/* Security Engineering Lab — Global Styles */

:root {
  color-scheme: light;

  --bg: #f8fbff;
  --surface: #ffffff;
  --surface-soft: #eff6ff;

  --primary: #2563eb;
  --primary-dark: #1e3a8a;

  --text: #0f172a;
  --muted: #64748b;
  --border: #e2e8f0;

  --shadow: 0 12px 32px rgba(15, 23, 42, 0.05);

  --max-width: 1120px;
  --radius: 16px;
}

/* Reset */

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 90px;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family:
    -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    "Noto Sans KR",
    sans-serif;
  font-size: 15px;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
}

a {
  color: inherit;
  text-decoration: none;
}

button,
input {
  font: inherit;
}

button {
  cursor: pointer;
}

a:focus-visible,
button:focus-visible,
input:focus-visible {
  outline: 3px solid var(--primary);
  outline-offset: 3px;
}

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

/* Layout */

.container {
  width: min(
    var(--max-width),
    calc(100% - 48px)
  );
  margin-inline: auto;
}

main {
  min-height: 70vh;
}

.section {
  padding: 56px 0;
}

.section-header {
  margin-bottom: 28px;
}

.section-title {
  margin: 0 0 10px;
  font-size: clamp(25px, 3vw, 34px);
  font-weight: 750;
  letter-spacing: -0.045em;
  line-height: 1.3;
}

.section-description {
  max-width: 720px;
  margin: 0;
  color: var(--muted);
}

/* Header */

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;

  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(16px);

  border-bottom: 1px solid var(--border);
}

.nav-container {
  width: min(
    var(--max-width),
    calc(100% - 48px)
  );

  min-height: 74px;
  margin: auto;

  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.site-logo {
  color: var(--primary-dark);
  font-size: 16px;
  font-weight: 800;
  white-space: nowrap;
  letter-spacing: -0.03em;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 24px;
}

.nav-link {
  color: var(--muted);
  font-size: 14px;
  font-weight: 600;
  transition: color 0.2s ease;
}

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

.language-toggle {
  padding: 7px 12px;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: var(--surface);
  color: var(--primary-dark);
  font-size: 12px;
  font-weight: 750;
}

.language-toggle:hover {
  background: var(--surface-soft);
}

/* Hero */

.hero {
  padding: 100px 0 80px;
}

.eyebrow {
  display: inline-block;
  margin-bottom: 20px;
  color: var(--primary);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.hero-title {
  max-width: 900px;
  margin: 0 0 24px;
  font-size: clamp(40px, 6vw, 72px);
  line-height: 1.12;
  letter-spacing: -0.055em;
  font-weight: 800;
}

.hero-title .accent {
  color: var(--primary);
}

.hero-description {
  max-width: 720px;
  margin: 0 0 32px;
  color: var(--muted);
  font-size: clamp(16px, 2vw, 19px);
  line-height: 1.8;
}

/* Buttons */

.button-group {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;

  padding: 12px 20px;
  min-height: 44px;

  border-radius: 10px;
  border: 1px solid transparent;

  font-size: 14px;
  font-weight: 700;

  transition:
    background 0.2s,
    transform 0.2s;
}

.button:hover {
  transform: translateY(-2px);
}

.button-primary {
  background: var(--primary);
  color: #ffffff;
}

.button-primary:hover {
  background: var(--primary-dark);
}

.button-secondary {
  background: var(--surface);
  color: var(--primary);
  border-color: var(--border);
}

/* Cards */

.grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 20px;
}

.grid-two {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.card {
  padding: 28px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);

  transition:
    transform 0.2s,
    border-color 0.2s;
}

.card:hover {
  transform: translateY(-3px);
  border-color: #bfdbfe;
}

.card-title {
  margin: 0 0 12px;
  font-size: 20px;
  line-height: 1.4;
  letter-spacing: -0.025em;
}

.card-description {
  margin: 0 0 18px;
  color: var(--muted);
  font-size: 14px;
}

.card-link {
  color: var(--primary);
  font-size: 13px;
  font-weight: 750;
}

/* Tags */

.tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.tag {
  display: inline-flex;
  align-items: center;

  padding: 5px 11px;
  border-radius: 999px;

  background: var(--surface-soft);
  color: var(--primary-dark);

  font-size: 12px;
  font-weight: 650;
}

.tag-outline {
  background: transparent;
  border: 1px solid var(--border);
}

/* Profile */

.profile-intro {
  padding: 72px 0 32px;
}

.profile-name {
  margin: 0 0 10px;
  font-size: clamp(38px, 5vw, 58px);
  letter-spacing: -0.05em;
  line-height: 1.2;
}

.profile-role {
  margin: 0 0 18px;
  color: var(--primary-dark);
  font-size: 21px;
  font-weight: 650;
}

.profile-description {
  max-width: 700px;
  color: var(--muted);
}

.profile-section {
  padding: 36px 0;
  border-bottom: 1px solid var(--border);
}

.profile-section h2 {
  margin: 0 0 24px;
  font-size: 24px;
  letter-spacing: -0.03em;
}

/* Experience Timeline */

.timeline-item {
  display: grid;
  grid-template-columns: 155px minmax(0, 1fr);
  gap: 26px;
  padding: 20px 0;
}

.timeline-date {
  color: var(--muted);
  font-size: 13px;
}

.timeline-content h3 {
  margin: 0 0 5px;
  font-size: 18px;
}

.timeline-company {
  color: var(--muted);
  font-size: 14px;
}

.timeline-list {
  margin: 16px 0;
  padding-left: 20px;
  color: var(--text);
}

.timeline-list li {
  margin-bottom: 8px;
}

/* Technical Skills */

.skill-group {
  display: grid;
  grid-template-columns: 210px minmax(0, 1fr);
  gap: 20px;
  padding: 16px 0;
}

.skill-label {
  color: var(--muted);
  font-size: 14px;
  font-weight: 650;
}

/* Certifications / Education */

.info-list {
  display: flex;
  flex-direction: column;
}

.info-item {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 20px;
  padding: 18px 0;
  border-bottom: 1px solid var(--border);
}

.info-item:last-child {
  border-bottom: 0;
}

.info-title {
  font-weight: 700;
}

.info-detail,
.info-date {
  color: var(--muted);
  font-size: 13px;
}

/* Project & Studies List */

.content-list {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.content-item {
  display: block;
  padding: 22px 0;
  border-bottom: 1px solid var(--border);
}

.content-item:hover .content-title {
  color: var(--primary);
}

.content-title {
  margin: 0 0 8px;
  font-size: 19px;
  font-weight: 700;
}

.content-summary {
  margin: 0 0 12px;
  color: var(--muted);
  font-size: 14px;
}

.content-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  color: var(--muted);
  font-size: 12px;
}

/* Filter Bar */

.filter-bar {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 28px;
}

.filter-button {
  padding: 8px 14px;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: var(--surface);
  color: var(--muted);
  font-size: 13px;
  font-weight: 600;
}

.filter-button:hover,
.filter-button.active {
  background: var(--primary);
  color: white;
  border-color: var(--primary);
}

/* Empty States */

.empty-state {
  padding: 48px 24px;
  border: 1px dashed #cbd5e1;
  border-radius: var(--radius);
  background: var(--surface);
  text-align: center;
}

.empty-state h3 {
  margin: 0 0 8px;
}

.empty-state p {
  margin: 0;
  color: var(--muted);
}

/* Footer */

.site-footer {
  margin-top: 72px;
  padding: 32px 0;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 13px;
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 16px;
}

/* Responsive — Tablet */

@media (max-width: 900px) {
  .nav-container {
    flex-wrap: wrap;
    padding: 16px 0;
  }

  .nav-links {
    width: 100%;
    gap: 16px;
    flex-wrap: wrap;
  }

  .grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .hero {
    padding: 72px 0 60px;
  }
}

/* Responsive — Mobile */

@media (max-width: 600px) {
  .container,
  .nav-container {
    width: calc(100% - 32px);
  }

  .nav-links {
    gap: 10px 15px;
  }

  .nav-link {
    font-size: 12px;
  }

  .site-logo {
    font-size: 15px;
  }

  .section {
    padding: 36px 0;
  }

  .hero {
    padding: 56px 0 48px;
  }

  .hero-title {
    font-size: 40px;
  }

  .grid,
  .grid-two {
    grid-template-columns: 1fr;
  }

  .card {
    padding: 22px;
  }

  .timeline-item,
  .skill-group {
    grid-template-columns: 1fr;
    gap: 8px;
  }

  .info-item {
    flex-direction: column;
    gap: 5px;
  }

  .profile-intro {
    padding-top: 48px;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
  }
}