:root {
  --bg: #f7f9fc;
  --fg: #1a2332;
  --muted: #6b7280;
  --card: #ffffff;
  --border: #e5e7eb;
  --accent: #2563eb;
  --radius: 14px;
}

* { box-sizing: border-box; }
html, body { height: 100%; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
               "Helvetica Neue", Arial, sans-serif;
  background: var(--bg);
  color: var(--fg);
  line-height: 1.6;
  font-size: 18px;
  display: flex;
  flex-direction: column;
}

.site-header {
  padding: 16px 24px;
  background: var(--card);
  border-bottom: 1px solid var(--border);
}

.brand {
  font-weight: 600;
  font-size: 1.1rem;
  text-decoration: none;
  color: var(--fg);
}

.container {
  flex: 1;
  max-width: 900px;
  width: 100%;
  margin: 0 auto;
  padding: 32px 24px;
}

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  box-shadow: 0 1px 3px rgba(0,0,0,0.04);
}

h1 { font-size: 1.75rem; margin: 0 0 1rem; }
p { margin: 0.5rem 0; }
.muted { color: var(--muted); font-size: 0.95rem; }

.site-footer {
  padding: 16px 24px;
  text-align: center;
  color: var(--muted);
  font-size: 0.85rem;
  border-top: 1px solid var(--border);
}

/* --- Login form --- */
.login-card { max-width: 460px; margin: 0 auto; }

.form { display: flex; flex-direction: column; gap: 16px; margin-top: 20px; }
.form label { display: flex; flex-direction: column; gap: 6px; }
.form label span { font-size: 0.95rem; color: var(--muted); }

.form input[type="text"],
.form input[type="password"] {
  font: inherit;
  padding: 12px 14px;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: #fff;
  outline: none;
  transition: border-color 0.15s;
}
.form input:focus { border-color: var(--accent); }

.btn-primary {
  font: inherit;
  font-weight: 600;
  padding: 12px 16px;
  border: none;
  border-radius: 10px;
  background: var(--accent);
  color: #fff;
  cursor: pointer;
  transition: filter 0.15s;
}
.btn-primary:hover { filter: brightness(1.08); }

.btn-link {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.9rem;
}
.btn-link:hover { color: var(--fg); }

.error {
  color: #b91c1c;
  background: #fef2f2;
  border: 1px solid #fecaca;
  padding: 10px 12px;
  border-radius: 8px;
  font-size: 0.95rem;
  margin: 0;
}

.small { font-size: 0.85rem; }

/* --- Nav --- */
.site-header { display: flex; align-items: center; justify-content: space-between; }
.nav { display: flex; gap: 16px; align-items: center; font-size: 0.95rem; }
.nav-name { color: var(--muted); }
.nav-link { color: var(--fg); text-decoration: none; }
.nav-link:hover { color: var(--accent); }

/* --- Dashboard --- */
.week-card { margin-top: 20px; }
.week-card h2 { font-size: 1.25rem; margin: 0 0 6px; }

.session-list { list-style: none; padding: 0; margin: 16px 0 0; }
.session-list li { border-top: 1px solid var(--border); }
.session-list li:first-child { border-top: none; }
.session-list a {
  display: flex; justify-content: space-between; align-items: center;
  padding: 14px 4px; text-decoration: none; color: var(--fg);
  transition: color 0.15s;
}
.session-list a:hover { color: var(--accent); }
.session-title { font-weight: 500; }
.session-arrow { color: var(--muted); }

.goals { padding-left: 20px; margin: 12px 0 0; color: var(--muted); }
.goals li { margin: 4px 0; }

/* --- Tabs --- */
.tabs { display: flex; gap: 8px; margin: 28px 0 18px; }
.tab-btn {
  font: inherit; font-weight: 500;
  padding: 10px 18px; border: 1px solid var(--border);
  background: var(--card); border-radius: 999px;
  cursor: pointer; color: var(--muted);
  transition: all 0.15s;
}
.tab-btn.active { background: var(--accent); color: #fff; border-color: var(--accent); }
.tab-count {
  display: inline-block; margin-left: 6px;
  font-size: 0.8rem; opacity: 0.75;
}
.tab-panel { display: none; }
.tab-panel.active { display: block; }

/* --- Question card --- */
.question-card { margin-bottom: 20px; }
.question-header {
  display: flex; align-items: center; gap: 12px;
  margin-bottom: 14px;
}
.badge {
  font-size: 0.8rem; padding: 3px 10px; border-radius: 999px;
  background: #eef2ff; color: #3730a3; font-weight: 600;
}
.q-num { color: var(--muted); font-size: 0.9rem; }
.question-prompt { font-size: 1.1rem; margin-bottom: 14px; white-space: pre-wrap; }
.question-body { margin-bottom: 14px; }

.choices { list-style: none; padding: 0; margin: 0; }
.choices li { padding: 8px 0; }
.choices label { display: flex; gap: 10px; align-items: center; cursor: pointer; }
.choices input { margin: 0; }

.input-num, .input-wide, .input-essay, .input-sign {
  font: inherit; padding: 10px 12px;
  border: 1px solid var(--border); border-radius: 10px;
  background: #fff; outline: none;
}
.input-num { width: 140px; }
.input-wide { width: 100%; }
.input-essay { width: 100%; resize: vertical; font-family: inherit; }
.input-num:focus, .input-wide:focus, .input-essay:focus, .input-sign:focus {
  border-color: var(--accent);
}
.unit { margin-left: 8px; color: var(--muted); }

.fields { list-style: none; padding: 0; margin: 0; }
.fields li {
  display: flex; align-items: center; gap: 12px;
  padding: 8px 0;
}
.fields li span:first-child { min-width: 200px; }

.items { font-weight: 600; letter-spacing: 0.02em; }

.hint { margin: 12px 0; }
.hint summary { cursor: pointer; color: var(--accent); }
.hint p { margin: 8px 0 0; padding-left: 20px; color: var(--muted); }

.question-footer { margin-top: 16px; }
.question-footer .btn-primary:disabled { opacity: 0.5; cursor: not-allowed; }

.essay-label {
  display: block; margin: 12px 0 6px;
  font-weight: 500; font-size: 0.95rem;
}

/* --- Feedback --- */
.feedback-slot { margin-top: 14px; }
.feedback-slot:empty { margin-top: 0; }

.feedback {
  padding: 12px 14px;
  border-radius: 10px;
  font-weight: 500;
  display: flex;
  align-items: center;
  gap: 8px;
}
.feedback.fb-correct {
  background: #ecfdf5; color: #065f46; border: 1px solid #a7f3d0;
}
.feedback.fb-wrong {
  background: #fef2f2; color: #991b1b; border: 1px solid #fecaca;
}
.feedback.fb-neutral {
  background: #f9fafb; color: #374151; border: 1px solid var(--border);
}
.fb-icon { font-weight: 700; font-size: 1.1rem; }

.expected {
  margin-top: 10px; padding: 10px 14px;
  background: #fffbeb; border: 1px solid #fde68a; border-radius: 10px;
}
.explain {
  margin-top: 10px; padding: 10px 14px;
  background: #f0f9ff; border: 1px solid #bae6fd; border-radius: 10px;
  white-space: pre-wrap; font-size: 0.98rem;
}
.hint-inline {
  margin-top: 10px; padding: 10px 14px;
  background: #fefce8; border: 1px solid #fde68a; border-radius: 10px;
  font-size: 0.98rem;
}

/* HTMX indicator (optional) */
.htmx-request .btn-primary { opacity: 0.6; pointer-events: none; }

/* --- Submit bar --- */
.panel-form { display: contents; }  /* để form không tạo wrapper layout */

.submit-bar {
  margin-top: 28px;
  padding: 24px 0;
  text-align: center;
}
.btn-lg { padding: 14px 32px; font-size: 1.05rem; }
.submitted-note {
  display: inline-block;
  color: #065f46;
  background: #ecfdf5;
  border: 1px solid #a7f3d0;
  padding: 12px 20px;
  border-radius: 10px;
  font-weight: 500;
  margin: 0;
}

.question-body input:disabled,
.question-body textarea:disabled,
.question-body select:disabled {
  background: #f3f4f6;
  color: #4b5563;
  cursor: not-allowed;
}

/* --- Essay review --- */
.essay-review { margin-top: 16px; }

.solution-block {
  margin-top: 12px;
  padding: 16px 20px;
  background: #f0f9ff;
  border: 1px solid #bae6fd;
  border-radius: 12px;
}
.solution-block h4 { margin: 0 0 10px; font-size: 1rem; }
.solution-text {
  margin: 0;
  font-family: inherit;
  font-size: 0.98rem;
  white-space: pre-wrap;
  color: #0c4a6e;
  line-height: 1.7;
}

.rubric-block {
  margin-top: 16px;
  padding: 16px 20px;
  background: #fffbeb;
  border: 1px solid #fde68a;
  border-radius: 12px;
}
.rubric-block h4 { margin: 0 0 6px; font-size: 1rem; }
.rubric-list { list-style: none; padding: 0; margin: 12px 0; }
.rubric-list li { padding: 6px 0; }
.rubric-list label {
  display: flex; gap: 10px; align-items: flex-start;
  cursor: pointer; font-size: 0.98rem;
}
.rubric-list input { margin: 4px 0 0; }
.rubric-list input:disabled + span { color: #4b5563; }

.btn-secondary {
  font: inherit; font-weight: 500;
  padding: 10px 20px; border: none; border-radius: 10px;
  background: #f59e0b; color: #fff; cursor: pointer;
  transition: filter 0.15s;
}
.btn-secondary:hover { filter: brightness(1.08); }

.self-score-note {
  margin: 10px 0 0;
  padding: 10px 14px;
  background: #ecfdf5; color: #065f46;
  border: 1px solid #a7f3d0; border-radius: 10px;
  font-size: 0.95rem;
}

/* --- Teacher --- */
.filter-form {
  display: flex; gap: 16px; align-items: flex-end;
  flex-wrap: wrap;
}
.filter-form label { display: flex; flex-direction: column; gap: 6px; }
.filter-form select {
  font: inherit; padding: 8px 12px;
  border: 1px solid var(--border); border-radius: 10px;
  background: #fff;
}

.attempt-table {
  width: 100%; border-collapse: collapse;
  font-size: 0.98rem;
}
.attempt-table th, .attempt-table td {
  padding: 12px 10px; text-align: left;
  border-bottom: 1px solid var(--border);
}
.attempt-table th {
  font-weight: 600; color: var(--muted);
  font-size: 0.9rem; text-transform: uppercase;
  letter-spacing: 0.03em;
}
.attempt-table tr:last-child td { border-bottom: none; }

.q-id { font-family: ui-monospace, monospace; font-size: 0.9rem; color: #3730a3; }

.badge-pending {
  display: inline-block; padding: 3px 10px; border-radius: 999px;
  background: #fef3c7; color: #92400e; font-size: 0.85rem;
  font-weight: 500;
}

.text-correct { color: #065f46; font-weight: 600; }
.text-wrong { color: #991b1b; font-weight: 600; }

.rubric-list-readonly {
  list-style: none; padding: 0; margin: 0;
}
.rubric-list-readonly li {
  padding: 8px 0;
  border-bottom: 1px dashed var(--border);
}
.rubric-list-readonly li:last-child { border-bottom: none; }
.rubric-list-readonly li::before {
  content: "☐"; margin-right: 10px; color: var(--muted);
}

.form-actions {
  display: flex; gap: 16px; align-items: center;
  margin-top: 12px;
}

.form textarea {
  font: inherit; padding: 12px 14px;
  border: 1px solid var(--border); border-radius: 10px;
  background: #fff; outline: none;
  width: 100%; resize: vertical; font-family: inherit;
}
.form textarea:focus { border-color: var(--accent); }
.form input[type="number"] {
  font: inherit; padding: 10px 12px;
  border: 1px solid var(--border); border-radius: 10px;
  width: 120px; outline: none;
}

/* --- Redo + delete --- */
.submit-bar { display: flex; flex-direction: column; gap: 12px; align-items: center; }

.btn-danger-small {
  font: inherit; font-size: 0.85rem;
  padding: 5px 12px; border: 1px solid #fecaca;
  background: #fef2f2; color: #991b1b;
  border-radius: 6px; cursor: pointer;
  transition: background 0.15s;
}
.btn-danger-small:hover { background: #fee2e2; }

.btn-danger {
  font: inherit; font-weight: 600;
  padding: 12px 20px; border: 1px solid #fecaca;
  background: #fef2f2; color: #991b1b;
  border-radius: 10px; cursor: pointer;
  transition: background 0.15s;
}
.btn-danger:hover { background: #fee2e2; }

.inline-form { display: inline; }
.divider {
  border: none; border-top: 1px dashed var(--border);
  margin: 24px 0;
}