:root {
  --bg: #f6f4ef;
  --surface: #ffffff;
  --surface-2: #f0ede6;
  --ink: #1d2321;
  --ink-2: #55605b;
  --line: #dcd7cc;
  --brand: #1f6f5c;
  --brand-ink: #ffffff;
  --brand-soft: #dcefe8;
  --ok: #1f7a4d;
  --ok-soft: #e1f3e8;
  --bad: #b4372f;
  --bad-soft: #fbe5e2;
  --warn: #a86a00;
  --warn-soft: #fdf1d8;
  --radius: 14px;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.05), 0 4px 16px rgba(0, 0, 0, 0.05);
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #141816;
    --surface: #1c211f;
    --surface-2: #242a27;
    --ink: #e8ece9;
    --ink-2: #9fa9a4;
    --line: #333b37;
    --brand: #5cc4a6;
    --brand-ink: #0d1f19;
    --brand-soft: #1f3a32;
    --ok: #5fd394;
    --ok-soft: #1b3326;
    --bad: #f08a80;
    --bad-soft: #3a1f1c;
    --warn: #f0bf5a;
    --warn-soft: #3a2f17;
    --shadow: none;
  }
}

* { box-sizing: border-box; }
html, body { margin: 0; }
body {
  background: var(--bg);
  color: var(--ink);
  font: 16px/1.55 "Be Vietnam Pro", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
}

.wrap { max-width: 860px; margin: 0 auto; padding: 20px 16px 64px; }

header.top {
  max-width: 860px;
  margin: 0 auto;
  padding: 14px 16px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
  border-bottom: 1px solid var(--line);
}
.brand { display: flex; align-items: center; gap: 10px; }
.logo {
  width: 36px;
  height: 36px;
  border-radius: 10px;
  background: var(--brand);
  color: var(--brand-ink);
  display: grid;
  place-items: center;
  font-weight: 700;
  flex: none;
}
h1 { font-size: 20px; margin: 0; letter-spacing: -0.01em; }
.topnav { align-items: center; gap: 16px; }
.topnav a { color: var(--ink-2); text-decoration: none; font-weight: 500; }
.topnav a:hover { color: var(--ink); }

.card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 20px;
  box-shadow: var(--shadow);
  margin-bottom: 16px;
}
h2 { font-size: 17px; margin: 0 0 12px; }
h3 { font-size: 15px; margin: 16px 0 8px; color: var(--ink-2); font-weight: 600; }
.muted { color: var(--ink-2); }
.small { font-size: 13px; }

button, .btn {
  font: inherit;
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--ink);
  border-radius: 10px;
  padding: 9px 16px;
  cursor: pointer;
  font-weight: 500;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  text-decoration: none;
}
button:hover, .btn:hover { border-color: var(--ink-2); }
button:disabled { opacity: 0.45; cursor: not-allowed; }
.primary { background: var(--brand); color: var(--brand-ink); border-color: var(--brand); }
.primary:hover { filter: brightness(1.05); border-color: var(--brand); }
.ghost { background: transparent; border-color: transparent; color: var(--ink-2); }
.ghost:hover { color: var(--ink); border-color: var(--line); }

.row { display: flex; gap: 10px; flex-wrap: wrap; align-items: center; }

.drop {
  border: 2px dashed var(--line);
  border-radius: var(--radius);
  padding: 28px 16px;
  text-align: center;
  transition: 0.15s;
}
.drop.over { border-color: var(--brand); background: var(--brand-soft); }
.drop strong { display: block; font-size: 16px; margin-bottom: 4px; }

.stats { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 12px; }
.stat { background: var(--surface-2); border-radius: 10px; padding: 8px 12px; font-size: 14px; }
.stat b { font-size: 17px; }

.alert { border-radius: 10px; padding: 10px 14px; font-size: 14px; margin-top: 12px; }
.alert.err { background: var(--bad-soft); color: var(--bad); }
.alert.info { background: var(--warn-soft); color: var(--warn); }
.alert.ok { background: var(--ok-soft); color: var(--ok); }

.tabs { display: inline-flex; border: 1px solid var(--line); border-radius: 10px; overflow: hidden; margin-top: 4px; }
.tabs .tab { border: 0; border-radius: 0; padding: 8px 14px; background: var(--surface); }
.tabs .tab.active { background: var(--brand); color: var(--brand-ink); }
.tab-panel { margin-top: 12px; }

label.field { display: flex; flex-direction: column; gap: 4px; font-size: 14px; color: var(--ink-2); margin-top: 12px; }
input[type="email"], input[type="number"], input[type="password"] {
  font: inherit;
  padding: 9px 12px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--surface);
  color: var(--ink);
}

.login-wrap { max-width: 420px; margin: 40px auto 0; }
.login-card h2 { margin-bottom: 4px; }
.login-footer { text-align: center; margin-top: 16px; }

.subject-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-top: 12px; }
.subject-card { margin-bottom: 0; }
.subject-card h3 { margin: 0 0 6px; color: var(--ink); font-size: 16px; }

@media (max-width: 640px) {
  header.top { padding: 12px 16px; }
  .subject-grid { grid-template-columns: 1fr; }
}