/* ==========================================================================
   AI & DATA SCIENCE PORTFOLIO — STYLESHEET
   Technology: Pure CSS3, No frameworks
   Approach: Mobile-first responsive
   Design: Dark olive palette, NO gradients, NO glassmorphism, NO blur
   ========================================================================== */

/* ==========================================================================
   CSS CUSTOM PROPERTIES — DARK MODE (DEFAULT)
   ========================================================================== */

:root {
  /* Background — Deep Dark Olive (darkened to match reference) */
  --color-bg-primary: #1a1a12;
  --color-bg-secondary: #25251c;
  --color-bg-tertiary: #313128;
  --color-bg-quaternary: #3d3d32;

  /* Text Colors */
  --color-text-primary: #F5F5F0;
  --color-text-secondary: #D4D4CC;
  --color-text-tertiary: #A8A89C;

  /* Accent & Buttons */
  --color-accent: #FFFFFF;
  --color-button-bg: #FFFFFF;
  --color-button-text: #1a1a12;

  /* Tags / Skills */
  --color-tag-bg: #25251c;
  --color-tag-text: #F5F5F0;
  --color-tag-border: #313128;

  /* Cards */
  --color-card-bg: #25251c;
  --color-card-border: #313128;

  /* Borders */
  --color-border: #25251c;

  /* Popup */
  --color-popup-bg: #1a1a12;
  --color-popup-border: #25251c;
  --color-popup-shadow: 0 10px 40px rgba(0, 0, 0, 0.5);

  /* Header */
  --header-height: 52px;

  /* Typography */
  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;

  /* Layout */
  --sidebar-width: 0px;

  /* Transitions */
  --transition-fast: 200ms cubic-bezier(0.25, 0.46, 0.45, 0.94);
  --transition-theme: 300ms ease-in-out;
}

/* ==========================================================================
   CSS CUSTOM PROPERTIES — LIGHT MODE
   ========================================================================== */

[data-theme="light"] {
  --color-bg-primary: #F5F5F0;
  --color-bg-secondary: #E8E8E0;
  --color-bg-tertiary: #D0D0C8;
  --color-bg-quaternary: #B8B8B0;

  --color-text-primary: #2a2a1f;
  --color-text-secondary: #4a4a3f;
  --color-text-tertiary: #6a6a5f;

  --color-accent: #2a2a1f;
  --color-button-bg: #2a2a1f;
  --color-button-text: #F5F5F0;

  --color-tag-bg: #E8E8E0;
  --color-tag-text: #2a2a1f;
  --color-tag-border: #D0D0C8;

  --color-card-bg: #E8E8E0;
  --color-card-border: #D0D0C8;

  --color-border: #D0D0C8;

  --color-popup-bg: #F5F5F0;
  --color-popup-border: #D0D0C8;
  --color-popup-shadow: 0 10px 40px rgba(0, 0, 0, 0.1);
}

/* ==========================================================================
   RESET & BASE STYLES
   ========================================================================== */

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family);
  font-size: 15px;
  font-weight: 400;
  line-height: 1.6;
  color: var(--color-text-secondary);
  background-color: var(--color-bg-primary);
  overflow-x: hidden;
  transition: background-color var(--transition-theme),
              color var(--transition-theme);
}

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color var(--transition-theme),
              text-decoration var(--transition-fast);
}

a:hover {
  text-decoration: underline;
}

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

button {
  cursor: pointer;
  border: none;
  outline: none;
  font-family: var(--font-family);
}

/* Focus-visible for accessibility (keyboard navigation) */
button:focus-visible,
a:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

/* ==========================================================================
   PARALLAX BACKGROUND
   ========================================================================== */

.parallax-bg {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 0;
  pointer-events: none;
  overflow: hidden;
}

.parallax-shape {
  position: absolute;
  will-change: transform;
  /* Mobile: static, reduced opacity */
  opacity: 0.35;
}

/* ==========================================================================
   SITE HEADER — Sticky nav with section links + theme toggle
   ========================================================================== */

.site-header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: var(--header-height);
  z-index: 900;
  display: flex;
  align-items: center;
  justify-content: flex-end;
  padding: 0 20px;
  background: rgba(26, 26, 18, 0.85);
  border-bottom: 1px solid var(--color-border);
  transition: background-color var(--transition-theme),
              border-color var(--transition-theme);
}

[data-theme="light"] .site-header {
  background: rgba(245, 245, 240, 0.85);
}

.header-nav {
  display: flex;
  align-items: center;
  gap: 8px;
  overflow-x: auto;
  -ms-overflow-style: none;
  scrollbar-width: none;
}

.header-nav::-webkit-scrollbar {
  display: none;
}

.header-nav a {
  font-size: 13px;
  font-weight: 500;
  color: var(--color-text-secondary);
  text-decoration: none;
  padding: 6px 10px;
  border-radius: 4px;
  white-space: nowrap;
  transition: color var(--transition-fast),
              background-color var(--transition-fast);
}

.header-nav a:hover,
.header-nav a:focus-visible {
  color: var(--color-text-primary);
  background: var(--color-bg-secondary);
  text-decoration: none;
}

/* Theme toggle inside header */
.theme-toggle {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: transparent;
  border: 1px solid var(--color-text-tertiary);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-left: 8px;
  flex-shrink: 0;
  transition: transform var(--transition-fast),
              border-color var(--transition-theme);
}

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

.theme-toggle .theme-icon {
  width: 18px;
  height: 18px;
  fill: var(--color-text-primary);
  transition: fill var(--transition-theme),
              transform var(--transition-theme);
}

/* Dark mode (default): show moon icon */
.moon-icon {
  display: block;
}

.sun-icon {
  display: none;
}

/* Light mode: show sun icon */
[data-theme="light"] .moon-icon {
  display: none;
}

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

/* ==========================================================================
   LEFT SIDEBAR
   ========================================================================== */

.sidebar {
  /* Mobile default: stacks at top */
  position: relative;
  width: 100%;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: center;
}

.sidebar-inner {
  padding: 60px 20px 24px;
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
}

/* Profile Image — ONLY fully rounded element on the page */
.profile-image-wrapper {
  width: 140px;
  height: 140px;
  border-radius: 50%;
  border: 2px solid #FFFFFF;
  overflow: hidden;
  margin-bottom: 16px;
  flex-shrink: 0;
}

.profile-image-wrapper img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

/* Placeholder avatar when no image is provided */
.profile-placeholder {
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-bg-secondary);
  transition: background-color var(--transition-theme);
}

.profile-placeholder svg {
  width: 64px;
  height: 64px;
  fill: var(--color-text-tertiary);
  transition: fill var(--transition-theme);
}

/* Sidebar Name */
.sidebar-name {
  font-size: 20px;
  font-weight: 600;
  color: var(--color-text-primary);
  line-height: 1.3;
  transition: color var(--transition-theme);
}

/* Sidebar Title */
.sidebar-title {
  font-size: 14px;
  font-weight: 400;
  color: var(--color-text-secondary);
  margin-top: 4px;
  margin-bottom: 16px;
  transition: color var(--transition-theme);
}

/* Social Icons */
.social-icons {
  display: flex;
  gap: 16px;
  margin-bottom: 20px;
}

.social-icons a {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 24px;
  height: 24px;
  transition: transform var(--transition-fast);
}

.social-icons a:hover {
  transform: scale(1.1);
  text-decoration: none;
}

.social-icons a svg {
  width: 24px;
  height: 24px;
  fill: var(--color-accent);
  transition: fill var(--transition-theme);
}

/* View Contact Info Button */
.contact-btn {
  width: 100%;
  max-width: 252px;
  height: 44px;
  background: var(--color-button-bg);
  color: var(--color-button-text);
  font-size: 14px;
  font-weight: 600;
  border-radius: 4px;
  padding: 12px 16px;
  transition: transform var(--transition-fast),
              box-shadow var(--transition-fast),
              background-color var(--transition-theme),
              color var(--transition-theme);
}

.contact-btn:hover {
  transform: scale(1.02);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
}

/* ==========================================================================
   MAIN CONTENT AREA
   ========================================================================== */

.main-content {
  margin-left: var(--sidebar-width);
  position: relative;
  z-index: 5;
  min-height: 100vh;
  transition: margin-left var(--transition-fast);
}

/* Generic section spacing */
.section {
  padding: 0 20px;
  margin-bottom: 48px;
}

/* Section headings */
.section-heading {
  font-size: 28px;
  font-weight: 700;
  color: var(--color-text-primary);
  margin-bottom: 24px;
  line-height: 1.3;
  transition: color var(--transition-theme);
}

/* ==========================================================================
   HERO SECTION
   ========================================================================== */

.hero-section {
  padding: 40px 20px;
  padding-top: calc(var(--header-height) + 32px);
  margin-bottom: 24px;
  min-height: 50vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.hero-inner {
  display: flex;
  flex-direction: column;
  gap: 40px;
}

.hero-image-wrapper {
  width: 100%;
  max-width: 320px;
  margin: 0 auto;
}

.hero-image {
  width: 100%;
  height: auto;
  display: block;
}

.hero-heading {
  font-size: 40px;
  font-weight: 700;
  color: var(--color-text-primary);
  line-height: 1.15;
  margin-bottom: 20px;
  transition: color var(--transition-theme);
}

.hero-subtext {
  font-size: 18px;
  font-weight: 400;
  color: var(--color-text-secondary);
  margin-bottom: 28px;
  max-width: 650px;
  line-height: 1.6;
  transition: color var(--transition-theme);
}

/* Download CV button inside hero */
.hero-content {
  display: flex;
  flex-direction: column;
}
.hero-content .download-cv-btn {
  margin-bottom: 0;
  align-self: flex-start;
}



/* ==========================================================================
   ABOUT ME SECTION
   ========================================================================== */

.about-text {
  font-size: 18px;
  font-weight: 400;
  color: var(--color-text-secondary);
  line-height: 1.7;
  max-width: 800px;
  margin-bottom: 16px;
  transition: color var(--transition-theme);
}

/* Larger heading specifically for About Me */
#about .section-heading {
  font-size: 34px;
}

.about-highlights {
  list-style: none;
  padding: 0;
  max-width: 700px;
}

.about-highlights li {
  font-size: 16px;
  color: var(--color-text-secondary);
  padding: 4px 0;
  padding-left: 20px;
  position: relative;
  transition: color var(--transition-theme);
}

.about-highlights li::before {
  content: '\2022';
  position: absolute;
  left: 0;
  color: var(--color-text-tertiary);
}

/* ==========================================================================
   EDUCATION SECTION
   ========================================================================== */

.education-degree {
  font-size: 18px;
  font-weight: 600;
  color: var(--color-text-primary);
  margin-bottom: 4px;
  transition: color var(--transition-theme);
}

.education-university {
  font-size: 16px;
  font-weight: 400;
  color: var(--color-text-secondary);
  margin-bottom: 4px;
  transition: color var(--transition-theme);
}

.education-duration {
  font-size: 14px;
  color: var(--color-text-tertiary);
  margin-bottom: 4px;
  transition: color var(--transition-theme);
}

.education-gpa {
  font-size: 14px;
  color: var(--color-text-tertiary);
  transition: color var(--transition-theme);
}

/* ==========================================================================
   SKILLS SECTION
   ========================================================================== */

.skills-container {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  max-width: 700px;
}

/* Skill tags — rectangular, NOT pill-shaped */
.skill-tag {
  background: var(--color-tag-bg);
  color: var(--color-tag-text);
  font-size: 14px;
  font-weight: 500;
  padding: 8px 12px;
  border-radius: 4px;
  border: 1px solid var(--color-tag-border);
  transition: transform var(--transition-fast),
              background-color var(--transition-theme),
              color var(--transition-theme),
              border-color var(--transition-theme);
}

.skill-tag:hover {
  transform: scale(1.05);
}

/* ==========================================================================
   PROJECTS SECTION — 3-CARD GRID
   ========================================================================== */

.projects-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 24px;
}

/* Project Card */
.project-card {
  background: var(--color-card-bg);
  border: 1px solid var(--color-card-border);
  border-radius: 4px;
  padding: 20px;
  min-height: 300px;
  display: flex;
  flex-direction: column;
  transition: transform var(--transition-fast),
              box-shadow var(--transition-fast),
              background-color var(--transition-theme),
              border-color var(--transition-theme);
}

.project-card:hover {
  transform: scale(1.02);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.15);
}

.project-title {
  font-size: 24px;
  font-weight: 700;
  color: var(--color-text-primary);
  margin-bottom: 8px;
  transition: color var(--transition-theme);
}

.project-subtitle {
  font-size: 14px;
  font-weight: 600;
  color: var(--color-text-tertiary);
  margin-bottom: 16px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.project-description {
  font-size: 16px;
  color: var(--color-text-secondary);
  line-height: 1.6;
  margin-bottom: 16px;
  flex-grow: 1;
  transition: color var(--transition-theme);
}

.project-tech {
  font-size: 15px;
  font-weight: 500;
  color: var(--color-text-tertiary);
  margin-bottom: 16px;
  transition: color var(--transition-theme);
}

.project-logos {
  display: flex;
  gap: 12px;
  margin-bottom: 24px;
  align-items: center;
}

.project-logos svg {
  width: 24px;
  height: 24px;
  fill: var(--color-text-secondary);
  transition: fill var(--transition-fast);
}

.project-logos svg:hover {
  fill: var(--color-text-primary);
}

.project-links {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

.project-links a {
  font-size: 14px;
  color: var(--color-accent);
  transition: color var(--transition-theme);
}

.project-links a:hover {
  text-decoration: underline;
}

/* ==========================================================================
   CERTIFICATIONS SECTION
   ========================================================================== */

.cert-list {
  display: flex;
  flex-direction: column;
  gap: 32px;
}

.cert-title {
  font-size: 18px;
  font-weight: 700;
  color: var(--color-text-primary);
  margin-bottom: 4px;
  transition: color var(--transition-theme);
}

.cert-meta {
  font-size: 14px;
  color: var(--color-text-tertiary);
  margin-bottom: 12px;
  transition: color var(--transition-theme);
}

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

.cert-btn {
  display: inline-block;
  font-size: 12px;
  font-weight: 600;
  padding: 8px 12px;
  border-radius: 4px;
  background: var(--color-button-bg);
  color: var(--color-button-text);
  text-decoration: none;
  transition: transform var(--transition-fast),
              box-shadow var(--transition-fast),
              background-color var(--transition-theme),
              color var(--transition-theme);
}

.cert-btn:hover {
  transform: scale(1.02);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
  text-decoration: none;
}

/* ==========================================================================
   RESUME / CV DOWNLOAD SECTION
   ========================================================================== */

.resume-section {
  margin-bottom: 80px;
}

.resume-heading {
  font-size: 20px;
  font-weight: 600;
  color: var(--color-text-primary);
  margin-bottom: 20px;
  transition: color var(--transition-theme);
}

.download-cv-btn {
  display: inline-block;
  font-size: 14px;
  font-weight: 600;
  padding: 10px 24px;
  border-radius: 4px;
  background: var(--color-button-bg);
  color: var(--color-button-text);
  text-decoration: none;
  transition: transform var(--transition-fast),
              box-shadow var(--transition-fast),
              background-color var(--transition-theme),
              color var(--transition-theme);
}

.download-cv-btn:hover {
  transform: scale(1.02);
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.2);
  text-decoration: none;
}

/* ==========================================================================
   FOOTER
   ========================================================================== */

.footer {
  text-align: center;
  padding: 24px 20px;
  margin-top: 60px;
  border-top: 1px solid var(--color-border);
  font-size: 12px;
  color: var(--color-text-tertiary);
  transition: color var(--transition-theme),
              border-color var(--transition-theme);
}

/* ==========================================================================
   CONTACT POPUP (MODAL)
   ========================================================================== */

/* Invisible full-screen overlay to catch outside clicks — NO blur, NO dimming */
.contact-popup-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: center;
  pointer-events: none;
  opacity: 0;
  visibility: hidden;
  transition: opacity 200ms ease,
              visibility 200ms ease;
}

.contact-popup-overlay.active {
  opacity: 1;
  visibility: visible;
  pointer-events: all;
}

/* Popup box */
.contact-popup {
  background: var(--color-popup-bg);
  border: 1px solid var(--color-popup-border);
  border-radius: 4px;
  width: 280px;
  height: auto;
  box-shadow: var(--color-popup-shadow);
  transform: scale(0.9);
  transition: transform 200ms ease,
              background-color var(--transition-theme),
              border-color var(--transition-theme),
              box-shadow var(--transition-theme);
  pointer-events: all;
}

.contact-popup-overlay.active .contact-popup {
  transform: scale(1);
}

/* Popup header */
.popup-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px;
}

.popup-name {
  font-size: 18px;
  font-weight: 700;
  color: var(--color-text-primary);
  transition: color var(--transition-theme);
}

/* Close button */
.popup-close {
  width: 28px;
  height: 28px;
  background: transparent;
  font-size: 20px;
  color: var(--color-text-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 0;
  transition: color var(--transition-fast),
              opacity var(--transition-fast);
}

.popup-close:hover {
  opacity: 0.7;
}

/* Popup content */
.popup-content {
  padding: 12px 16px 16px;
}

.popup-content p {
  font-size: 14px;
  color: var(--color-text-primary);
  margin-bottom: 20px;
  line-height: 1.5;
  transition: color var(--transition-theme);
}

.popup-content p:last-child {
  margin-bottom: 0;
}

.popup-label {
  color: var(--color-text-secondary);
  transition: color var(--transition-theme);
}

/* ==========================================================================
   RESPONSIVE — TABLET (≥768px)
   ========================================================================== */

@media (min-width: 768px) {
  :root {
    --sidebar-width: 280px;
  }

  body {
    font-size: 16px;
  }

  /* Sidebar becomes fixed on tablet+ */
  .sidebar {
    position: fixed;
    left: 0;
    top: 0;
    width: var(--sidebar-width);
    height: 100vh;
    border-right: 1px solid var(--color-border);
  }

  .sidebar-inner {
    padding: 24px;
  }

  /* Profile image full size */
  .profile-image-wrapper {
    width: 160px;
    height: 160px;
  }

  .profile-placeholder svg {
    width: 72px;
    height: 72px;
  }

  .sidebar-name {
    font-size: 22px;
  }

  /* Main content adjusts for sidebar */
  .main-content {
    margin-left: var(--sidebar-width);
  }

  /* Section spacing */
  .section {
    padding: 0 32px;
    margin-bottom: 60px;
  }

  .section-heading {
    font-size: 30px;
  }

  /* Hero */
  .hero-section {
    padding: 40px 32px;
    padding-top: calc(var(--header-height) + 40px);
    margin-bottom: 60px;
    min-height: 55vh;
  }

  .hero-heading {
    font-size: 46px;
  }

  .hero-subtext {
    font-size: 19px;
  }

  /* About */
  .about-text {
    font-size: 16px;
  }

  /* Projects grid: 1 column on tablet to allow wide layout */
  .projects-grid {
    grid-template-columns: 1fr;
  }

  /* Popup */
  .contact-popup {
    width: 320px;
    height: 240px;
  }

  /* Footer */
  .footer {
    padding: 32px;
    margin-top: 70px;
  }
}

/* ==========================================================================
   RESPONSIVE — DESKTOP (≥1024px)
   ========================================================================== */

@media (min-width: 1024px) {
  :root {
    --sidebar-width: 300px;
  }

  /* Profile image full spec size */
  .profile-image-wrapper {
    width: 180px;
    height: 180px;
  }

  .profile-placeholder svg {
    width: 80px;
    height: 80px;
  }

  .sidebar-name {
    font-size: 24px;
  }

  /* Section spacing */
  .section {
    padding: 0 40px;
    margin-bottom: 60px;
  }

  .section-heading {
    font-size: 32px;
  }

  /* Hero — two columns on desktop */
  .hero-section {
    padding: 60px 40px;
    padding-top: calc(var(--header-height) + 48px);
    margin-bottom: 60px;
    min-height: 55vh;
  }

  .hero-inner {
    display: grid;
    grid-template-columns: 1.2fr 0.8fr;
    gap: 40px;
    align-items: center;
  }

  .hero-image-wrapper {
    max-width: 500px;
    margin-left: auto;
    margin-right: 0;
  }

  .hero-heading {
    font-size: 56px;
  }

  .hero-subtext {
    font-size: 20px;
    max-width: 700px;
  }

  /* Projects grid: 1 column on desktop for deep content */
  .projects-grid {
    grid-template-columns: 1fr;
  }

  /* Parallax shapes at full opacity on desktop */
  .parallax-shape {
    opacity: 0.7;
  }

  /* Popup desktop size */
  .contact-popup {
    width: 380px;
    height: 280px;
  }

  /* Footer */
  .footer {
    padding: 40px;
    margin-top: 80px;
  }
}