/* ============================================================
   58个人学习 · 站点样式
   设计基准：Apple 官网设计系统
     · 单一强调色 Apple Blue #0071e3（只用于交互元素）
     · 黑白灰节奏：黑底沉浸区 / 浅灰 #f5f5f7 信息区 交替
     · 排版：SF Pro 字系（系统字体回退），标题行高 1.07，全尺寸负字距
     · 最大内容宽 980px，8px 间距基数
   ============================================================ */

:root{
  --black:#000000;
  --gray:#f5f5f7;
  --ink:#1d1d1f;
  --ink80:rgba(0,0,0,.8);
  --ink48:rgba(0,0,0,.48);
  --line:#d2d2d7;
  --blue:#0071e3;
  --blue-hover:#0077ed;
  --blue-link:#0066cc;
  --blue-dark:#2997ff;
  --shadow:3px 5px 30px rgba(0,0,0,.22);
  --maxw:980px;
  --nav-h:48px;
  --r-lg:12px;
  --r-sm:8px;
  --pill:980px;
}

*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{
  margin:0;
  padding-top:var(--nav-h);
  font-family:system-ui,-apple-system,"SF Pro Text","PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;
  font-size:17px;
  line-height:1.47;
  letter-spacing:-.374px;
  color:var(--ink);
  background:#fff;
  -webkit-font-smoothing:antialiased;
}
img,video{max-width:100%;display:block}
a{color:var(--blue-link);text-decoration:none}
a:hover{text-decoration:underline}
.wrap{max-width:var(--maxw);margin:0 auto;padding:0 22px}

/* ---------------- 导航：深色玻璃（Apple 标志性） ---------------- */
.nav{
  position:fixed;top:0;left:0;right:0;z-index:50;
  height:var(--nav-h);
  background:rgba(0,0,0,.8);
  -webkit-backdrop-filter:saturate(180%) blur(20px);
  backdrop-filter:saturate(180%) blur(20px);
}
.nav .wrap{height:100%;display:flex;align-items:center;justify-content:space-between;gap:16px}
.brand{color:#fff;font-size:17px;font-weight:600;letter-spacing:-.374px;white-space:nowrap}
.brand span{font-weight:400;color:rgba(255,255,255,.86)}
.brand:hover{text-decoration:none;opacity:.86}
.menu{display:flex;gap:24px;overflow-x:auto;scrollbar-width:none;-ms-overflow-style:none}
.menu::-webkit-scrollbar{display:none}
.menu a{color:rgba(255,255,255,.82);font-size:12px;letter-spacing:-.12px;white-space:nowrap}
.menu a:hover{color:#fff;text-decoration:none}

/* ---------------- 首屏：黑底沉浸区 ---------------- */
.hero{background:var(--black);color:#fff;text-align:center;padding:96px 22px 104px}
.hero .eyebrow{
  margin:0 0 16px;font-size:21px;font-weight:400;line-height:1.19;
  letter-spacing:.231px;color:rgba(255,255,255,.62);
}
.hero h1{margin:0;font-size:56px;font-weight:600;line-height:1.07;letter-spacing:-.28px}
.hero .lead{
  text-wrap:pretty;margin:22px auto 0;max-width:620px;font-size:21px;font-weight:400;
  line-height:1.4;letter-spacing:.231px;color:rgba(255,255,255,.82);
}
.btnrow{margin:30px 0 0;display:flex;gap:26px;justify-content:center;align-items:center;flex-wrap:wrap}
.btn{
  display:inline-block;background:var(--blue);color:#fff;
  border-radius:var(--pill);padding:12px 25px;
  font-size:17px;line-height:1.2;letter-spacing:-.374px;
  transition:background .2s ease;
}
.btn:hover{background:var(--blue-hover);color:#fff;text-decoration:none}
.link-arrow{color:var(--blue-dark);font-size:17px;letter-spacing:-.374px}
.tagrow{margin:44px 0 0;display:flex;gap:8px;justify-content:center;flex-wrap:wrap}
.tag{
  font-size:12px;letter-spacing:-.12px;color:rgba(255,255,255,.86);
  background:rgba(255,255,255,.12);border-radius:var(--pill);padding:6px 14px;
}

.hero .lead,.sec-sub,.about-lead,.cinfo p,.feat p,#notes .card p,.card.shot .cap{text-wrap:pretty}

/* ---------------- 区块节奏：黑 → 浅灰 → 白 交替 ---------------- */
.band{padding:84px 0}
.band.gray{background:var(--gray)}
.band h2.sec{margin:0;font-size:40px;font-weight:600;line-height:1.1;letter-spacing:0}
.sec-sub{
  text-wrap:pretty;margin:12px 0 44px;font-size:17px;line-height:1.47;
  letter-spacing:-.374px;color:var(--ink80);max-width:660px;
}

/* ---------------- 特点：白卡铺在浅灰底上（4 等分） ---------------- */
.features{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:20px}
.feat{background:#fff;border-radius:var(--r-lg);padding:30px 26px 32px}
.feat .big{margin:0 0 12px;font-size:40px;font-weight:600;line-height:1.05;letter-spacing:-.28px}
.feat h3{margin:0 0 8px;font-size:17px;font-weight:600;line-height:1.24;letter-spacing:-.374px}
.feat p{margin:0;font-size:14px;line-height:1.43;letter-spacing:-.224px;color:var(--ink80)}

/* ---------------- 作品：三列等高磁贴，图片不裁切 ---------------- */
.grid.works{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:20px}
.card.shot{
  margin:0;display:flex;flex-direction:column;
  background:var(--gray);border-radius:var(--r-lg);padding:22px 22px 0;
}
.shot-media,.vwrap{position:relative;height:300px;display:flex;align-items:center;justify-content:center}
.shot-media img,.vwrap video{width:100%;height:100%;max-width:100%;object-fit:contain;border-radius:6px}
.vwrap video{background:#000}
.card.shot .cap{
  margin:20px -22px 0;padding:0 22px 22px;min-height:54px;
  font-size:12px;line-height:1.33;letter-spacing:-.12px;color:var(--ink48);text-align:center;
}
/* 播放控件：Apple media control */
.vplay{
  position:absolute;width:56px;height:56px;border:0;border-radius:50%;cursor:pointer;
  background:rgba(210,210,215,.64);
  display:flex;align-items:center;justify-content:center;
  transition:transform .2s ease,opacity .2s ease;
}
.vplay svg{width:22px;height:22px;fill:rgba(0,0,0,.75);margin-left:3px}
.vplay:hover{transform:scale(1.06)}
.vplay.hide{opacity:0;pointer-events:none}

/* ---------------- 笔记：白卡铺在浅灰底上（2 等分） ---------------- */
#notes .grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:20px}
#notes .grid .card.wide{grid-column:1/-1}
#notes .card{background:#fff;border-radius:var(--r-lg);padding:28px 26px 24px}
#notes h3{margin:0 0 10px;font-size:21px;font-weight:600;line-height:1.3;letter-spacing:.231px}
#notes h3 a{color:var(--ink)}
#notes h3 a:hover{color:var(--blue-link);text-decoration:none}
#notes .card p{margin:0 0 20px;font-size:14px;line-height:1.43;letter-spacing:-.224px;color:var(--ink80)}
.meta{display:flex;gap:14px;flex-wrap:wrap;font-size:12px;letter-spacing:-.12px;color:var(--ink48)}

/* ---------------- 参数速查：细线表格 ---------------- */
.tablecard{background:var(--gray);border-radius:var(--r-lg);padding:6px 24px 10px;overflow-x:auto}
table{width:100%;border-collapse:collapse;font-size:14px;letter-spacing:-.224px}
th{
  text-align:left;font-weight:600;font-size:12px;letter-spacing:-.12px;color:var(--ink48);
  padding:18px 12px 12px;border-bottom:1px solid var(--line);white-space:nowrap;
}
th:first-child,td:first-child{padding-left:0}
th:last-child,td:last-child{padding-right:0}
td{padding:16px 12px;border-bottom:1px solid var(--line);vertical-align:top}
td:nth-child(3),td:nth-child(4){white-space:nowrap}
tbody tr:last-child td,table tr:last-child td{border-bottom:none}

/* ---------------- 关于：左文右码，二维码固定尺寸 ---------------- */
.about-card{background:#fff;border-radius:var(--r-lg);padding:34px 34px 30px}
.about-lead{margin:0 0 26px;max-width:640px;font-size:17px;line-height:1.47;letter-spacing:-.374px;color:var(--ink80)}
.about-inner{
  display:grid;grid-template-columns:minmax(0,1fr) 168px;gap:44px;align-items:start;
}
.ctitle{margin:0 0 10px;font-size:21px;font-weight:600;line-height:1.19;letter-spacing:.231px}
.cinfo p{margin:0 0 16px;max-width:620px;font-size:14px;line-height:1.43;letter-spacing:-.224px;color:var(--ink80)}
.cinfo b{color:var(--ink)}
.mail{font-size:17px;letter-spacing:-.374px}
.about-qr{display:flex;flex-direction:column;align-items:center}
.qr{width:148px;height:148px;border-radius:6px;display:block}
.qr-cap{margin:12px 0 0;font-size:12px;line-height:1.5;letter-spacing:-.12px;color:#6e6e73;text-align:center}
.cap-mobile{display:none}

/* ---------------- 页脚 ---------------- */
.site{
  background:var(--gray);border-top:1px solid var(--line);
  padding:24px 0;font-size:12px;letter-spacing:-.12px;color:var(--ink48);
}
.site .wrap{display:flex;gap:6px 12px;flex-wrap:wrap;align-items:center;justify-content:center}

/* ---------------- 笔记正文页 ---------------- */
.post{max-width:720px;margin:0 auto;padding:60px 0 76px}
.post h1{margin:0 0 14px;font-size:40px;font-weight:600;line-height:1.1;letter-spacing:0}
.postmeta{margin:0 0 36px;font-size:14px;line-height:1.43;letter-spacing:-.224px;color:var(--ink48)}
.post h2{margin:48px 0 14px;font-size:28px;font-weight:600;line-height:1.14;letter-spacing:.196px}
.post p{margin:0 0 18px;font-size:17px;line-height:1.47}
.post ul,.post ol{margin:0 0 18px;padding-left:22px}
.post li{margin:0 0 8px}
.post img{border-radius:var(--r-sm)}
.post video{width:100%;border-radius:var(--r-sm);background:#000;margin:6px 0 18px}
.post code{
  font-family:ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,monospace;
  font-size:14px;letter-spacing:0;background:var(--gray);padding:2px 6px;border-radius:5px;
}
.post .tablecard{padding:6px 20px 10px;margin:0 0 20px}
.backlink{display:inline-block;margin-bottom:22px;font-size:14px;letter-spacing:-.224px}
.note{
  background:rgba(0,113,227,.08);border-radius:var(--r-sm);
  padding:16px 18px;margin:0 0 18px;font-size:14px;line-height:1.43;letter-spacing:-.224px;
}
.note p:last-child{margin-bottom:0}

/* ---------------- 响应式 ---------------- */
@media (max-width:1068px){
  .wrap{padding:0 20px}
}
@media (max-width:834px){
  .hero{padding:76px 20px 84px}
  .hero h1{font-size:44px}
  .band{padding:64px 0}
  .band h2.sec{font-size:32px}
  .features{grid-template-columns:repeat(2,minmax(0,1fr))}
  .grid.works{grid-template-columns:repeat(2,minmax(0,1fr))}
  #notes .grid{grid-template-columns:1fr}
}
@media (max-width:640px){
  .hero{padding:60px 18px 68px}
  .hero h1{font-size:34px;letter-spacing:-.2px}
  .hero .eyebrow{font-size:17px}
  .hero .lead{font-size:17px;letter-spacing:-.374px}
  .tagrow{margin-top:32px}
  .band{padding:56px 0}
  .band h2.sec{font-size:28px}
  .sec-sub{margin-bottom:32px}
  .features,.grid.works{grid-template-columns:1fr}
  .shot-media,.vwrap{height:240px}
  .about-card{padding:28px 22px}
  .about-inner{grid-template-columns:1fr;gap:32px}
  .about-qr{align-items:center}
  .site .sep{display:none}
  .cap-desktop{display:none}
  .cap-mobile{display:inline}
  .post{padding:40px 0 60px}
  .post h1{font-size:28px}
  .post h2{font-size:22px}
  .menu{gap:18px}
}