
  margin-bottom: 12px;
}

.focus-column ul {
  list-style: none;
  color: var(--gray);
}

.focus-column li {
  padding: 4px 0;
  font-size: 0.9375rem;
}

.goal {
  color: var(--gray);
  font-size: 0.9375rem;
}

/* Experience enhancements */
.type {
  font-size: 0.8125rem;
  color: var(--gray);
  font-style: italic;
}

.overview {
  color: var(--gray);
  font-size: 0.9375rem;
  margin: 12px 0;
}

.experience-item h4 {
  font-size: 0.75rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--gray);
  margin: 16px 0 8px;
}

.responsibilities, .impact {
  list-style: none;
  color: var(--gray);
}

.responsibilities li, .impact li {
  position: relative;
  padding-left: 16px;
  margin-bottom: 6px;
  font-size: 0.9375rem;
}

.responsibilities li::before, .impact li::before {
  content: "–";
  position: absolute;
  left: 0;
}

.tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.tag {
  padding: 4px 10px;
  background: var(--light-gray);
  border-radius: 4px;
  font-size: 0.75rem;
  color: var(--black);
}

/* Project details */
.project-details {
  list-style: none;
  color: var(--gray);
  margin: 8px 0 12px;
}

.project-details li {
  position: relative;
  padding-left: 16px;
  margin-bottom: 4px;
  font-size: 0.875rem;
}

.project-details li::before {
  content: "–";
  position: absolute;
  left: 0;
}

/* Hackathons */
.hackathon-item {
  padding: 24px 0;
  border-bottom: 1px solid var(--border);
}

.hackathon-item:first-child {
  padding-top: 0;
}

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

.hackathon-header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 8px;
}

.hackathon-header h3 {
  font-size: 1rem;
  font-weight: 600;
}

.badge {
  padding: 4px 10px;
  background: var(--black);
  color: var(--white);
  border-radius: 4px;
  font-size: 0.75rem;
  font-weight: 500;
}

.project-name {
  font-size: 0.875rem;
  color: var(--gray);
  margin-bottom: 8px;
}

/* Research */
.research-item {
  padding: 20px 0;
  border-bottom: 1px solid var(--border);
}

.research-item:first-child {
  padding-top: 0;
}

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

.research-item h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 4px;
}

.research-item .meta {
  font-size: 0.875rem;
  color: var(--gray);
}

/* Skills categories */
.skill-category {
  margin-bottom: 24px;
}

.skill-category:last-child {
  margin-bottom: 0;
}

.skill-category h3 {
  font-size: 0.875rem;
  font-weight: 600;
  margin-bottom: 10px;
}

/* Certifications & Languages */
.certifications-list, .languages-list {
  list-style: none;
  color: var(--gray);
}

.certifications-list li, .languages-list li {
  padding: 6px 0;
  font-size: 0.9375rem;
  border-bottom: 1px solid var(--border);
}

.certifications-list li:last-child, .languages-list li:last-child {
  border-bottom: none;
}

/* Contact info */
.contact-info {
  margin-bottom: 24px;
}

.contact-info p {
  color: var(--gray);
  font-size: 0.9375rem;
  margin-bottom: 8px;
}

.contact-info a {
  color: var(--black);
}

/* Reference */
.reference {
  padding: 16px;
  background: var(--light-gray);
  border-radius: 6px;
}

.reference p {
  margin-bottom: 4px;
  font-size: 0.9375rem;
}

.reference a {
  color: var(--black);
}

/* Theme Toggle */
.theme-toggle {
  position: fixed;
  bottom: 24px;
  right: 24px;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: var(--black);
  color: var(--white);
  border: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 2px 10px rgba(0,0,0,0.2);
  transition: transform 0.2s, background 0.3s;
  z-index: 1000;
}

.theme-toggle:hover {
  transform: scale(1.1);
}

.theme-toggle svg {
  width: 20px;
  height: 20px;
}

.theme-toggle .icon-sun,
.theme-toggle .icon-moon {
  display: none;
}

[data-theme="dark"] .theme-toggle .icon-sun {
  display: block;
}

[data-theme="light"] .theme-toggle .icon-moon,
:root:not([data-theme]) .theme-toggle .icon-moon {
  display: block;
}

/* Responsive */
@media (max-width: 600px) {
  section {
    padding: 60px 0;
  }
  
  section:first-of-type {
    padding-top: 100px;
  }
  
  .experience-header {
    flex-direction: column;
    gap: 4px;
  }
  
  .focus-grid {
    grid-template-columns: 1fr;
    gap: 24px;
  }
  
  .hackathon-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 8px;
  }
}