/* =============================================================
   Düsseldorf Explained — light, wiz.io-inspired theme
   ============================================================= */

:root {
  /* Surfaces */
  --bg: #ffffff;
  --bg-soft: #f7f9fc;
  --bg-tint: #f1f5fb;

  /* Borders */
  --border: #e6ecf3;
  --border-strong: #d7dfeb;

  /* Text */
  --text: #0a1330;            /* near-black navy, wiz primary */
  --text-strong: #060c22;
  --text-muted: #4b5670;      /* slate-ish */
  --text-dim: #8893a8;

  /* Accents */
  --accent: #2453ff;          /* bright wiz blue */
  --accent-strong: #1a3fd1;
  --accent-soft: #eaf0ff;
  --accent-ring: rgba(36, 83, 255, 0.16);

  --accent-2: #0ea5e9;        /* sky / teal */
  --accent-3: #8b5cf6;        /* violet */

  /* Hero gradient stops (used in SVG and in CSS) */
  --grad-1: #6ee7f9;          /* cyan */
  --grad-2: #818cf8;          /* indigo */
  --grad-3: #f0abfc;          /* pink */
  --grad-4: #fde68a;          /* warm soft */

  /* Effects */
  --shadow-sm: 0 1px 2px rgba(10, 19, 48, 0.04);
  --shadow-md: 0 8px 24px -10px rgba(10, 19, 48, 0.10);
  --shadow-lg: 0 30px 70px -30px rgba(10, 19, 48, 0.20);
  --shadow-card-hover: 0 18px 40px -20px rgba(10, 19, 48, 0.18);

  /* Typography */
  --font-sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI",
    Roboto, "Helvetica Neue", Arial, sans-serif;

  /* Radii */
  --radius-sm: 8px;
  --radius: 16px;
  --radius-lg: 24px;
}

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

html {
  background: var(--bg);
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: 16.5px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}

/* -------- Header -------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.82);
  backdrop-filter: blur(14px) saturate(150%);
  -webkit-backdrop-filter: blur(14px) saturate(150%);
  border-bottom: 1px solid var(--border);
}

.site-header__inner {
  max-width: 1240px;
  margin: 0 auto;
  padding: 0.95rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 2rem;
}

.site-title {
  display: inline-flex;
  align-items: center;
  gap: 0.7rem;
  font-weight: 700;
  font-size: 1.02rem;
  color: var(--text);
  text-decoration: none;
  letter-spacing: -0.01em;
}

.site-title__mark {
  width: 28px;
  height: 28px;
  border-radius: 8px;
  background: linear-gradient(135deg, #2453ff 0%, #6366f1 55%, #8b5cf6 100%);
  position: relative;
  box-shadow: 0 6px 18px -6px rgba(36, 83, 255, 0.5);
}

.site-title__mark::after {
  content: "D";
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  color: #ffffff;
  font-weight: 800;
  font-size: 0.95rem;
  letter-spacing: 0;
}

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

.site-nav ul {
  display: flex;
  align-items: center;
  gap: 0.15rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.site-nav a {
  display: block;
  padding: 0.45rem 0.9rem;
  border-radius: 999px;
  font-size: 0.93rem;
  font-weight: 500;
  color: var(--text-muted);
  text-decoration: none;
  transition: color 0.15s ease, background 0.15s ease;
}

.site-nav a:hover {
  color: var(--text);
  background: var(--accent-soft);
}

/* -------- Main -------- */
main {
  max-width: 1240px;
  margin: 0 auto;
  padding: 1.5rem 1.5rem 6rem;
  position: relative;
}

/* -------- Hero -------- */
.hero {
  position: relative;
  padding: 5.5rem 0 4rem;
  text-align: center;
  overflow: hidden;
  isolation: isolate;
}

/* Soft gradient blob backdrop, wiz.io-style */
.hero::before,
.hero::after {
  content: "";
  position: absolute;
  border-radius: 50%;
  filter: blur(80px);
  z-index: -1;
  pointer-events: none;
  opacity: 0.75;
}

.hero::before {
  top: -120px;
  left: -120px;
  width: 520px;
  height: 520px;
  background: radial-gradient(circle, var(--grad-1) 0%, transparent 65%);
}

.hero::after {
  top: -80px;
  right: -160px;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, var(--grad-3) 0%, transparent 65%);
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  padding: 0.32rem 0.95rem;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.85);
  border: 1px solid var(--border);
  font-size: 0.82rem;
  color: var(--text-muted);
  font-weight: 500;
  margin-bottom: 1.75rem;
  box-shadow: var(--shadow-sm);
  backdrop-filter: blur(8px);
}

.hero-badge .dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 4px var(--accent-ring);
}

.hero h1 {
  font-size: clamp(2.6rem, 6vw, 4.6rem);
  font-weight: 800;
  line-height: 1.04;
  letter-spacing: -0.035em;
  margin: 0 0 1.5rem;
  color: var(--text);
}

.hero h1 .accent {
  background: linear-gradient(120deg, #2453ff 0%, #6366f1 50%, #c026d3 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.hero .lede {
  font-size: clamp(1.05rem, 1.5vw, 1.25rem);
  color: var(--text-muted);
  max-width: 720px;
  margin: 0 auto 2.5rem;
  line-height: 1.55;
}

.hero-ctas {
  display: flex;
  gap: 0.75rem;
  justify-content: center;
  flex-wrap: wrap;
  margin: 0 0 3.5rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.82rem 1.4rem;
  border-radius: 999px;
  font-weight: 600;
  font-size: 0.96rem;
  text-decoration: none;
  border: 1px solid transparent;
  transition: transform 0.15s ease, box-shadow 0.2s ease,
    background 0.15s ease, border-color 0.15s ease, color 0.15s ease;
  white-space: nowrap;
}

.btn-primary {
  background: var(--text);
  color: #ffffff;
  box-shadow: 0 12px 28px -14px rgba(10, 19, 48, 0.55);
}

.btn-primary:hover {
  background: var(--text-strong);
  transform: translateY(-1px);
  box-shadow: 0 18px 36px -16px rgba(10, 19, 48, 0.55);
}

.btn-ghost {
  background: #ffffff;
  border-color: var(--border-strong);
  color: var(--text);
  box-shadow: var(--shadow-sm);
}

.btn-ghost:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.hero-image {
  display: block;
  width: 100%;
  max-width: 1080px;
  margin: 0 auto;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--border);
}

/* -------- Home wrapper -------- */
.home {
  max-width: 1240px;
  margin: 0 auto;
}

.home-intro {
  color: var(--text-muted);
  font-size: 1.05rem;
  max-width: 720px;
  margin: 0 0 1rem;
}

.home-note-h {
  margin-top: 5rem;
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--text);
  letter-spacing: -0.015em;
}

/* -------- Category sections -------- */
.category {
  margin-top: 5rem;
}

.category h2 {
  display: flex;
  align-items: center;
  gap: 0.85rem;
  font-size: 1.7rem;
  font-weight: 700;
  letter-spacing: -0.022em;
  color: var(--text);
  margin: 0 0 0.4rem;
  padding: 0;
  border: none;
}

.category h2::before {
  content: "";
  display: inline-block;
  width: 28px;
  height: 3px;
  border-radius: 999px;
  background: var(--accent);
  flex: 0 0 28px;
}

.category .cat-lede {
  color: var(--text-muted);
  margin: 0 0 1.75rem;
  font-size: 1rem;
  font-family: var(--font-sans);
}

/* -------- Topic cards -------- */
.topics {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1rem;
}

.topics li {
  margin: 0;
}

.topics a {
  position: relative;
  display: flex;
  gap: 1rem;
  align-items: flex-start;
  padding: 1.4rem 1.4rem 1.5rem;
  background: #ffffff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  text-decoration: none;
  color: var(--text);
  transition: border-color 0.2s ease, box-shadow 0.2s ease,
    transform 0.2s ease;
  box-shadow: var(--shadow-sm);
  overflow: hidden;
}

.topics a::after {
  content: "";
  position: absolute;
  top: 1.5rem;
  right: 1.3rem;
  width: 18px;
  height: 18px;
  background: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%232453ff' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='M7 17L17 7M9 7h8v8'/%3E%3C/svg%3E")
    center / contain no-repeat;
  opacity: 0;
  transform: translate(-4px, 4px);
  transition: opacity 0.2s ease, transform 0.2s ease;
}

.topics a:hover {
  border-color: var(--accent);
  box-shadow: var(--shadow-card-hover);
  transform: translateY(-2px);
}

.topics a:hover::after {
  opacity: 1;
  transform: translate(0, 0);
}

.topics .icon {
  flex: 0 0 42px;
  width: 42px;
  height: 42px;
  display: grid;
  place-items: center;
  border-radius: 12px;
  background: var(--accent-soft);
  color: var(--accent);
}

.topics .icon svg {
  width: 20px;
  height: 20px;
}

.topics .title {
  display: block;
  font-weight: 600;
  font-size: 1rem;
  color: var(--text);
  margin: 0 0 0.3rem;
  letter-spacing: -0.005em;
  padding-right: 1.5rem;
}

.topics .desc {
  display: block;
  font-size: 0.9rem;
  line-height: 1.55;
  color: var(--text-muted);
}

/* -------- Articles (inner pages) -------- */
article {
  max-width: 760px;
  margin: 0 auto;
}

article h1 {
  font-size: clamp(2.1rem, 4vw, 3rem);
  font-weight: 800;
  letter-spacing: -0.025em;
  line-height: 1.1;
  color: var(--text);
  margin: 0 0 1rem;
}

article h2 {
  font-size: 1.55rem;
  font-weight: 700;
  letter-spacing: -0.015em;
  color: var(--text);
  margin: 3rem 0 1rem;
}

article h3 {
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--text);
  margin: 1.75rem 0 0.5rem;
}

article p {
  margin: 0 0 1.05rem;
  color: var(--text-muted);
}

article p strong,
article li strong {
  color: var(--text);
  font-weight: 600;
}

article em {
  color: var(--text);
  font-style: italic;
}

article ul,
article ol {
  color: var(--text-muted);
  padding-left: 1.4rem;
  margin: 0.6rem 0 1.3rem;
}

article li {
  margin: 0.4rem 0;
}

article li::marker {
  color: var(--accent);
}

article a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px solid var(--accent-soft);
  transition: border-color 0.15s ease, color 0.15s ease;
}

article a:hover {
  border-bottom-color: var(--accent);
  color: var(--accent-strong);
}

/* -------- Callout -------- */
.callout {
  position: relative;
  padding: 1.05rem 1.25rem;
  margin: 1.75rem 0;
  background: var(--accent-soft);
  border: 1px solid #d4dffc;
  border-left: 3px solid var(--accent);
  border-radius: var(--radius);
  color: var(--text);
  font-size: 0.96rem;
}

.callout strong {
  color: var(--accent-strong);
}

/* -------- Tables -------- */
table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.5rem 0 1.75rem;
  background: #ffffff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  font-size: 0.95rem;
  box-shadow: var(--shadow-sm);
}

th,
td {
  text-align: left;
  padding: 0.9rem 1.15rem;
  border-bottom: 1px solid var(--border);
  color: var(--text);
  vertical-align: top;
}

th {
  background: var(--bg-soft);
  font-weight: 600;
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
}

tbody tr:last-child td {
  border-bottom: none;
}

tbody tr:hover {
  background: var(--bg-soft);
}

td p,
td ul {
  color: var(--text-muted);
  margin: 0;
}

/* -------- TOC -------- */
.toc {
  background: var(--bg-soft);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.05rem 1.3rem;
  margin: 1.5rem 0 2.5rem;
  font-size: 0.94rem;
}

.toc strong {
  display: block;
  font-size: 0.7rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-dim);
  margin-bottom: 0.65rem;
  font-weight: 700;
}

.toc ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 0.3rem 1rem;
}

.toc li {
  margin: 0;
}

.toc a {
  color: var(--text-muted);
  border-bottom: none;
}

.toc a:hover {
  color: var(--accent);
}

/* -------- Definition lists -------- */
dl.terms {
  margin: 1rem 0 1.5rem;
}

dl.terms dt {
  font-weight: 700;
  color: var(--accent-strong);
  margin-top: 1.2rem;
  letter-spacing: -0.005em;
}

dl.terms dd {
  margin: 0.3rem 0 0;
  color: var(--text-muted);
}

/* -------- Steps -------- */
.steps {
  counter-reset: step;
  list-style: none;
  padding: 0;
  margin: 1.5rem 0;
}

.steps li {
  counter-increment: step;
  position: relative;
  padding: 0.2rem 0 1.05rem 3rem;
  color: var(--text-muted);
}

.steps li::before {
  content: counter(step);
  position: absolute;
  left: 0;
  top: 0.05rem;
  width: 2rem;
  height: 2rem;
  border-radius: 50%;
  background: var(--accent-soft);
  color: var(--accent);
  display: grid;
  place-items: center;
  font-weight: 700;
  font-size: 0.95rem;
}

/* -------- Tag -------- */
.tag {
  display: inline-block;
  padding: 0.18rem 0.7rem;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--accent);
  background: var(--accent-soft);
  border-radius: 999px;
}

/* -------- Breadcrumb -------- */
.breadcrumb {
  font-size: 0.86rem;
  color: var(--text-dim);
  margin: 0.5rem auto 1rem;
  max-width: 760px;
}

.breadcrumb a {
  color: var(--text-muted);
  text-decoration: none;
  border-bottom: none;
}

.breadcrumb a:hover {
  color: var(--accent);
}

/* -------- Page banner: hidden for minimal feel -------- */
.page-banner {
  display: none;
}

/* -------- Footer -------- */
.site-footer {
  border-top: 1px solid var(--border);
  margin-top: 6rem;
  padding: 3rem 1.5rem 4rem;
  text-align: center;
  color: var(--text-dim);
  font-size: 0.88rem;
  background: var(--bg-soft);
}

.site-footer p {
  margin: 0.25rem 0;
}

.site-footer a {
  color: var(--text-muted);
  text-decoration: none;
}

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

/* -------- Responsive -------- */
@media (max-width: 760px) {
  .site-header__inner {
    flex-wrap: wrap;
    gap: 0.5rem;
  }

  .site-nav ul {
    flex-wrap: wrap;
    gap: 0;
  }

  .site-nav a {
    padding: 0.3rem 0.6rem;
    font-size: 0.85rem;
  }

  .hero {
    padding: 3.5rem 0 2.5rem;
  }

  main {
    padding: 1.25rem 1rem 4rem;
  }

  .hero h1 {
    letter-spacing: -0.03em;
  }
}