:root {
  /* Typography */
  --font-sans: "Inter", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
    Roboto, sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, Consolas,
    monospace;

  /* Colors */
  --color-bg: #ffffff;
  --color-bg-alt: #f8f8f8;
  --color-text: #111827;
  --color-text-muted: #6b7280;
  --color-primary: #b02b2c;
  --color-primary-dark: #8f2324;
  --color-primary-soft: #fbecec;
  --color-border: #e5e7eb;
  --color-border-strong: #d1d5db;

  /* Sizing */
  --radius: 0.75rem;
  --radius-sm: 0.5rem;
  --header-height: 4rem;
}

/* ---------- Base ---------- */
body {
  font-family: var(--font-sans);
  background: var(--color-bg);
  color: var(--color-text);
  -webkit-font-smoothing: antialiased;
}

h1,
h2,
h3,
h4,
h5,
h6 {
  font-family: var(--font-sans);
  font-weight: 700;
  color: var(--color-text);
  letter-spacing: -0.02em;
}

a {
  color: var(--color-primary);
  text-decoration: none;
}

a:hover {
  color: var(--color-primary-dark);
}

a:focus-visible,
button:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

/* ---------- Header / Navigation ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1030;
  background: rgba(255, 255, 255, 0.92);
  -webkit-backdrop-filter: blur(8px);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--color-border);
}

.site-header .navbar {
  padding-top: 0.875rem;
  padding-bottom: 0.875rem;
}

.navbar-brand {
  font-weight: 800;
  font-size: 1.25rem;
  color: var(--color-text);
  letter-spacing: -0.02em;
}

.navbar-brand:hover {
  color: var(--color-text);
}

.navbar-brand .brand-accent {
  color: var(--color-primary);
}

.brand-accent-mono {
  font-family: var(--font-mono);
  font-weight: 600;
}

.brand-mark {
  flex-shrink: 0;
  border-radius: 6px;
}

.site-header .nav-link {
  color: var(--color-text-muted);
  font-weight: 500;
  transition: color 0.15s ease;
}

.site-header .nav-link:hover,
.site-header .nav-link.active {
  color: var(--color-text);
}

.theme-toggle {
  border: 1px solid var(--color-border);
  background: var(--color-bg);
  border-radius: 999px;
  width: 2.25rem;
  height: 2.25rem;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  color: var(--color-text);
  cursor: pointer;
  transition: border-color 0.15s ease;
}

.theme-toggle:hover {
  border-color: var(--color-border-strong);
}

/* ---------- Hero ---------- */
.hero {
  position: relative;
  text-align: center;
  max-width: 46rem;
  margin: 0 auto;
  padding: 4rem 0 2.5rem;
}

.hero::before {
  content: "";
  position: absolute;
  inset: -2rem -4rem auto -4rem;
  height: 26rem;
  background-image: radial-gradient(var(--color-border-strong) 1px, transparent 1px);
  background-size: 22px 22px;
  -webkit-mask-image: radial-gradient(ellipse 60% 60% at 50% 15%, black 40%, transparent 80%);
  mask-image: radial-gradient(ellipse 60% 60% at 50% 15%, black 40%, transparent 80%);
  opacity: 0.6;
  z-index: -2;
  pointer-events: none;
}

.hero::after {
  content: "";
  position: absolute;
  top: -3rem;
  left: 50%;
  transform: translateX(-50%);
  width: 42rem;
  height: 22rem;
  background: radial-gradient(circle, var(--color-primary-soft) 0%, transparent 70%);
  z-index: -1;
  pointer-events: none;
}

.hero .eyebrow {
  display: inline-block;
  background: var(--color-primary-soft);
  color: var(--color-primary-dark);
  font-family: var(--font-mono);
  font-weight: 600;
  font-size: 0.8125rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  border-radius: 999px;
  padding: 0.35rem 0.9rem;
  margin-bottom: 1.25rem;
}

.hero h1 {
  font-size: clamp(2.25rem, 5vw, 3.5rem);
  font-weight: 800;
  line-height: 1.08;
  letter-spacing: -0.03em;
}

.hero .lead {
  font-size: 1.2rem;
  color: var(--color-text-muted);
  margin-top: 1.25rem;
  line-height: 1.65;
}

.hero .cta-row {
  display: flex;
  gap: 0.75rem;
  justify-content: center;
  flex-wrap: wrap;
  margin-top: 2rem;
}

/* ---------- Hero code window visual ---------- */
.code-window {
  position: relative;
  margin: 2.5rem auto 0;
  max-width: 34rem;
  text-align: left;
  background: #0d1117;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  box-shadow: 0 20px 50px rgba(16, 24, 40, 0.18);
  overflow: hidden;
}

.code-window__titlebar {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.7rem 1rem;
  background: #161b22;
  border-bottom: 1px solid rgba(255, 255, 255, 0.06);
}

.code-window__dot {
  width: 0.65rem;
  height: 0.65rem;
  border-radius: 50%;
  display: inline-block;
}

.code-window__dot--red { background: #ff5f56; }
.code-window__dot--yellow { background: #ffbd2e; }
.code-window__dot--green { background: #27c93f; }

.code-window__body {
  margin: 0;
  padding: 1.25rem 1.5rem;
  font-family: var(--font-mono);
  font-size: 0.875rem;
  line-height: 1.7;
  color: #c9d1d9;
  overflow-x: auto;
}

.code-window__body .tok-kw { color: #ff7b72; }
.code-window__body .tok-fn { color: #d2a8ff; }
.code-window__body .tok-str { color: #a5d6ff; }
.code-window__body .tok-num { color: #79c0ff; }
.code-window__body .tok-comment { color: #8b949e; font-style: italic; }
.code-window__body .tok-out { color: #56d364; }

/* ---------- Sections ---------- */
.section {
  padding: 3.5rem 0;
}

.section h2 {
  font-size: clamp(1.6rem, 3vw, 2.1rem);
  margin-bottom: 0.75rem;
}

.section .section-sub {
  color: var(--color-text-muted);
  font-size: 1.1rem;
  line-height: 1.7;
}

.section .highlight-card {
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.75rem;
  height: 100%;
}

.section .highlight-card h3 {
  font-size: 1.15rem;
}

.section .highlight-card p {
  color: var(--color-text-muted);
  margin-bottom: 0;
}

/* ---------- Cards / Content sections ---------- */
.content-section {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  box-shadow: 0 1px 2px rgba(16, 24, 40, 0.04);
  transition: box-shadow 0.15s ease, border-color 0.15s ease,
    transform 0.15s ease;
}

.content-section:hover {
  border-color: var(--color-border-strong);
  box-shadow: 0 10px 28px rgba(16, 24, 40, 0.08);
  transform: translateY(-2px);
}

.post-card {
  padding: 1.5rem 1.75rem;
}

.post-card .post-meta {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--color-text-muted);
}

.post-card .post-title {
  font-size: 1.375rem;
  font-weight: 700;
  line-height: 1.3;
  margin-bottom: 0.5rem;
}

.post-card .post-title a {
  color: var(--color-text);
}

.post-card .post-title a:hover {
  color: var(--color-primary);
}

.post-card .post-excerpt {
  color: var(--color-text-muted);
  margin-bottom: 0.75rem;
}

.read-more {
  font-weight: 600;
  font-size: 0.9375rem;
}

/* Tag chips */
.tag-chip {
  display: inline-block;
  background: var(--color-primary-soft);
  color: var(--color-primary-dark);
  border-radius: 999px;
  padding: 0.2rem 0.7rem;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  font-weight: 600;
}

.tag-chip-locked {
  background: var(--color-primary);
  color: #ffffff;
}

.premium-teaser {
  background: var(--color-bg-alt);
  border: 1px dashed var(--color-border-strong);
  border-radius: var(--radius);
  padding: 1.5rem;
  text-align: center;
}

.status-card {
  max-width: 36rem;
  margin: 2rem auto;
  text-align: center;
}

/* ---------- Article detail ---------- */
.article-title {
  color: var(--color-text);
  transition: color 0.2s ease-in-out;
}

a.article-title:hover,
a.article-title:focus {
  color: var(--color-primary);
  text-decoration: none;
}

.article-content {
  white-space: pre-line;
  font-size: 1.125rem;
  line-height: 1.75;
}

.article-body {
  font-size: 1.0625rem;
  line-height: 1.75;
}

.article-body h1,
.article-body h2,
.article-body h3,
.article-body h4 {
  margin: 1.5rem 0 0.75rem;
}

.article-body p {
  margin-bottom: 1rem;
}

.article-body pre {
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  padding: 1rem;
  overflow-x: auto;
}

.article-body code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.9em;
}

.article-body img {
  max-width: 100%;
  border-radius: var(--radius-sm);
}

.article-body table {
  border-collapse: collapse;
  margin: 1rem 0;
  width: 100%;
}

.article-body th,
.article-body td {
  border: 1px solid var(--color-border);
  padding: 0.5rem 0.75rem;
}

/* Pygments (nbconvert) code highlighting */
.highlight pre {
  margin: 0;
}

.highlight .c,
.highlight .c1,
.highlight .cm,
.highlight .cs,
.highlight .ch {
  color: #6a737d;
  font-style: italic;
}

.highlight .k,
.highlight .kc,
.highlight .kd,
.highlight .kn,
.highlight .kp,
.highlight .kr,
.highlight .kt,
.highlight .ow {
  color: #d73a49;
  font-weight: 600;
}

.highlight .s,
.highlight .s1,
.highlight .s2,
.highlight .sa,
.highlight .sb,
.highlight .sc,
.highlight .dl,
.highlight .sd,
.highlight .se,
.highlight .sh,
.highlight .si,
.highlight .sx,
.highlight .sr {
  color: #032f62;
}

.highlight .nb,
.highlight .m,
.highlight .mi,
.highlight .mf,
.highlight .mh,
.highlight .mo,
.highlight .il {
  color: #005cc5;
}

.highlight .nf,
.highlight .fm,
.highlight .nd {
  color: #6f42c1;
}

.highlight .n,
.highlight .nn,
.highlight .nc,
.highlight .no,
.highlight .o,
.highlight .p {
  color: #24292e;
}

.article-img {
  height: 4rem;
  width: 4rem;
  flex-shrink: 0;
  object-fit: cover;
  border-radius: 50%;
  border: 1px solid var(--color-border);
}

.article-metadata {
  padding-bottom: 0.25rem;
  border-bottom: 1px solid var(--color-border);
}

.article-metadata a {
  transition: color 0.2s ease-in-out;
}

.article-metadata a:hover,
.article-metadata a:focus {
  color: var(--color-text);
  text-decoration: none;
}

.article-svg {
  width: 1.25rem;
  height: 1.25rem;
  vertical-align: middle;
}

/* ---------- Account ---------- */
.account-img {
  height: 7.5rem;
  width: 7.5rem;
  object-fit: cover;
  border-radius: 50%;
}

.account-heading {
  font-size: 2.5rem;
}

.file-input-sm {
  max-width: 300px;
}

/* ---------- Buttons ---------- */
.btn {
  border-radius: var(--radius-sm);
  font-weight: 600;
}

.btn-lg {
  padding: 0.75rem 1.5rem;
  font-size: 1rem;
}

.btn-primary {
  --bs-btn-color: #fff;
  --bs-btn-bg: var(--color-primary);
  --bs-btn-border-color: var(--color-primary);
  --bs-btn-hover-color: #fff;
  --bs-btn-hover-bg: var(--color-primary-dark);
  --bs-btn-hover-border-color: var(--color-primary-dark);
  --bs-btn-active-color: #fff;
  --bs-btn-active-bg: var(--color-primary-dark);
  --bs-btn-active-border-color: var(--color-primary-dark);
}

.btn-outline-primary {
  --bs-btn-color: var(--color-primary);
  --bs-btn-border-color: var(--color-primary);
  --bs-btn-hover-color: #fff;
  --bs-btn-hover-bg: var(--color-primary);
  --bs-btn-hover-border-color: var(--color-primary);
  --bs-btn-active-color: #fff;
  --bs-btn-active-bg: var(--color-primary-dark);
  --bs-btn-active-border-color: var(--color-primary-dark);
}

/* ---------- Forms ---------- */
.form-control {
  border-radius: var(--radius-sm);
}

.form-control:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 0.2rem rgba(176, 43, 44, 0.15);
}

.newsletter-form {
  display: flex;
  gap: 0.5rem;
  max-width: 26rem;
  margin: 1.5rem auto 0;
}

/* ---------- Footer ---------- */
.site-footer {
  margin-top: auto;
  background: var(--color-bg-alt);
  border-top: 1px solid var(--color-border);
  padding: 3rem 0 2rem;
  color: var(--color-text-muted);
}

.site-footer h5 {
  color: var(--color-text);
  font-size: 0.8125rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.75rem;
}

.site-footer ul {
  font-size: 0.9375rem;
}

.site-footer ul li {
  margin-bottom: 0.4rem;
}

.site-footer a {
  color: var(--color-text-muted);
}

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

.footer-bottom {
  border-top: 1px solid var(--color-border);
  margin-top: 2rem;
  padding-top: 1.5rem;
  font-size: 0.875rem;
}

/* ---------- Responsive ---------- */
@media (max-width: 768px) {
  .hero {
    padding: 2.5rem 0 1.5rem;
  }

  .account-heading {
    font-size: 2rem;
  }

  .article-img {
    height: 3rem;
    width: 3rem;
  }
}

/* ---------- Dark mode ---------- */
[data-bs-theme="dark"] {
  --color-bg: #111827;
  --color-bg-alt: #1f2937;
  --color-text: #f3f4f6;
  --color-text-muted: #9ca3af;
  --color-border: #374151;
  --color-border-strong: #4b5563;
  --color-primary-soft: #3b1d1e;
}

[data-bs-theme="dark"] .site-header {
  background: rgba(17, 24, 39, 0.92);
}

[data-bs-theme="dark"] .theme-toggle {
  background: var(--color-bg);
}

[data-bs-theme="dark"] .btn-outline-primary {
  --bs-btn-color: #e08a8b;
  --bs-btn-border-color: #e08a8b;
  --bs-btn-hover-color: #000;
  --bs-btn-hover-bg: #e08a8b;
  --bs-btn-hover-border-color: #e08a8b;
  --bs-btn-active-color: #000;
  --bs-btn-active-bg: #e79d9e;
  --bs-btn-active-border-color: #e79d9e;
}

/* ---------- Modal header color helpers ---------- */
.modal-header.bg-success,
.modal-header.bg-danger {
  color: #ffffff;
}

.modal-header.bg-success .modal-title,
.modal-header.bg-danger .modal-title {
  color: #ffffff;
}