/* 学习站外壳：首页、登录、我的账号、后台共用。纸 + 墨的安静书房感，跟随系统深浅色。 */
:root {
  --bg: #f6f2ea;
  --card: #fffdf8;
  --ink: #23201b;
  --muted: #776f62;
  --line: #e2dacb;
  --mark: #a8452f;
  --mark-soft: #f3e3db;
  --ok: #3f7a52;
  --shadow: 0 1px 2px rgba(35, 32, 27, 0.05), 0 8px 24px rgba(35, 32, 27, 0.06);
  --serif: 'Songti SC', 'Noto Serif SC', 'Source Han Serif SC', STSong, SimSun, serif;
  --sans: -apple-system, BlinkMacSystemFont, 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #1b1916;
    --card: #24211d;
    --ink: #ece5d8;
    --muted: #a49b8c;
    --line: #38332c;
    --mark: #e07b62;
    --mark-soft: #3a2a24;
    --ok: #7fbf8f;
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.3), 0 8px 24px rgba(0, 0, 0, 0.25);
    color-scheme: dark;
  }
}
* { box-sizing: border-box; }
[hidden] { display: none !important; }
html, body { margin: 0; }
body {
  background: var(--bg);
  color: var(--ink);
  font: 15px/1.65 var(--sans);
  min-height: 100dvh;
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; }
.wrap { max-width: 980px; margin: 0 auto; padding: 0 16px; }

.top {
  display: flex; align-items: center; justify-content: space-between; gap: 12px;
  padding: max(18px, env(safe-area-inset-top)) 0 18px;
}
.brand { display: flex; align-items: baseline; gap: 10px; text-decoration: none; }
.brand b { font: 700 24px/1 var(--serif); letter-spacing: 0.06em; }
.seal {
  display: inline-grid; place-items: center; width: 30px; height: 30px; border-radius: 6px;
  background: var(--mark); color: #fff; font: 700 16px/1 var(--serif); align-self: center;
}
.chip {
  display: inline-flex; align-items: center; gap: 6px; min-height: 36px; padding: 0 14px;
  border: 1px solid var(--line); border-radius: 999px; background: var(--card);
  text-decoration: none; font-size: 14px; white-space: nowrap;
}
.chip:hover { border-color: var(--mark); }

.hero { padding: 18px 0 8px; }
.hero h1 { font: 700 clamp(26px, 5vw, 34px)/1.25 var(--serif); margin: 0 0 6px; letter-spacing: 0.02em; }
.hero p { margin: 0; color: var(--muted); }

.notice {
  margin: 16px 0 0; padding: 12px 14px; border-radius: 10px;
  background: var(--mark-soft); border: 1px solid var(--line); font-size: 14px;
}

.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 14px; padding: 22px 0 40px; }
.card {
  position: relative; display: flex; gap: 14px; align-items: flex-start; padding: 18px;
  background: var(--card); border: 1px solid var(--line); border-radius: 14px;
  box-shadow: var(--shadow); text-decoration: none; transition: transform 0.15s, border-color 0.15s;
  min-height: 108px;
}
a.card:hover { transform: translateY(-2px); border-color: var(--mark); }
.card .ic {
  flex: none; width: 48px; height: 48px; display: grid; place-items: center; font-size: 26px;
  border-radius: 12px; background: var(--bg); border: 1px solid var(--line);
}
.card h3 { margin: 0 0 4px; font: 700 17px/1.35 var(--serif); }
.card p { margin: 0; color: var(--muted); font-size: 13.5px; line-height: 1.55; }
.card.off { opacity: 0.6; }
.card .tag {
  position: absolute; top: 12px; right: 12px; font-size: 12px; color: var(--muted);
  border: 1px solid var(--line); border-radius: 999px; padding: 1px 8px; background: var(--bg);
}
.card.feature { grid-column: 1 / -1; }
@media (min-width: 640px) {
  .card.feature { padding: 24px; }
  .card.feature .ic { width: 64px; height: 64px; font-size: 34px; }
  .card.feature h3 { font-size: 22px; }
}

/* 表单 */
.panel {
  max-width: 420px; margin: 24px auto 60px; padding: 26px 22px; background: var(--card);
  border: 1px solid var(--line); border-radius: 16px; box-shadow: var(--shadow);
}
.panel h2 { margin: 0 0 4px; font: 700 22px/1.3 var(--serif); }
.panel .sub { margin: 0 0 18px; color: var(--muted); font-size: 14px; }
label { display: block; margin: 12px 0 0; font-size: 13px; color: var(--muted); }
input, select, textarea {
  width: 100%; margin-top: 5px; min-height: 44px; padding: 10px 12px; font: 16px/1.4 var(--sans);
  color: var(--ink); background: var(--bg); border: 1px solid var(--line); border-radius: 10px;
}
input:focus, select:focus, textarea:focus { outline: 2px solid var(--mark); outline-offset: 1px; border-color: transparent; }
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 6px; min-height: 44px;
  padding: 0 18px; border-radius: 10px; border: 1px solid var(--mark); background: var(--mark);
  color: #fff; font: 600 15px/1 var(--sans); cursor: pointer; text-decoration: none;
}
.btn.ghost { background: transparent; color: var(--ink); border-color: var(--line); }
.btn.small { min-height: 32px; padding: 0 10px; font-size: 13px; border-radius: 8px; }
.btn:disabled { opacity: 0.5; cursor: default; }
.btn.block { width: 100%; margin-top: 18px; }
.links { display: flex; justify-content: space-between; gap: 10px; margin-top: 14px; font-size: 14px; color: var(--muted); }
.err { margin: 12px 0 0; color: var(--mark); font-size: 14px; min-height: 1em; }
.okmsg { color: var(--ok); }
.row { display: flex; gap: 10px; flex-wrap: wrap; align-items: center; }
hr { border: 0; border-top: 1px solid var(--line); margin: 22px 0; }

.foot { padding: 20px 0 max(24px, env(safe-area-inset-bottom)); color: var(--muted); font-size: 12.5px; text-align: center; }