:root {
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --bg: #f1f5f9;
  --card: #ffffff;
  --text: #1e293b;
  --border: #e2e8f0;
  --danger: #c0392b;
  --success: #1d9d5e;
}

* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
}

/* Topbar */
.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: var(--primary);
  color: #fff;
  padding: 12px 24px;
}
.brand { font-weight: 700; font-size: 1.1rem; display: flex; align-items: center; gap: 8px; }
.brand-logo { width: 30px; height: 30px; border-radius: 7px; background: #fff; padding: 3px; object-fit: contain; box-shadow: 0 1px 3px rgba(0,0,0,.25); }
.nav-links { display: flex; gap: 16px; align-items: center; }
.nav-links a { color: #e0e7ff; text-decoration: none; padding: 4px 8px; border-radius: 6px; font-weight: 500; }
.nav-links a:hover, .nav-links a.active { background: rgba(255,255,255,.18); color: #fff; }
.nav-links .logout { color: #fecaca; }
.user-chip { background: rgba(255,255,255,.2); padding: 4px 10px; border-radius: 20px; font-size: .85rem; }

.content { max-width: 1000px; margin: 24px auto; padding: 0 16px; }
h1 { margin-top: 0; }
.subtitle { color: #64748b; }
.empty { color: #94a3b8; font-style: italic; }

/* Cards */
.card-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px,1fr)); gap: 16px; margin: 20px 0; }
.card {
  display: block; background: var(--card); border: 1px solid var(--border);
  border-radius: 12px; padding: 18px; text-decoration: none; color: var(--text);
  box-shadow: 0 1px 3px rgba(0,0,0,.06); transition: transform .1s, box-shadow .1s;
}
.card:hover { transform: translateY(-2px); box-shadow: 0 4px 12px rgba(0,0,0,.12); }
.card-title { font-weight: 700; font-size: 1.05rem; margin-bottom: 6px; }
.card-desc { color: #64748b; font-size: .9rem; margin-bottom: 10px; }
.card-action { color: var(--primary); font-weight: 600; font-size: .9rem; }
.card-main { display: block; text-decoration: none; color: var(--text); }
.card-detail { margin-top: 12px; padding-top: 10px; border-top: 1px dashed var(--border); font-size: .85rem; }
.detail-line { margin: 6px 0; color: #475569; }
.schedule-table.mini { width: 100%; margin: 6px 0; font-size: .82rem; }
.schedule-table.mini th, .schedule-table.mini td { padding: 4px 6px; text-align: left; }
.excl-chip { display: inline-block; background: #fdecea; color: #c0392b; border-radius: 6px; padding: 1px 6px; margin: 1px 2px; font-size: .78rem; }

/* Panels */
.panel { background: var(--card); border: 1px solid var(--border); border-radius: 12px; padding: 18px; margin: 18px 0; }
.panel h3 { margin-top: 0; }

/* Forms */
label { display: block; margin: 8px 0; font-weight: 500; color: #475569; }
input, select, button { padding: 8px 12px; border: 1px solid var(--border); border-radius: 8px; font-size: .95rem; }
input[type=time]{ font-family: monospace; }
button, .btn {
  background: var(--primary); color: #fff; border: none; cursor: pointer; font-weight: 600;
  padding: 9px 16px; border-radius: 8px; text-decoration: none; display: inline-block;
}
button:hover, .btn:hover { opacity: .92; }
.btn-primary { background: var(--primary); }
.btn { background: #64748b; }
.inline-form { display: flex; gap: 12px; flex-wrap: wrap; align-items: flex-end; }
.form-row { display: flex; gap: 14px; flex-wrap: wrap; margin-bottom: 12px; }
.form-row label { display: flex; flex-direction: column; gap: 4px; font-weight: 600; flex: 1; min-width: 200px; }
.form-row input { width: 100%; padding: 9px 10px; }
.form-actions { display: flex; gap: 10px; margin-top: 16px; }
.inline { display: inline; }
.inline button { background: #64748b; padding: 6px 10px; font-size: .8rem; }
.danger button { background: var(--danger); }
.checkbox { display: flex; align-items: center; gap: 8px; }
.checkbox input { width: auto; }

/* Tables */
.data-table { width: 100%; border-collapse: collapse; background: var(--card); border-radius: 10px; overflow: hidden; }
.data-table th, .data-table td { padding: 10px 12px; border-bottom: 1px solid var(--border); text-align: left; }
.data-table thead th { background: #f8fafc; font-weight: 600; }
.data-table tr.totals td { background: #eff6ff; font-weight: 700; }
.actions { display: flex; gap: 10px; align-items: center; }
.actions a { color: var(--primary); }
.schedule-table td.weekday { font-weight: 600; }
.hint { color: #94a3b8; font-size: .85rem; }
code { background: #eef2f7; padding: 2px 5px; border-radius: 4px; }

/* Encode */
.session-bar { margin: 16px 0; display: flex; gap: 16px; align-items: center; flex-wrap: wrap; }
.session-bar form { display: flex; gap: 12px; align-items: flex-end; flex-wrap: wrap; padding: 12px; background: var(--card); border: 1px solid var(--border); border-radius: 10px; }
.period-badge { background: #e0e7ff; color: var(--primary-dark); padding: 6px 14px; border-radius: 20px; font-weight: 600; }
.schedule-editor { display: flex; gap: 16px; align-items: flex-end; background: var(--card); border: 1px solid var(--border); padding: 14px; border-radius: 10px; margin: 14px 0; flex-wrap: wrap; }
.encode-table { width: 100%; border-collapse: collapse; background: var(--card); }
.encode-table th, .encode-table td { padding: 8px 10px; border: 1px solid var(--border); }
.encode-table select { width: 110px; }
.student-name { font-weight: 500; }
.hours-cell { font-weight: 700; }
tr.alert-row td { background: #fef9e7; }
.actions-bar { margin-top: 16px; }

/* Alerts */
.alert { padding: 12px 14px; border-radius: 8px; margin: 10px 0; }
.alert.success { background: #e6f7ee; color: var(--success); }
.alert.error { background: #fdecea; color: var(--danger); }
.alert-warning-box { background: #fef9e7; border: 1px solid #f5d76e; border-radius: 10px; padding: 14px; margin: 14px 0; }
.alert-warning-box div { margin: 6px 0; }
.filter-bar { display: flex; gap: 12px; align-items: flex-end; background: var(--card); padding: 14px; border-radius: 10px; border: 1px solid var(--border); margin-bottom: 16px; flex-wrap: wrap; }
.export-actions { margin: 16px 0; }

/* Login */
.login-body { display: flex; align-items: center; justify-content: center; min-height: 100vh; background: linear-gradient(135deg, #2563eb, #1d4ed8); }
.login-card { background: #fff; padding: 36px; border-radius: 16px; width: 100%; max-width: 380px; box-shadow: 0 10px 30px rgba(0,0,0,.2); text-align: center; }
.login-logo { width: 96px; height: 96px; object-fit: contain; margin-bottom: 12px; }
.login-card h1 { margin-top: 0; font-size: 1.4rem; }
.login-card .subtitle { margin-bottom: 20px; }
.login-card label { font-weight: 600; }
.login-card input { width: 100%; padding: 11px; margin-top: 4px; }
.login-card button { width: 100%; margin-top: 14px; padding: 12px; font-size: 1rem; }