/* ==========================================================================
   见白 · base
   Load after tokens.css. Reset + native de-skinning + editorial typography.
   ========================================================================== */

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

[hidden] {
  display: none !important;
}

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
}

body,
h1,
h2,
h3,
h4,
p,
figure,
blockquote,
dl,
dd,
ul,
ol {
  margin: 0;
}

ul,
ol {
  padding: 0;
  list-style: none;
}

img,
picture,
svg,
video {
  display: block;
  max-inline-size: 100%;
}

body {
  min-block-size: 100dvh;
  background: var(--bw-bg);
  color: var(--bw-text);
  font-family: var(--font-read);
  font-size: 16px;
  line-height: 1.8;
  font-kerning: normal;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}

/* ---- native controls: nothing keeps its OS skin ------------------------- */
select,
input,
textarea,
button {
  font: inherit;
  color: inherit;
  -webkit-appearance: none;
  appearance: none;
  -webkit-tap-highlight-color: transparent;
  border-radius: 0;
}

button {
  background: none;
  border: 0;
  padding: 0;
  cursor: pointer;
}

input[type="search"]::-webkit-search-decoration,
input[type="search"]::-webkit-search-cancel-button,
input[type="number"]::-webkit-outer-spin-button,
input[type="number"]::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

::-webkit-calendar-picker-indicator {
  opacity: 0;
  position: absolute;
  inset: 0;
  cursor: pointer;
}

input[type="file"] {
  cursor: pointer;
}
input[type="file"]::file-selector-button {
  font: inherit;
  margin-inline-end: 12px;
  padding: 7px 14px;
  border: 1px solid var(--bw-border-strong);
  background: transparent;
  color: var(--bw-text);
  cursor: pointer;
}

input:-webkit-autofill,
input:-webkit-autofill:hover,
input:-webkit-autofill:focus {
  -webkit-text-fill-color: var(--bw-text);
  -webkit-box-shadow: 0 0 0 1000px var(--bw-surface) inset;
}

* {
  scrollbar-width: thin;
  scrollbar-color: var(--bw-border-strong) transparent;
}
::-webkit-scrollbar {
  inline-size: 10px;
  block-size: 10px;
}
::-webkit-scrollbar-track {
  background: transparent;
}
::-webkit-scrollbar-thumb {
  background-color: var(--bw-border-strong);
  border: 3px solid transparent;
  background-clip: content-box;
  border-radius: var(--bw-radius-pill);
}
::-webkit-scrollbar-thumb:hover {
  background-color: var(--bw-text-muted);
}

::selection {
  background: color-mix(in srgb, var(--bw-accent) 22%, transparent);
  color: var(--bw-text);
}

:focus-visible {
  outline: 2px solid var(--bw-focus-ring);
  outline-offset: 3px;
}

/* ---- type --------------------------------------------------------------- */
h1,
h2,
h3,
h4 {
  font-family: var(--font-head);
  font-weight: 600;
  line-height: 1.28;
  letter-spacing: -0.012em;
  text-wrap: balance;
}

p {
  text-wrap: pretty;
}

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

.display {
  font-family: var(--font-head);
  font-size: clamp(2rem, 5.2vw, 3.25rem);
  line-height: 1.22;
  font-weight: 600;
  letter-spacing: -0.018em;
}

/* Small meta label. Chinese gets tracking instead of uppercase. */
.kicker {
  font-family: var(--font-head);
  font-size: 11px;
  line-height: 1.4;
  letter-spacing: 0.16em;
  color: var(--bw-text-muted);
  font-weight: 400;
  text-transform: uppercase;
}

.kicker--cn {
  font-size: 12px;
  letter-spacing: 0.14em;
  text-transform: none;
}

.meta {
  font-family: var(--font-head);
  font-size: 12.5px;
  line-height: 1.6;
  color: var(--bw-text-muted);
  letter-spacing: 0.02em;
  font-variant-numeric: tabular-nums;
}

/* Dates and figures: one geometric numeral face across the site. */
.num {
  font-family: var(--font-num);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.015em;
  font-feature-settings: "tnum" 1;
}

.shell {
  inline-size: 100%;
  max-inline-size: var(--shell);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

@media (max-width: 640px) {
  :root {
    --gutter: 20px;
  }
}

.rule {
  block-size: 1px;
  background: var(--bw-border);
  border: 0;
}

/* ---- icons -------------------------------------------------------------- */
[class^="ri-"],
[class*=" ri-"] {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  line-height: 1;
  font-size: inherit;
  vertical-align: -0.125em;
  flex: none;
}

/* ---- buttons ------------------------------------------------------------ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-block-size: 44px;
  padding: 10px 20px;
  border: 1px solid var(--bw-accent);
  background: var(--bw-accent);
  color: var(--bw-on-accent);
  font-family: var(--font-ui);
  font-size: 14px;
  letter-spacing: 0.04em;
  line-height: 1.2;
  border-radius: var(--bw-radius-sm);
  cursor: pointer;
  white-space: nowrap;
  transition:
    background-color var(--bw-dur-fast) var(--bw-ease-out),
    border-color var(--bw-dur-fast) var(--bw-ease-out),
    color var(--bw-dur-fast) var(--bw-ease-out),
    transform var(--bw-dur-instant) var(--bw-ease-out);
}
.btn:hover {
  background: var(--bw-accent-hover);
  border-color: var(--bw-accent-hover);
}
.btn:active {
  transform: scale(0.985);
}
.btn:disabled,
.btn[aria-disabled="true"] {
  opacity: 0.42;
  pointer-events: none;
}

.btn--ghost {
  background: transparent;
  border-color: var(--bw-border-strong);
  color: var(--bw-text);
}
.btn--ghost:hover {
  background: color-mix(in srgb, var(--bw-text) 5%, transparent);
  border-color: var(--bw-text-muted);
}

.btn--quiet {
  background: transparent;
  border-color: transparent;
  color: var(--bw-text-secondary);
  padding-inline: 8px;
}
.btn--quiet:hover {
  background: transparent;
  color: var(--bw-text);
  text-decoration: underline;
  text-underline-offset: 4px;
}

/* text link with a moving arrow */
.arrow-link {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  min-block-size: 44px;
  font-family: var(--font-ui);
  font-size: 13.5px;
  letter-spacing: 0.05em;
  color: var(--bw-text);
  border-block-end: 1px solid var(--bw-border-strong);
  transition: border-color var(--bw-dur-fast) var(--bw-ease-out);
}
.arrow-link i {
  font-size: 16px;
  color: var(--bw-text-muted);
  transition:
    transform var(--bw-dur-base) var(--bw-ease-out),
    color var(--bw-dur-fast) var(--bw-ease-out);
}
.arrow-link:hover {
  border-color: var(--bw-text);
}
.arrow-link:hover i {
  transform: translateX(4px);
  color: var(--bw-text);
}

.icon-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  inline-size: 44px;
  block-size: 44px;
  border: 1px solid transparent;
  border-radius: var(--bw-radius-sm);
  background: transparent;
  color: var(--bw-text-secondary);
  font-size: 19px;
  transition:
    background-color var(--bw-dur-fast) var(--bw-ease-out),
    border-color var(--bw-dur-fast) var(--bw-ease-out),
    color var(--bw-dur-fast) var(--bw-ease-out),
    transform var(--bw-dur-instant) var(--bw-ease-out);
}
.icon-btn:hover {
  background: color-mix(in srgb, var(--bw-text) 6%, transparent);
  color: var(--bw-text);
}
.icon-btn:active {
  transform: scale(0.94);
}

/* Keep the theme control the same size as the outlined "写文章" button */
.site-head .icon-btn {
  inline-size: 36px;
  block-size: 36px;
  font-size: 18px;
  border-radius: var(--bw-radius-sm);
}
@media (max-width: 640px) {
  .site-head .icon-btn {
    inline-size: 44px;
    block-size: 44px;
  }
}

/* theme toggle: two icons crossfade, never a hard swap */
.theme-toggle[aria-pressed="true"] {
  background: transparent;
  border-color: transparent;
  color: var(--bw-text-secondary);
}
.site-head .theme-toggle:hover {
  background: color-mix(in srgb, var(--bw-text) 5%, transparent);
  border-color: transparent;
}
.theme-toggle:hover[aria-pressed="true"] {
  background: color-mix(in srgb, var(--bw-text) 6%, transparent);
  color: var(--bw-text);
}
.theme-toggle {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}
.theme-toggle i {
  position: absolute;
  inset: 0;
  margin: auto;
  inline-size: 1em;
  block-size: 1em;
  transition:
    opacity var(--bw-dur-base) var(--bw-ease-out),
    transform var(--bw-dur-base) var(--bw-ease-out),
    filter var(--bw-dur-base) var(--bw-ease-out);
}
.theme-toggle__sun {
  opacity: 0;
  transform: rotate(-35deg) scale(0.9);
  filter: blur(3px);
}
.theme-toggle__moon {
  opacity: 1;
  transform: rotate(0) scale(1);
}
.dark .theme-toggle__sun {
  opacity: 1;
  transform: rotate(0) scale(1);
  filter: blur(0);
}
.dark .theme-toggle__moon {
  opacity: 0;
  transform: rotate(35deg) scale(0.9);
  filter: blur(3px);
}

/* ---- glass -------------------------------------------------------------- */
.glass {
  background-color: var(--bw-glass-bg);
  -webkit-backdrop-filter: blur(var(--bw-glass-blur)) saturate(var(--bw-glass-saturate));
  backdrop-filter: blur(var(--bw-glass-blur)) saturate(var(--bw-glass-saturate));
  border: 1px solid var(--bw-glass-border);
  box-shadow:
    var(--bw-glass-shadow),
    inset 0 1px 0 var(--bw-glass-highlight);
  isolation: isolate;
  overflow: clip;
}

@supports not ((backdrop-filter: blur(1px)) or (-webkit-backdrop-filter: blur(1px))) {
  .glass {
    background-color: color-mix(in srgb, var(--bw-surface) 96%, var(--bw-bg));
  }
}

/* ---- site header -------------------------------------------------------- */
.skip-link {
  position: absolute;
  inset-block-start: -100px;
  inset-inline-start: 16px;
  z-index: 90;
  padding: 10px 16px;
  background: var(--bw-surface-raised);
  border: 1px solid var(--bw-border-strong);
  font-size: 13px;
}
.skip-link:focus {
  inset-block-start: 12px;
}

.site-head {
  position: fixed;
  inset-block-start: 0;
  inset-inline: 0;
  z-index: 40;
  block-size: 68px;
  display: flex;
  align-items: center;
  background-color: transparent;
  border-block-end: 1px solid transparent;
  transition:
    background-color var(--bw-dur-slow) var(--bw-ease-out),
    border-color var(--bw-dur-slow) var(--bw-ease-out),
    backdrop-filter var(--bw-dur-slow) var(--bw-ease-out);
}
.site-head[data-scrolled="true"] {
  /* Slightly denser than the generic glass recipe: on paper-coloured pages a
     0.7 tint lets headings ghost through the bar while you read underneath. */
  background-color: color-mix(in srgb, var(--bw-bg) 94%, transparent);
  -webkit-backdrop-filter: blur(22px) saturate(150%);
  backdrop-filter: blur(22px) saturate(150%);
  border-block-end-color: var(--bw-border);
}

.site-head__inner {
  display: flex;
  align-items: center;
  gap: 24px;
  inline-size: 100%;
}

.brand {
  display: inline-flex;
  align-items: baseline;
  gap: 9px;
  min-block-size: 44px;
  margin-inline-end: auto;
  align-content: center;
  flex-wrap: wrap;
}
.brand__cn {
  font-family: var(--font-read);
  font-size: 20px;
  letter-spacing: 0.05em;
  font-weight: 700;
  line-height: 1;
}
.brand__en {
  font-family: var(--font-type);
  font-size: 13px;
  font-weight: 600; /* Cutive Mono ships 400 only — the browser adds a light synthetic weight */
  letter-spacing: 0.06em;
  color: var(--bw-text-secondary);
  line-height: 1;
  padding-block-end: 2px;
}

.nav {
  display: flex;
  align-items: center;
  gap: 4px;
}
.nav__link {
  display: inline-flex;
  align-items: center;
  min-block-size: 44px;
  padding-inline: 12px;
  font-family: var(--font-ui);
  font-size: 13px;
  letter-spacing: 0.09em;
  color: var(--bw-text-secondary);
  transition: color var(--bw-dur-fast) var(--bw-ease-out);
}
.nav__link:hover {
  color: var(--bw-text);
}
.nav__link:not(.nav__write)[aria-current="page"] {
  color: var(--bw-text);
}
.nav__link:not(.nav__write)[aria-current="page"]::after {
  content: "";
  inline-size: 4px;
  block-size: 4px;
  margin-inline-start: 7px;
  border-radius: 50%;
  background: var(--bw-accent);
}
.nav__write {
  margin-inline-start: 8px;
  padding-inline: 16px;
  min-block-size: 36px;
  border: 1px solid var(--bw-border-strong);
  border-radius: var(--bw-radius-sm);
  font-size: 12.5px;
  color: var(--bw-text);
}
.nav__write:hover {
  background: color-mix(in srgb, var(--bw-text) 5%, transparent);
}

@media (max-width: 640px) {
  .site-head {
    block-size: 58px;
  }
  .nav__link--optional {
    display: none;
  }
  .nav__write {
    margin-inline-start: 0;
    padding-inline: 0;
    inline-size: 44px;
    border: 0;
    font-size: 19px;
  }
  .nav__write span {
    display: none;
  }
  .brand__en {
    display: none;
  }
}

/* ---- footer ------------------------------------------------------------- */
.site-foot {
  margin-block-start: 96px;
  padding-block: 40px 56px;
  border-block-start: 1px solid var(--bw-border);
}
.site-foot__inner {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px 32px;
}
.site-foot__links {
  display: flex;
  flex-wrap: wrap;
  gap: 4px 20px;
}
.site-foot__links a {
  font-family: var(--font-ui);
  font-size: 12.5px;
  letter-spacing: 0.06em;
  color: var(--bw-text-secondary);
  min-block-size: 36px;
  display: inline-flex;
  align-items: center;
  transition: color var(--bw-dur-fast) var(--bw-ease-out);
}
.site-foot__links a:hover {
  color: var(--bw-text);
}
.site-foot__note {
  font-size: 11.5px;
  letter-spacing: 0.06em;
  color: var(--bw-text-muted);
}

@media (max-width: 640px) {
  .site-foot {
    margin-block-start: 64px;
    padding-block: 32px calc(40px + env(safe-area-inset-bottom));
  }
  .site-foot__inner {
    flex-direction: column;
    gap: 20px;
  }
}

/* ---- toast -------------------------------------------------------------- */
.toast-stack {
  position: fixed;
  inset-block-end: calc(20px + env(safe-area-inset-bottom));
  inset-inline: 0;
  z-index: 80;
  display: grid;
  justify-items: center;
  gap: 8px;
  pointer-events: none;
  padding-inline: 16px;
}
.toast {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 16px;
  font-family: var(--font-ui);
  font-size: 13px;
  letter-spacing: 0.03em;
  color: var(--bw-text);
  border-radius: var(--bw-radius-sm);
  animation: bw-sharpen-in var(--bw-dur-slow) var(--bw-ease-out) both;
}
.toast[data-leaving="true"] {
  animation: bw-blur-out var(--bw-dur-fast) var(--bw-ease-in-out) both;
}
.toast i {
  font-size: 16px;
  color: var(--bw-accent);
}

/* ---- shared bits -------------------------------------------------------- */
.sr-only {
  position: absolute;
  inline-size: 1px;
  block-size: 1px;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
}

::view-transition-old(root),
::view-transition-new(root) {
  animation: none;
  mix-blend-mode: normal;
}