/* ==========================================================================
   CSS Variables & Theming
   ========================================================================== */
:root {
  /* Color Palette - Light Mode */
  --bg-main: #f8fafc;
  --bg-alt: #f1f5f9;
  --bg-card: #ffffff;
  --text-main: #0f172a;
  --text-muted: #475569;
  --border-color: #e2e8f0;
  
  --primary-color: #3b82f6;
  --primary-hover: #2563eb;
  --secondary-color: #8b5cf6;
  
  --success: #10b981;
  --error: #ef4444;

  /* Typography */
  --font-sans: 'Inter', system-ui, -apple-system, sans-serif;
  --font-display: 'Outfit', system-ui, -apple-system, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  
  /* Type Scale */
  --text-xs: 0.75rem;
  --text-sm: 0.875rem;
  --text-base: 1rem;
  --text-lg: 1.125rem;
  --text-xl: 1.25rem;
  --text-2xl: clamp(1.5rem, 4vw, 2rem);
  --text-3xl: clamp(1.875rem, 5vw, 3rem);
  --text-4xl: clamp(2.25rem, 6vw, 4rem);

  /* Spacing Scale */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-24: 6rem;

  /* Layout */
  --container-width: 1100px;
  --header-height: 4rem;
  
  /* Radii & Shadows */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 1rem;
  --radius-xl: 1.5rem;
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
  
  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-normal: 250ms ease;
}

[data-theme="dark"] {
  --bg-main: #0f172a;
  --bg-alt: #1e293b;
  --bg-card: #1e293b;
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --border-color: #334155;
  
  --primary-color: #60a5fa;
  --primary-hover: #3b82f6;
  --secondary-color: #a78bfa;
  
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.5);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.5);
}

/* ==========================================================================
   Reset & Base Styles
   ========================================================================== */
*, *::before, *::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--header-height);
}

body {
  margin: 0;
  font-family: var(--font-sans);
  background-color: var(--bg-main);
  color: var(--text-main);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  transition: background-color var(--transition-normal), color var(--transition-normal);
}

h1, h2, h3, h4, h5, h6 {
  margin-top: 0;
  margin-bottom: var(--space-4);
  font-family: var(--font-display);
  font-weight: 700;
  line-height: 1.2;
}

p, ul, ol, dl {
  margin-top: 0;
  margin-bottom: var(--space-4);
}

a {
  color: var(--primary-color);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover, a:focus {
  color: var(--primary-hover);
}

img, svg {
  max-width: 100%;
  height: auto;
  display: block;
}

button, input, textarea {
  font-family: inherit;
  font-size: inherit;
}

/* Utility Classes */
.container {
  width: 100%;
  max-width: var(--container-width);
  margin-inline: auto;
  padding-inline: var(--space-6);
}

.section {
  padding-block: var(--space-16);
}

@media (min-width: 768px) {
  .section {
    padding-block: var(--space-24);
  }
}

.bg-alt {
  background-color: var(--bg-alt);
}

.text-gradient {
  background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hidden {
  display: none !important;
}

.w-full {
  width: 100%;
}

.card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
}

.center {
  text-align: center;
}

/* Focus States for Accessibility */
:focus-visible {
  outline: 2px solid var(--primary-color);
  outline-offset: 4px;
}

/* Accessibility: Skip to Main Content */
.skip-to-main {
  position: absolute;
  top: -100px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--primary-color);
  color: white;
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-sm);
  z-index: 1000;
  transition: top var(--transition-fast);
}

.skip-to-main:focus {
  top: var(--space-4);
}

/* ==========================================================================
   Buttons
   ========================================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius-md);
  font-weight: 500;
  cursor: pointer;
  border: 1px solid transparent;
  transition: all var(--transition-fast);
}

.btn-sm {
  padding: 0.5rem 1rem;
  font-size: var(--text-sm);
}

.btn-primary {
  background-color: var(--primary-color);
  color: white;
  box-shadow: var(--shadow-sm);
}

.btn-primary:hover, .btn-primary:focus {
  background-color: var(--primary-hover);
  color: white;
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.btn-secondary {
  background-color: var(--bg-alt);
  color: var(--text-main);
  border-color: var(--border-color);
}

.btn-secondary:hover, .btn-secondary:focus {
  background-color: var(--border-color);
}

.btn-outline {
  background-color: transparent;
  color: var(--text-main);
  border-color: var(--border-color);
}

.btn-outline:hover, .btn-outline:focus {
  border-color: var(--primary-color);
  color: var(--primary-color);
}

.btn-text {
  background: none;
  border: none;
  color: var(--text-muted);
  padding: 0;
}

.btn-text:hover, .btn-text:focus {
  color: var(--primary-color);
}

.icon-toggle {
  background: none;
  border: none;
  color: var(--text-main);
  cursor: pointer;
  padding: var(--space-2);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background-color var(--transition-fast);
}

.icon-toggle:hover {
  background-color: var(--bg-alt);
}

/* ==========================================================================
   Header & Navigation
   ========================================================================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: rgba(var(--bg-card), 0.8);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border-color);
  height: var(--header-height);
  display: flex;
  align-items: center;
}

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

.logo {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  font-weight: 800;
  color: var(--text-main);
}

.menu-toggle {
  display: flex;
  background: none;
  border: none;
  color: var(--text-main);
  cursor: pointer;
  padding: var(--space-2);
}

@media (min-width: 768px) {
  .menu-toggle {
    display: none;
  }
}

.main-nav {
  position: absolute;
  top: var(--header-height);
  left: 0;
  right: 0;
  background-color: var(--bg-card);
  border-bottom: 1px solid var(--border-color);
  padding: var(--space-4) var(--space-6);
  flex-direction: column;
  gap: var(--space-4);
  display: none;
}

.main-nav.open {
  display: flex;
}

@media (min-width: 768px) {
  .main-nav {
    position: static;
    display: flex;
    flex-direction: row;
    align-items: center;
    background: none;
    border: none;
    padding: 0;
  }
}

.nav-links {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
}

@media (min-width: 768px) {
  .nav-links {
    flex-direction: row;
    gap: var(--space-6);
  }
}

.nav-links a {
  color: var(--text-muted);
  font-weight: 500;
}

.nav-links a:hover, .nav-links a:focus {
  color: var(--text-main);
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}

/* ==========================================================================
   Hero Section
   ========================================================================== */
.hero-container {
  display: grid;
  gap: var(--space-8);
  align-items: center;
}

@media (min-width: 768px) {
  .hero-container {
    grid-template-columns: 3fr 2fr;
    gap: var(--space-12);
  }
}

.hero-badge {
  display: inline-block;
  padding: var(--space-1) var(--space-3);
  background-color: var(--bg-alt);
  color: var(--text-muted);
  border-radius: 999px;
  font-size: var(--text-sm);
  font-weight: 500;
  margin-bottom: var(--space-6);
}

.hero-title {
  font-size: var(--text-4xl);
  margin-bottom: var(--space-4);
}

.hero-subtitle {
  font-size: var(--text-lg);
  color: var(--text-muted);
  margin-bottom: var(--space-8);
  max-width: 600px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-4);
  align-items: center;
}

.hero-visual {
  display: flex;
  justify-content: center;
}

.profile-placeholder {
  width: 100%;
  max-width: 320px;
  aspect-ratio: 1/1;
  position: relative;
}

.profile-svg {
  width: 100%;
  height: 100%;
  border-radius: var(--radius-xl);
  filter: drop-shadow(var(--shadow-lg));
  animation: float 6s ease-in-out infinite;
}

@keyframes float {
  0% { transform: translateY(0px); }
  50% { transform: translateY(-15px); }
  100% { transform: translateY(0px); }
}

.currently-row {
  margin-top: var(--space-16);
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-4);
}

@media (min-width: 768px) {
  .currently-row {
    grid-template-columns: repeat(3, 1fr);
  }
}

.currently-item {
  background-color: var(--bg-alt);
  padding: var(--space-4);
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.currently-icon {
  font-size: var(--text-xl);
}

/* ==========================================================================
   Projects Section
   ========================================================================== */
.section-header {
  margin-bottom: var(--space-12);
}

.section-title {
  font-size: var(--text-3xl);
  position: relative;
  display: inline-block;
}

.section-title::after {
  content: '';
  position: absolute;
  bottom: -10px;
  left: 0;
  width: 50px;
  height: 4px;
  background-color: var(--primary-color);
  border-radius: var(--radius-sm);
}

.center .section-title::after {
  left: 50%;
  transform: translateX(-50%);
}

.section-description {
  color: var(--text-muted);
  font-size: var(--text-lg);
  margin-top: var(--space-4);
  max-width: 600px;
}

.filter-ui {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
  margin-bottom: var(--space-8);
}

.filter-btn {
  background-color: transparent;
  border: 1px solid var(--border-color);
  padding: var(--space-2) var(--space-4);
  border-radius: 999px;
  color: var(--text-muted);
  cursor: pointer;
  transition: all var(--transition-fast);
  font-weight: 500;
}

.filter-btn:hover, .filter-btn:focus {
  border-color: var(--text-muted);
  color: var(--text-main);
}

.filter-btn.active {
  background-color: var(--text-main);
  border-color: var(--text-main);
  color: var(--bg-main);
}

.projects-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-6);
}

@media (min-width: 768px) {
  .projects-grid {
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  }
}

.project-card {
  display: flex;
  flex-direction: column;
  overflow: hidden;
  transition: transform var(--transition-normal), box-shadow var(--transition-normal);
}

.project-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-lg);
}

.card-thumbnail {
  width: 100%;
  aspect-ratio: 16/9;
  background-color: var(--bg-alt);
  overflow: hidden;
}

.placeholder-thumbnail {
  width: 100%;
  height: 100%;
}

.bg-gradient-1 { background: linear-gradient(45deg, #10b981, #3b82f6); }
.bg-gradient-2 { background: linear-gradient(45deg, #8b5cf6, #ec4899); }
.bg-gradient-3 { background: linear-gradient(45deg, #f59e0b, #ef4444); }

.card-content {
  padding: var(--space-6);
  flex: 1;
  display: flex;
  flex-direction: column;
}

.tech-tags {
  list-style: none;
  padding: 0;
  margin: 0 0 var(--space-3) 0;
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
}

.tech-tags li {
  font-size: var(--text-xs);
  font-family: var(--font-mono);
  color: var(--primary-color);
  background-color: rgba(59, 130, 246, 0.1);
  padding: 2px 8px;
  border-radius: 4px;
}

.card-title {
  font-size: var(--text-xl);
  margin-bottom: var(--space-2);
}

.card-desc {
  color: var(--text-muted);
  font-size: var(--text-sm);
  flex: 1;
}

.card-actions {
  display: flex;
  gap: var(--space-3);
  margin-top: var(--space-4);
}

/* ==========================================================================
   Skills Section
   ========================================================================== */
.skills-layout {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-6);
  margin-bottom: var(--space-8);
}

@media (min-width: 768px) {
  .skills-layout {
    grid-template-columns: 1fr 1fr;
  }
}

.skills-column {
  padding: var(--space-8);
}

.skills-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: var(--space-3);
}

.skills-list li {
  position: relative;
  padding-left: var(--space-6);
  color: var(--text-muted);
}

.skills-list li::before {
  content: "▹";
  position: absolute;
  left: 0;
  color: var(--primary-color);
  font-size: 1.2em;
  line-height: 1;
}

.strengths-row {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: var(--space-4);
}

.strength-chip {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  padding: var(--space-3) var(--space-4);
  border-radius: 999px;
  box-shadow: var(--shadow-sm);
}

.chip-icon {
  font-size: var(--text-lg);
}

/* ==========================================================================
   About Section
   ========================================================================== */
.about-container {
  display: grid;
  gap: var(--space-12);
}

@media (min-width: 768px) {
  .about-container {
    grid-template-columns: 1fr 1fr;
  }
}

.bio p {
  color: var(--text-muted);
  font-size: var(--text-lg);
}

.about-timeline {
  padding: var(--space-8);
}

.timeline {
  list-style: none;
  padding: 0;
  margin: 0;
  position: relative;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 3px;
  top: 0;
  bottom: 0;
  width: 2px;
  background-color: var(--border-color);
}

.timeline-item {
  position: relative;
  padding-left: var(--space-6);
  margin-bottom: var(--space-6);
}

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

.timeline-item::before {
  content: '';
  position: absolute;
  left: 0;
  top: 6px;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background-color: var(--primary-color);
  box-shadow: 0 0 0 4px var(--bg-card);
}

.timeline-date {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--primary-color);
  margin-bottom: var(--space-1);
  display: block;
}

.timeline-title {
  font-size: var(--text-lg);
  margin-bottom: var(--space-1);
}

.timeline-desc {
  color: var(--text-muted);
  font-size: var(--text-sm);
  margin-bottom: 0;
}

/* ==========================================================================
   Contact Section
   ========================================================================== */
.contact-container {
  display: grid;
  gap: var(--space-12);
}

@media (min-width: 768px) {
  .contact-container {
    grid-template-columns: 1fr 1fr;
  }
}

.contact-links {
  padding: var(--space-6);
  margin-top: var(--space-6);
}

.contact-link-item {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
  margin-bottom: var(--space-4);
  padding-bottom: var(--space-4);
  border-bottom: 1px solid var(--border-color);
}

.contact-label {
  font-size: var(--text-sm);
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  font-weight: 600;
}

.email-copy-wrapper {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
}

.email-copy-wrapper a {
  font-family: var(--font-mono);
  font-size: var(--text-lg);
  font-weight: 500;
  word-break: break-all;
}

.social-links {
  display: flex;
  gap: var(--space-4);
}

.social-links a {
  font-weight: 500;
  font-size: var(--text-lg);
}

.pgp-accordion {
  margin-top: var(--space-4);
}

.pgp-accordion summary {
  cursor: pointer;
  font-weight: 500;
  color: var(--text-muted);
}

.pgp-accordion summary:hover {
  color: var(--text-main);
}

.pgp-content {
  margin-top: var(--space-4);
  background-color: var(--bg-alt);
  padding: var(--space-4);
  border-radius: var(--radius-md);
  overflow-x: auto;
}

.pgp-content pre {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--text-muted);
}

.contact-form-wrapper {
  padding: var(--space-8);
}

.contact-form .form-group {
  margin-bottom: var(--space-4);
}

.contact-form label {
  display: block;
  font-weight: 500;
  margin-bottom: var(--space-2);
}

.contact-form input,
.contact-form textarea {
  width: 100%;
  padding: var(--space-3);
  background-color: var(--bg-alt);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  color: var(--text-main);
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.contact-form input:focus,
.contact-form textarea:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.2);
}

.contact-form input.invalid,
.contact-form textarea.invalid {
  border-color: var(--error);
}

.error-message {
  display: none;
  color: var(--error);
  font-size: var(--text-xs);
  margin-top: var(--space-1);
}

.contact-form .form-group.has-error .error-message {
  display: block;
}

.form-success {
  margin-top: var(--space-4);
  padding: var(--space-4);
  background-color: rgba(16, 185, 129, 0.1);
  border: 1px solid var(--success);
  border-radius: var(--radius-sm);
  color: var(--success);
  text-align: center;
}

/* ==========================================================================
   Footer
   ========================================================================== */
.site-footer {
  border-top: 1px solid var(--border-color);
  padding-block: var(--space-8);
  margin-top: var(--space-16);
}

.footer-container {
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
  align-items: center;
  text-align: center;
}

@media (min-width: 768px) {
  .footer-container {
    flex-direction: row;
    justify-content: space-between;
    text-align: left;
  }
}

.footer-copy {
  color: var(--text-muted);
  font-size: var(--text-sm);
}

.footer-links {
  display: flex;
  gap: var(--space-6);
  font-size: var(--text-sm);
}

/* ==========================================================================
   Modals & Toasts
   ========================================================================== */
.modal {
  padding: 0;
  border: none;
  background: transparent;
  max-width: 500px;
  width: 90%;
}

.modal::backdrop {
  background: rgba(0, 0, 0, 0.5);
  backdrop-filter: blur(4px);
}

.modal-content {
  display: flex;
  flex-direction: column;
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--space-4) var(--space-6);
  border-bottom: 1px solid var(--border-color);
  color: var(--text-main);
}

.modal-header h3 {
  margin: 0;
  font-size: var(--text-lg);
}

.modal-close {
  background: none;
  border: none;
  font-size: 1.5rem;
  line-height: 1;
  color: var(--text-muted);
  cursor: pointer;
}

.modal-close:hover {
  color: var(--text-main);
}

.modal-body {
  padding: var(--space-6);
  color: var(--text-muted);
}

.modal-body code {
  background-color: var(--bg-alt);
  padding: var(--space-1) var(--space-2);
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
}

/* Toast */
.toast {
  position: fixed;
  bottom: var(--space-6);
  right: var(--space-6);
  background-color: var(--bg-card);
  color: var(--text-main);
  padding: var(--space-3) var(--space-6);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  border-left: 4px solid var(--primary-color);
  transform: translateY(150%);
  opacity: 0;
  transition: transform 0.3s cubic-bezier(0.68, -0.55, 0.265, 1.55), opacity 0.3s ease;
  z-index: 1000;
}

.toast.show {
  transform: translateY(0);
  opacity: 1;
}

/* ==========================================================================
   Animations
   ========================================================================== */
@media (prefers-reduced-motion: no-preference) {
  .animate-on-scroll {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease-out, transform 0.6s ease-out;
  }
  
  .animate-on-scroll.is-visible {
    opacity: 1;
    transform: translateY(0);
  }
}