/* ==========================================================================
   CSS Variables & Theming (Light & Dark Mode)
   ========================================================================== */
:root {
  /* Light Theme */
  --bg-color: #ffffff;
  --bg-alt: #f9fafb;
  --text-main: #1f2937;
  --text-muted: #6b7280;
  --border-color: #e5e7eb;
  --accent: #3b82f6;
  --accent-hover: #2563eb;
  --card-bg: #ffffff;
  --card-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --header-bg: rgba(255, 255, 255, 0.9);
  --bar-bg: rgba(0, 0, 0, 0.05);
}

[data-theme="dark"] {
  /* Dark Theme */
  --bg-color: #111827;
  --bg-alt: #1f2937;
  --text-main: #f9fafb;
  --text-muted: #9ca3af;
  --border-color: #374151;
  --accent: #60a5fa;
  --accent-hover: #3b82f6;
  --card-bg: #1f2937;
  --card-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.5), 0 2px 4px -1px rgba(0, 0, 0, 0.3);
  --header-bg: rgba(17, 24, 39, 0.9);
  --bar-bg: rgba(255, 255, 255, 0.1);
}

/* ==========================================================================
   Base Styles
   ========================================================================== */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: 'Inter', sans-serif;
  background-color: var(--bg-color);
  color: var(--text-main);
  line-height: 1.6;
  transition: background-color 0.3s ease, color 0.3s ease;
}

a {
  color: var(--accent);
  text-decoration: none;
  transition: color 0.2s ease;
}

a:hover {
  color: var(--accent-hover);
}

.container {
  width: 90%;
  max-width: 1100px;
  margin: 0 auto;
}

.section {
  padding: 5rem 0;
}

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

h1, h2, h3, h4 {
  font-weight: 700;
  margin-bottom: 1rem;
  color: var(--text-main);
}

p {
  margin-bottom: 1rem;
}

.muted {
  color: var(--text-muted);
}

/* ==========================================================================
   Buttons
   ========================================================================== */
.btn {
  display: inline-block;
  padding: 0.75rem 1.5rem;
  border-radius: 6px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
  text-align: center;
  border: none;
}

.btn-primary {
  background-color: var(--accent);
  color: #fff !important;
}

.btn-primary:hover {
  background-color: var(--accent-hover);
  transform: translateY(-2px);
}

.btn-outline {
  background-color: transparent;
  color: var(--text-main);
  border: 1px solid var(--border-color);
}

.btn-outline:hover {
  border-color: var(--accent);
  color: var(--accent);
}

/* ==========================================================================
   Header & Navigation
   ========================================================================== */
.site-header {
  position: fixed;
  top: 0;
  width: 100%;
  background: var(--header-bg);
  backdrop-filter: blur(8px);
  z-index: 1000;
  border-bottom: 1px solid var(--border-color);
}

.header-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 70px;
}

.brand {
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--text-main);
}

.nav-group {
  display: flex;
  align-items: center;
  gap: 1.5rem;
}

.nav {
  display: flex;
  gap: 1.5rem;
}

.nav a {
  color: var(--text-main);
  font-weight: 600;
}

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

.theme-toggle {
  background: none;
  border: none;
  cursor: pointer;
  font-size: 1.2rem;
  color: var(--text-main);
  transition: transform 0.2s ease;
}
.theme-toggle:hover {
  transform: scale(1.1);
  color: var(--accent);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
}

.nav-toggle span {
  width: 25px;
  height: 3px;
  background-color: var(--text-main);
  transition: 0.3s;
}

@media (max-width: 768px) {
  .nav {
    display: none;
    position: absolute;
    top: 70px;
    left: 0;
    width: 100%;
    background: var(--bg-color);
    flex-direction: column;
    padding: 1rem 0;
    border-bottom: 1px solid var(--border-color);
  }
  .nav.open {
    display: flex;
    align-items: center;
  }
  .nav-toggle {
    display: flex;
  }
}

/* ==========================================================================
   Layouts & Cards
   ========================================================================== */
.hero {
  padding: 8rem 0 4rem;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: center;
}

@media (max-width: 768px) {
  .hero-grid { grid-template-columns: 1fr; }
}

.card {
  background-color: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 2rem;
  box-shadow: var(--card-shadow);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.card:hover {
  transform: translateY(-5px);
  box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}

.two-col {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem;
}

@media (max-width: 768px) {
  .two-col { grid-template-columns: 1fr; }
}

/* ==========================================================================
   Restored Sections (About, Skills, Experience, Certs)
   ========================================================================== */
.timeline {
  list-style: none;
  padding: 0;
  margin: 0;
  color: var(--text-muted);
}
.timeline li {
  margin-bottom: 1rem;
}
.timeline strong {
  color: var(--text-main);
}

/* Skills */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.5rem;
}
@media (max-width: 768px) {
  .skills-grid { grid-template-columns: 1fr; }
}
.skill {
  background: transparent;
  padding: 0.6rem;
  border-radius: 8px;
}
.skill-head {
  display: flex;
  justify-content: space-between;
  margin-bottom: 0.5rem;
  color: var(--text-muted);
  font-weight: 600;
}
.bar {
  height: 10px;
  background: var(--bar-bg);
  border-radius: 999px;
  overflow: hidden;
}
.bar-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--accent), #7dd3fc);
  border-radius: 999px;
}

/* Experience */
.exp-card {
  background: var(--card-bg);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
  border-radius: 12px;
  border: 1px solid var(--border-color);
  box-shadow: var(--card-shadow);
  transition: transform 0.3s ease;
}
.exp-card:hover {
  transform: translateY(-3px);
}
.exp-card h3 {
  margin: 0 0 0.2rem;
}

/* Projects Grid */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 2rem;
  margin-top: 2rem;
}

/* Certifications */
.certs {
  list-style: disc;
  padding-left: 1.2rem;
  color: var(--text-muted);
}
.certs li {
  margin-bottom: 0.5rem;
}
.certs strong {
  color: var(--text-main);
}

/* ==========================================================================
   Forms & Contact
   ========================================================================== */
.contact-list {
  list-style: none;
  padding: 0;
  margin: 0;
  color: var(--text-muted);
}
.contact-list li {
  margin-bottom: 0.5rem;
}
.contact-list strong {
  color: var(--text-main);
}

form label {
  display: block;
  margin-bottom: 1rem;
}

form span {
  display: block;
  margin-bottom: 0.5rem;
  font-weight: 600;
}

form input, form textarea {
  width: 100%;
  padding: 0.75rem;
  border: 1px solid var(--border-color);
  border-radius: 6px;
  background-color: var(--bg-color);
  color: var(--text-main);
  font-family: inherit;
  transition: border-color 0.2s;
}

form input:focus, form textarea:focus {
  outline: none;
  border-color: var(--accent);
}

/* ==========================================================================
   Scroll Animations (Intersection Observer)
   ========================================================================== */
.reveal-hidden {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

.reveal-hidden.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ==========================================================================
   Toast Notifications
   ========================================================================== */
.toast-container {
  position: fixed;
  bottom: 20px;
  right: 20px;
  z-index: 9999;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.toast {
  padding: 15px 20px;
  border-radius: 8px;
  background: var(--card-bg);
  color: var(--text-main);
  box-shadow: var(--card-shadow);
  border-left: 5px solid var(--accent);
  opacity: 0;
  transform: translateX(100%);
  transition: all 0.4s cubic-bezier(0.68, -0.55, 0.265, 1.55);
  display: flex;
  align-items: center;
  gap: 10px;
  min-width: 250px;
}

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

.toast.success { border-left-color: #22c55e; }
.toast.error { border-left-color: #ef4444; }

/* ==========================================================================
   Footer
   ========================================================================== */
.site-footer {
  text-align: center;
  padding: 2rem 0;
  border-top: 1px solid var(--border-color);
  margin-top: 4rem;
}