/* Variables */
:root {
  --bg: #ffffff;
  --fg: #111111;
  --fg-muted: #555555;
  --border: #111111;
  --link: #003DA5;
  --link-hover: #002880;
  --max-width: 860px;
  --sidebar-width: 130px;

  --red:    #D40000;
  --blue:   #003DA5;
  --yellow: #F5C400;
  --line:   3px;
}

[data-theme="dark"] {
  --bg: #1c1c1e;
  --fg: #e0e0e0;
  --fg-muted: #888888;
  --border: #e0e0e0;
  --link: #6b9ff5;
  --link-hover: #4d8ef0;
}

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

/* Mondrian top strip */
body::before {
  content: '';
  display: block;
  height: 6px;
  background: linear-gradient(
    to right,
    var(--red)    0%   33.3%,
    var(--yellow) 33.3% 66.6%,
    var(--blue)   66.6% 100%
  );
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Georgia, serif;
  background: var(--bg);
  color: var(--fg);
  line-height: 1.7;
  font-size: 1rem;
  transition: background 0.2s, color 0.2s;
  position: relative;
}

/* Blue vertical line — rises from page bottom at screen right side */
body::after {
  content: '';
  position: absolute;
  right: calc(38vw - var(--max-width) / 2 - 2rem);
  bottom: 0;
  width: var(--line);
  height: 8%;
  background: var(--blue);
  pointer-events: none;
}

/* Hide blue line on blog pages */
.blog-page ~ footer ~ body::after,
body:has(.blog-page)::after {
  display: none;
}

a {
  color: var(--link);
  text-decoration: underline;
  text-underline-offset: 3px;
}

a:hover {
  color: var(--link-hover);
}

/* Header */
header {
  padding: 0;
}

.header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 1rem 1.5rem;
  border-bottom: var(--line) solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.header-left {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.header-social-links {
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

.social-link-icon {
  display: inline-flex;
  color: var(--fg-muted);
  transition: color 0.15s;
  text-decoration: none;
}

.social-link-icon:hover {
  color: var(--fg);
}

.social-link-icon svg {
  width: 18px;
  height: 18px;
}

.site-name {
  font-size: 1.1rem;
  font-weight: 600;
  text-decoration: none;
  color: var(--fg);
}

nav {
  display: flex;
  align-items: center;
  gap: 1.5rem;
}

nav a {
  font-size: 0.9rem;
  text-decoration: none;
  color: var(--fg-muted);
}

nav a:hover {
  color: var(--fg);
}

.theme-toggle {
  background: none;
  border: none;
  cursor: pointer;
  font-size: 1rem;
  color: var(--fg-muted);
  padding: 0;
  line-height: 1;
}

/* Layout: sidebar + main */
.layout {
  max-width: var(--max-width);
  margin: 0 auto;
  display: grid;
  grid-template-columns: var(--sidebar-width) 1fr;
  min-height: calc(100vh - 6px - 57px - 53px); /* strip + header + footer */
  position: relative;
}

/* Yellow horizontal line — from screen left edge to sidebar/main divider */
.layout::before {
  content: '';
  position: absolute;
  left: calc(-50vw + var(--max-width) / 2); /* reach back to screen left edge */
  bottom: 18rem; /* middle position between sidebar end and screen bottom */
  width: calc(30vw - var(--max-width) / 2 + var(--sidebar-width) - var(--line));
  height: var(--line);
  background: var(--yellow);
}

/* Sidebar */
.sidebar {
  position: relative;
  padding: 2.5rem 1rem;
}

.sidebar::after {
  content: '';
  position: absolute;
  right: 0;
  top: 0;
  width: var(--line);
  height: 120px;
  background: var(--red);
}

.social-link {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.35rem;
  text-decoration: none;
  color: var(--fg-muted);
  font-size: 0.6rem;
  letter-spacing: 0.05em;
  transition: color 0.15s;
}

.social-link:hover {
  color: var(--fg);
}

.social-link svg {
  width: 16px;
  height: 16px;
}

.social-link.small {
  font-size: 0.6rem;
}

.social-link.small svg {
  width: 16px;
  height: 16px;
}

/* Main content */
main {
  padding: 3rem 2rem;
}

/* Intro */
.intro {
  margin-bottom: 3rem;
  color: var(--fg-muted);
  font-size: 0.95rem;
}

/* Sections */
section {
  margin-bottom: 0;
}

section + section {
  border-top: var(--line) solid var(--border);
  padding-top: 2.5rem;
  margin-top: 2.5rem;
}

/* Section headings */
h2 {
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--fg-muted);
  margin-bottom: 1.5rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

h2::before {
  content: '';
  display: inline-block;
  width: 10px;
  height: 10px;
  flex-shrink: 0;
}

#blogs h2::before    { background: var(--red); }
#resources h2::before { background: var(--yellow); }
#misc h2::before { background: var(--blue); }

/* Posts */
.blog-entry {
  margin-bottom: 2rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid #ccc;
}

[data-theme="dark"] .blog-entry {
  border-bottom-color: #333;
}

.blog-entry:last-child {
  border-bottom: none;
  margin-bottom: 0;
  padding-bottom: 0;
}

.blog-entry h3 {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 0.25rem;
}

.blog-entry h3 a {
  text-decoration: none;
}

.blog-entry h3 a:hover {
  text-decoration: underline;
}

.meta {
  font-size: 0.8rem;
  color: var(--fg-muted);
  margin-bottom: 0.5rem;
}

.blog-entry p {
  font-size: 0.95rem;
  color: var(--fg-muted);
}

/* Resources */
.resource-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.85rem;
}

.resource-list li {
  font-size: 0.95rem;
  color: var(--fg-muted);
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 0.0rem;
}

.resource-title {
  color: var(--fg);
}

.resource-links {
  display: inline-flex;
  gap: 0.4rem;
}

.resource-link {
  text-decoration: none;
  color: var(--link);
  font-size: 0.9rem;
}

.resource-link:hover {
  text-decoration: underline;
  color: var(--link-hover);
}

/* Misc section lists */
#misc ul {
  padding-left: 2rem;
  margin-bottom: 1rem;
}

#misc ul li {
  font-size: 0.95rem;
  line-height: 1.7;
  margin-bottom: 0.5rem;
}

/* Footer */
footer {
  padding: 0;
}

.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 1.5rem 1.5rem;
  border-top: var(--line) solid var(--border);
  text-align: center;
  font-size: 0.8rem;
  color: var(--fg-muted);
}

/* ─── Blog page ─────────────────────────────────────────── */

.blog-page {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 3rem 4rem 4rem 4rem;
}

/* Blog header */
.blog-header {
  margin-bottom: 2.5rem;
}

.blog-tags {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 0.75rem;
}

.tag {
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 0.2rem 0.5rem;
  border: 1.5px solid var(--border);
  color: var(--fg-muted);
}

.blog-header h1 {
  font-size: 2rem;
  font-weight: 700;
  line-height: 1.25;
  margin-bottom: 0.75rem;
  letter-spacing: -0.01em;
}

.blog-meta {
  font-size: 0.85rem;
  color: var(--fg-muted);
}

/* Table of contents */
.toc {
  border: var(--line) solid var(--border);
  border-left: var(--line) solid var(--red);
  border-right: var(--line) solid var(--blue);
  padding: 1.25rem 1.5rem;
  margin-bottom: 2.5rem;
  font-size: 0.9rem;
}

.toc-title {
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--fg-muted);
  margin-bottom: 0.75rem;
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: center;
  gap: 0.4rem;
  user-select: none;
}

.toc-title::-webkit-details-marker { display: none; }

.toc-title::after {
  content: '▸';
  font-size: 0.65rem;
  transition: transform 0.2s;
}

details[open] .toc-title::after {
  transform: rotate(90deg);
}

.toc ol {
  padding-left: 1.25rem;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
}

.toc ol ol {
  margin-top: 0.3rem;
}

.toc a {
  text-decoration: none;
  color: var(--fg-muted);
}

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

/* Blog body */
.blog-body h2 {
  font-size: 1.3rem;
  font-weight: 700;
  letter-spacing: normal;
  text-transform: none;
  color: var(--fg);
  margin-top: 2.5rem;
  margin-bottom: 0.75rem;
  padding-bottom: 0.4rem;
  border-bottom: var(--line) solid var(--border);
  display: block; /* override index page flex */
}

.blog-body h2::before {
  display: none; /* no colored dot on post headings */
}

.blog-body h3 {
  font-size: 1.05rem;
  font-weight: 600;
  margin-top: 1.75rem;
  margin-bottom: 0.5rem;
  color: var(--fg);
}

.blog-body p {
  margin-bottom: 1.1rem;
  font-size: 1rem;
  color: var(--fg);
  line-height: 1.8;
}

.blog-body a {
  color: var(--link);
}

.link-list {
  padding-left: 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  margin-bottom: 1.1rem;
}

.link-list li {
  font-size: 1rem;
  line-height: 1.8;
}

.blog-divider {
  border: none;
  border-top: var(--line) solid var(--border);
  margin: 2.5rem 0;
}

/* References */
.references h2 {
  font-size: 1rem;
  font-weight: 700;
  text-transform: none;
  letter-spacing: normal;
  color: var(--fg-muted);
  margin-bottom: 0.75rem;
  border: none;
  padding: 0;
}

.references ol {
  list-style: none;
  padding-left: 0;
  counter-reset: ref-counter;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.references li {
  counter-increment: ref-counter;
  font-size: 0.88rem;
  color: var(--fg-muted);
  line-height: 1.6;
  padding-left: 2.8rem;
  position: relative;
}

.references li::before {
  content: '[' counter(ref-counter) ']';
  position: absolute;
  left: 0;
  color: var(--fg-muted);
  font-size: 0.88rem;
  white-space: nowrap;
}

/* Inline citations */
a.cite {
  text-decoration: none;
  color: var(--link);
  font-size: 0.88rem;
  vertical-align: baseline;
}

a.cite:hover {
  color: var(--link-hover);
  text-decoration: underline;
}

/* Algorithm block */
.algorithm {
  margin: 1.5rem 0;
  padding: 0;
  background: var(--bg);
}

.algorithm-header {
  padding: 0.5rem 1rem;
  font-size: 1rem;
}

.algorithm-body {
  padding: 0.75rem 1rem;
}

.algorithm-body ol {
  list-style-type: none;
  counter-reset: line-counter;
  padding-left: 0;
  margin: 0;
}

.algorithm-body ol li {
  counter-increment: line-counter;
  position: relative;
  padding-left: 3rem;
  margin-bottom: 0.3rem;
  font-size: 1rem;
  line-height: 1.6;
}

.algorithm-body ol li::before {
  content: counter(line-counter) ":";
  position: absolute;
  left: 0.5rem;
  width: 2rem;
  text-align: right;
  color: var(--fg-muted);
}

.algorithm-keyword {
  color: var(--red);
  font-weight: bold;
}

/* Responsive */
@media (max-width: 600px) {
  .layout {
    grid-template-columns: 1fr;
  }

  .sidebar {
    border-right: none;
    border-bottom: var(--line) solid var(--red);
    flex-direction: row;
    padding: 1rem 1.5rem;
    position: static;
  }
}