:root{--sky:#38bdf8;--sky-deep:#0ea5e9;--ink:#0f172a;--muted:#64748b;--line:#e2e8f0;}
  *{box-sizing:border-box;}
  html,body{margin:0;padding:0;}
  body{
    min-height:100vh;display:flex;flex-direction:column;background:#f1f5f9;color:var(--ink);
    font-family:"Noto Sans JP","Microsoft YaHei","PingFang SC",system-ui,-apple-system,sans-serif;
  }

  /* 区域编号 */
  .chip{position:absolute;top:-9px;right:-6px;z-index:6;font-size:10px;line-height:1;font-weight:700;color:#0369a1;
    background:#e0f2fe;border-radius:4px;padding:2px 4px;pointer-events:none;white-space:nowrap;}
  .cap{position:absolute;top:12px;left:50%;transform:translateX(-50%);z-index:6;font-size:11px;font-weight:700;
    letter-spacing:.08em;color:#94a3b8;pointer-events:none;}
  .toast{position:fixed;left:50%;bottom:40px;transform:translate(-50%,14px);z-index:99;background:rgba(15,23,42,.92);
    color:#fff;font-size:13px;padding:9px 18px;border-radius:999px;opacity:0;pointer-events:none;transition:.25s;}
  .toast.on{opacity:1;transform:translate(-50%,0);}

  /* ---------- 区域1：页眉（每页都有） ---------- */
  .r1{position:sticky;top:0;z-index:40;height:96px;flex:0 0 96px;display:flex;align-items:center;gap:14px;
    padding:0 26px;background:#fff;border-bottom:1px solid var(--line);}
  .r1 .logo{width:60px;height:60px;border-radius:12px;border:1px solid var(--line);display:grid;place-items:center;
    font-weight:900;color:var(--sky-deep);font-size:20px;flex:0 0 60px;text-decoration:none;position:relative;transition:.18s;}
  .r1 .logo:hover{border-color:var(--sky);}
  .r1 .sitname{font-weight:900;font-size:26px;letter-spacing:.04em;white-space:nowrap;color:var(--ink);
    text-decoration:none;position:relative;padding:4px 8px;transition:.18s;}
  .r1 .sitname:hover{color:var(--sky-deep);}
  .r1 .search{flex:1;display:flex;align-items:center;gap:8px;padding:6px 8px 6px 18px;background:#f8fafc;
    border:1px solid var(--line);border-radius:999px;position:relative;}
  .r1 .search input{border:0;outline:0;flex:1;font:inherit;font-size:14px;background:transparent;color:var(--ink);}
  .r1 .search button{border:0;border-radius:999px;background:var(--sky);color:#fff;font:inherit;font-weight:700;padding:8px 20px;cursor:pointer;}
  .r1 .search button:hover{background:var(--sky-deep);}
  .r1 .user{display:flex;flex-direction:column;align-items:center;gap:4px;margin-left:6px;}
  .r1 .avatar{width:54px;height:54px;border-radius:50%;border:2px solid var(--line);
    background:linear-gradient(135deg,#f8fafc,#e2e8f0);display:grid;place-items:center;font-size:22px;
    cursor:pointer;text-decoration:none;position:relative;color:var(--ink);}
  .r1 .uname{font-size:12px;color:#334155;background:#f1f5f9;border:1px solid var(--line);border-radius:6px;
    padding:2px 8px;cursor:pointer;text-decoration:none;position:relative;}
  .r1 .uname:hover{background:var(--sky);border-color:var(--sky);color:#fff;}

  /* ---------- 区域4：页脚（每页都有） ---------- */
  .r4{flex:0 0 auto;display:flex;align-items:center;gap:20px;padding:16px 26px;background:#fff;border-top:1px solid var(--line);}
  .r4 .logo{width:42px;height:42px;border-radius:9px;border:1px solid var(--line);display:grid;place-items:center;font-weight:900;color:var(--sky-deep);font-size:15px;flex:0 0 42px;text-decoration:none;}
  .r4 .sitname{font-size:17px;font-weight:900;text-decoration:none;color:var(--ink);}
  .r4 .beian{flex:1;font-size:12px;color:#475569;text-align:center;background:#f8fafc;border:1px solid var(--line);border-radius:9px;padding:10px;line-height:1.6;}
  .r4 .contact{font-size:12px;color:#475569;text-align:right;line-height:1.7;background:#f8fafc;border:1px solid var(--line);border-radius:9px;padding:10px 12px;}

  /* ---------- 区域d1：登录卡片 ---------- */
  .stage{flex:1;display:flex;align-items:center;justify-content:center;padding:40px 20px;}
  .d1{
    position:relative;width:100%;max-width:580px;background:#fff;border:1px solid var(--line);border-radius:18px;
    box-shadow:0 14px 40px rgba(15,23,42,.09);
    padding:112px 34px 82px;                       /* 上方给 d1.1/d1.2 留位，下方给 d1.8 留位 */
    display:flex;flex-direction:column;gap:18px;
  }

  /* d1.1 网站logo：贴左上角（加大） + d1.2 网站站名：置顶、紧邻、缩小 */
  .top{position:absolute;top:16px;left:16px;display:flex;align-items:flex-start;gap:10px;z-index:5;}
  .d11{
    position:relative;width:78px;height:78px;border-radius:14px;border:1px solid var(--line);background:#fff;
    display:grid;place-items:center;font-weight:900;color:var(--sky-deep);font-size:30px;text-decoration:none;
    flex:0 0 78px;transition:.18s;
  }
  .d11:hover{border-color:var(--sky);box-shadow:0 6px 16px rgba(15,23,42,.12);}
  .d12{
    position:relative;align-self:flex-start;font-weight:900;font-size:18px;letter-spacing:.03em;color:var(--ink);
    text-decoration:none;padding:2px 4px 2px 0;transition:.18s;
  }
  .d12:hover{color:var(--sky-deep);}

  /* d1.3 头像 */
  .d13-wrap{display:flex;justify-content:center;padding:2px 0;}
  .d13{
    position:relative;width:96px;height:96px;border-radius:50%;border:2px solid var(--line);
    background:linear-gradient(135deg,#f8fafc,#e2e8f0);display:grid;place-items:center;font-size:44px;transition:.25s;
  }
  .d13.has{border-color:var(--sky);box-shadow:0 0 0 6px rgba(56,189,248,.14);}

  /* d1.4~d1.7：输入栏（d1.5 / d1.7）居中且变窄；
     标签（d1.4 / d1.6）不参与居中，紧贴在输入栏左侧 */
  .row{display:flex;justify-content:center;}
  .inp-wrap{position:relative;flex:0 0 220px;}
  .lb{
    position:absolute;right:calc(100% + 12px);top:50%;transform:translateY(-50%);
    font-size:14px;font-weight:700;color:#334155;white-space:nowrap;
  }
  .inp{
    width:100%;font:inherit;font-size:14px;padding:11px 16px;border-radius:10px;
    border:1px solid var(--line);background:#f8fafc;outline:0;color:var(--ink);transition:.18s;
  }
  .inp::placeholder{color:#94a3b8;}
  .inp:focus{background:#fff;border-color:var(--sky);box-shadow:0 0 0 4px rgba(56,189,248,.15);}

  /* 登录按钮（文档未列出，为可用性补充；宽度与上面表单行一致并居中） */
  .submit{
    align-self:center;width:200px;font:inherit;font-weight:700;font-size:14px;padding:9px;border:0;
    border-radius:10px;cursor:pointer;background:var(--sky);color:#fff;transition:.18s;
  }
  .submit:hover{background:var(--sky-deep);}
  .submit:active{transform:scale(.99);}

  /* d1.8 帮助：贴右下角 */
  /* d1.8 帮助：不要框，只有文本 */
  .d18{
    position:absolute;right:18px;bottom:16px;z-index:5;font-size:13px;font-weight:700;color:#475569;
    text-decoration:none;background:#f8fafc;border:1px solid var(--line);border-radius:999px;padding:8px 20px;transition:.18s;
  }
  .d18:hover{background:#e0f2fe;border-color:var(--sky);color:#0369a1;}

  /* ---------- 注册页：邮箱验证码一行 ---------- */
  .otp-wrap{flex:0 0 340px;display:flex;align-items:center;gap:10px;}
  .otp-wrap .inp{flex:1;min-width:0;}
  .otp-btn{
    flex:0 0 auto;font:inherit;font-size:13px;font-weight:700;cursor:pointer;white-space:nowrap;
    color:#0369a1;background:#e0f2fe;border:1px solid #bae6fd;border-radius:8px;padding:9px 14px;transition:.18s;
  }
  .otp-btn:hover{background:var(--sky);border-color:var(--sky);color:#fff;}
  .otp-btn:disabled{cursor:not-allowed;}
  .otp-btn:disabled,
  .otp-btn:disabled:hover{opacity:.55;background:#e0f2fe;border-color:#bae6fd;color:#0369a1;}

  .tip{margin:0;font-size:12px;color:var(--muted);text-align:center;}

/* ================= 移动端适配（登录 / 注册页） ================= */
@media (max-width: 768px) {
  .stage { padding: 18px 14px; }
  .d1 { padding: 86px 20px 66px; border-radius: 14px; gap: 14px; }
  .d11 { width: 60px; height: 60px; font-size: 20px; }
  .d12 { font-size: 16px; }
  .d13 { width: 82px; height: 82px; font-size: 34px; }
  /* 标签移到输入框上方，输入框占满 */
  .row { display: block; }
  .lb { position: static; display: block; transform: none; margin: 0 0 6px 4px; font-size: 13px; }
  .inp-wrap { flex: 0 0 auto; width: 100%; }
  .submit { width: 100%; max-width: 100%; align-self: stretch; margin: 4px 0 2px; }
  .d18 { right: 16px; bottom: 14px; }
}


/* ================= 移动端适配（页眉 / 页脚） ================= */
@media (max-width: 1024px) {
  .r1 { height: auto !important; flex: 0 0 auto !important; flex-wrap: wrap; padding: 10px 14px; gap: 10px; }
  .r1 .logo { width: 46px; height: 46px; flex: 0 0 46px; font-size: 17px; border-radius: 10px; }
  .r1 .sitname { font-size: 20px; padding: 2px 6px; }
  .r1 .search { order: 3; flex: 1 0 100%; padding: 5px 6px 5px 14px; }
  .r1 .search input { font-size: 13.5px; }
  .r1 .search button { padding: 7px 16px; font-size: 13px; }
  .r1 .user { flex-direction: row; align-items: center; gap: 8px; margin-left: auto; }
  .r1 .avatar { width: 40px; height: 40px; font-size: 16px; }
  .r1 .uname { font-size: 11px; padding: 2px 6px; }
  .r4 { flex-wrap: wrap; padding: 14px; gap: 10px; }
  .r4 .logo { font-size: 18px; }
  .r4 .beian { flex: 1 0 100%; order: 3; text-align: left; }
  .r4 .contact { text-align: left; margin-left: auto; }
}
@media (max-width: 480px) {
  .r1 { padding: 8px 10px; gap: 8px; }
  .r1 .sitname { font-size: 17px; }
  .r1 .search { padding-left: 12px; }
  .r4 { font-size: 12px; }
}


/* ================= 移动端兜底：不允许横向溢出 ================= */
@media (max-width: 1024px) {
  html, body { max-width: 100%; overflow-x: hidden; }
  .r1 .search, .r1 .search input { min-width: 0; }
  .r4 { position: relative !important; margin-top: auto; }   /* 手机上页脚跟随内容：用 relative（不能用 static，否则背景层会铺满整页） */        /* 手机上页脚跟随内容，不吸在屏幕底部 */
  .r4 .beian, .r4 .contact { overflow-wrap: anywhere; }
  .card, .cards, .panel, .col, .row, .item, .msg, .post, .c13, .b2-scroll { min-width: 0; }
  .card .meta .t, .wall .msg, .post .ttl, .row h3, .row p,
  .card .cover .c-title, .paper h1 { overflow-wrap: anywhere; word-break: break-word; }
}