/* LearnPage · Direction B 原子组件库.
   依赖 theme.css 提供的 --b-* token + 字体. 所有组件用 CSS 自定义属性
   (--b-tag-c / --b-btn-c / --b-corner-c) 解耦颜色, modifier class 切色. */

/* ═════════════════════════ 1. Grid background ════════════════════════ */
.b-grid {
  position: relative;
  background-color: var(--b-bg-0);
  background-image:
    linear-gradient(var(--b-grid-line) 1px, transparent 1px),
    linear-gradient(90deg, var(--b-grid-line) 1px, transparent 1px);
  background-size: 40px 40px;
  background-position: -1px -1px;
  color: var(--b-fg-0);
  font-family: var(--b-sans);
  overflow: hidden;
}
.b-grid::before {
  content: ""; position: absolute; inset: 0; pointer-events: none; z-index: 0;
  background:
    radial-gradient(900px 500px at 12% -10%,
      color-mix(in srgb, var(--b-cyan) 13%, transparent), transparent 60%),
    radial-gradient(700px 400px at 98% 8%,
      color-mix(in srgb, var(--b-magenta) 11%, transparent), transparent 60%);
}
.b-grid::after {
  content: ""; position: absolute; inset: 0; pointer-events: none; z-index: 0;
  background: repeating-linear-gradient(0deg,
    rgba(255,255,255,0.012) 0 1px, transparent 1px 3px);
}
.b-grid > * { position: relative; z-index: 1; }
:root[data-theme="light"] .b-grid::after { display: none; }
/* 浅色: 辉光降浓度, 暗色 accent 全浓度会在白底上显浊 */
:root[data-theme="light"] .b-grid::before {
  background:
    radial-gradient(900px 500px at 12% -10%,
      color-mix(in srgb, var(--b-cyan) 6%, transparent), transparent 60%),
    radial-gradient(700px 400px at 98% 8%,
      color-mix(in srgb, var(--b-magenta) 5%, transparent), transparent 60%);
}
.b-grid--no-glow::before { display: none; }
.b-grid--cyan-scan::after {
  background: repeating-linear-gradient(0deg,
    transparent 0 2px,
    color-mix(in srgb, var(--b-cyan) 4%, transparent) 2px 3px);
  opacity: 0.4;
}

/* ═════════════════════════ 2. Corner brackets ════════════════════════ */
/* 用法: 父级 position:relative + .b-card / .b-card-cyan 等设置 --b-corner-c.
   或在父级直接放 4 个 span.b-corner.b-corner-{tl,tr,bl,br}. */
.b-corner {
  position: absolute;
  width: 10px; height: 10px;
  border-color: var(--b-corner-c, var(--b-cyan));
  border-style: solid; border-width: 0;
  pointer-events: none;
}
.b-corner--tl { top: -1px; left: -1px;  border-top-width: 1.5px; border-left-width: 1.5px; }
.b-corner--tr { top: -1px; right: -1px; border-top-width: 1.5px; border-right-width: 1.5px; }
.b-corner--bl { bottom: -1px; left: -1px;  border-bottom-width: 1.5px; border-left-width: 1.5px; }
.b-corner--br { bottom: -1px; right: -1px; border-bottom-width: 1.5px; border-right-width: 1.5px; }
.b-corner--lg { width: 14px; height: 14px; }
.b-corner--sm { width: 8px;  height: 8px;  }

/* ═════════════════════════ 3. Card surface ═══════════════════════════ */
.b-card {
  position: relative;
  background: var(--b-bg-1);
  border: 1px solid var(--b-line);
  padding: 22px;
}
.b-card--cyan {
  border-color: color-mix(in srgb, var(--b-cyan) 33%, transparent);
  box-shadow: 0 0 28px color-mix(in srgb, var(--b-cyan) 10%, transparent);
  --b-corner-c: var(--b-cyan);
}
.b-card--magenta {
  border-color: color-mix(in srgb, var(--b-magenta) 33%, transparent);
  box-shadow: 0 0 28px color-mix(in srgb, var(--b-magenta) 10%, transparent);
  --b-corner-c: var(--b-magenta);
}
.b-card--amber {
  border-color: color-mix(in srgb, var(--b-amber) 40%, transparent);
  box-shadow: 0 0 24px color-mix(in srgb, var(--b-amber) 10%, transparent);
  --b-corner-c: var(--b-amber);
}
.b-card--purple {
  border-color: color-mix(in srgb, var(--b-purple) 40%, transparent);
  --b-corner-c: var(--b-purple);
}

/* ═════════════════════════ 4. Tag / Pill ═════════════════════════════ */
.b-tag {
  --b-tag-c: var(--b-fg-2);
  display: inline-block;
  font-family: var(--b-mono);
  font-size: 10px;
  letter-spacing: 0.2em;
  line-height: 1;
  text-transform: uppercase;
  color: var(--b-tag-c);
  padding: 3px 8px;
  border: 1px solid color-mix(in srgb, var(--b-tag-c) 33%, transparent);
  background: color-mix(in srgb, var(--b-tag-c) 6%, transparent);
}
.b-pill {
  display: inline-flex; align-items: center; gap: 4px;
  padding: 2px 8px;
  background: color-mix(in srgb, var(--b-tag-c) 10%, transparent);
}
/* 颜色变体: 复用 --b-tag-c, 统一覆盖 .b-tag/.b-pill */
.b-tag--cyan,    .b-pill--cyan    { --b-tag-c: var(--b-cyan); }
.b-tag--magenta, .b-pill--magenta { --b-tag-c: var(--b-magenta); }
.b-tag--amber,   .b-pill--amber   { --b-tag-c: var(--b-amber); }
.b-tag--good,    .b-pill--good    { --b-tag-c: var(--b-good); }
.b-tag--bad,     .b-pill--bad     { --b-tag-c: var(--b-bad); }
.b-tag--purple,  .b-pill--purple  { --b-tag-c: var(--b-purple); }
.b-tag--fg0,     .b-pill--fg0     { --b-tag-c: var(--b-fg-0); }
.b-tag--fg1,     .b-pill--fg1     { --b-tag-c: var(--b-fg-1); }

/* ═════════════════════════ 5. Button ═════════════════════════════════ */
.b-btn {
  --b-btn-c: var(--b-cyan);
  display: inline-block;
  font-family: var(--b-mono);
  font-size: 11px;
  letter-spacing: 0.22em;
  line-height: 1;
  text-transform: uppercase;
  cursor: pointer;
  padding: 9px 14px;
  background: transparent;
  color: var(--b-btn-c);
  border: 1px solid color-mix(in srgb, var(--b-btn-c) 40%, transparent);
  font-weight: 500;
  text-decoration: none;
  transition: filter 0.12s, box-shadow 0.12s;
}
.b-btn:hover  { filter: brightness(1.15); }
.b-btn:active { filter: brightness(0.92); }
.b-btn:disabled { opacity: 0.5; cursor: not-allowed; filter: none; }
.b-btn--sm    { padding: 6px 10px;   font-size: 10px; }
.b-btn--lg    { padding: 12px 18px;  font-size: 12px; letter-spacing: 0.28em; }
.b-btn--block { display: block; width: 100%; }
.b-btn--fill  {
  background: var(--b-btn-c);
  color: var(--b-bg-0);
  border-color: transparent;
  font-weight: 700;
}
.b-btn--fill:hover {
  box-shadow: 0 0 18px color-mix(in srgb, var(--b-btn-c) 50%, transparent);
}
.b-btn--cyan    { --b-btn-c: var(--b-cyan); }
.b-btn--magenta { --b-btn-c: var(--b-magenta); }
.b-btn--amber   { --b-btn-c: var(--b-amber); }
.b-btn--good    { --b-btn-c: var(--b-good); }
.b-btn--bad     { --b-btn-c: var(--b-bad); }
.b-btn--fg1     { --b-btn-c: var(--b-fg-1); }

/* ═════════════════════════ 6. Brand mark ═════════════════════════════ */
.b-brand {
  display: inline-flex; align-items: center; gap: 10px;
  text-decoration: none;
}
.b-brand-mark {
  width: 28px; height: 28px;
  border: 1.5px solid var(--b-cyan);
  display: inline-flex; align-items: center; justify-content: center;
  font-family: var(--b-mono); font-size: 13px; color: var(--b-cyan);
  font-weight: 600;
  box-shadow: 0 0 14px color-mix(in srgb, var(--b-cyan) 40%, transparent);
  position: relative;
  flex-shrink: 0;
}
.b-brand-mark::after {
  content: ""; position: absolute;
  bottom: -2px; right: -2px;
  width: 4px; height: 4px;
  background: var(--b-magenta);
  box-shadow: 0 0 6px var(--b-magenta);
}
.b-brand-text {
  font-family: var(--b-display);
  font-size: 15px; font-weight: 600;
  letter-spacing: -0.01em;
  color: var(--b-fg-0);
}
.b-brand-text em { color: var(--b-cyan); font-style: normal; }
.b-brand-sub {
  font-family: var(--b-mono); font-size: 9px;
  letter-spacing: 0.22em; color: var(--b-fg-2); text-transform: uppercase;
  margin-top: 2px;
}
.b-brand--sm .b-brand-mark { width: 22px; height: 22px; font-size: 11px; }
.b-brand--sm .b-brand-text { font-size: 13px; }
.b-brand--lg .b-brand-mark { width: 36px; height: 36px; font-size: 16px; }
.b-brand--lg .b-brand-text { font-size: 18px; }

/* ═════════════════════════ 7. UserPill (avatar / credit / menu) ══════ */
.b-userpill {
  display: inline-flex; align-items: stretch;
  border: 1px solid var(--b-line);
  background: var(--b-bg-1);
  font-family: var(--b-mono); font-size: 11px;
  text-decoration: none;
  color: var(--b-fg-0);
}
.b-userpill > div, .b-userpill > a, .b-userpill > span {
  padding: 8px 12px;
  border-right: 1px solid var(--b-line);
  display: inline-flex; align-items: center; gap: 8px;
  text-decoration: none; color: inherit;
}
.b-userpill > :last-child { border-right: 0; }
.b-userpill-avatar {
  width: 18px; height: 18px;
  background: var(--b-cyan);
  color: var(--b-bg-0);
  display: inline-flex; align-items: center; justify-content: center;
  font-weight: 700; font-size: 10px;
  flex-shrink: 0;
}
.b-userpill-admin {
  padding: 1px 5px;
  font-size: 9px; letter-spacing: 0.2em;
  background: color-mix(in srgb, var(--b-magenta) 13%, transparent);
  color: var(--b-magenta);
  border: 1px solid color-mix(in srgb, var(--b-magenta) 33%, transparent);
}
.b-userpill-credit { color: var(--b-good); }
.b-userpill-menu { color: var(--b-fg-2); letter-spacing: 0.2em; cursor: pointer; }
.b-userpill:hover { border-color: var(--b-cyan); }

/* ═════════════════════════ 8. Cursor blink ═══════════════════════════ */
.b-cursor {
  display: inline-block;
  width: 8px; height: 17px;
  background: var(--b-cyan);
  animation: b-blink 1s step-end infinite;
  vertical-align: text-bottom;
}
.b-cursor--sm      { width: 6px; height: 14px; }
.b-cursor--magenta { background: var(--b-magenta); }

/* ═════════════════════════ 9. Misc utilities ═════════════════════════ */
.b-mono     { font-family: var(--b-mono); }
.b-sans     { font-family: var(--b-sans); }
.b-display  { font-family: var(--b-display); }
.b-uppercase { text-transform: uppercase; letter-spacing: 0.18em; }
/* 单色辅助 (常用于 mono 标签里突出某段) */
.b-c-cyan    { color: var(--b-cyan); }
.b-c-magenta { color: var(--b-magenta); }
.b-c-amber   { color: var(--b-amber); }
.b-c-good    { color: var(--b-good); }
.b-c-bad     { color: var(--b-bad); }
.b-c-purple  { color: var(--b-purple); }
.b-c-fg1     { color: var(--b-fg-1); }
.b-c-fg2     { color: var(--b-fg-2); }

/* Hero 标题渐变 (cyan → magenta) */
.b-grad-text {
  background: linear-gradient(90deg, var(--b-cyan), var(--b-magenta));
  -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent; color: transparent;
}

/* Live dot (●) 用于 "online" / "live" 状态 */
.b-dot {
  display: inline-block; width: 6px; height: 6px; border-radius: 50%;
  background: currentColor;
  box-shadow: 0 0 8px currentColor;
  vertical-align: middle; margin-right: 4px;
}
.b-dot--pulse { animation: b-pulse 2s ease-in-out infinite; }

/* ═════════════════════════ 10. Keyframes ═════════════════════════════ */
@keyframes b-blink { 50% { opacity: 0; } }
@keyframes b-pulse { 0%, 100% { opacity: 0.5; } 50% { opacity: 1; } }
@keyframes b-dot   { 0%, 100% { opacity: 0.3; } 50% { opacity: 1; } }