/* ============================================================
   From Friction to Flow — custom theme
   High-contrast accessible palette:
     - light: pure black text on pure white
     - dark:  pure white text on pure black
   Brand gradient: cyan -> blue -> purple
   ============================================================ */

:root {
  --f2f-cyan:   #00e5ff;
  --f2f-blue:   #2563ff;
  --f2f-purple: #a855f7;
  --f2f-gradient: linear-gradient(
    90deg,
    var(--f2f-cyan)   0%,
    var(--f2f-blue)   50%,
    var(--f2f-purple) 100%
  );
}

/* ---------- LIGHT scheme: black on white ---------- */
[data-md-color-scheme="f2f-light"] {
  --md-default-bg-color:           #ffffff;
  --md-default-fg-color:           #000000;
  --md-default-fg-color--light:    #000000;
  --md-default-fg-color--lighter:  #000000;
  --md-default-fg-color--lightest: #ffffff;
  --md-typeset-color:              #000000;
  --md-typeset-a-color:            #2563ff;
  --md-primary-fg-color:           #2563ff;
  --md-primary-fg-color--light:    #2563ff;
  --md-primary-fg-color--dark:     #2563ff;
  --md-primary-bg-color:           #ffffff;
  --md-accent-fg-color:            #a855f7;
  --md-code-bg-color:              #ffffff;
  --md-code-fg-color:              #000000;
  --f2f-rule: #000000;
}

/* ---------- DARK scheme: white on black ---------- */
[data-md-color-scheme="f2f-dark"] {
  --md-default-bg-color:           #000000;
  --md-default-fg-color:           #ffffff;
  --md-default-fg-color--light:    #ffffff;
  --md-default-fg-color--lighter:  #ffffff;
  --md-default-fg-color--lightest: #000000;
  --md-typeset-color:              #ffffff;
  --md-typeset-a-color:            #00e5ff;
  --md-primary-fg-color:           #000000;
  --md-primary-bg-color:           #ffffff;
  --md-accent-fg-color:            #00e5ff;
  --md-code-bg-color:              #000000;
  --md-code-fg-color:              #ffffff;
  --f2f-rule: #ffffff;
}

/* Body text — force pure foreground colour, no greys */
.md-typeset,
.md-typeset p,
.md-typeset li,
.md-typeset blockquote,
.md-typeset h1,
.md-typeset h2,
.md-typeset h3,
.md-typeset h4,
.md-typeset h5,
.md-typeset h6,
.md-typeset strong,
.md-typeset em {
  color: var(--md-default-fg-color);
}

/* Gradient header bar */
.md-header {
  background: var(--f2f-gradient) !important;
  color: #ffffff;
}
.md-header__title,
.md-header__topic,
.md-header__button,
.md-header a {
  color: #ffffff !important;
}

/* Gradient tabs row */
.md-tabs {
  background: var(--f2f-gradient) !important;
}
.md-tabs__link {
  color: #ffffff !important;
  opacity: 1;
}
.md-tabs__link--active {
  text-decoration: underline;
  text-underline-offset: 6px;
  text-decoration-thickness: 3px;
}

/* Search input contrast */
.md-search__input {
  background: rgba(255, 255, 255, 0.15);
  color: #ffffff;
}
.md-search__input::placeholder { color: #ffffff; opacity: 0.85; }

/* Links: visible, underlined for accessibility */
.md-typeset a {
  color: var(--md-typeset-a-color);
  text-decoration: underline;
  text-underline-offset: 3px;
}
.md-typeset a:hover,
.md-typeset a:focus {
  color: var(--md-accent-fg-color);
  text-decoration-thickness: 2px;
}

/* Focus ring (a11y) */
a:focus-visible,
button:focus-visible,
.md-tabs__link:focus-visible,
.md-nav__link:focus-visible,
.md-search__input:focus-visible {
  outline: 3px solid var(--f2f-purple);
  outline-offset: 2px;
}

/* Blockquotes: gradient left bar */
.md-typeset blockquote {
  border-left: 6px solid transparent;
  border-image: var(--f2f-gradient) 1;
  padding-left: 1rem;
  color: var(--md-default-fg-color);
}

/* Horizontal rules */
.md-typeset hr {
  border: 0;
  height: 3px;
  background: var(--f2f-gradient);
  margin: 2.5rem 0;
}

/* H1 — gradient underline */
.md-typeset h1 {
  position: relative;
  padding-bottom: 0.5rem;
  margin-bottom: 1.25rem;
}
.md-typeset h1::after {
  content: "";
  display: block;
  width: 100%;
  height: 4px;
  margin-top: 0.5rem;
  background: var(--f2f-gradient);
  border-radius: 2px;
}

/* Hero image at the top of each chapter */
.md-typeset img.hero {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  border-radius: 12px;
  margin: 0 0 2rem 0;
  box-shadow: 0 0 0 3px transparent;
  border-image: var(--f2f-gradient) 1;
  border: 3px solid transparent;
  background-image: var(--f2f-gradient);
  background-origin: border-box;
  background-clip: border-box;
}

/* Code blocks: pure contrast, no muddy backgrounds */
.md-typeset code,
.md-typeset pre code {
  background: var(--md-code-bg-color);
  color: var(--md-code-fg-color);
  border: 1px solid var(--f2f-rule);
  border-radius: 6px;
}
.md-typeset pre > code {
  padding: 0.85rem 1rem;
  display: block;
}

/* Tables */
.md-typeset table:not([class]) {
  border: 2px solid var(--f2f-rule);
}
.md-typeset table:not([class]) th {
  background: var(--f2f-gradient);
  color: #ffffff;
}
.md-typeset table:not([class]) td,
.md-typeset table:not([class]) th {
  border: 1px solid var(--f2f-rule);
  color: var(--md-default-fg-color);
}

/* Sidebar nav text — full contrast */
.md-nav__link,
.md-nav__title {
  color: var(--md-default-fg-color) !important;
  opacity: 1;
}
.md-nav__link--active,
.md-nav__link[aria-current="page"] {
  font-weight: 700;
  background: var(--f2f-gradient);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent !important;
}

/* Footer */
.md-footer,
.md-footer-meta {
  background: #000000;
  color: #ffffff;
}
[data-md-color-scheme="f2f-light"] .md-footer,
[data-md-color-scheme="f2f-light"] .md-footer-meta {
  background: #000000;
  color: #ffffff;
}

/* ===========================================================
   Landing page
   =========================================================== */

/* Hero block */
.f2f-hero {
  padding: 3rem 2rem;
  border-radius: 20px;
  background: var(--f2f-gradient);
  color: #ffffff;
  margin: 0 0 2.5rem 0;
  text-align: center;
}
.f2f-hero h1,
.f2f-hero p,
.f2f-hero a,
.f2f-hero strong {
  color: #ffffff !important;
}
.f2f-hero h1 {
  font-size: 2.6rem;
  line-height: 1.1;
  margin: 0 0 0.75rem 0;
}
.f2f-hero h1::after { display: none; }
.f2f-hero p { font-size: 1.05rem; max-width: 60ch; margin: 0.5rem auto; }

.f2f-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  justify-content: center;
  margin-top: 1.5rem !important;
}
.f2f-btn {
  display: inline-block;
  padding: 0.75rem 1.5rem;
  border-radius: 999px;
  font-weight: 700;
  text-decoration: none !important;
  border: 2px solid #ffffff;
  transition: transform 0.15s ease;
}
.f2f-btn:hover { transform: translateY(-2px); }
.f2f-btn--solid,
.f2f-hero a.f2f-btn--solid {
  background: #ffffff;
  color: #000000 !important;
}
.f2f-btn--ghost,
.f2f-hero a.f2f-btn--ghost {
  background: transparent;
  color: #ffffff !important;
}

/* Intro paragraph */
.f2f-intro {
  max-width: 75ch;
  margin: 0 auto 2.5rem auto;
  font-size: 1.05rem;
}
.f2f-intro p { color: var(--md-default-fg-color); }

/* Closing meta block */
.f2f-meta {
  margin-top: 3rem;
  padding-top: 2rem;
  border-top: 3px solid;
  border-image: var(--f2f-gradient) 1;
}

/* ===========================================================
   Chapter gallery — image hero cards
   =========================================================== */

.f2f-gallery {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.25rem;
  margin: 1.5rem 0 2rem 0;
}

.f2f-tile {
  position: relative;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  border-radius: 16px;
  text-decoration: none !important;
  color: var(--md-default-fg-color) !important;
  background: var(--md-default-bg-color);
  border: 3px solid transparent;
  background-image:
    linear-gradient(var(--md-default-bg-color), var(--md-default-bg-color)),
    var(--f2f-gradient);
  background-origin: border-box;
  background-clip: padding-box, border-box;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  isolation: isolate;
}
.f2f-tile:hover,
.f2f-tile:focus-visible {
  transform: translateY(-4px);
  box-shadow: 0 12px 32px -8px rgba(168, 85, 247, 0.45);
}

.f2f-tile img {
  display: block;
  width: 100%;
  height: 180px;
  object-fit: cover;
  object-position: center;
  background: #000000;
}

.f2f-tile__body {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  padding: 1rem 1.1rem 1.15rem 1.1rem;
  background: var(--md-default-bg-color);
  flex: 1;
}
.f2f-tile__body--center {
  text-align: center;
  justify-content: center;
  align-items: center;
  min-height: 180px;
  background: var(--f2f-gradient);
}
.f2f-tile__body--center .f2f-tile__num,
.f2f-tile__body--center .f2f-tile__title,
.f2f-tile__body--center .f2f-tile__desc {
  color: #ffffff !important;
}

.f2f-tile__num {
  font-family: "JetBrains Mono", ui-monospace, monospace;
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  background: var(--f2f-gradient);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.f2f-tile__title {
  font-size: 1.15rem;
  font-weight: 700;
  line-height: 1.25;
  color: var(--md-default-fg-color);
}
.f2f-tile__desc {
  font-size: 0.92rem;
  color: var(--md-default-fg-color);
  opacity: 1;
}

/* Demo tile — no image, gradient fill */
.f2f-tile--demo img { display: none; }
.f2f-tile--demo .f2f-tile__title { font-size: 1.3rem; }
.f2f-tile--demo .f2f-tile__num { font-size: 2rem; -webkit-text-fill-color: #ffffff; color: #ffffff; background: none; }

/* Demo video container — responsive 16:9 */
.f2f-video {
  position: relative;
  width: 100%;
  padding-top: 56.25%;
  border-radius: 12px;
  overflow: hidden;
  border: 3px solid transparent;
  background-image:
    linear-gradient(var(--md-default-bg-color), var(--md-default-bg-color)),
    var(--f2f-gradient);
  background-origin: border-box;
  background-clip: padding-box, border-box;
  margin: 1.5rem 0 2rem 0;
}
.f2f-video video {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  background: #000000;
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; animation: none !important; }
}

/* Wider responsive type at small viewports */
@media (max-width: 600px) {
  .md-typeset h1 { font-size: 1.8rem; }
  .md-typeset h2 { font-size: 1.4rem; }
  .f2f-hero { padding: 1.25rem 1rem; }
}