/* ============================================================================
 * 上课 · ShangKeSchedule — 官网样式表
 * ----------------------------------------------------------------------------
 * 设计语言：「书卷」— 暖砂纸底 + 赤陶主色 + 衬线标题（Anthropic 设计系统）
 * 与 App 内「书卷」主题同源，色值取自 claude-schedule-page.design/docs/设计token规范.md
 * ========================================================================== */

/* ---------------------------------------------------------------- 字体 */
/* 每个字体声明两条 src：woff2 优先（实测省 52%~68%），TTF 兜底。
   两者同字体族同字重，浏览器只下载第一条支持的格式，不会重复下载。 */
@font-face {
  font-family: 'Newsreader';
  font-style: normal;
  font-weight: 200 800;
  font-display: swap;
  src: url('../fonts/Newsreader-Variable.woff2') format('woff2'),
       url('../fonts/Newsreader-Variable.ttf') format('truetype');
}
@font-face {
  font-family: 'Poppins';
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: url('../fonts/Poppins-Regular.woff2') format('woff2'),
       url('../fonts/Poppins-Regular.ttf') format('truetype');
}
@font-face {
  font-family: 'Poppins';
  font-style: normal;
  font-weight: 600;
  font-display: swap;
  src: url('../fonts/Poppins-SemiBold.woff2') format('woff2'),
       url('../fonts/Poppins-SemiBold.ttf') format('truetype');
}
@font-face {
  font-family: 'Geist Mono';
  font-style: normal;
  font-weight: 300 700;
  font-display: swap;
  src: url('../fonts/GeistMono-Variable.woff2') format('woff2'),
       url('../fonts/GeistMono-Variable.ttf') format('truetype');
}
/* 中文衬线（仅标题使用，已按站点标题用字子集化：461 字 / 约 99KB） */
@font-face {
  font-family: 'Noto Serif SC';
  font-style: normal;
  font-weight: 500;
  font-display: swap;
  src: url('../fonts/NotoSerifSC-Subset.woff2') format('woff2');
}

/* ------------------------------------------------------------ 设计 token */
:root {
  --paper:        #faf9f5;
  --paper-2:      #f5f4ef;
  --paper-3:      #ede9de;
  --card:         #ffffff;
  --ink:          #28261b;
  --ink-2:        #3d3929;
  --muted:        #4a483e;
  --faint:        #6b6961;
  --line:         #e9e6dc;
  --line-2:       #dad9d4;
  --brand:        #c96442;
  --brand-2:      #b0562f;
  --brand-soft:   #fbf2ed;
  --brand-line:   #ebc6b6;
  --sage:         #788c5d;
  --violet:       #9c87f5;
  --shadow-s:     0 1px 2px rgba(61, 57, 41, .05), 0 2px 8px rgba(61, 57, 41, .04);
  --shadow-m:     0 2px 4px rgba(61, 57, 41, .05), 0 12px 28px -8px rgba(61, 57, 41, .12);
  --shadow-l:     0 4px 8px rgba(61, 57, 41, .05), 0 32px 64px -20px rgba(61, 57, 41, .22);
  --grain:        .038;

  --font-display: 'Newsreader', 'Noto Serif SC', 'Songti SC', Georgia, serif;
  --font-sans:    'Poppins', -apple-system, BlinkMacSystemFont, 'PingFang SC',
                  'HarmonyOS Sans SC', 'Noto Sans SC', 'Microsoft YaHei', sans-serif;
  --font-mono:    'Geist Mono', ui-monospace, SFMono-Regular, Menlo, Consolas,
                  'PingFang SC', 'Microsoft YaHei', monospace;

  --wrap:         1160px;
  --pad:          clamp(20px, 5vw, 40px);
  --r-s:          10px;
  --r-m:          16px;
  --r-l:          24px;
}

[data-theme='dark'] {
  --paper:        #1b1b19;
  --paper-2:      #262624;
  --paper-3:      #2c2c2b;
  --card:         #242422;
  --ink:          #faf9f5;
  --ink-2:        #f1f1ef;
  --muted:        #b7b5a9;
  --faint:        #97958b;
  --line:         #343430;
  --line-2:       #3e3e38;
  --brand:        #d97757;
  --brand-2:      #e08d6f;
  --brand-soft:   #3a2a22;
  --brand-line:   #6b4533;
  --sage:         #8ca06f;
  --shadow-s:     0 1px 2px rgba(0, 0, 0, .3);
  --shadow-m:     0 2px 4px rgba(0, 0, 0, .3), 0 12px 28px -8px rgba(0, 0, 0, .5);
  --shadow-l:     0 4px 8px rgba(0, 0, 0, .35), 0 32px 64px -20px rgba(0, 0, 0, .7);
  --grain:        .05;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: 88px;
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink-2);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.75;
  font-weight: 400;
  letter-spacing: .002em;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* 纸张颗粒 */
body::before {
  content: '';
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  opacity: var(--grain);
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='180' height='180'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='180' height='180' filter='url(%23n)'/%3E%3C/svg%3E");
}

body > * { position: relative; z-index: 1; }

img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }

h1, h2, h3, h4 {
  font-family: var(--font-display);
  color: var(--ink);
  font-weight: 500;
  line-height: 1.16;
  letter-spacing: -.012em;
  margin: 0;
  text-wrap: balance;
}
h1 { font-size: clamp(2.6rem, 6.4vw, 4.6rem); }
h2 { font-size: clamp(1.85rem, 3.5vw, 2.7rem); }
h3 { font-size: 1.22rem; letter-spacing: -.005em; }
h4 { font-size: 1.02rem; letter-spacing: 0; }

p { margin: 0; }
ul, ol { margin: 0; padding: 0; }

::selection { background: var(--brand-line); color: var(--ink); }

:focus-visible {
  outline: 2px solid var(--brand);
  outline-offset: 3px;
  border-radius: 4px;
}

/* -------------------------------------------------------------- 布局件 */
.wrap {
  width: 100%;
  max-width: var(--wrap);
  margin-inline: auto;
  padding-inline: var(--pad);
}
.wrap-narrow { max-width: 820px; }

.section { padding-block: clamp(64px, 9vw, 128px); }
.section-tight { padding-block: clamp(48px, 6vw, 80px); }
.section-plain { background: none; }
.section-tint { background: var(--paper-2); }
.section-ink { background: var(--ink); color: var(--paper-2); }
.section-ink h2, .section-ink h3 { color: var(--paper); }

.hairline { border-top: 1px solid var(--line); }

/* ------------------------------------------------------------- 文本件 */
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-mono);
  font-size: .72rem;
  font-weight: 500;
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--brand-2);
}
.eyebrow::before {
  content: '';
  width: 22px;
  height: 1px;
  background: currentColor;
  opacity: .55;
}
.eyebrow-plain::before { display: none; }

.lead {
  font-size: clamp(1.02rem, 1.35vw, 1.15rem);
  color: var(--muted);
  line-height: 1.8;
  max-width: 62ch;
}

.section-head { margin-bottom: clamp(36px, 4.5vw, 60px); }
.section-head .eyebrow { margin-bottom: 16px; }
.section-head h2 { max-width: 24ch; }
.section-head .lead { margin-top: 18px; }
.section-head-center { text-align: center; }
.section-head-center h2, .section-head-center .lead { margin-inline: auto; }

.mono {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: .82em;
  letter-spacing: 0;
}

.serif-latin {
  font-family: var(--font-display);
  font-style: italic;
  font-weight: 400;
}

/* --------------------------------------------------------------- 按钮 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 9px;
  padding: 13px 24px;
  border: 1px solid transparent;
  border-radius: 999px;
  font-family: var(--font-sans);
  font-size: .94rem;
  font-weight: 600;
  letter-spacing: .01em;
  line-height: 1;
  cursor: pointer;
  white-space: nowrap;
  transition: transform .18s cubic-bezier(.2,.8,.3,1), box-shadow .18s ease,
              background-color .18s ease, border-color .18s ease, color .18s ease;
}
.btn svg { width: 17px; height: 17px; flex: none; }

.btn-primary {
  background: var(--brand);
  color: #fff;
  box-shadow: 0 1px 2px rgba(88, 46, 29, .2), 0 8px 20px -8px rgba(201, 100, 66, .65);
}
.btn-primary:hover {
  background: var(--brand-2);
  transform: translateY(-2px);
  box-shadow: 0 2px 4px rgba(88, 46, 29, .2), 0 14px 28px -10px rgba(201, 100, 66, .7);
}
.btn-ghost {
  background: transparent;
  color: var(--ink);
  border-color: var(--line-2);
}
.btn-ghost:hover {
  border-color: var(--brand);
  color: var(--brand-2);
  transform: translateY(-2px);
}
.btn-quiet {
  background: var(--paper-2);
  color: var(--ink-2);
  border-color: var(--line);
}
.btn-quiet:hover { background: var(--paper-3); transform: translateY(-2px); }
.btn-sm { padding: 9px 17px; font-size: .85rem; }
.btn-block { width: 100%; }

.btn-row {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  align-items: center;
}

.link-arrow {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  color: var(--brand-2);
  font-weight: 600;
  font-size: .92rem;
  border-bottom: 1px solid transparent;
  transition: gap .18s ease, border-color .18s ease;
}
.link-arrow:hover { gap: 11px; border-bottom-color: currentColor; }

/* --------------------------------------------------------------- 导航 */
.nav {
  position: sticky;
  top: 0;
  z-index: 60;
  background: color-mix(in srgb, var(--paper) 82%, transparent);
  backdrop-filter: saturate(180%) blur(16px);
  -webkit-backdrop-filter: saturate(180%) blur(16px);
  border-bottom: 1px solid transparent;
  transition: border-color .25s ease, background-color .25s ease;
}
.nav.is-stuck {
  border-bottom-color: var(--line);
  background: color-mix(in srgb, var(--paper) 92%, transparent);
}
.nav-inner {
  display: flex;
  align-items: center;
  gap: 20px;
  height: 68px;
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  font-weight: 600;
  color: var(--ink);
  letter-spacing: -.01em;
}
.brand img {
  width: 32px;
  height: 32px;
  border-radius: 9px;
  box-shadow: 0 1px 3px rgba(61, 57, 41, .18);
}
.brand-text { display: flex; flex-direction: column; line-height: 1.15; }
.brand-text b { font-size: .98rem; font-weight: 600; }
.brand-text span {
  font-family: var(--font-mono);
  font-size: .6rem;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--faint);
}

.nav-links {
  display: flex;
  gap: 4px;
  margin-left: auto;
  list-style: none;
}
.nav-links a {
  display: block;
  padding: 8px 13px;
  border-radius: 999px;
  font-size: .89rem;
  font-weight: 500;
  color: var(--muted);
  transition: color .16s ease, background-color .16s ease;
}
.nav-links a:hover { color: var(--ink); background: var(--paper-3); }
.nav-links a[aria-current='page'] { color: var(--brand-2); background: var(--brand-soft); }

.nav-end { display: flex; align-items: center; gap: 10px; }

.theme-toggle {
  display: inline-grid;
  place-items: center;
  width: 36px;
  height: 36px;
  border-radius: 999px;
  border: 1px solid var(--line-2);
  background: transparent;
  color: var(--muted);
  cursor: pointer;
  transition: color .16s ease, border-color .16s ease, transform .16s ease;
}
.theme-toggle:hover { color: var(--brand-2); border-color: var(--brand); transform: rotate(-12deg); }
.theme-toggle svg { width: 17px; height: 17px; }
.theme-toggle .i-sun { display: none; }
[data-theme='dark'] .theme-toggle .i-sun { display: block; }
[data-theme='dark'] .theme-toggle .i-moon { display: none; }

.nav-burger {
  display: none;
  width: 38px; height: 38px;
  place-items: center;
  border: 1px solid var(--line-2);
  border-radius: 10px;
  background: transparent;
  color: var(--ink);
  cursor: pointer;
}
.nav-burger svg { width: 18px; height: 18px; }

/* --------------------------------------------------------------- Hero */
.hero { position: relative; padding-block: clamp(48px, 7vw, 96px) clamp(56px, 7vw, 104px); overflow: hidden; }
.hero::after {
  content: '';
  position: absolute;
  top: -20%;
  right: -12%;
  width: 46rem;
  height: 46rem;
  border-radius: 50%;
  background: radial-gradient(circle, color-mix(in srgb, var(--brand) 15%, transparent) 0%, transparent 62%);
  pointer-events: none;
  z-index: -1;
}
/* 手账横格线 */
.hero-rules {
  position: absolute;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  background-image: repeating-linear-gradient(
    to bottom,
    transparent 0 47px,
    color-mix(in srgb, var(--line-2) 55%, transparent) 47px 48px
  );
  mask-image: linear-gradient(to bottom, transparent, #000 18%, #000 62%, transparent);
  -webkit-mask-image: linear-gradient(to bottom, transparent, #000 18%, #000 62%, transparent);
  opacity: .8;
}

.hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.02fr) minmax(0, .98fr);
  gap: clamp(32px, 5vw, 72px);
  align-items: center;
}

.hero h1 { margin: 20px 0 0; }
.hero-copy { min-width: 0; }
.hero h1 .accent { color: var(--brand); }
.hero-sub {
  margin-top: 22px;
  font-size: clamp(1.03rem, 1.4vw, 1.18rem);
  color: var(--muted);
  line-height: 1.82;
  max-width: 54ch;
}
.hero-sub strong { color: var(--ink-2); font-weight: 600; }
.hero .btn-row { margin-top: 32px; }

.hero-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 20px;
  margin-top: 26px;
  font-family: var(--font-mono);
  font-size: .74rem;
  letter-spacing: .06em;
  color: var(--faint);
  text-transform: uppercase;
}
.hero-meta span { display: inline-flex; align-items: center; gap: 7px; }
.hero-meta span::before {
  content: '';
  width: 5px; height: 5px;
  border-radius: 50%;
  background: var(--sage);
}

/* 统计条 */
.stat-strip {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 1px;
  margin-top: clamp(40px, 5vw, 64px);
  background: var(--line);
  border: 1px solid var(--line);
  border-radius: var(--r-m);
  overflow: hidden;
}
.stat {
  background: var(--paper);
  padding: 22px 20px;
}
.stat b {
  display: block;
  font-family: var(--font-display);
  font-size: clamp(1.7rem, 3vw, 2.2rem);
  font-weight: 500;
  color: var(--ink);
  line-height: 1;
  letter-spacing: -.02em;
}
.stat b .unit { font-size: .5em; color: var(--brand); margin-left: 2px; }
.stat span {
  display: block;
  margin-top: 9px;
  font-size: .8rem;
  color: var(--faint);
  letter-spacing: .03em;
}

/* ---------------------------------------------------------- 手机样机 */
.hero-visual { position: relative; display: flex; justify-content: center; }

.phone {
  position: relative;
  width: min(300px, 74vw);
  aspect-ratio: 540 / 1170;
  border-radius: 40px;
  background: linear-gradient(160deg, #4a4a43, #232320);
  padding: 9px;
  box-shadow: var(--shadow-l), inset 0 0 0 1px rgba(255, 255, 255, .12);
  transform: rotate(-1.6deg);
}
[data-theme='dark'] .phone { background: linear-gradient(160deg, #3a3a38, #131312); }
.phone::after {
  content: '';
  position: absolute;
  top: 20px; left: 50%;
  transform: translateX(-50%);
  width: 74px; height: 6px;
  border-radius: 999px;
  background: #1a1a18;
  opacity: .5;
  z-index: 3;
}
.phone-screen {
  position: relative;
  width: 100%;
  height: 100%;
  border-radius: 32px;
  overflow: hidden;
  background: var(--paper-2);
}
.phone-screen img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: top center;
}

/* 悬浮卡片 */
.float-card {
  position: absolute;
  background: color-mix(in srgb, var(--card) 92%, transparent);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 13px 16px;
  box-shadow: var(--shadow-m);
  font-size: .8rem;
  line-height: 1.5;
  animation: floaty 7s ease-in-out infinite;
}
.float-card .fc-label {
  display: block;
  font-family: var(--font-mono);
  font-size: .62rem;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--faint);
  margin-bottom: 5px;
}
.float-card b { display: block; color: var(--ink); font-weight: 600; font-size: .95rem; }
.float-card small { color: var(--muted); font-size: .76rem; }
.fc-1 { top: 8%; left: -6%; animation-delay: -1.2s; }
.fc-2 { bottom: 16%; right: -5%; animation-delay: -3.4s; }
.fc-3 { bottom: 3%; left: -2%; animation-delay: -5.1s; }

@keyframes floaty {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-9px); }
}

/* ------------------------------------------------------- 功能卡片网格 */
.grid { display: grid; gap: clamp(14px, 1.6vw, 20px); }
.g-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.g-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.g-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.g-2-1 { grid-template-columns: minmax(0, 1.35fr) minmax(0, 1fr); }

.card {
  position: relative;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--r-m);
  padding: clamp(20px, 2.2vw, 28px);
  box-shadow: var(--shadow-s);
  transition: transform .22s cubic-bezier(.2,.8,.3,1), box-shadow .22s ease, border-color .22s ease;
}
.card-warm { background: var(--paper-2); }
.card-hover:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-m);
  border-color: var(--brand-line);
}
.card h3 { margin-bottom: 10px; }
.card p { color: var(--muted); font-size: .93rem; line-height: 1.72; }

.card-icon {
  display: grid;
  place-items: center;
  width: 42px; height: 42px;
  margin-bottom: 18px;
  border-radius: 12px;
  background: var(--brand-soft);
  color: var(--brand-2);
  border: 1px solid color-mix(in srgb, var(--brand) 22%, transparent);
}
.card-icon svg { width: 20px; height: 20px; }

.card-num {
  font-family: var(--font-mono);
  font-size: .68rem;
  letter-spacing: .14em;
  color: var(--faint);
  display: block;
  margin-bottom: 12px;
}

.card-list {
  list-style: none;
  margin-top: 16px;
  display: grid;
  gap: 9px;
}
.card-list li {
  position: relative;
  padding-left: 20px;
  font-size: .88rem;
  color: var(--muted);
  line-height: 1.65;
}
.card-list li::before {
  content: '';
  position: absolute;
  left: 3px; top: .62em;
  width: 7px; height: 7px;
  border-radius: 2px;
  background: var(--brand);
  opacity: .45;
  transform: rotate(45deg);
}

/* 药丸标签 */
.pill {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 11px;
  border-radius: 999px;
  background: var(--paper-3);
  border: 1px solid var(--line);
  font-size: .74rem;
  font-weight: 500;
  color: var(--muted);
  letter-spacing: .02em;
}
.pill-brand {
  background: var(--brand-soft);
  border-color: var(--brand-line);
  color: var(--brand-2);
}
.pill-sage { background: color-mix(in srgb, var(--sage) 14%, transparent); border-color: color-mix(in srgb, var(--sage) 34%, transparent); color: var(--sage); }
.pills { display: flex; flex-wrap: wrap; gap: 8px; }

/* -------------------------------------------------------------- 跑马灯 */
.marquee {
  overflow: hidden;
  border-block: 1px solid var(--line);
  background: var(--paper-2);
  padding-block: 15px;
  mask-image: linear-gradient(to right, transparent, #000 8%, #000 92%, transparent);
  -webkit-mask-image: linear-gradient(to right, transparent, #000 8%, #000 92%, transparent);
}
.marquee-track {
  display: flex;
  gap: 44px;
  width: max-content;
  animation: slide 42s linear infinite;
}
.marquee-track span {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  font-family: var(--font-mono);
  font-size: .79rem;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--muted);
  white-space: nowrap;
}
.marquee-track span::after {
  content: '';
  width: 5px; height: 5px;
  border-radius: 50%;
  background: var(--brand);
  opacity: .5;
}
@keyframes slide {
  from { transform: translateX(0); }
  to { transform: translateX(-50%); }
}
.marquee:hover .marquee-track { animation-play-state: paused; }

/* ------------------------------------------------------------ 课表演示 */
.demo-board {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--r-l);
  box-shadow: var(--shadow-m);
  overflow: hidden;
}
.demo-head {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 15px 20px;
  border-bottom: 1px solid var(--line);
  background: var(--paper-2);
}
.demo-dots { display: flex; gap: 6px; }
.demo-dots i { width: 9px; height: 9px; border-radius: 50%; background: var(--line-2); display: block; }
.demo-dots i:first-child { background: color-mix(in srgb, var(--brand) 70%, transparent); }
.demo-title {
  font-family: var(--font-mono);
  font-size: .74rem;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--faint);
}
.demo-body { padding: clamp(14px, 2vw, 22px); }

.week-mini {
  display: grid;
  grid-template-columns: 54px repeat(5, minmax(0, 1fr));
  gap: 5px;
  min-width: 520px;
}
.week-scroll { overflow-x: auto; padding-bottom: 4px; }
.wm-col {
  font-family: var(--font-mono);
  font-size: .68rem;
  text-align: center;
  color: var(--faint);
  padding-bottom: 8px;
  letter-spacing: .06em;
}
.wm-col b { display: block; font-family: var(--font-sans); font-size: .8rem; color: var(--ink-2); font-weight: 600; letter-spacing: 0; }
.wm-col.is-today b { color: var(--brand); }
.wm-time {
  font-family: var(--font-mono);
  font-size: .66rem;
  color: var(--faint);
  text-align: right;
  padding-right: 8px;
  padding-top: 6px;
  border-right: 1px solid var(--line);
}
.wm-cell {
  min-height: 52px;
  border-radius: 8px;
  padding: 7px 8px;
  font-size: .72rem;
  line-height: 1.32;
  font-weight: 600;
  color: #3d3929;
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 2px;
  transition: transform .18s ease, box-shadow .18s ease;
}
.wm-cell:hover { transform: translateY(-2px) scale(1.015); box-shadow: var(--shadow-m); z-index: 2; }
.wm-cell em {
  font-style: normal;
  font-weight: 400;
  font-size: .9em;
  opacity: .68;
}
.wm-cell.c1 { background: #d7e8d2; }
.wm-cell.c2 { background: #f6ddd2; }
.wm-cell.c3 { background: #e7dcf7; }
.wm-cell.c4 { background: #f7e6c4; }
.wm-cell.c5 { background: #d3e6f0; }
.wm-cell.c6 { background: #f2d8e0; }
.wm-empty { background: var(--paper-2); border: 1px dashed var(--line-2); }

/* ------------------------------------------------------------ 主题切换 */
.theme-tabs {
  display: inline-flex;
  gap: 4px;
  padding: 4px;
  background: var(--paper-2);
  border: 1px solid var(--line);
  border-radius: 999px;
}
.theme-tabs button {
  border: 0;
  background: transparent;
  color: var(--muted);
  font-family: var(--font-sans);
  font-size: .87rem;
  font-weight: 600;
  padding: 8px 20px;
  border-radius: 999px;
  cursor: pointer;
  transition: background-color .2s ease, color .2s ease;
}
.theme-tabs button[aria-selected='true'] {
  background: var(--card);
  color: var(--ink);
  box-shadow: var(--shadow-s);
}
.theme-tabs button:hover:not([aria-selected='true']) { color: var(--ink-2); }

.theme-stage {
  position: relative;
  margin-top: 34px;
  border-radius: var(--r-l);
  padding: clamp(24px, 4vw, 52px);
  border: 1px solid var(--line);
  overflow: hidden;
  transition: background .5s ease;
}
.theme-stage[data-stage='cjk'] {
  background:
    radial-gradient(120% 90% at 82% 8%, #f3e7dc 0%, transparent 58%),
    linear-gradient(170deg, #faf9f5, #f0ebe1);
}
.theme-stage[data-stage='glass'] {
  background: linear-gradient(165deg, #eef2fb 0%, #dfe8f7 48%, #f2eefb 100%);
}
.theme-stage[data-stage='soft'] {
  background:
    radial-gradient(90% 70% at 18% 12%, #efe4f8 0%, transparent 60%),
    radial-gradient(80% 70% at 88% 88%, #fbe6e9 0%, transparent 62%),
    linear-gradient(150deg, #f8f5fb, #f4eef2);
}
.theme-stage[data-stage='dark'] {
  background:
    radial-gradient(90% 70% at 76% 10%, #33322c 0%, transparent 60%),
    linear-gradient(165deg, #1d1d1b, #141413);
}
.theme-panel { display: none; }
.theme-panel.is-active {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: clamp(24px, 4vw, 56px);
  align-items: center;
  animation: fadeUp .5s ease both;
}
.theme-panel h3 { font-size: clamp(1.35rem, 2.4vw, 1.9rem); }
.theme-stage[data-stage='dark'] .theme-panel h3,
.theme-stage[data-stage='dark'] .theme-panel p { color: #f1f1ef; }
.theme-panel p {
  margin-top: 14px;
  color: var(--muted);
  font-size: .95rem;
  max-width: 44ch;
}
.theme-stage[data-stage='dark'] .theme-panel p { color: #b7b5a9; }
.theme-panel .pills { margin-top: 22px; }
.theme-shot {
  /* 与 .shot 同理：flex 消除缩进空白文本节点的行盒，并让图片区与说明区贴合 */
  display: flex;
  flex-direction: column;
  width: min(230px, 46vw);
  border-radius: 24px;
  overflow: hidden;
  box-shadow: var(--shadow-l);
  border: 6px solid rgba(255, 255, 255, .7);
}
.theme-stage[data-stage='dark'] .theme-shot { border-color: #3e3e38; }
.theme-shot img { width: 100%; }
/* 手机截图为超长竖屏(540×1170)，统一限高，超高即等比收缩居中显示、不裁切内容 */
/* ⚠️ 必须同时给 aspect-ratio：只设 max-height 时，盒子仍按「未收缩前的布局高度」撑开，
   而画面按 contain 等比缩小后只占盒子中间一段 ⇒ 上下各留大片空白（实测图册卡片
   每图上下共空 235.5px、单侧 117.8px）。加上 aspect-ratio 让盒高随画面等比贴合，
   容器就正好包住画面，消除余空。 */
.shot img,
.theme-shot img {
  aspect-ratio: 540 / 1170;
  height: auto;
  max-height: min(620px, 76vh);
  object-fit: contain;
}

@keyframes fadeUp {
  from { opacity: 0; transform: translateY(14px); }
  to { opacity: 1; transform: none; }
}

/* 明暗主题切换块 */
.split-theme {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px;
  margin-top: 20px;
  /* 两列并列手机截图易过大，收窄居中使每台手机约 310px 宽、不顶满整列 */
  max-width: 640px;
  margin-inline: auto;
}
.split-theme figure { margin: 0; }
.split-theme figcaption {
  margin-top: 12px;
  font-family: var(--font-mono);
  font-size: .72rem;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--faint);
}

/* --------------------------------------------------------- 截图图册 */
.shot {
  /* flex 让容器忽略 picture 与 figcaption 之间的缩进空白文本节点 —— 这些纯空白
     行盒会把容器撑高（实测 20.2px）；普通块级布局下它们是要参与排版的。 */
  display: flex;
  flex-direction: column;
  border-radius: var(--r-m);
  overflow: hidden;
  border: 1px solid var(--line);
  background: var(--paper-2);
  box-shadow: var(--shadow-s);
  transition: transform .3s cubic-bezier(.2,.8,.3,1), box-shadow .3s ease;
}
.shot:hover { transform: translateY(-6px) scale(1.012); box-shadow: var(--shadow-m); }
/* picture 默认是 inline，行盒会在基线下方留出间隙（实测 .shot 容器多出 20.6px）。
   统一设为 block，容器高度正好等于「图片 + 说明文字」。 */
.shot picture,
.theme-shot picture { display: block; }
/* <source> 本身不渲染内容，但默认是 inline，会在 picture 内产生一个行盒，
   把容器撑高（实测 .shot 多出 20.6px）。设为 block 且高度 0 即可消除。 */
.shot picture source,
.theme-shot picture source { display: block; height: 0; }
/* 图片区不参与收缩，只让说明区撑满被 grid 拉伸出的剩余高度 */
.shot picture { flex-shrink: 0; }
.shot img { width: 100%; }
.shot figcaption {
  /* flex:1 撑满被 grid 拉伸出的剩余高度：同排卡片若说明文字行数不同，
     较短的那张底部会露出容器底色（实测 20.2px）。撑满后说明区与卡片同高，
     不再出现断层色块。 */
  flex: 1;
  padding: 13px 16px 15px;
  font-size: .86rem;
  font-weight: 600;
  color: var(--ink-2);
  background: var(--card);
  border-top: 1px solid var(--line);
}
.shot figcaption small {
  display: block;
  margin-top: 3px;
  font-family: var(--font-mono);
  font-size: .68rem;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--faint);
  font-weight: 400;
}
.gallery { display: grid; gap: clamp(14px, 1.8vw, 22px); grid-template-columns: repeat(4, minmax(0, 1fr)); }

/* ------------------------------------------------------------- 步骤条 */
.steps { display: grid; gap: 0; margin-top: 8px; }
.step {
  display: grid;
  grid-template-columns: 46px minmax(0, 1fr);
  gap: 20px;
  padding-block: 24px;
  border-top: 1px solid var(--line);
}
.step:last-child { border-bottom: 1px solid var(--line); }
.step-idx {
  font-family: var(--font-mono);
  font-size: .92rem;
  color: var(--brand);
  padding-top: 2px;
}
.step h3 { font-size: 1.05rem; margin-bottom: 7px; }
.step p { color: var(--muted); font-size: .91rem; }
.step code {
  font-family: var(--font-mono);
  font-size: .85em;
  background: var(--paper-3);
  border: 1px solid var(--line);
  border-radius: 5px;
  padding: 1px 6px;
  color: var(--brand-2);
}

/* ------------------------------------------------------------ 下载区 */
.download-secondary { color: #faf9f5; border-color: #4a4a43; }
.download-secondary[hidden], .secret[hidden] { display: none; }
.dl-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
  margin-top: 28px;
}
.dl-card {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 22px;
  border: 1px solid var(--line);
  border-radius: var(--r-m);
  background: var(--card);
  box-shadow: var(--shadow-s);
  transition: transform .22s cubic-bezier(.2,.8,.3,1), box-shadow .22s ease, border-color .22s ease;
}
.dl-card:hover { transform: translateY(-4px); border-color: var(--brand-line); box-shadow: var(--shadow-m); }
.dl-card .abi {
  font-family: var(--font-mono);
  font-size: .86rem;
  font-weight: 600;
  color: var(--ink);
}
.dl-card .abi-desc { font-size: .8rem; color: var(--muted); }
.dl-card .size {
  margin-top: 12px;
  font-family: var(--font-mono);
  font-size: .7rem;
  line-height: 1.55;
  letter-spacing: 0;
  color: var(--faint);
  word-break: break-all;
}

/* 分享口令块（夸克口令 / 提取码） */
.secret {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 16px;
  margin-top: 26px;
  padding: 18px 22px;
  border-radius: var(--r-m);
  border: 1px dashed var(--line-2);
  background: var(--paper-2);
}
.secret-body { flex: 1 1 320px; min-width: 0; }
.secret-label {
  display: block;
  font-family: var(--font-mono);
  font-size: .68rem;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--faint);
  margin-bottom: 8px;
}
.secret-code {
  font-family: var(--font-mono);
  font-size: 1.08rem;
  font-weight: 600;
  letter-spacing: .05em;
  color: var(--brand-2);
  word-break: break-all;
}
.section-ink .secret { background: #232320; border-color: #3a3a36; }
.section-ink .secret-code { color: var(--brand); }
.section-ink .dl-note a { color: var(--brand); border-bottom: 1px solid var(--brand-line); }
.dl-note {
  margin-top: 22px;
  padding: 18px 20px;
  border-radius: var(--r-m);
  background: var(--paper-2);
  border: 1px solid var(--line);
  font-size: .88rem;
  color: var(--muted);
}
.dl-note b { color: var(--ink-2); }

/* 深色下载区 */
.section-ink .dl-card {
  background: #232320;
  border-color: #3a3a36;
  box-shadow: none;
}
.section-ink .dl-card:hover { border-color: var(--brand); }
.section-ink .dl-card .abi,
.section-ink .dl-card .abi-desc,
.section-ink .dl-card .size { color: inherit; }
.section-ink .dl-card .abi-desc { color: #b7b5a9; }
.section-ink .dl-card .size { color: #908e84; }
.section-ink .dl-note { background: #232320; border-color: #3a3a36; color: #b7b5a9; }
.section-ink .dl-note b { color: #faf9f5; }

/* ---------------------------------------------------------- 版本时间线 */
.timeline { position: relative; margin-top: 8px; }
.tl-item {
  display: grid;
  grid-template-columns: 150px minmax(0, 1fr);
  gap: 28px;
  padding-block: 26px;
  border-top: 1px solid var(--line);
}
.tl-item:last-child { border-bottom: 1px solid var(--line); }
/* 版本条目本身是 h2（可被搜索引擎与读屏器识别为版本分组）；
   仅重置 h2 的默认 margin/字号，外观完全沿用原有的 .tl-ver / .tl-date。 */
.tl-h {
  margin: 0;
  font-size: inherit;
  font-weight: inherit;
  line-height: inherit;
}
.tl-ver {
  font-family: var(--font-mono);
  font-size: .95rem;
  font-weight: 600;
  color: var(--brand-2);
}
.tl-date {
  display: block;
  margin-top: 5px;
  font-family: var(--font-mono);
  font-size: .72rem;
  color: var(--faint);
  letter-spacing: .06em;
}
.tl-body h3 { font-size: 1.06rem; margin-bottom: 10px; }
.tl-tag {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: .62rem;
  letter-spacing: .1em;
  text-transform: uppercase;
  padding: 2px 8px;
  border-radius: 999px;
  margin-right: 8px;
  vertical-align: 2px;
}
.tag-feat { background: var(--brand-soft); color: var(--brand-2); border: 1px solid var(--brand-line); }
.tag-fix  { background: color-mix(in srgb, var(--sage) 14%, transparent); color: var(--sage); border: 1px solid color-mix(in srgb, var(--sage) 34%, transparent); }
.tag-ui   { background: color-mix(in srgb, var(--violet) 16%, transparent); color: #6f5bd0; border: 1px solid color-mix(in srgb, var(--violet) 36%, transparent); }
[data-theme='dark'] .tag-ui { color: #b9a8f8; }
.tl-body ul { list-style: none; display: grid; gap: 8px; }
.tl-body li {
  position: relative;
  padding-left: 18px;
  font-size: .9rem;
  color: var(--muted);
  line-height: 1.68;
}
.tl-body li::before {
  content: '';
  position: absolute;
  left: 2px; top: .68em;
  width: 6px; height: 6px;
  border-radius: 50%;
  background: var(--line-2);
}

/* ------------------------------------------------------------- 手风琴 */
.acc { border-top: 1px solid var(--line); margin-top: 8px; }
.acc details { border-bottom: 1px solid var(--line); }
.acc summary {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 20px 4px;
  cursor: pointer;
  list-style: none;
  font-weight: 600;
  font-size: 1rem;
  color: var(--ink-2);
  transition: color .16s ease;
}
.acc summary::-webkit-details-marker { display: none; }
.acc summary::after {
  content: '';
  margin-left: auto;
  width: 9px; height: 9px;
  border-right: 1.6px solid var(--faint);
  border-bottom: 1.6px solid var(--faint);
  transform: rotate(45deg) translate(-2px, -2px);
  transition: transform .25s ease;
  flex: none;
}
.acc details[open] summary { color: var(--brand-2); }
.acc details[open] summary::after { transform: rotate(-135deg) translate(-2px, -2px); }
.acc .acc-body {
  padding: 0 4px 22px;
  color: var(--muted);
  font-size: .92rem;
  line-height: 1.78;
  max-width: 74ch;
}
.acc .acc-body p + p { margin-top: 12px; }
.acc summary:hover { color: var(--brand-2); }

/* ------------------------------------------------------------ 文档正文 */
.doc { padding-block: clamp(44px, 6vw, 76px) clamp(64px, 9vw, 120px); }
.doc-head { max-width: 74ch; margin-bottom: 44px; }
.doc-head h1 { font-size: clamp(2.1rem, 4.6vw, 3.2rem); margin-bottom: 18px; }
.doc-head .lead { max-width: 66ch; }
.doc-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 22px;
  margin-top: 24px;
  font-family: var(--font-mono);
  font-size: .74rem;
  letter-spacing: .07em;
  text-transform: uppercase;
  color: var(--faint);
}
.doc-body { max-width: 74ch; }
.doc-body h2 {
  font-size: clamp(1.4rem, 2.4vw, 1.8rem);
  margin: 52px 0 16px;
  padding-top: 34px;
  border-top: 1px solid var(--line);
}
.doc-body h2:first-child { margin-top: 0; padding-top: 0; border-top: 0; }
.doc-body h3 { font-size: 1.08rem; margin: 28px 0 10px; }
.doc-body p { color: var(--muted); margin-bottom: 14px; }
.doc-body ul, .doc-body ol { margin: 0 0 16px; padding-left: 0; list-style: none; display: grid; gap: 9px; }
.doc-body li {
  position: relative;
  padding-left: 22px;
  color: var(--muted);
  font-size: .95rem;
  line-height: 1.72;
}
.doc-body li::before {
  content: '';
  position: absolute;
  left: 4px; top: .66em;
  width: 7px; height: 7px;
  border-radius: 2px;
  background: var(--brand);
  opacity: .45;
  transform: rotate(45deg);
}
.doc-body ol { counter-reset: n; }
.doc-body ol li { counter-increment: n; }
.doc-body ol li::before {
  content: counter(n);
  width: auto; height: auto;
  background: none;
  transform: none;
  left: 0; top: 0;
  font-family: var(--font-mono);
  font-size: .78rem;
  color: var(--brand-2);
}
.doc-body strong { color: var(--ink-2); font-weight: 600; }
.doc-body code {
  font-family: var(--font-mono);
  font-size: .85em;
  background: var(--paper-3);
  border: 1px solid var(--line);
  border-radius: 5px;
  padding: 1px 6px;
  color: var(--brand-2);
}
.doc-body a { color: var(--brand-2); border-bottom: 1px solid var(--brand-line); }
.doc-body a:hover { border-bottom-color: currentColor; }

.callout {
  margin: 26px 0;
  padding: 20px 24px;
  border-radius: var(--r-m);
  background: var(--brand-soft);
  border: 1px solid var(--brand-line);
  font-size: .92rem;
  color: var(--ink-2);
}
[data-theme='dark'] .callout { color: #f1f1ef; }
.callout b { color: var(--brand-2); }

.toc {
  margin: 0 0 40px;
  padding: 22px 26px;
  background: var(--paper-2);
  border: 1px solid var(--line);
  border-radius: var(--r-m);
}
.toc-title {
  font-family: var(--font-mono);
  font-size: .7rem;
  letter-spacing: .14em;
  text-transform: uppercase;
  color: var(--faint);
  margin-bottom: 14px;
}
.toc ol { list-style: none; display: grid; gap: 8px; counter-reset: t; }
.toc li { counter-increment: t; }
.toc a {
  display: flex;
  gap: 12px;
  font-size: .91rem;
  color: var(--muted);
  transition: color .16s ease;
}
.toc a::before {
  content: counter(t, decimal-leading-zero);
  font-family: var(--font-mono);
  font-size: .74rem;
  color: var(--brand);
  padding-top: .15em;
}
.toc a:hover { color: var(--brand-2); }

/* --------------------------------------------------------- 表格 / 样式 */
.table-scroll { overflow-x: auto; margin: 22px 0; border: 1px solid var(--line); border-radius: var(--r-m); }
table { width: 100%; border-collapse: collapse; font-size: .89rem; min-width: 480px; }
th, td { padding: 13px 18px; text-align: left; border-bottom: 1px solid var(--line); }
th {
  background: var(--paper-2);
  font-family: var(--font-mono);
  font-size: .7rem;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--faint);
  font-weight: 500;
}
td { color: var(--muted); }
tbody tr:last-child td { border-bottom: 0; }
td strong { color: var(--ink-2); }

/* ---------------------------------------------------------------- 页脚 */
.footer {
  background: var(--paper-2);
  border-top: 1px solid var(--line);
  padding-block: clamp(48px, 6vw, 76px) 34px;
}
.footer-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.5fr) repeat(3, minmax(0, 1fr));
  gap: clamp(28px, 4vw, 56px);
}
.footer-brand { display: flex; gap: 13px; align-items: flex-start; }
.footer-brand img { width: 44px; height: 44px; border-radius: 12px; box-shadow: var(--shadow-s); flex: none; }
.footer-brand b { display: block; color: var(--ink); font-size: 1rem; margin-bottom: 7px; }
.footer-brand p { font-size: .86rem; color: var(--muted); max-width: 32ch; line-height: 1.7; }
.footer h4 {
  font-family: var(--font-mono);
  font-size: .7rem;
  letter-spacing: .13em;
  text-transform: uppercase;
  color: var(--faint);
  font-weight: 500;
  margin-bottom: 16px;
}
.footer ul { list-style: none; display: grid; gap: 10px; }
.footer ul a { font-size: .89rem; color: var(--muted); transition: color .16s ease; }
.footer ul a:hover { color: var(--brand-2); }
.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  gap: 12px 24px;
  align-items: center;
  justify-content: space-between;
  margin-top: clamp(38px, 5vw, 60px);
  padding-top: 26px;
  border-top: 1px solid var(--line);
  font-size: .8rem;
  color: var(--faint);
}
.footer-bottom p { max-width: 68ch; line-height: 1.7; }
.footer-bottom a { color: var(--muted); border-bottom: 1px solid var(--line-2); }
.footer-bottom a:hover { color: var(--brand-2); border-bottom-color: currentColor; }

/* -------------------------------------------------------------- 动效 */
.reveal {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity .7s cubic-bezier(.2,.7,.3,1), transform .7s cubic-bezier(.2,.7,.3,1);
  transition-delay: var(--d, 0ms);
}
.reveal.is-in { opacity: 1; transform: none; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: .001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .001ms !important;
  }
  .reveal { opacity: 1; transform: none; }
}

/* 回到顶部 */
.to-top {
  position: fixed;
  right: 22px; bottom: 22px;
  z-index: 50;
  display: grid;
  place-items: center;
  width: 42px; height: 42px;
  border-radius: 999px;
  border: 1px solid var(--line-2);
  background: color-mix(in srgb, var(--card) 86%, transparent);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  color: var(--muted);
  cursor: pointer;
  box-shadow: var(--shadow-m);
  opacity: 0;
  transform: translateY(10px);
  pointer-events: none;
  transition: opacity .25s ease, transform .25s ease, color .16s ease;
}
.to-top.is-on { opacity: 1; transform: none; pointer-events: auto; }
.to-top:hover { color: var(--brand-2); }
.to-top svg { width: 17px; height: 17px; }

/* 跳过导航 */
.skip {
  position: absolute;
  left: -9999px;
  top: 8px;
  z-index: 100;
  padding: 10px 18px;
  background: var(--brand);
  color: #fff;
  border-radius: 999px;
  font-size: .85rem;
}
.skip:focus { left: 16px; }

/* ------------------------------------------------------------ 响应式 */
@media (max-width: 1024px) {
  .hero-grid { grid-template-columns: 1fr; }
  .hero-visual { margin-top: 18px; }
  .gallery { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .g-4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .g-3 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer-brand { grid-column: 1 / -1; }
}

@media (max-width: 760px) {
  .nav-links { display: none; }
  .nav-links.is-open {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 68px; left: var(--pad); right: var(--pad);
    margin: 0;
    padding: 10px;
    background: var(--card);
    border: 1px solid var(--line);
    border-radius: var(--r-m);
    box-shadow: var(--shadow-m);
  }
  .nav-burger { display: grid; }
  .nav-end { margin-left: auto; }
  .hero { padding-block: 34px 48px; }
  .float-card { display: none; }
  .stat-strip { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .g-2, .g-3, .g-4, .g-2-1 { grid-template-columns: 1fr; }
  .gallery { grid-template-columns: 1fr; }
  .dl-grid { grid-template-columns: 1fr; }
  .split-theme { grid-template-columns: 1fr; }
  .theme-panel.is-active { grid-template-columns: 1fr; }
  .theme-shot { width: min(220px, 60vw); margin-inline: auto; }
  .tl-item { grid-template-columns: 1fr; gap: 12px; }
  .step { grid-template-columns: 28px minmax(0, 1fr); gap: 14px; }
  .footer-grid { grid-template-columns: 1fr; }
  .footer-brand { grid-column: auto; }
  .section-head h2 { max-width: none; }
  .phone { transform: none; }
  .theme-tabs { width: 100%; overflow-x: auto; }
  .theme-tabs button { flex: 1 0 auto; }
}

@media (max-width: 420px) {
  .btn { padding: 12px 18px; font-size: .9rem; }
  .hero .btn-row .btn { flex: 1 1 100%; }
}