:root {
  --bg: #f6f7fb; --card: #fff; --text: #1f2937; --muted: #6b7280;
  --primary: #2563eb; --primary-text: #fff; --border: #e5e7eb; --danger: #dc2626; --ok: #16a34a;
}
@media (prefers-color-scheme: dark) {
  :root { --bg: #0f172a; --card: #1e293b; --text: #e5e7eb; --muted: #94a3b8; --border: #334155; --primary: #3b82f6; }
}
* { box-sizing: border-box; }
body { margin: 0; font: 16px/1.5 system-ui, "Noto Sans Thai", sans-serif; background: var(--bg); color: var(--text); }
#topbar { display: flex; align-items: center; gap: 12px; padding: 10px 16px; background: var(--card); border-bottom: 1px solid var(--border); }
#topbar #whoami { flex: 1; min-width: 0; color: var(--muted); font-size: 14px; text-align: right; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
main { max-width: 720px; margin: 0 auto; padding: 16px; }
.card { background: var(--card); border: 1px solid var(--border); border-radius: 12px; padding: 16px; margin-bottom: 16px; }
h1, h2 { margin: 0 0 12px; } h1 { font-size: 1.4rem; } h2 { font-size: 1.15rem; }
label { display: block; margin: 12px 0 4px; font-size: 14px; color: var(--muted); }
input, textarea { width: 100%; padding: 12px; font: inherit; color: inherit; background: var(--bg); border: 1px solid var(--border); border-radius: 8px; }
textarea { min-height: 140px; font-family: ui-monospace, monospace; font-size: 14px; }
button { font: inherit; cursor: pointer; border: 0; border-radius: 8px; padding: 12px 16px; background: var(--primary); color: var(--primary-text); }
button.secondary { background: transparent; color: var(--primary); border: 1px solid var(--primary); }
button.link { background: none; color: var(--primary); padding: 4px; }
button:disabled { opacity: .6; cursor: default; }
.row { display: flex; gap: 8px; margin-top: 16px; flex-wrap: wrap; }
.row > * { flex: 1; }
.tabs { display: flex; gap: 8px; margin-bottom: 12px; }
.tabs button { flex: 1; background: transparent; color: var(--muted); border: 1px solid var(--border); }
.tabs button.active { background: var(--primary); color: var(--primary-text); border-color: var(--primary); }
.error { color: var(--danger); margin-top: 8px; min-height: 1.4em; }
table { width: 100%; border-collapse: collapse; font-size: 14px; }
th, td { text-align: left; padding: 8px 6px; border-bottom: 1px solid var(--border); }
code.cls { font-size: 1.1rem; letter-spacing: 2px; font-weight: 600; }
.muted { color: var(--muted); }
#toast { position: fixed; left: 50%; bottom: 24px; transform: translateX(-50%); background: #111827; color: #fff; padding: 10px 16px; border-radius: 8px; }

/* ---------- ขั้นที่ 2: บทเรียนและแบบฝึก ---------- */
a { color: var(--primary); }
a.card { display: block; color: inherit; text-decoration: none; }
a.card:hover { border-color: var(--primary); }
a.button { display: inline-block; text-align: center; text-decoration: none; border-radius: 8px; padding: 12px 16px; background: var(--primary); color: var(--primary-text); }
.back { display: inline-block; margin-bottom: 8px; text-decoration: none; }
.small { font-size: 13px; }
.center { text-align: center; }
.highlight { border-color: var(--primary); background: color-mix(in srgb, var(--primary) 8%, var(--card)); }
.badge { display: inline-block; padding: 2px 10px; border-radius: 999px; font-size: 13px; background: var(--primary); color: var(--primary-text); }
.badge.ok { background: var(--ok); }
.bar { height: 6px; border-radius: 3px; background: var(--border); overflow: hidden; margin: 8px 0 4px; }
.bar > div { height: 100%; background: var(--ok); transition: width .3s; }
.progress-text { font-size: 14px; color: var(--muted); margin-bottom: 8px; }
.progress-text .bar > div { background: var(--primary); }

.unit-card.recommended { border-color: var(--primary); border-width: 2px; }
.unit-head { display: flex; justify-content: space-between; align-items: center; margin-bottom: 4px; }
.unit-no { font-size: 13px; color: var(--muted); }
.review-card { display: flex !important; justify-content: space-between; align-items: center; }
.review-card h2 { margin-bottom: 4px; }

.section-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(140px, 1fr)); gap: 12px; }
.section-card { text-align: center; margin: 0; display: flex !important; flex-direction: column; align-items: center; gap: 6px; }
.section-icon { font-size: 28px; }

.icon-btn { background: transparent; color: var(--primary); border: 1px solid var(--border); padding: 6px 10px; font-size: 15px; }
.audio-row { display: flex; gap: 8px; margin-bottom: 12px; flex-wrap: wrap; align-items: center; }
.vocab-head { display: flex; align-items: center; gap: 8px; }
.vocab .word { font-size: 1.15rem; }
.pos { font-size: 12px; color: var(--muted); border: 1px solid var(--border); border-radius: 4px; padding: 0 6px; }
.vocab-head .icon-btn { margin-left: auto; }
.example { display: flex; align-items: center; gap: 8px; margin-top: 8px; }
.explain li { margin-bottom: 6px; }
.reading-text { font-size: 1.05rem; line-height: 1.8; }

.question { font-size: 1.15rem; font-weight: 500; }
.choices { display: grid; gap: 8px; }
.choice { background: var(--bg); color: var(--text); border: 1px solid var(--border); text-align: left; }
.choice.right { background: color-mix(in srgb, var(--ok) 20%, var(--card)); border-color: var(--ok); }
.choice.wrong { background: color-mix(in srgb, var(--danger) 20%, var(--card)); border-color: var(--danger); }
.fill-line { line-height: 2.4; }
input.blank { display: inline-block; width: 8em; padding: 4px 8px; margin: 0 4px; text-align: center; }
.feedback { margin-top: 16px; padding: 12px; border-radius: 8px; }
.feedback.ok { background: color-mix(in srgb, var(--ok) 15%, var(--card)); }
.feedback.bad { background: color-mix(in srgb, var(--danger) 12%, var(--card)); }
.chips { display: flex; flex-wrap: wrap; gap: 8px; min-height: 48px; padding: 8px 0; }
.chips.built { border-bottom: 2px dashed var(--border); margin-bottom: 8px; }
.chip { background: var(--bg); color: var(--text); border: 1px solid var(--border); padding: 8px 12px; }
.diff { margin: 8px 0; line-height: 2; }
.diff span { padding: 2px 4px; margin-right: 4px; border-radius: 4px; }
.w-ok { background: color-mix(in srgb, var(--ok) 20%, transparent); }
.w-missing { background: color-mix(in srgb, var(--danger) 25%, transparent); font-weight: 600; }
.w-extra { text-decoration: line-through; color: var(--muted); }
.score { font-size: 2.6rem; font-weight: 700; color: var(--primary); }
.small-score { font-size: 1.4rem; margin: 8px 0; }

.flash { text-align: center; }
.flash-word { font-size: 2rem; font-weight: 700; margin: 16px 0; }
.flash-th { font-size: 1.4rem; margin: 12px 0; }
.flash .example { justify-content: center; }
.grades { display: grid; grid-template-columns: repeat(4, 1fr); gap: 8px; margin-top: 8px; }
.grades button { padding: 12px 4px; }
.g-again { background: var(--danger); } .g-hard { background: #d97706; } .g-good { background: var(--ok); } .g-easy { background: var(--primary); }

/* ---------- ขั้นที่ 3: เสียง ---------- */
select { width: 100%; padding: 12px; font: inherit; color: inherit; background: var(--bg); border: 1px solid var(--border); border-radius: 8px; }
input[type=range] { width: 100%; padding: 0; }
#settings-link { text-decoration: none; font-size: 18px; }
.support { list-style: none; padding: 0; margin: 0 0 8px; }
.mic { width: 100%; font-size: 1.05rem; }
.mic[data-state=listening] { background: var(--danger); animation: pulse 1.2s infinite; }
.mic[data-state=processing] { background: var(--muted); }
@keyframes pulse { 50% { opacity: .75; } }
.speak-head { display: flex; align-items: center; gap: 10px; }
.speak-text { flex: 1; font-size: 1.15rem; font-weight: 500; }
.live { min-height: 1.5em; margin-top: 8px; font-style: italic; }
.speak-result { margin-top: 4px; }
.badge.mid { background: #d97706; }
.badge.low { background: var(--danger); }

/* ---------- ขั้นที่ 4: AI ---------- */
.row.space { justify-content: space-between; align-items: center; }
.row.space > * { flex: 0 0 auto; }
.chat-head { display: flex; justify-content: space-between; align-items: center; margin-bottom: 8px; color: var(--muted); }
.chat-card { padding: 12px; }
.chat-log { display: flex; flex-direction: column; gap: 8px; max-height: 55vh; overflow-y: auto; padding: 4px 0 12px; }
.bubble { max-width: 85%; padding: 10px 12px; border-radius: 14px; line-height: 1.45; display: flex; gap: 6px; align-items: flex-start; }
.bubble.assistant { align-self: flex-start; background: var(--bg); border: 1px solid var(--border); border-bottom-left-radius: 4px; }
.bubble.user { align-self: flex-end; background: var(--primary); color: var(--primary-text); border-bottom-right-radius: 4px; }
.bubble .icon-btn { padding: 2px 6px; font-size: 13px; flex: none; }
.bubble.typing { color: var(--muted); font-style: italic; }
.composer { border-top: 1px solid var(--border); padding-top: 10px; }
.chat-input, .free-text { width: 100%; padding: 10px; font: inherit; color: inherit; background: var(--bg); border: 1px solid var(--border); border-radius: 8px; resize: vertical; min-height: 0; }
.free-text { min-height: 120px; }
.composer-actions { display: flex; gap: 8px; margin-top: 8px; }
.composer-actions .mic { flex: 1; }
.composer-actions button[type=submit] { flex: 0 0 90px; }
.toggle { display: flex; align-items: center; gap: 8px; color: var(--muted); font-size: 14px; margin: 8px 0; }
.toggle input { width: auto; }
.correction { padding: 10px 0; border-bottom: 1px solid var(--border); }
.correction:last-child { border-bottom: 0; }
.wrong-text { text-decoration: line-through; color: var(--danger); }
.right-text { color: var(--ok); font-weight: 500; display: flex; align-items: center; gap: 6px; flex-wrap: wrap; }
details summary { cursor: pointer; color: var(--primary); }
details .chat-log { max-height: none; margin-top: 8px; }

/* ---------- ขั้นที่ 5: แดชบอร์ดครู ---------- */
body.wide main { max-width: 1100px; }
.teacher .tabs { flex-wrap: wrap; }
.filter-row { display: flex; gap: 12px; flex-wrap: wrap; align-items: center; }
.filter-row select, .filter-row input[type=search] { flex: 1 1 220px; width: auto; }
.export { display: flex; gap: 8px; flex-wrap: wrap; }
a.secondary-btn { background: transparent; color: var(--primary); border: 1px solid var(--primary); padding: 10px 14px; font-size: 14px; }
.class-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 16px; }
.class-card { margin: 0; }
.stats { display: grid; grid-template-columns: repeat(auto-fit, minmax(110px, 1fr)); gap: 8px; margin: 12px 0; }
.stat { background: var(--bg); border-radius: 8px; padding: 8px 10px; }
.stat-value { font-size: 1.25rem; font-weight: 700; }
.stat-label { font-size: 12px; color: var(--muted); }
.skill-bar { display: grid; grid-template-columns: 48px 1fr 44px; align-items: center; gap: 8px; font-size: 14px; }
.skill-bar .bar { margin: 4px 0; height: 8px; }
.fill-ok { background: var(--ok) !important; } .fill-mid { background: #d97706 !important; } .fill-low { background: var(--danger) !important; }
.warn { color: #b45309; margin-top: 8px; }
.warn-card { border-color: #d97706; background: color-mix(in srgb, #d97706 10%, var(--card)); }
.table-wrap { overflow-x: auto; -webkit-overflow-scrolling: touch; }
table.dash { min-width: 720px; }
table.dash th.sortable { cursor: pointer; user-select: none; white-space: nowrap; }
table.dash th.sorted { color: var(--primary); }
table.dash tbody tr { cursor: pointer; }
table.dash tbody tr:hover, table.dash tbody tr:focus { background: var(--bg); outline: none; }
table.dash tr.inactive td:first-child { box-shadow: inset 3px 0 0 var(--danger); }
td.num { text-align: right; white-space: nowrap; font-variant-numeric: tabular-nums; }
.score-ok { color: var(--ok); font-weight: 600; } .score-mid { color: #d97706; font-weight: 600; } .score-low { color: var(--danger); font-weight: 600; }
.badge.tiny { font-size: 11px; padding: 0 6px; margin-left: 6px; vertical-align: middle; }
dialog.student-dialog { width: min(900px, calc(100vw - 32px)); max-height: calc(100vh - 32px); border: 1px solid var(--border); border-radius: 12px; background: var(--card); color: var(--text); padding: 16px; }
dialog.student-dialog::backdrop { background: rgb(0 0 0 / .5); }
.dialog-head { display: flex; justify-content: flex-end; }
dialog h3 { margin: 16px 0 8px; font-size: 1rem; }
.time-chart { display: flex; align-items: flex-end; gap: 4px; height: 120px; padding: 8px 0; border-bottom: 1px solid var(--border); }
.time-col { flex: 1; height: 100%; display: flex; flex-direction: column; justify-content: flex-end; align-items: center; }
.time-bar { width: 100%; background: var(--primary); border-radius: 3px 3px 0 0; min-height: 2px; }
.time-label { font-size: 10px; color: var(--muted); margin-top: 2px; }
.setting { margin-bottom: 4px; }