/* ============================================
   Yun Nara — Product Operations Portfolio
   Design System & Global Styles
   ============================================ */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800;900&display=swap');

:root {
  /* Colors */
  --c-black: #0a0a0a;
  --c-dark: #1a1a1a;
  --c-gray-900: #262626;
  --c-gray-700: #525252;
  --c-gray-500: #737373;
  --c-gray-400: #a3a3a3;
  --c-gray-300: #d4d4d4;
  --c-gray-200: #e5e5e5;
  --c-gray-100: #f5f5f5;
  --c-gray-50: #fafafa;
  --c-white: #ffffff;
  --c-accent: #2563eb;
  --c-accent-light: #eff6ff;
  --c-red: #ef4444;
  --c-green: #22c55e;

  /* Typography */
  --font-sans: 'Pretendard Variable', 'Inter', -apple-system, BlinkMacSystemFont, system-ui, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;

  /* Spacing */
  --section-padding: 160px;
  --container-max: 1200px;
  --container-narrow: 800px;

  /* Transitions */
  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  --duration: 0.6s;
}

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

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-sans);
  color: var(--c-black);
  background: var(--c-white);
  line-height: 1.6;
  overflow-x: hidden;
  font-size: 16px;
}

a { color: inherit; text-decoration: none; }
img { display: block; max-width: 100%; height: auto; }
button { cursor: pointer; font-family: inherit; }
ul { list-style: none; }


/* ============================================
   Layout
   ============================================ */

.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 40px;
}

.container--narrow {
  max-width: var(--container-narrow);
  margin: 0 auto;
  padding: 0 40px;
}

.grid-2 {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 80px;
  align-items: center;
}

.grid-2--reverse {
  direction: rtl;
}
.grid-2--reverse > * {
  direction: ltr;
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}


/* ============================================
   Navigation
   ============================================ */

.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 72px;
  z-index: 1000;
  background: rgba(255, 255, 255, 0.8);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid rgba(0, 0, 0, 0.06);
  transition: background 0.3s ease;
}

.nav__inner {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 40px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav__logo {
  font-size: 18px;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--c-black);
}

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

.nav__link {
  font-size: 14px;
  font-weight: 500;
  color: var(--c-gray-500);
  transition: color 0.2s;
  letter-spacing: -0.01em;
}

.nav__link:hover {
  color: var(--c-black);
}

.nav__cta {
  font-size: 14px;
  font-weight: 600;
  color: var(--c-white);
  background: var(--c-black);
  padding: 10px 20px;
  border-radius: 8px;
  border: none;
  transition: opacity 0.2s;
}

.nav__cta:hover {
  opacity: 0.85;
}


/* ============================================
   Sticky Section Navigation
   ============================================ */

.section-nav {
  position: sticky;
  top: 72px;
  z-index: 900;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid rgba(0, 0, 0, 0.06);
}

.section-nav__inner {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 40px;
  display: flex;
  gap: 48px;
}

.section-nav__link {
  font-size: 15px;
  font-weight: 600;
  color: var(--c-gray-400);
  padding: 20px 0;
  border-bottom: 2px solid transparent;
  transition: color 0.2s, border-color 0.2s;
  white-space: nowrap;
}

.section-nav__link:hover {
  color: var(--c-gray-700);
}

.section-nav__link.active {
  color: var(--c-black);
  border-bottom-color: var(--c-black);
}


/* ============================================
   Hero
   ============================================ */

.hero {
  padding: 200px 0 140px;
  position: relative;
}

.hero__eyebrow {
  font-size: 14px;
  font-weight: 600;
  color: var(--c-accent);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 24px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.hero__eyebrow::before {
  content: '';
  display: inline-block;
  width: 24px;
  height: 2px;
  background: var(--c-accent);
}

.hero__title {
  font-size: 64px;
  font-weight: 800;
  line-height: 1.15;
  letter-spacing: -0.035em;
  color: var(--c-black);
  margin-bottom: 32px;
  max-width: 800px;
  word-break: keep-all;
}

.hero__desc {
  font-size: 20px;
  line-height: 1.7;
  color: var(--c-gray-500);
  max-width: 640px;
  word-break: keep-all;
}


/* ============================================
   Timeline
   ============================================ */

.timeline-section {
  padding: var(--section-padding) 0;
  background: var(--c-gray-50);
}

.section-label {
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--c-gray-400);
  margin-bottom: 16px;
}

.section-heading {
  font-size: 40px;
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.2;
  color: var(--c-black);
  margin-bottom: 16px;
  word-break: keep-all;
}

.section-desc {
  font-size: 18px;
  color: var(--c-gray-500);
  margin-bottom: 64px;
  line-height: 1.7;
}

.timeline {
  position: relative;
  padding-left: 32px;
  border-left: 2px solid var(--c-gray-200);
}

.tl-entry {
  position: relative;
  padding-bottom: 48px;
}

.tl-entry:last-child {
  padding-bottom: 0;
}

.tl-entry__dot {
  position: absolute;
  left: -41px;
  top: 4px;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--c-white);
  border: 3px solid var(--c-gray-300);
  z-index: 2;
}

.tl-entry--active .tl-entry__dot {
  border-color: var(--c-accent);
  box-shadow: 0 0 0 6px rgba(37, 99, 235, 0.12);
}

.tl-entry__date {
  font-size: 13px;
  font-weight: 700;
  color: var(--c-gray-400);
  margin-bottom: 4px;
  font-variant-numeric: tabular-nums;
}

.tl-entry--active .tl-entry__date {
  color: var(--c-accent);
}

.tl-entry__title {
  font-size: 20px;
  font-weight: 700;
  color: var(--c-black);
  margin-bottom: 8px;
  letter-spacing: -0.02em;
}

.tl-entry__body {
  font-size: 15px;
  color: var(--c-gray-500);
  line-height: 1.65;
  word-break: keep-all;
}

/* ============================================
   Phone Mockup (Clone App Experience)
   ============================================ */

.phone-mockup {
  width: 100%;
  max-width: 390px;
  height: 800px; /* Fixed height for scrollable content */
  background: #000;
  border-radius: 54px;
  border: 12px solid #1a1a1a;
  overflow: hidden;
  position: relative;
  box-shadow: 0 50px 100px -20px rgba(0,0,0,0.3);
  margin: 0 auto;
}

.mockup-header {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  background: white;
  z-index: 100;
  border-bottom: 1px solid #f0f1f3;
}

.mockup-tabs {
  display: flex;
  padding: 8px 12px;
  gap: 8px;
  background: #fff;
}

.mockup-tab {
  flex: 1;
  padding: 10px 4px;
  font-size: 13px;
  font-weight: 600;
  text-align: center;
  border-radius: 8px;
  cursor: pointer;
  color: var(--c-gray-400);
  background: var(--c-gray-50);
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

.mockup-tab.active {
  background: var(--c-blue);
  color: white;
  box-shadow: 0 4px 12px rgba(0, 107, 255, 0.2);
}

.phone-mockup__screen {
  height: 100%;
  padding-top: 100px; /* Header space */
  overflow-y: auto;
  background: #f9fafb;
  -webkit-overflow-scrolling: touch;
}

.phone-mockup__screen::-webkit-scrollbar {
  width: 4px;
}

.phone-mockup__screen::-webkit-scrollbar-thumb {
  background: rgba(0,0,0,0.1);
  border-radius: 10px;
}

.mockup-img {
  width: 100%;
  display: block;
}

/* ============================================
   Asset Viewer (Desktop/Static)
   ============================================ */

.asset-viewer {
  position: relative;
  width: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
}

.asset-viewer__desktop {
  width: 100%;
  border-radius: 12px;
  overflow: hidden;
  background: #fff;
  box-shadow: 0 4px 24px rgba(0,0,0,0.08);
  border: 1px solid #eee;
}

.asset-viewer__img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.asset-viewer__caption {
  font-size: 14px;
  color: var(--c-gray-500);
  text-align: center;
}

/* ============================================
   Experience Tracking (Career Timeline)
   ============================================ */

.project {
  padding: var(--section-padding) 0;
}

.project--alt {
  background: var(--c-gray-50);
}

.project__header {
  margin-bottom: 80px;
}

.project__number {
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.1em;
  color: var(--c-gray-400);
  margin-bottom: 16px;
  font-variant-numeric: tabular-nums;
}

.project__title {
  font-size: 48px;
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.2;
  color: var(--c-black);
  margin-bottom: 16px;
  word-break: keep-all;
}

.project__subtitle {
  font-size: 18px;
  color: var(--c-gray-500);
  line-height: 1.6;
}

.project__body {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 80px;
  align-items: start;
}

.project__text h3 {
  font-size: 28px;
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.3;
  margin-bottom: 20px;
  color: var(--c-black);
  word-break: keep-all;
}

.project__text p {
  font-size: 16px;
  line-height: 1.75;
  color: var(--c-gray-700);
  margin-bottom: 24px;
  word-break: keep-all;
}


/* ============================================
   Info Boxes
   ============================================ */

.info-box {
  padding: 24px;
  border-radius: 12px;
  margin-bottom: 24px;
}

.info-box--problem {
  background: #fef2f2;
  border: 1px solid #fecaca;
}

.info-box--insight {
  background: var(--c-accent-light);
  border: 1px solid #bfdbfe;
}

.info-box--neutral {
  background: var(--c-gray-50);
  border: 1px solid var(--c-gray-200);
}

.info-box__label {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin-bottom: 8px;
}

.info-box--problem .info-box__label { color: var(--c-red); }
.info-box--insight .info-box__label { color: var(--c-accent); }

.info-box p {
  font-size: 15px;
  line-height: 1.7;
  color: var(--c-gray-700);
  word-break: keep-all;
}

.info-box strong {
  color: var(--c-black);
}


/* ============================================
   Bullet List
   ============================================ */

.bullet-list {
  margin: 16px 0;
}

.bullet-list li {
  position: relative;
  padding-left: 16px;
  font-size: 15px;
  color: var(--c-gray-700);
  margin-bottom: 10px;
  line-height: 1.6;
  word-break: keep-all;
}

.bullet-list li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 9px;
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--c-accent);
}


/* ============================================
   Metrics
   ============================================ */

.metrics {
  display: flex;
  gap: 48px;
  margin-top: 40px;
  flex-wrap: wrap;
}

.metric {
  display: flex;
  flex-direction: column;
}

.metric__value {
  font-size: 48px;
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1;
  color: var(--c-black);
}

.metric__value--accent {
  color: var(--c-accent);
}

.metric__label {
  font-size: 14px;
  color: var(--c-gray-500);
  margin-top: 8px;
  word-break: keep-all;
}


/* Section Nav Styles Refinement */
.section-nav__inner::-webkit-scrollbar {
  display: none;
}
.section-nav__inner {
  -ms-overflow-style: none;
  scrollbar-width: none;
}

/* ============================
   Toss UI Experience Section
   ============================ */
.toss-experience {
  padding: 120px 0;
  background-color: #f9fafb;
}

.toss-intro {
  margin-bottom: 80px;
}
.toss-intro__headline {
  font-size: 34px;
  font-weight: 800;
  color: #191f28;
  line-height: 1.5;
  margin-bottom: 24px;
  letter-spacing: -0.5px;
}
.text-blue {
  color: #3182f6;
}
.toss-intro__desc {
  font-size: 17px;
  line-height: 1.7;
  color: #4e5968;
}

.toss-section-title {
  font-size: 24px;
  font-weight: 800;
  color: #191f28;
  margin-bottom: 24px;
}

/* Toss Card */
.toss-card {
  background: white;
  border-radius: 20px;
  padding: 40px;
  margin-bottom: 24px;
  box-shadow: 0 4px 20px rgba(0,0,0,0.03);
}

.toss-card__header {
  margin-bottom: 20px;
}
.toss-card__title {
  display: flex;
  align-items: center;
  gap: 12px;
}
.toss-card__title h4 {
  font-size: 22px;
  font-weight: 700;
  color: #191f28;
  margin: 0;
}
.toss-badge {
  background: #e8f3ff;
  color: #3182f6;
  font-size: 13px;
  font-weight: 700;
  padding: 4px 10px;
  border-radius: 6px;
}

.toss-card__meta {
  font-size: 15px;
  color: #8b95a1;
  margin-top: 8px;
}

.toss-card__desc {
  font-size: 16px;
  line-height: 1.6;
  color: #4e5968;
  padding-bottom: 24px;
  border-bottom: 1px solid #f2f4f6;
  margin-bottom: 24px;
}

.toss-project-item {
  margin-bottom: 24px;
}
.toss-project-item:last-child {
  margin-bottom: 0;
}
.toss-project-title {
  font-size: 16px;
  font-weight: 700;
  color: #333d4b;
  margin-bottom: 12px;
}

.toss-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}
.toss-tag {
  background: #f2f4f6;
  color: #4e5968;
  font-size: 14px;
  font-weight: 500;
  padding: 8px 14px;
  border-radius: 10px;
}

/* Grid Layout for Skills/Ed */
.toss-info-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
  margin-top: 80px;
}

.toss-info-card {
  background: white;
  border-radius: 20px;
  padding: 40px;
  box-shadow: 0 4px 20px rgba(0,0,0,0.03);
}

.toss-skill-group {
  margin-bottom: 32px;
}
.toss-skill-group:last-child {
  margin-bottom: 0;
}
.toss-skill-label {
  font-size: 14px;
  font-weight: 700;
  color: #8b95a1;
  margin-bottom: 12px;
}

.toss-edu-item h4 {
  font-size: 18px;
  font-weight: 700;
  color: #191f28;
  margin-bottom: 4px;
}
.toss-edu-meta {
  font-size: 14px;
  color: #8b95a1;
  margin-bottom: 16px;
}
.toss-edu-list {
  list-style: none;
  padding: 0;
  margin: 0;
}
.toss-edu-list li {
  font-size: 15px;
  color: #4e5968;
  line-height: 1.6;
  position: relative;
  padding-left: 14px;
  margin-bottom: 8px;
}
.toss-edu-list li::before {
  content: "•";
  position: absolute;
  left: 0;
  color: #8b95a1;
  font-weight: bold;
}

@media (max-width: 900px) {
  .toss-info-grid {
    grid-template-columns: 1fr;
  }
}


/* ============================================
   Metrics Row (Full Width)
   ============================================ */

.metrics-row {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px;
  margin-top: 80px;
  padding: 48px;
  background: var(--c-gray-50);
  border-radius: 16px;
  border: 1px solid var(--c-gray-200);
}

.metrics-row .metric {
  text-align: center;
  align-items: center;
}


/* ============================================
   CTA Section
   ============================================ */

.cta {
  padding: var(--section-padding) 0;
  background: var(--c-black);
  color: var(--c-white);
  text-align: center;
}

.cta__title {
  font-size: 48px;
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.2;
  margin-bottom: 20px;
  word-break: keep-all;
}

.cta__desc {
  font-size: 18px;
  color: var(--c-gray-400);
  margin-bottom: 48px;
  line-height: 1.7;
  max-width: 640px;
  margin-left: auto;
  margin-right: auto;
  word-break: keep-all;
}

.cta__button {
  display: inline-block;
  padding: 16px 40px;
  background: var(--c-white);
  color: var(--c-black);
  font-size: 16px;
  font-weight: 700;
  border-radius: 12px;
  border: none;
  transition: transform 0.2s var(--ease-out), box-shadow 0.2s;
}

.cta__button:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 32px rgba(255, 255, 255, 0.15);
}


/* ============================================
   Footer
   ============================================ */

.footer {
  padding: 40px;
  text-align: center;
  font-size: 13px;
  color: var(--c-gray-400);
  background: var(--c-gray-50);
  border-top: 1px solid var(--c-gray-200);
}


/* ============================================
   Scroll Animations
   ============================================ */

.reveal {
  opacity: 0;
  transform: translateY(40px);
  transition: opacity 0.8s var(--ease-out), transform 0.8s var(--ease-out);
}

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

.reveal--delay-1 { transition-delay: 0.1s; }
.reveal--delay-2 { transition-delay: 0.2s; }
.reveal--delay-3 { transition-delay: 0.3s; }


/* ============================================
   Image & Screenshot Containers
   ============================================ */

.screenshot {
  border-radius: 16px;
  overflow: hidden;
  border: 1px solid var(--c-gray-200);
  box-shadow: 0 4px 24px rgba(0, 0, 0, 0.04);
}

.screenshot img {
  width: 100%;
  display: block;
}

.img-caption {
  font-size: 13px;
  color: var(--c-gray-400);
  text-align: center;
  margin-top: 12px;
}


/* ============================================
   Responsive
   ============================================ */

@media (max-width: 1024px) {
  :root {
    --section-padding: 100px;
  }

  .hero__title {
    font-size: 48px;
  }

  .project__title {
    font-size: 36px;
  }

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

  .project__body {
    grid-template-columns: 1fr;
    gap: 48px;
  }

  .grid-2 {
    grid-template-columns: 1fr;
    gap: 48px;
  }

  .grid-2--reverse {
    direction: ltr;
  }

  .metrics-row {
    grid-template-columns: 1fr;
    gap: 24px;
  }
}

@media (max-width: 768px) {
  .container, .container--narrow {
    padding: 0 20px;
  }

  .nav__inner {
    padding: 0 20px;
  }

  .nav__links {
    display: none;
  }

  .hero {
    padding: 140px 0 80px;
  }

  .hero__title {
    font-size: 36px;
  }

  .hero__desc {
    font-size: 17px;
  }

  .project__title {
    font-size: 28px;
  }

  .section-heading {
    font-size: 28px;
  }

  .cta__title {
    font-size: 32px;
  }

  .metric__value {
    font-size: 36px;
  }

  .metrics {
    gap: 32px;
  }

  .grid-3 {
    grid-template-columns: 1fr;
  }

  .section-nav__inner {
    gap: 24px;
    padding: 0 20px;
    overflow-x: auto;
    -ms-overflow-style: none;
    scrollbar-width: none;
  }

  .section-nav__inner::-webkit-scrollbar {
    display: none;
  }

  .project__body[style*="rtl"] {
    direction: ltr;
  }

  .phone-mockup {
    max-width: 320px;
  }

  .phone-mockup__screen {
    height: 600px;
  }
}

@media (max-width: 480px) {
  .hero__title {
    font-size: 28px;
  }

  .metrics {
    flex-direction: column;
    gap: 24px;
  }
}