@import url("https://fonts.googleapis.com/css2?family=Noto+Sans+Bengali:wght@400;500;600;700;800&family=Noto+Sans:wght@400;500;600;700&display=swap");

:root {
  --bg: #f4faf9;
  --bg-alt: #ffffff;
  --ink: #12241f;
  --ink-soft: #4d635d;
  --border: #d9e9e4;
  --brand: #0f7a63;
  --brand-dark: #0a5a49;
  --brand-soft: #e3f4ee;
  --accent: #f2a541;
  --danger: #d64545;
  --danger-soft: #fdeaea;
  --warn-soft: #fff6e2;
  --gold: #b8860b;
  --radius: 14px;
  --shadow: 0 2px 10px rgba(15, 60, 50, 0.08);
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0d1613;
    --bg-alt: #131f1b;
    --ink: #e9f5f1;
    --ink-soft: #9db5ae;
    --border: #223832;
    --brand: #2fbf96;
    --brand-dark: #24a583;
    --brand-soft: #16302a;
    --accent: #f2b25a;
    --danger: #ef6b6b;
    --danger-soft: #331a1a;
    --warn-soft: #322a13;
    --gold: #e0b23a;
    --shadow: 0 2px 14px rgba(0, 0, 0, 0.35);
    color-scheme: dark;
  }
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
}

body {
  background: var(--bg);
  color: var(--ink);
  font-family: "Noto Sans Bengali", "Noto Sans", system-ui, sans-serif;
  min-height: 100vh;
  line-height: 1.55;
}

.wrap {
  max-width: 640px;
  margin: 0 auto;
  padding: 16px 16px 48px;
}

.wrap.wide {
  max-width: 960px;
}

/* ---- topbar ---- */
.topbar {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 14px 16px;
  background: var(--brand);
  color: #fff;
  position: sticky;
  top: 0;
  z-index: 20;
  box-shadow: var(--shadow);
}

.topbar .brand {
  font-weight: 800;
  font-size: 17px;
  flex: 1;
}

.topbar .brand small {
  display: block;
  font-weight: 500;
  font-size: 11.5px;
  opacity: 0.85;
}

.topbar button.ghost {
  background: rgba(255, 255, 255, 0.15);
  color: #fff;
  border: 1px solid rgba(255, 255, 255, 0.35);
}

/* ---- cards ---- */
.card {
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px;
  box-shadow: var(--shadow);
  margin-bottom: 14px;
}

.card h2 {
  margin: 0 0 4px;
  font-size: 18px;
}

.card p.hint {
  color: var(--ink-soft);
  font-size: 13.5px;
  margin: 4px 0 14px;
}

/* ---- forms ---- */
label {
  display: block;
  font-size: 13.5px;
  font-weight: 600;
  margin: 12px 0 6px;
  color: var(--ink-soft);
}

label:first-child {
  margin-top: 0;
}

input[type="text"],
input[type="tel"],
input[type="number"],
input[type="password"],
input[type="email"],
select,
textarea {
  width: 100%;
  padding: 11px 12px;
  border-radius: 10px;
  border: 1.5px solid var(--border);
  background: var(--bg);
  color: var(--ink);
  font-family: inherit;
  font-size: 15px;
}

textarea {
  min-height: 110px;
  resize: vertical;
}

input:focus,
select:focus,
textarea:focus {
  outline: none;
  border-color: var(--brand);
}

button {
  font-family: inherit;
  font-size: 15px;
  font-weight: 700;
  padding: 11px 16px;
  border-radius: 10px;
  border: none;
  cursor: pointer;
  background: var(--brand);
  color: #fff;
  transition: transform 0.05s ease, opacity 0.15s ease;
}

button:hover {
  opacity: 0.92;
}

button:active {
  transform: scale(0.98);
}

button:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

button.block {
  width: 100%;
}

button.secondary {
  background: var(--brand-soft);
  color: var(--brand-dark);
}

button.outline {
  background: transparent;
  color: var(--brand);
  border: 1.5px solid var(--brand);
}

button.danger {
  background: var(--danger);
}

button.small {
  padding: 7px 12px;
  font-size: 13px;
}

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

.row > * {
  flex: 1;
}

/* ---- chapter / topic list ---- */
.list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 14px;
  border: 1.5px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg-alt);
  color: var(--ink);
  cursor: pointer;
  text-align: left;
}

.item .ic {
  width: 40px;
  height: 40px;
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 19px;
  flex-shrink: 0;
  background: var(--brand-soft);
}

.item .info {
  flex: 1;
  min-width: 0;
}

.item .info .t {
  font-weight: 700;
  font-size: 15.5px;
}

.item .info .s {
  font-size: 12.5px;
  color: var(--ink-soft);
  margin-top: 2px;
}

.badge {
  font-size: 11.5px;
  font-weight: 700;
  padding: 3px 9px;
  border-radius: 999px;
  white-space: nowrap;
}

.badge.locked {
  background: var(--danger-soft);
  color: var(--danger);
}

.badge.pending {
  background: var(--warn-soft);
  color: var(--gold);
}

.badge.unlocked {
  background: var(--brand-soft);
  color: var(--brand-dark);
}

/* ---- quiz ---- */
.quiz-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 10px;
  font-size: 13.5px;
  color: var(--ink-soft);
  font-weight: 600;
}

.timer {
  font-variant-numeric: tabular-nums;
  font-weight: 800;
  color: var(--brand-dark);
}

.timer.low {
  color: var(--danger);
}

.progress-bar {
  height: 6px;
  border-radius: 999px;
  background: var(--border);
  overflow: hidden;
  margin-bottom: 18px;
}

.progress-bar > div {
  height: 100%;
  background: var(--brand);
  transition: width 0.25s ease;
}

.qtext {
  font-size: 17px;
  font-weight: 700;
  margin-bottom: 16px;
}

.options {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.opt {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 13px 14px;
  border: 1.5px solid var(--border);
  border-radius: 12px;
  background: var(--bg-alt);
  color: var(--ink);
  cursor: pointer;
  font-size: 15px;
  text-align: left;
}

.opt .k {
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: var(--brand-soft);
  color: var(--brand-dark);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 13px;
  flex-shrink: 0;
}

.opt.selected {
  border-color: var(--brand);
  background: var(--brand-soft);
}

.opt.correct {
  border-color: var(--brand);
  background: var(--brand-soft);
}

.opt.correct .k {
  background: var(--brand);
  color: #fff;
}

.opt.wrong {
  border-color: var(--danger);
  background: var(--danger-soft);
}

.opt.wrong .k {
  background: var(--danger);
  color: #fff;
}

.opt:disabled,
.opt[disabled] {
  cursor: default;
}

.explain {
  margin-top: 12px;
  padding: 12px 14px;
  border-radius: 10px;
  background: var(--brand-soft);
  color: var(--ink);
  font-size: 14px;
}

/* ---- result screen ---- */
.score-circle {
  width: 130px;
  height: 130px;
  border-radius: 50%;
  border: 8px solid var(--brand);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  margin: 10px auto 18px;
  background: var(--brand-soft);
}

.score-circle .n {
  font-size: 30px;
  font-weight: 800;
  color: var(--brand-dark);
}

.score-circle .d {
  font-size: 12px;
  color: var(--ink-soft);
}

.stat-row {
  display: flex;
  justify-content: space-around;
  text-align: center;
  margin-bottom: 16px;
}

.stat-row .stat b {
  display: block;
  font-size: 18px;
}

.stat-row .stat span {
  font-size: 12px;
  color: var(--ink-soft);
}

/* ---- leaderboard ---- */
table.lb {
  width: 100%;
  border-collapse: collapse;
  font-size: 14px;
}

table.lb th,
table.lb td {
  padding: 10px 8px;
  text-align: left;
  border-bottom: 1px solid var(--border);
}

table.lb th {
  color: var(--ink-soft);
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.03em;
}

table.lb tr:first-child td {
  font-weight: 800;
}

.rank-medal {
  font-size: 16px;
}

/* ---- misc ---- */
.center {
  text-align: center;
}

.muted {
  color: var(--ink-soft);
  font-size: 13.5px;
}

.error-msg {
  color: var(--danger);
  font-size: 13.5px;
  margin-top: 8px;
}

.ok-msg {
  color: var(--brand-dark);
  font-size: 13.5px;
  margin-top: 8px;
}

.tabs {
  display: flex;
  gap: 6px;
  overflow-x: auto;
  margin-bottom: 16px;
  padding-bottom: 2px;
}

.tabs button {
  background: var(--bg-alt);
  color: var(--ink-soft);
  border: 1.5px solid var(--border);
  white-space: nowrap;
  font-size: 13.5px;
  padding: 9px 14px;
}

.tabs button.active {
  background: var(--brand);
  color: #fff;
  border-color: var(--brand);
}

.spinner {
  width: 26px;
  height: 26px;
  border: 3px solid var(--border);
  border-top-color: var(--brand);
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
  margin: 20px auto;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

.qrow {
  border: 1.5px solid var(--border);
  border-radius: 12px;
  padding: 12px;
  margin-bottom: 10px;
  background: var(--bg-alt);
}

.qrow .qh {
  display: flex;
  justify-content: space-between;
  gap: 8px;
  align-items: flex-start;
}

.qrow .qh b {
  flex: 1;
}

.chip {
  display: inline-block;
  font-size: 11.5px;
  font-weight: 700;
  padding: 2px 8px;
  border-radius: 999px;
  background: var(--brand-soft);
  color: var(--brand-dark);
  margin-right: 6px;
}

.chip.pending {
  background: var(--warn-soft);
  color: var(--gold);
}

footer.note {
  text-align: center;
  color: var(--ink-soft);
  font-size: 12px;
  margin-top: 24px;
}

/* ---- notice / announcement banner (student front page) ---- */
.notice-banner {
  border: 1.5px solid var(--accent);
  background: var(--warn-soft);
}

.notice-banner img {
  width: 100%;
  border-radius: 10px;
  display: block;
  margin-bottom: 12px;
}

.notice-banner h2 {
  color: var(--brand-dark);
}

.notice-banner p {
  margin: 6px 0 0;
  font-size: 14.5px;
  white-space: pre-wrap;
}