/* ==========================================================================
   Apple-Inspired Dark Portfolio — Modern Minimalist Design System
   Developer: Sayan Dey
   ========================================================================== */

/* --------------------------------------------------------------------------
   1. CSS Variables & Design Tokens
   -------------------------------------------------------------------------- */
:root {
  --bg-primary: #0b0b0e;
  --bg-secondary: #13131c;
  --bg-tertiary: #191924;
  
  --card-bg: #161620;
  --card-bg-hover: #1d1d2b;
  --card-border: rgba(255, 255, 255, 0.07);
  --card-border-hover: rgba(0, 113, 227, 0.4);

  --accent-blue: #0071e3;
  --accent-blue-hover: #0077ed;
  --accent-purple: #6e56cf;
  --accent-green: #34c759;
  
  --text-primary: #f5f5f7;
  --text-secondary: #a1a1a6;
  --text-muted: #6e6e73;

  --font-sans: -apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Text", "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --font-mono: "SF Mono", SFMono-Regular, ui-monospace, Menlo, Monaco, Consolas, monospace;

  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-pill: 9999px;

  --shadow-sm: 0 4px 12px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 12px 36px rgba(0, 0, 0, 0.5);
  --shadow-glow: 0 0 30px rgba(0, 113, 227, 0.25);

  --transition-fast: 0.2s cubic-bezier(0.16, 1, 0.3, 1);
  --transition-normal: 0.35s cubic-bezier(0.16, 1, 0.3, 1);
  --transition-slow: 0.6s cubic-bezier(0.16, 1, 0.3, 1);

  --nav-height: 72px;
}

/* --------------------------------------------------------------------------
   2. Reset & Core Base Styles
   -------------------------------------------------------------------------- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
  color-scheme: dark;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  letter-spacing: -0.01em;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
  position: relative;
  transition: background-color 0.4s ease, color 0.4s ease;
}

/* Ambient Shifting Gradient Background */
body::before {
  content: "";
  position: fixed;
  top: -30%;
  left: -20%;
  width: 140%;
  height: 140%;
  background: radial-gradient(circle at 30% 20%, rgba(0, 113, 227, 0.08) 0%, transparent 40%),
              radial-gradient(circle at 70% 80%, rgba(110, 86, 207, 0.06) 0%, transparent 45%);
  z-index: -1;
  pointer-events: none;
  animation: ambientBgShift 16s ease-in-out infinite alternate;
}

@keyframes ambientBgShift {
  0% { transform: translate(0, 0) scale(1); }
  50% { transform: translate(3%, 4%) scale(1.05); }
  100% { transform: translate(-3%, -2%) scale(0.98); }
}

/* Scroll Progress Bar at Top */
.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  height: 3px;
  width: 0%;
  background: linear-gradient(90deg, var(--accent-blue) 0%, var(--accent-purple) 100%);
  z-index: 2000;
  box-shadow: 0 0 10px rgba(0, 113, 227, 0.7);
  transition: width 0.1s ease-out;
}

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

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
}

ul {
  list-style: none;
}

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

/* --------------------------------------------------------------------------
   3. Typography & Utilities
   -------------------------------------------------------------------------- */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

.section-padding {
  padding: 110px 0;
}

.section-tag {
  display: inline-block;
  font-size: 0.85rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--accent-blue);
  margin-bottom: 12px;
}

.section-title {
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.15;
  color: var(--text-primary);
  margin-bottom: 16px;
}

.section-description {
  font-size: clamp(1.05rem, 2vw, 1.25rem);
  color: var(--text-secondary);
  max-width: 680px;
  font-weight: 400;
  margin-bottom: 48px;
}

/* --------------------------------------------------------------------------
   4. Header & Navigation Bar
   -------------------------------------------------------------------------- */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: var(--nav-height);
  z-index: 1000;
  background-color: rgba(11, 11, 14, 0.8);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--card-border);
  transition: background-color var(--transition-fast), border-color var(--transition-fast);
}

.nav-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}

.logo {
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: 8px;
}

.logo-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background-color: var(--accent-blue);
  box-shadow: 0 0 10px var(--accent-blue);
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: 36px;
}

.nav-link {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text-secondary);
  position: relative;
  padding: 6px 0;
  transition: color var(--transition-fast);
}

.nav-link:hover,
.nav-link.active {
  color: var(--text-primary);
}

/* Navigation Underline Animation */
.nav-link::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 2px;
  background-color: var(--accent-blue);
  border-radius: 2px;
  transform: scaleX(0);
  transform-origin: right;
  transition: transform var(--transition-normal);
}

.nav-link:hover::after,
.nav-link.active::after {
  transform: scaleX(1);
  transform-origin: left;
}

/* Mobile Hamburger Toggle */
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 6px;
  width: 32px;
  height: 32px;
  z-index: 1001;
}

.nav-toggle span {
  display: block;
  width: 100%;
  height: 2px;
  background-color: var(--text-primary);
  border-radius: 2px;
  transition: transform var(--transition-fast), opacity var(--transition-fast);
}

.nav-toggle.open span:nth-child(1) {
  transform: translateY(8px) rotate(45deg);
}

.nav-toggle.open span:nth-child(2) {
  opacity: 0;
}

.nav-toggle.open span:nth-child(3) {
  transform: translateY(-8px) rotate(-45deg);
}

/* --------------------------------------------------------------------------
   5. Buttons & Interactive Elements
   -------------------------------------------------------------------------- */
.btn-group {
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 14px 28px;
  border-radius: var(--radius-pill);
  font-size: 0.95rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  transition: all var(--transition-normal);
  position: relative;
  overflow: hidden;
  user-select: none;
}

.btn-ripple {
  position: absolute;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.4);
  transform: scale(0);
  animation: rippleExpand 0.6s linear;
  pointer-events: none;
}

@keyframes rippleExpand {
  to {
    transform: scale(4);
    opacity: 0;
  }
}

.btn-primary {
  background-color: var(--accent-blue);
  color: #ffffff;
  box-shadow: 0 4px 16px rgba(0, 113, 227, 0.3);
}

.btn-primary:hover {
  background-color: var(--accent-blue-hover);
  box-shadow: 0 6px 24px rgba(0, 113, 227, 0.5);
  transform: translateY(-2px);
}

.btn-secondary {
  background-color: rgba(255, 255, 255, 0.08);
  color: var(--text-primary);
  border: 1px solid var(--card-border);
}

.btn-secondary:hover {
  background-color: rgba(255, 255, 255, 0.14);
  border-color: rgba(255, 255, 255, 0.2);
  transform: translateY(-2px);
}

.btn-icon {
  width: 18px;
  height: 18px;
  fill: currentColor;
}

/* --------------------------------------------------------------------------
   6. Hero Section
   -------------------------------------------------------------------------- */
.hero-section {
  min-height: 100vh;
  padding-top: calc(var(--nav-height) + 60px);
  padding-bottom: 80px;
  display: flex;
  align-items: center;
  position: relative;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  align-items: center;
  gap: 60px;
}

.hero-content {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
}

.hero-greeting {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 14px;
  border-radius: var(--radius-pill);
  background-color: rgba(0, 113, 227, 0.1);
  border: 1px solid rgba(0, 113, 227, 0.2);
  color: var(--accent-blue);
  font-size: 0.9rem;
  font-weight: 600;
  margin-bottom: 24px;
}

.hero-title {
  font-size: clamp(2.5rem, 5.5vw, 4.2rem);
  font-weight: 800;
  letter-spacing: -0.04em;
  line-height: 1.08;
  color: var(--text-primary);
  margin-bottom: 20px;
}

.hero-title span {
  background: linear-gradient(135deg, #0071e3 0%, #6e56cf 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-tagline {
  font-size: clamp(1.1rem, 2vw, 1.35rem);
  color: var(--text-secondary);
  line-height: 1.5;
  margin-bottom: 36px;
  max-width: 540px;
}

.hero-visual {
  width: 100%;
  display: flex;
  justify-content: center;
  align-items: center;
}

.hero-illustration-wrap {
  width: 100%;
  max-width: 540px;
  filter: drop-shadow(0 20px 40px rgba(0,0,0,0.5));
  transition: transform var(--transition-slow);
}

.hero-illustration-wrap:hover {
  transform: translateY(-4px) scale(1.01);
}

/* --------------------------------------------------------------------------
   7. About Section
   -------------------------------------------------------------------------- */
.about-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 40px;
}

.about-card {
  background-color: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-lg);
  padding: 36px;
  transition: transform var(--transition-normal), border-color var(--transition-normal), box-shadow var(--transition-normal);
}

.about-card:hover {
  transform: translateY(-4px);
  border-color: var(--card-border-hover);
  box-shadow: var(--shadow-md);
}

.about-card-title {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 20px;
  display: flex;
  align-items: center;
  gap: 12px;
}

.about-card-icon {
  width: 24px;
  height: 24px;
  color: var(--accent-blue);
}

.role-list {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.role-item {
  background-color: var(--bg-tertiary);
  border-radius: var(--radius-md);
  padding: 16px;
  border: 1px solid var(--card-border);
}

.role-item-title {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 4px;
}

.role-item-desc {
  font-size: 0.825rem;
  color: var(--text-muted);
}

.interest-list {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(130px, 1fr));
  gap: 14px;
}

.interest-tag {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 18px 12px;
  background-color: var(--bg-tertiary);
  border-radius: var(--radius-md);
  border: 1px solid var(--card-border);
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text-secondary);
  text-align: center;
  transition: color var(--transition-fast), border-color var(--transition-fast);
}

.interest-tag:hover {
  color: var(--text-primary);
  border-color: var(--accent-purple);
}

.interest-icon {
  width: 28px;
  height: 28px;
  color: var(--accent-purple);
}

/* --------------------------------------------------------------------------
   8. Skills Section
   -------------------------------------------------------------------------- */
.skills-container {
  display: flex;
  flex-direction: column;
  gap: 40px;
}

.skill-category {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.category-header {
  display: flex;
  align-items: center;
  gap: 12px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--card-border);
}

.category-icon {
  width: 22px;
  height: 22px;
  color: var(--accent-purple);
}

.category-title {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--text-primary);
}

.premium-skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(130px, 1fr));
  gap: 16px;
}

.premium-skill-card {
  background-color: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-lg);
  padding: 24px 16px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 16px;
  transition: transform var(--transition-normal), border-color var(--transition-normal), box-shadow var(--transition-normal), background-color var(--transition-normal);
  position: relative;
  overflow: hidden;
}

.premium-skill-card:hover {
  transform: translateY(-6px);
  border-color: rgba(110, 86, 207, 0.4);
  background-color: var(--card-bg-hover);
  box-shadow: 0 12px 24px rgba(0, 0, 0, 0.4), 0 0 20px rgba(110, 86, 207, 0.15);
}

.premium-skill-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: radial-gradient(120px circle at 50% -20%, rgba(110, 86, 207, 0.1), transparent);
  opacity: 0;
  transition: opacity var(--transition-normal);
  pointer-events: none;
}

.premium-skill-card:hover::before {
  opacity: 1;
}

.premium-skill-icon {
  width: 48px;
  height: 48px;
  transition: transform var(--transition-normal);
  display: flex;
  align-items: center;
  justify-content: center;
}

.premium-skill-card:hover .premium-skill-icon {
  transform: scale(1.12);
}

.premium-skill-name {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-primary);
  text-align: center;
  letter-spacing: 0.02em;
}

/* --------------------------------------------------------------------------
   9. Projects Section
   -------------------------------------------------------------------------- */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 32px;
}

.project-card {
  background-color: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  transition: transform var(--transition-normal), border-color var(--transition-normal), box-shadow var(--transition-normal);
}

.project-card:hover {
  transform: translateY(-6px);
  border-color: var(--card-border-hover);
  box-shadow: var(--shadow-md), var(--shadow-glow);
}

.project-image-wrap {
  width: 100%;
  aspect-ratio: 16 / 9;
  background-color: var(--bg-secondary);
  overflow: hidden;
  position: relative;
  border-bottom: 1px solid var(--card-border);
}

.project-image {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform var(--transition-slow);
}

.project-card:hover .project-image {
  transform: scale(1.03);
}

.project-content {
  padding: 28px;
  display: flex;
  flex-direction: column;
  flex-grow: 1;
}

.project-title {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 10px;
}

.project-description {
  font-size: 0.925rem;
  color: var(--text-secondary);
  line-height: 1.55;
  margin-bottom: 20px;
  flex-grow: 1;
}

.project-tech-stack {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 24px;
}

.tech-tag {
  font-size: 0.775rem;
  font-family: var(--font-mono);
  font-weight: 500;
  padding: 4px 10px;
  border-radius: var(--radius-sm);
  background-color: rgba(255, 255, 255, 0.05);
  color: var(--accent-blue);
  border: 1px solid rgba(0, 113, 227, 0.2);
}

.project-footer {
  margin-top: auto;
}

/* --------------------------------------------------------------------------
   10. Contact Section
   -------------------------------------------------------------------------- */
.contact-wrap {
  background-color: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-xl);
  padding: 56px;
  text-align: center;
  max-width: 840px;
  margin: 0 auto;
}

.contact-links-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(170px, 1fr));
  gap: 16px;
  margin-top: 36px;
}

.contact-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  padding: 24px 16px;
  background-color: var(--bg-tertiary);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  transition: all var(--transition-normal);
}

.contact-card:hover {
  border-color: var(--accent-blue);
  background-color: var(--card-bg-hover);
  transform: translateY(-4px);
}

.contact-card-icon {
  width: 28px;
  height: 28px;
  fill: currentColor;
  color: var(--accent-blue);
}

.contact-card-label {
  font-size: 0.95rem;
  font-weight: 600;
}

.contact-card-sub {
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* Copy Email Toast / Feedback */
.copy-email-box {
  margin-top: 36px;
  display: inline-flex;
  align-items: center;
  gap: 12px;
  padding: 10px 20px;
  background-color: var(--bg-tertiary);
  border: 1px dashed var(--card-border);
  border-radius: var(--radius-pill);
  font-size: 0.9rem;
  color: var(--text-secondary);
  cursor: pointer;
  transition: border-color var(--transition-fast);
}

.copy-email-box:hover {
  border-color: var(--accent-blue);
  color: var(--text-primary);
}

/* --------------------------------------------------------------------------
   11. Footer
   -------------------------------------------------------------------------- */
.footer {
  padding: 40px 0;
  border-top: 1px solid var(--card-border);
  background-color: var(--bg-primary);
}

.footer-content {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 20px;
}

.footer-text {
  font-size: 0.875rem;
  color: var(--text-muted);
}

.back-to-top {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: color var(--transition-fast);
}

.back-to-top:hover {
  color: var(--accent-blue);
}

/* --------------------------------------------------------------------------
   12. Animations & Scroll Reveal
   -------------------------------------------------------------------------- */
.fade-in {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.7s cubic-bezier(0.16, 1, 0.3, 1), transform 0.7s cubic-bezier(0.16, 1, 0.3, 1);
  will-change: opacity, transform;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* Stagger delay helpers */
.delay-1 { transition-delay: 0.1s; }
.delay-2 { transition-delay: 0.2s; }
.delay-3 { transition-delay: 0.3s; }
.delay-4 { transition-delay: 0.4s; }

/* Dynamic Spotlight Hover Effects for Cards */
.project-card,
.about-card,
.skill-category-card,
.contact-card {
  position: relative;
}

.project-card::before,
.about-card::before,
.skill-category-card::before,
.contact-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  border-radius: inherit;
  background: radial-gradient(
    600px circle at var(--mouse-x, 50%) var(--mouse-y, 50%),
    rgba(0, 113, 227, 0.12),
    transparent 40%
  );
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-normal);
  z-index: 1;
}

.project-card:hover::before,
.about-card:hover::before,
.skill-category-card:hover::before,
.contact-card:hover::before {
  opacity: 1;
}

/* Pulsing Status Badge Dot */
.hero-greeting svg {
  animation: pulseDot 2.2s infinite;
}

@keyframes pulseDot {
  0%, 100% { transform: scale(1); opacity: 1; }
  50% { transform: scale(1.25); opacity: 0.6; }
}

/* Button Shimmer Sweep Effect */
.btn-primary::after {
  content: "";
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: linear-gradient(
    60deg,
    transparent 30%,
    rgba(255, 255, 255, 0.25) 50%,
    transparent 70%
  );
  transform: rotate(30deg) translateX(-100%);
  transition: transform 0.75s ease;
}

.btn-primary:hover::after {
  transform: rotate(30deg) translateX(100%);
}


/* --------------------------------------------------------------------------
   13. Responsive Media Queries
   -------------------------------------------------------------------------- */
@media (max-width: 992px) {
  .hero-grid {
    grid-template-columns: 1fr;
    gap: 40px;
    text-align: center;
  }

  .hero-content {
    align-items: center;
  }

  .hero-tagline {
    max-width: 100%;
  }

  .about-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 768px) {
  .nav-menu {
    position: fixed;
    top: 0;
    right: -100%;
    width: 80%;
    max-width: 320px;
    height: 100vh;
    background-color: rgba(19, 19, 28, 0.96);
    backdrop-filter: blur(25px);
    -webkit-backdrop-filter: blur(25px);
    flex-direction: column;
    justify-content: center;
    gap: 28px;
    padding: 40px;
    transition: right var(--transition-normal);
    box-shadow: -10px 0 30px rgba(0, 0, 0, 0.5);
  }

  .nav-menu.open {
    right: 0;
  }

  .nav-toggle {
    display: flex;
  }

  .contact-wrap {
    padding: 32px 20px;
  }

  .role-list {
    grid-template-columns: 1fr;
  }

  .section-padding {
    padding: 80px 0;
  }
}