feat: 简航 SimpleNav 个人网站导航系统（PHP + SQLite）

- 前台：搜索引擎切换+联想下拉、网格板块（常用/工具）、合集标签页
- 后台：初始化/登录、网站/板块/引擎增删改、上下移排序
- 添加网站自动抓取名称与图标（存储于服务器），支持自定义简称
- 一键全部更新（批量刷新图标+名称，保留自定义简称）
- 搜索联想服务端代理（必应/百度/谷歌/搜狗/360/DuckDuckGo）
- 零依赖：原生 CSS/JS，PDO SQLite

assets/css/admin.css

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+/* 简航 SimpleNav —— 后台样式 */
+body.admin { background: #eef0f3; color: #333; font-size: 14px; }
+.topbar {
+  display: flex; align-items: center; gap: 16px; padding: 0 20px; height: 56px;
+  background: #fff; box-shadow: 0 1px 4px rgba(0,0,0,.06); position: sticky; top: 0; z-index: 50;
+}
+.topbar .brand { font-size: 17px; font-weight: 700; }
+.topbar .brand a { color: #2F6BF7; }
+.topbar .brand span { color: #999; font-weight: 400; font-size: 13px; margin-left: 6px; }
+.topnav { display: flex; gap: 4px; flex: 1; }
+.topnav a { padding: 8px 14px; border-radius: 8px; color: #555; }
+.topnav a:hover { background: #f2f4f7; }
+.topnav a.active { background: #2F6BF7; color: #fff; }
+.topright { display: flex; align-items: center; gap: 10px; color: #666; }
+.wrap { max-width: 1140px; margin: 20px auto 60px; padding: 0 16px; }
+
+.card { background: #fff; border-radius: 12px; padding: 18px; margin-bottom: 18px; box-shadow: 0 2px 10px rgba(0,0,0,.04); }
+.card-head { display: flex; align-items: center; justify-content: space-between; margin-bottom: 14px; }
+.card-head h2 { font-size: 16px; margin: 0; }
+
+.grid-form { display: grid; grid-template-columns: 1fr 1fr; gap: 12px 16px; }
+.grid-form label { display: flex; flex-direction: column; font-size: 13px; color: #555; gap: 5px; }
+.grid-form label.chk { flex-direction: row; align-items: center; gap: 6px; }
+.grid-form .span2 { grid-column: 1 / -1; }
+.grid-form .row { display: flex; gap: 8px; }
+.grid-form .row input { flex: 1; }
+.grid-form input[type=text], .grid-form input[type=password], .grid-form select {
+  height: 38px; padding: 0 10px; border: 1px solid #d9dde3; border-radius: 8px; font-size: 14px; width: 100%;
+}
+.grid-form input:focus, .grid-form select:focus { outline: none; border-color: #2F6BF7; }
+.form-actions { display: flex; align-items: center; gap: 10px; }
+.hint { color: #999; font-size: 12px; }
+
+.btn { display: inline-flex; align-items: center; gap: 6px; height: 38px; padding: 0 16px; border: none; border-radius: 8px; cursor: pointer; font-size: 14px; }
+.btn.primary { background: #2F6BF7; color: #fff; }
+.btn.primary:hover { background: #2456cc; }
+.btn.ghost { background: #f2f4f7; color: #444; }
+.btn.ghost:hover { background: #e6e9ee; }
+.btn.block { width: 100%; justify-content: center; }
+
+.alert { padding: 10px 14px; border-radius: 8px; margin-bottom: 14px; font-size: 13px; }
+.alert.ok { background: #e8f6ee; color: #1a7f45; }
+.alert.err { background: #fdecec; color: #c0392b; }
+
+.tbl { width: 100%; border-collapse: collapse; font-size: 13px; }
+.tbl th, .tbl td { padding: 9px 8px; text-align: left; border-bottom: 1px solid #f0f1f3; vertical-align: middle; }
+.tbl th { color: #888; font-weight: 500; }
+.tbl tr:hover td { background: #fafbfc; }
+.tbl .muted { color: #999; }
+.tbl .ell { max-width: 240px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+.tbl .nowrap { white-space: nowrap; }
+.mini { width: 26px; height: 26px; border-radius: 6px; object-fit: contain; background: #f4f5f7; }
+.mini.letter { display: inline-flex; align-items: center; justify-content: center; color: #fff; font-size: 13px; }
+.inline { display: inline; }
+.ico-btn { border: none; background: #f2f4f7; width: 28px; height: 28px; border-radius: 6px; cursor: pointer; color: #555; margin: 0 1px; }
+.ico-btn:hover { background: #e6e9ee; }
+.ico-btn.danger { color: #c0392b; }
+.ok-dot { color: #1a7f45; font-size: 12px; }
+
+/* 登录页 */
+.login-wrap { min-height: 100vh; display: flex; align-items: center; justify-content: center; }
+.login-card { width: 340px; background: #fff; border-radius: 14px; padding: 30px 26px; box-shadow: 0 10px 30px rgba(0,0,0,.08); text-align: center; }
+.login-card h1 { font-size: 20px; margin: 8px 0 2px; }
+.login-card .sub { color: #999; font-size: 13px; margin: 0 0 18px; }
+.login-card input { width: 100%; height: 42px; margin-bottom: 12px; padding: 0 12px; border: 1px solid #d9dde3; border-radius: 8px; font-size: 14px; }
+.login-card input:focus { outline: none; border-color: #2F6BF7; }
+.login-card .btn { height: 42px; }
+.login-logo { width: 56px; height: 56px; }
+
+@media (max-width: 720px) {
+  .grid-form { grid-template-columns: 1fr; }
+  .topbar { flex-wrap: wrap; height: auto; padding: 10px 14px; }
+  .tbl .ell { max-width: 120px; }
+}

assets/css/style.css

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+/* 简航 SimpleNav —— 样式（复刻 n.yangyq.net 的灰底白卡片风格，去 Bootstrap 依赖） */
+:root { --primary: #2F6BF7; }
+* { box-sizing: border-box; }
+body {
+  margin: 0;
+  font-size: 14px;
+  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
+  background: #d8d9da;
+  color: #333;
+  overflow-x: hidden;
+}
+a { text-decoration: none; color: inherit; }
+.container { max-width: 1140px; margin: 50px auto 40px; padding: 0 15px; }
+
+/* ---------- 搜索 ---------- */
+.s-search { position: relative; z-index: 2000; margin-bottom: 10px; }
+.search-type { margin-bottom: 0; }
+.s-engine {
+  display: inline-block; padding: 6px 14px; margin: 0 2px 0 0;
+  background: rgba(255,255,255,.45); border-radius: 5px 5px 0 0; cursor: pointer;
+  font-size: 14px; line-height: 20px; transition: background .2s;
+}
+.s-engine span { color: var(--ec, #555); }
+.s-engine:hover { background: rgba(255,255,255,.75); }
+.s-engine.active { background: #fff; }
+#search-form { position: relative; }
+#search-text {
+  width: 100%; height: 50px; line-height: 50px; text-indent: 14px; font-size: 16px;
+  border: none; border-radius: 5px; background: #fff; outline: 0;
+  box-shadow: 0 0.5rem 0.625rem rgba(212,212,212,.3); transition: box-shadow .3s;
+}
+#search-text:focus { box-shadow: 0 0 24px 0 rgba(50,50,50,.08); }
+#search button.submit {
+  position: absolute; top: 7px; right: 7px; width: 60px; height: 36px;
+  background: none; border: 0; border-radius: 3px; cursor: pointer; outline: none;
+}
+#search button.submit::after {
+  content: ""; display: block; width: 16px; height: 16px; margin: 0 auto;
+  border: 2px solid #c9c9c9; border-radius: 50%; position: relative;
+}
+#search button.submit::before {
+  content: ""; position: absolute; right: 20px; bottom: 9px; width: 7px; height: 2px;
+  background: #c9c9c9; transform: rotate(45deg);
+}
+#word {
+  position: absolute; list-style: none; top: 55px; left: 0; width: 100%; margin: 0;
+  background: #fff; border-radius: 5px; z-index: 20000; padding: 10px;
+  box-shadow: 0 0 10px #bbb; display: none;
+}
+#word li { height: 35px; padding: 0 8px; line-height: 35px; cursor: pointer; font-size: 16px; border-radius: 5px; }
+#word li:hover { background: #eee; }
+
+/* ---------- 板块卡片 ---------- */
+.mylist {
+  list-style: none; margin: 16px 0; padding: 12px 20px;
+  background: #fff; border-radius: 15px; box-shadow: 0 0.5rem 0.625rem rgba(212,212,212,.3);
+  display: flex; flex-wrap: wrap;
+}
+.mylist > li.title {
+  width: 100%; margin: 0 0 10px; padding: 0 0 8px 10px; height: auto;
+  font-size: 16px; font-weight: 600; line-height: 24px;
+  border-bottom: 1px solid #eee; position: relative;
+}
+.mylist > li.title::before {
+  content: ""; position: absolute; left: 0; top: 3px; width: 4px; height: 18px;
+  background: var(--primary); border-radius: 2px;
+}
+.mylist > li.site { margin: 2px; }
+.mylist li.site a {
+  display: flex; flex-direction: column; align-items: center; width: 100px; padding: 10px 4px;
+  border-radius: 10px; transition: background .2s;
+}
+.mylist li.site a:hover { background: #f0f1f2; }
+.mylist li.site .icon { width: 45px; height: 45px; border-radius: 10px; background: #fff; object-fit: contain; }
+.mylist li.site .ico-letter {
+  width: 45px; height: 45px; border-radius: 10px; color: #fff; font-size: 20px; font-weight: 600;
+  display: flex; align-items: center; justify-content: center;
+}
+.mylist li.site .name {
+  width: 100%; margin-top: 6px; text-align: center; font-size: 13px; color: #555;
+  white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
+}
+
+/* ---------- 合集标签页 ---------- */
+.collections { margin: 16px 0; }
+.collections-title {
+  font-size: 16px; font-weight: 600; padding: 0 0 8px 10px; margin: 0 0 10px;
+  position: relative;
+}
+.collections-title::before {
+  content: ""; position: absolute; left: 0; top: 3px; width: 4px; height: 18px;
+  background: var(--primary); border-radius: 2px;
+}
+.tabs { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 10px; }
+.tabs .tab {
+  border: none; background: rgba(255,255,255,.65); color: #444; cursor: pointer;
+  padding: 7px 16px; border-radius: 18px; font-size: 14px; transition: all .2s;
+}
+.tabs .tab:hover { background: #fff; }
+.tabs .tab.active { background: var(--primary); color: #fff; }
+.tab-panel { display: none; }
+.tab-panel.active { display: flex; }
+
+/* ---------- 页脚 ---------- */
+.foot { text-align: center; color: #8a8a8a; font-size: 12px; margin: 24px 0 0; }
+.foot a { color: #8a8a8a; }
+.foot a:hover { color: var(--primary); }
+
+/* ---------- 响应式 ---------- */
+@media (max-width: 767px) {
+  .container { margin-top: 24px; }
+  .mylist { border-radius: 10px; padding: 10px 12px; }
+  .mylist li.site a { width: 25%; }
+  .mylist li.site .icon, .mylist li.site .ico-letter { width: 40px; height: 40px; }
+  .mylist li.site .name { font-size: 12px; }
+}