/* mistrelle · 半窗烟雨 —— 官网共享设计系统
   被 public/index.html 与 /download 页共用；纯静态、无第三方外链。 */

:root {
  /* 色 */
  --bg: #0a0f1e;
  --bg-soft: #0f1730;
  --card: #111a33;
  --card-2: #16203c;
  --line: rgba(148, 163, 255, 0.14);
  --line-strong: rgba(148, 163, 255, 0.3);
  --accent: #7c8cff;
  --accent-2: #5eead4;
  --text: #e8edff;
  --muted: #9aa7c7;
  /* 用于卡片内的 12.5–13px 小字，需在 --card 底上仍达 AA（#7481a1 仅 4.4:1） */
  --muted-2: #7d8aab;

  /* 形 */
  --radius: 16px;
  --radius-sm: 10px;
  --radius-pill: 999px;

  /* 间距 */
  --sp-1: 4px;
  --sp-2: 8px;
  --sp-3: 12px;
  --sp-4: 16px;
  --sp-5: 24px;
  --sp-6: 32px;
  --sp-7: 48px;
  --sp-8: 72px;
  --sp-9: 104px;

  /* 字 */
  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC',
    'Hiragino Sans GB', 'Microsoft YaHei', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --font-serif: 'Songti SC', 'STSong', 'Source Han Serif SC', 'Noto Serif SC',
    'SimSun', Songti, 'Times New Roman', serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Consolas, 'Liberation Mono', monospace;

  --wrap: 1080px;
}

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

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

/* 背景三层：远雾 / 近雾 / 斜雨丝 / 噪点纸纹 */
body {
  position: relative;
  min-height: 100vh;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

body::before,
body::after {
  content: '';
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 0;
}

body::before {
  background:
    radial-gradient(760px 460px at 82% -12%, rgba(124, 140, 255, 0.16), transparent 62%),
    radial-gradient(620px 420px at -8% 12%, rgba(94, 234, 212, 0.07), transparent 58%),
    radial-gradient(900px 620px at 50% 112%, rgba(124, 140, 255, 0.1), transparent 60%);
}

/* 雨丝 + 纸纹 */
body::after {
  background-image:
    repeating-linear-gradient(
      102deg,
      rgba(196, 210, 255, 0.055) 0 1px,
      transparent 1px 5px
    ),
    repeating-linear-gradient(
      102deg,
      rgba(196, 210, 255, 0.028) 0 1px,
      transparent 1px 13px
    );
  opacity: 0.55;
  mask-image: linear-gradient(180deg, #000 0%, #000 62%, transparent 100%);
  -webkit-mask-image: linear-gradient(180deg, #000 0%, #000 62%, transparent 100%);
}

/* 噪点纸纹（data-URI 内联 SVG，无外部请求） */
html::before {
  content: '';
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  opacity: 0.035;
  mix-blend-mode: soft-light;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='140' height='140'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='3' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='140' height='140' filter='url(%23n)'/%3E%3C/svg%3E");
}

/* ------------------------------ 排版 ------------------------------ */

h1,
h2,
h3,
h4 {
  font-family: var(--font-serif);
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: 0.01em;
}

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

code,
kbd,
pre {
  font-family: var(--font-mono);
}

code {
  font-size: 0.85em;
  color: var(--accent-2);
  background: rgba(124, 140, 255, 0.1);
  padding: 1px 7px;
  border-radius: 6px;
}

::selection {
  background: rgba(124, 140, 255, 0.32);
}

/* 标题关键词下的手写感波浪线（两页共用） */
.mark {
  position: relative;
  white-space: nowrap;
}

.mark svg {
  position: absolute;
  left: 0;
  right: 0;
  bottom: -0.22em;
  width: 100%;
  height: 0.34em;
  color: var(--accent-2);
  opacity: 0.75;
  overflow: visible;
}

/* 焦点环：全站统一 */
:where(a, button, input, textarea, select, summary, [tabindex]):focus-visible {
  outline: 2px solid var(--accent-2);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}

.skip-link {
  position: absolute;
  left: var(--sp-4);
  top: -60px;
  z-index: 40;
  padding: 10px 16px;
  border-radius: var(--radius-sm);
  background: var(--card-2);
  border: 1px solid var(--line-strong);
  font-size: 14px;
  transition: top 0.16s ease;
}

.skip-link:focus {
  top: var(--sp-4);
}

/* ------------------------------ 骨架 ------------------------------ */

.wrap {
  position: relative;
  z-index: 1;
  width: 100%;
  max-width: var(--wrap);
  margin: 0 auto;
  padding: clamp(40px, 7vw, 88px) clamp(18px, 4vw, 32px) var(--sp-7);
}

.section {
  margin-top: clamp(56px, 9vw, var(--sp-9));
  scroll-margin-top: 96px;
}

.eyebrow {
  display: flex;
  align-items: center;
  gap: var(--sp-3);
  font-size: 13px;
  font-weight: 600;
  color: var(--accent);
  letter-spacing: 0.22em;
}

.eyebrow::after {
  content: '';
  flex: 1;
  height: 1px;
  background: linear-gradient(90deg, var(--line-strong), transparent);
}

/* ------------------------------ 顶栏 ------------------------------ */

.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  border-bottom: 1px solid transparent;
  transition: border-color 0.24s ease, background-color 0.24s ease;
}

.topbar.is-stuck {
  background: rgba(10, 15, 30, 0.72);
  backdrop-filter: saturate(150%) blur(14px);
  -webkit-backdrop-filter: saturate(150%) blur(14px);
  border-bottom-color: var(--line);
}

.topbar-inner {
  display: flex;
  align-items: center;
  gap: var(--sp-5);
  width: 100%;
  max-width: var(--wrap);
  margin: 0 auto;
  padding: 14px clamp(18px, 4vw, 32px);
}

.topbar .logo {
  flex: none;
  padding: 6px 14px;
  font-size: 17px;
}

.topbar-nav {
  display: flex;
  align-items: center;
  gap: var(--sp-5);
  margin-left: auto;
  font-size: 14px;
  color: var(--muted);
}

.topbar-nav a {
  padding: 6px 2px;
  border-bottom: 1px solid transparent;
  transition: color 0.16s ease, border-color 0.16s ease;
}

.topbar-nav a:hover {
  color: var(--text);
  border-bottom-color: var(--accent-2);
}

.btn-sm {
  padding: 8px 16px;
  font-size: 14px;
  border-radius: var(--radius-sm);
}

/* ------------------------------ 标识 ------------------------------ */

.logo {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-serif);
  font-size: 19px;
  font-weight: 700;
  letter-spacing: 0.4px;
  padding: 8px 18px;
  border: 1px solid var(--line);
  border-radius: var(--radius-pill);
  background: linear-gradient(180deg, rgba(124, 140, 255, 0.09), rgba(124, 140, 255, 0));
}

.logo .cn {
  color: var(--muted);
  font-weight: 500;
  letter-spacing: 0.16em;
}

.dot {
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--accent-2);
  box-shadow: 0 0 12px var(--accent-2);
}

/* ------------------------------ 按钮 ------------------------------ */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--sp-2);
  padding: 12px 24px;
  border: 1px solid transparent;
  border-radius: var(--radius-sm);
  font-family: var(--font-sans);
  font-size: 15px;
  font-weight: 600;
  color: #fff;
  cursor: pointer;
  background: linear-gradient(135deg, var(--accent), #5b6cff);
  box-shadow: 0 10px 28px -14px rgba(124, 140, 255, 0.9);
  transition: transform 0.16s ease, filter 0.16s ease, background-color 0.16s ease;
}

.btn:hover {
  transform: translateY(-2px);
  filter: brightness(1.07);
}

.btn:active {
  transform: translateY(0);
}

.btn.ghost {
  background: transparent;
  color: var(--text);
  border-color: var(--line-strong);
  box-shadow: none;
}

.btn.ghost:hover {
  background: rgba(124, 140, 255, 0.08);
  border-color: var(--accent);
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-3);
  margin-top: var(--sp-6);
}

/* ------------------------------ 卡片 ------------------------------ */

.card {
  position: relative;
  display: flex;
  flex-direction: column;
  padding: var(--sp-5);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: linear-gradient(180deg, var(--card), var(--bg-soft));
  overflow: hidden;
  transition: border-color 0.2s ease, transform 0.2s ease;
}

/* 跟随光标的高光，--mx/--my 由脚本写入 */
.card::after {
  content: '';
  position: absolute;
  inset: 0;
  pointer-events: none;
  opacity: 0;
  transition: opacity 0.3s ease;
  background: radial-gradient(
    340px circle at var(--mx, 50%) var(--my, 0%),
    rgba(124, 140, 255, 0.16),
    transparent 62%
  );
}

@media (hover: hover) {
  .card:hover {
    border-color: var(--line-strong);
    transform: translateY(-3px);
  }

  .card:hover::after {
    opacity: 1;
  }
}

.card h3 {
  display: flex;
  align-items: center;
  gap: var(--sp-3);
  font-size: 17px;
}

.card h3 em {
  margin-left: auto;
  font-family: var(--font-sans);
  font-style: normal;
  font-size: 12.5px;
  font-weight: 500;
  color: var(--muted-2);
  white-space: nowrap;
}

.card p {
  margin-top: var(--sp-2);
  color: var(--muted);
  font-size: 14.5px;
}

.card ul {
  display: grid;
  gap: var(--sp-2);
  margin-top: var(--sp-4);
  list-style: none;
}

.card li {
  display: flex;
  gap: var(--sp-2);
  font-size: 13.5px;
}

.card li::before {
  content: '·';
  color: var(--accent);
  font-weight: 700;
}

/* 卡片图标 */
.icon {
  flex: none;
  width: 22px;
  height: 22px;
  color: var(--accent);
}

/* ------------------------------ 栅格 ------------------------------ */

.grid {
  display: grid;
  gap: var(--sp-4);
  margin-top: var(--sp-5);
  grid-template-columns: repeat(12, 1fr);
}

.span-4 {
  grid-column: span 4;
}

.span-5 {
  grid-column: span 5;
}

.span-6 {
  grid-column: span 6;
}

.span-7 {
  grid-column: span 7;
}

.span-12 {
  grid-column: span 12;
}

/* ------------------------------ 标签 ------------------------------ */

.pill-row {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-2) var(--sp-3);
  margin-top: var(--sp-5);
  padding-top: var(--sp-4);
  border-top: 1px solid var(--line);
}

.pill {
  font-size: 12.5px;
  color: var(--muted-2);
  padding: 3px 11px;
  border: 1px solid var(--line);
  border-radius: var(--radius-pill);
  background: rgba(124, 140, 255, 0.04);
}

/* ------------------------------ 页脚 ------------------------------ */

.footer {
  margin-top: clamp(56px, 8vw, var(--sp-9));
  padding-top: var(--sp-5);
  border-top: 1px solid var(--line);
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-2) var(--sp-5);
  justify-content: space-between;
  color: var(--muted-2);
  font-size: 13px;
}

/* ------------------------------ 入场动效 ------------------------------ */

.js .reveal {
  opacity: 0;
  transform: translateY(14px);
}

.js .reveal.is-in {
  opacity: 1;
  transform: none;
  transition: opacity 0.7s cubic-bezier(0.2, 0.7, 0.2, 1),
    transform 0.7s cubic-bezier(0.2, 0.7, 0.2, 1);
}

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

  .js .reveal {
    opacity: 1;
    transform: none;
    transition: none;
  }

  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }
}

/* ------------------------------ 响应式 ------------------------------ */

@media (max-width: 980px) {
  .span-4,
  .span-5,
  .span-6,
  .span-7 {
    grid-column: span 12;
  }
}

@media (max-width: 640px) {
  .topbar-nav {
    display: none;
  }

  /* 导航隐藏后，把顶栏按钮推到右侧 */
  .topbar-inner > .btn {
    margin-left: auto;
  }

  .actions .btn {
    flex: 1 1 100%;
  }
}