/*
  Ho Quoc Thai Cybersecurity Portfolio
  Static website ready for GitHub Pages.
  Features: dark/light mode, EN/VI language support, mobile-first responsive layout.
*/

:root {
  color-scheme: dark;
  --bg: #071018;
  --bg-soft: #0b1622;
  --bg-elevated: rgba(13, 28, 42, 0.78);
  --bg-solid: #0d1c2a;
  --border: rgba(124, 255, 218, 0.14);
  --border-strong: rgba(124, 255, 218, 0.28);
  --text: #e6f1ff;
  --heading: #f3f8ff;
  --muted: #9db0c5;
  --muted-2: #6f8399;
  --accent: #64ffda;
  --accent-soft: rgba(100, 255, 218, 0.1);
  --accent-blue: #38bdf8;
  --accent-green: #22c55e;
  --danger: #fb7185;
  --warning: #facc15;
  --shadow: 0 24px 80px rgba(0, 0, 0, 0.35);
  --radius-sm: 12px;
  --radius-md: 18px;
  --radius-lg: 28px;
  --container: 1120px;
  --header-height: 76px;
  --font-main: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-mono: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  --step--1: clamp(0.82rem, 0.78rem + 0.16vw, 0.94rem);
  --step-0: clamp(0.95rem, 0.9rem + 0.22vw, 1.04rem);
  --step-1: clamp(1.05rem, 0.98rem + 0.35vw, 1.2rem);
  --step-2: clamp(1.35rem, 1.15rem + 0.85vw, 1.85rem);
  --step-3: clamp(2rem, 1.45rem + 2.4vw, 3.4rem);
  --step-4: clamp(2.65rem, 1.85rem + 5vw, 6rem);
}

:root[data-theme="light"] {
  color-scheme: light;
  --bg: #f5f8fb;
  --bg-soft: #eef4f8;
  --bg-elevated: rgba(255, 255, 255, 0.82);
  --bg-solid: #ffffff;
  --border: rgba(15, 118, 110, 0.15);
  --border-strong: rgba(14, 116, 144, 0.26);
  --text: #193042;
  --heading: #0f1f2d;
  --muted: #4f6476;
  --muted-2: #6e8191;
  --accent: #0f766e;
  --accent-soft: rgba(15, 118, 110, 0.09);
  --accent-blue: #0369a1;
  --accent-green: #15803d;
  --danger: #be123c;
  --warning: #a16207;
  --shadow: 0 20px 70px rgba(15, 31, 45, 0.12);
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--header-height);
  -webkit-text-size-adjust: 100%;
}

body {
  min-height: 100vh;
  overflow-x: hidden;
  font-family: var(--font-main);
  font-size: var(--step-0);
  line-height: 1.65;
  color: var(--text);
  background:
    radial-gradient(circle at top left, rgba(56, 189, 248, 0.14), transparent 30rem),
    radial-gradient(circle at 85% 10%, rgba(100, 255, 218, 0.11), transparent 26rem),
    linear-gradient(135deg, #050a10 0%, var(--bg) 46%, #081521 100%);
}

:root[data-theme="light"] body {
  background:
    radial-gradient(circle at top left, rgba(14, 116, 144, 0.12), transparent 28rem),
    radial-gradient(circle at 85% 10%, rgba(15, 118, 110, 0.1), transparent 24rem),
    linear-gradient(135deg, #f8fbfd 0%, var(--bg) 52%, #edf6f8 100%);
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  background-image:
    linear-gradient(rgba(100, 255, 218, 0.035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(100, 255, 218, 0.035) 1px, transparent 1px);
  background-size: 48px 48px;
  mask-image: linear-gradient(to bottom, black 0%, transparent 85%);
}

:root[data-theme="light"] body::before {
  background-image:
    linear-gradient(rgba(15, 118, 110, 0.055) 1px, transparent 1px),
    linear-gradient(90deg, rgba(15, 118, 110, 0.055) 1px, transparent 1px);
}

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

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

ul {
  list-style: none;
}

button,
a {
  -webkit-tap-highlight-color: transparent;
}

button,
input,
textarea,
select {
  font: inherit;
}

:focus-visible {
  outline: 3px solid color-mix(in srgb, var(--accent) 75%, transparent);
  outline-offset: 4px;
}

.skip-link {
  position: fixed;
  left: 16px;
  top: 16px;
  z-index: 2000;
  transform: translateY(-130%);
  padding: 10px 14px;
  border-radius: 999px;
  background: var(--bg-solid);
  color: var(--text);
  border: 1px solid var(--border-strong);
  box-shadow: var(--shadow);
  transition: transform 0.2s ease;
}

.skip-link:focus {
  transform: translateY(0);
}

.container {
  width: min(100% - 32px, var(--container));
  margin-inline: auto;
}

.section-padding {
  padding: clamp(68px, 8vw, 104px) 0;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  height: var(--header-height);
  border-bottom: 1px solid var(--border);
  background: color-mix(in srgb, var(--bg) 86%, transparent);
  backdrop-filter: blur(18px);
}

.navbar {
  position: relative;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.logo {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  min-width: 0;
  font-weight: 750;
  letter-spacing: 0.01em;
}

.logo-mark {
  display: grid;
  place-items: center;
  flex: 0 0 auto;
  width: 42px;
  height: 42px;
  border: 1px solid var(--border-strong);
  border-radius: 14px;
  color: var(--accent);
  background: var(--accent-soft);
  font-family: var(--font-mono);
  font-size: 0.85rem;
  box-shadow: 0 0 28px color-mix(in srgb, var(--accent) 13%, transparent);
}

.logo-text {
  overflow: hidden;
  color: var(--heading);
  text-overflow: ellipsis;
  white-space: nowrap;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-left: auto;
}

.control-btn,
.nav-toggle {
  min-width: 44px;
  min-height: 44px;
  border: 1px solid var(--border);
  border-radius: 999px;
  color: var(--text);
  background: color-mix(in srgb, var(--bg-solid) 72%, transparent);
  cursor: pointer;
  transition: transform 0.2s ease, border-color 0.2s ease, background 0.2s ease, color 0.2s ease;
}

.control-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 0 13px;
  font-size: 0.88rem;
  font-weight: 700;
}

.control-btn:hover,
.nav-toggle:hover {
  color: var(--accent);
  border-color: var(--border-strong);
  transform: translateY(-1px);
}

.theme-icon,
.lang-current {
  font-family: var(--font-mono);
}

.nav-toggle {
  display: none;
  width: 44px;
  height: 44px;
  border-radius: 14px;
}

.nav-toggle span {
  display: block;
  width: 20px;
  height: 2px;
  margin: 5px auto;
  border-radius: 999px;
  background: var(--text);
  transition: transform 0.2s ease, opacity 0.2s ease;
}

.nav-toggle.active span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

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

.nav-toggle.active span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 6px;
}

.nav-links a {
  display: inline-flex;
  align-items: center;
  min-height: 40px;
  padding: 8px 12px;
  border-radius: 999px;
  color: var(--muted);
  font-size: var(--step--1);
  font-weight: 650;
  transition: color 0.2s ease, background 0.2s ease, border-color 0.2s ease;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--accent);
  background: var(--accent-soft);
}

.nav-links .nav-cta {
  margin-left: 4px;
  color: var(--heading);
  border: 1px solid var(--border-strong);
}

.hero {
  position: relative;
  min-height: calc(100svh - var(--header-height));
  display: flex;
  align-items: center;
}

.hero::after {
  content: "";
  position: absolute;
  right: -18%;
  top: 12%;
  width: 420px;
  height: 420px;
  border-radius: 999px;
  background: color-mix(in srgb, var(--accent-blue) 12%, transparent);
  filter: blur(80px);
  pointer-events: none;
}

.hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.08fr) minmax(320px, 0.92fr);
  gap: clamp(36px, 6vw, 64px);
  align-items: center;
}

.eyebrow {
  margin-bottom: 14px;
  color: var(--accent);
  font-family: var(--font-mono);
  font-size: clamp(0.75rem, 0.72rem + 0.15vw, 0.84rem);
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

h1,
h2,
h3 {
  color: var(--heading);
  line-height: 1.12;
}

.hero h1 {
  margin-bottom: 22px;
  font-size: var(--step-4);
  line-height: 0.98;
  letter-spacing: -0.065em;
}

.hero h1 span {
  display: block;
  color: transparent;
  background: linear-gradient(90deg, var(--heading), var(--accent-blue), var(--accent));
  -webkit-background-clip: text;
  background-clip: text;
}

.hero h2 {
  max-width: 760px;
  margin-bottom: 20px;
  color: var(--muted);
  font-size: clamp(1.04rem, 0.96rem + 0.55vw, 1.45rem);
  font-weight: 650;
}

.hero-description,
.section-heading > p,
.about-content p,
.project-card p,
.writeup-card p,
.contact-card > p {
  color: var(--muted);
}

.hero-description {
  max-width: 680px;
  margin-bottom: 30px;
  font-size: var(--step-1);
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-bottom: 34px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: 0 20px;
  border-radius: 999px;
  font-weight: 780;
  transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease, background 0.2s ease;
}

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

.btn-primary {
  color: #041013;
  background: linear-gradient(135deg, var(--accent), var(--accent-blue));
  box-shadow: 0 14px 38px color-mix(in srgb, var(--accent-blue) 22%, transparent);
}

:root[data-theme="light"] .btn-primary {
  color: #ffffff;
}

.btn-secondary {
  color: var(--heading);
  border: 1px solid var(--border-strong);
  background: color-mix(in srgb, var(--bg-solid) 55%, transparent);
}

.hero-metrics {
  display: grid;
  max-width: 560px;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
}

.hero-metrics div {
  padding: 16px;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  background: var(--bg-elevated);
}

.hero-metrics strong {
  display: block;
  color: var(--accent);
  font-family: var(--font-mono);
  font-size: 0.92rem;
}

.hero-metrics span {
  color: var(--muted);
  font-size: var(--step--1);
}

.terminal-card,
.skill-card,
.project-card,
.writeup-card,
.note-card,
.timeline-item,
.contact-card {
  border: 1px solid var(--border);
  background: var(--bg-elevated);
  box-shadow: var(--shadow);
  backdrop-filter: blur(16px);
}

.terminal-card {
  position: relative;
  overflow: hidden;
  border-radius: var(--radius-lg);
}

.terminal-card::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: linear-gradient(120deg, color-mix(in srgb, var(--accent) 10%, transparent), transparent 42%);
}

.terminal-header {
  position: relative;
  display: flex;
  align-items: center;
  gap: 8px;
  min-height: 50px;
  padding: 0 18px;
  border-bottom: 1px solid var(--border);
  background: color-mix(in srgb, var(--bg-solid) 78%, transparent);
}

.dot {
  width: 11px;
  height: 11px;
  border-radius: 999px;
}

.red { background: var(--danger); }
.yellow { background: var(--warning); }
.green { background: var(--accent-green); }

.terminal-title {
  margin-left: 8px;
  color: var(--muted);
  font-family: var(--font-mono);
  font-size: 0.82rem;
}

.terminal-body {
  position: relative;
  padding: clamp(20px, 4vw, 28px);
  font-family: var(--font-mono);
  font-size: clamp(0.82rem, 0.75rem + 0.25vw, 0.96rem);
}

.terminal-body p {
  overflow-wrap: anywhere;
  margin-bottom: 14px;
  color: var(--muted);
}

.prompt,
.cursor {
  color: var(--accent);
}

.cursor {
  animation: blink 1s steps(2, start) infinite;
}

@keyframes blink {
  50% { opacity: 0; }
}

.two-column {
  display: grid;
  grid-template-columns: 0.8fr 1.2fr;
  gap: clamp(28px, 6vw, 72px);
}

.section-heading {
  max-width: 760px;
  margin-bottom: 34px;
}

.section-heading.centered {
  margin-inline: auto;
  text-align: center;
}

.section-heading h2 {
  margin-bottom: 14px;
  font-size: var(--step-3);
  letter-spacing: -0.04em;
}

.about-content p + p {
  margin-top: 18px;
}

.about-tags,
.tags,
.contact-links {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.about-tags {
  margin-top: 28px;
}

.about-tags span,
.tags span,
.category {
  display: inline-flex;
  align-items: center;
  min-height: 32px;
  padding: 6px 11px;
  border: 1px solid var(--border);
  border-radius: 999px;
  color: var(--accent);
  background: var(--accent-soft);
  font-family: var(--font-mono);
  font-size: 0.78rem;
}

.skills-grid,
.project-grid,
.writeup-grid,
.notes-grid {
  display: grid;
  gap: 18px;
}

.skills-grid {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

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

.notes-grid {
  grid-template-columns: repeat(7, minmax(150px, 1fr));
}

.skill-card,
.project-card,
.writeup-card,
.note-card {
  position: relative;
  overflow: hidden;
  border-radius: var(--radius-md);
  transition: transform 0.2s ease, border-color 0.2s ease, background 0.2s ease, box-shadow 0.2s ease;
}

.skill-card,
.project-card,
.writeup-card {
  padding: clamp(20px, 3vw, 26px);
}

.skill-card:hover,
.project-card:hover,
.writeup-card:hover,
.note-card:hover {
  transform: translateY(-5px);
  border-color: var(--border-strong);
  box-shadow: 0 26px 90px color-mix(in srgb, var(--accent-blue) 14%, transparent);
}

.card-icon {
  display: inline-grid;
  place-items: center;
  width: 42px;
  height: 42px;
  margin-bottom: 18px;
  border: 1px solid var(--border);
  border-radius: 14px;
  color: var(--accent);
  background: var(--accent-soft);
  font-family: var(--font-mono);
  font-size: 0.86rem;
}

.skill-card h3,
.project-card h3,
.writeup-card h3 {
  margin-bottom: 14px;
  font-size: clamp(1.05rem, 0.98rem + 0.3vw, 1.24rem);
}

.skill-card li {
  position: relative;
  margin: 9px 0;
  padding-left: 18px;
  color: var(--muted);
  font-size: var(--step--1);
}

.skill-card li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.72em;
  width: 7px;
  height: 7px;
  border-radius: 999px;
  background: var(--accent-blue);
}

.project-topline {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 14px;
  color: var(--accent);
  font-family: var(--font-mono);
  font-size: 0.8rem;
}

.status-dot {
  width: 8px;
  height: 8px;
  border-radius: 999px;
  background: var(--accent-green);
  box-shadow: 0 0 14px var(--accent-green);
}

.project-card p,
.writeup-card p {
  margin-bottom: 18px;
}

.writeup-card .difficulty {
  margin-bottom: 10px;
  color: var(--muted-2);
  font-family: var(--font-mono);
  font-size: 0.82rem;
}

.read-more {
  display: inline-flex;
  align-items: center;
  color: var(--accent);
  font-weight: 750;
}

.read-more::after {
  content: "→";
  margin-left: 8px;
  transition: transform 0.2s ease;
}

.read-more:hover::after {
  transform: translateX(4px);
}

.note-card {
  min-height: 134px;
  padding: 18px;
}

.note-card span,
.timeline-item span {
  display: inline-flex;
  color: var(--accent);
  font-family: var(--font-mono);
  font-size: 0.82rem;
}

.note-card h3 {
  margin-top: 14px;
  font-size: 1rem;
}

.timeline {
  position: relative;
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 16px;
}

.timeline-item {
  min-height: 128px;
  padding: 20px;
  border-radius: var(--radius-md);
  transition: transform 0.2s ease, border-color 0.2s ease;
}

.timeline-item:hover {
  transform: translateY(-4px);
  border-color: var(--border-strong);
}

.timeline-item p {
  margin-top: 14px;
  color: var(--heading);
  font-weight: 720;
}

.contact-card {
  max-width: 880px;
  margin-inline: auto;
  padding: clamp(28px, 5vw, 48px);
  border-radius: var(--radius-lg);
  text-align: center;
}

.contact-card h2 {
  margin-bottom: 12px;
  font-size: var(--step-3);
  letter-spacing: -0.04em;
}

.contact-links {
  justify-content: center;
  margin: 28px 0;
}

.contact-links a {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 10px 14px;
  border: 1px solid var(--border);
  border-radius: 999px;
  color: var(--heading);
  background: color-mix(in srgb, var(--bg-solid) 55%, transparent);
  font-size: var(--step--1);
  transition: color 0.2s ease, border-color 0.2s ease, transform 0.2s ease;
}

.contact-links a:hover {
  color: var(--accent);
  border-color: var(--border-strong);
  transform: translateY(-2px);
}

.closing-line {
  color: var(--accent) !important;
  font-family: var(--font-mono);
}

.site-footer {
  border-top: 1px solid var(--border);
  padding: 24px 0;
  color: var(--muted);
}

.footer-content {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  font-size: var(--step--1);
}

.footer-content a {
  color: var(--accent);
}

.reveal {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.55s ease, transform 0.55s ease;
}

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

@media (max-width: 1080px) {
  .nav-toggle {
    display: inline-block;
  }

  .nav-links {
    position: absolute;
    top: calc(100% + 12px);
    left: 0;
    right: 0;
    display: grid;
    gap: 4px;
    padding: 14px;
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    background: color-mix(in srgb, var(--bg-solid) 94%, transparent);
    box-shadow: var(--shadow);
    transform: translateY(-8px);
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.2s ease, transform 0.2s ease;
  }

  .nav-links.open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
  }

  .nav-links a {
    justify-content: center;
    min-height: 46px;
  }

  .nav-links .nav-cta {
    margin-left: 0;
  }

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

  .hero {
    min-height: auto;
  }

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

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

@media (max-width: 720px) {
  :root {
    --header-height: 68px;
  }

  .container {
    width: min(100% - 24px, var(--container));
  }

  .logo-text {
    display: none;
  }

  .nav-actions {
    gap: 6px;
  }

  .control-btn {
    min-width: 42px;
    min-height: 42px;
    padding: 0 10px;
  }

  .theme-text {
    display: none;
  }

  .hero-grid {
    gap: 34px;
  }

  .hero h1 {
    letter-spacing: -0.052em;
  }

  .hero-actions {
    display: grid;
    grid-template-columns: 1fr;
  }

  .btn {
    width: 100%;
  }

  .hero-metrics,
  .skills-grid,
  .project-grid,
  .writeup-grid,
  .notes-grid,
  .timeline {
    grid-template-columns: 1fr;
  }

  .terminal-card {
    border-radius: 22px;
  }

  .section-heading.centered {
    text-align: left;
  }

  .contact-card {
    text-align: left;
  }

  .contact-links {
    justify-content: flex-start;
  }

  .contact-links a {
    width: 100%;
    justify-content: flex-start;
    border-radius: 16px;
    overflow-wrap: anywhere;
  }

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

@media (max-width: 390px) {
  .navbar {
    gap: 8px;
  }

  .logo-mark {
    width: 38px;
    height: 38px;
    border-radius: 12px;
    font-size: 0.78rem;
  }

  .control-btn,
  .nav-toggle {
    min-width: 40px;
    min-height: 40px;
  }

  .lang-toggle {
    padding: 0 9px;
  }

  .terminal-title {
    display: none;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }

  .reveal {
    opacity: 1;
    transform: none;
  }
}