/* ===== TNPSC Group I Prep — UI (refined) ===== */
:root {
  --page: #f5f6fb;
  --surface: #ffffff;
  --panel: #ffffff;
  --panel-2: #eef1f8;
  --ink: #10132a;
  --ink-2: #4b5169;
  --muted: #8a90a6;
  --line: #e6e9f2;
  --line-strong: #d4d9e8;
  --primary: #4361ee;
  --primary-ink: #3a52c9;
  --primary-soft: #e9edff;
  --accent-grad: linear-gradient(135deg, #4361ee 0%, #7aa0ff 100%);
  --good: #12a150;
  --good-ink: #0e8a44;
  --warn: #d98a00;
  --bad: #e0413d;
  --tier1: #2f4bc0;
  --tier2: #4d7bec;
  --tier3: #97b6f4;
  --radius: 18px;
  --radius-sm: 12px;
  --radius-xs: 9px;
  --shadow-sm: 0 1px 2px rgba(16,19,42,.05), 0 1px 3px rgba(16,19,42,.04);
  --shadow: 0 2px 6px rgba(16,19,42,.05), 0 14px 34px -14px rgba(16,19,42,.14);
  --shadow-lg: 0 8px 40px -12px rgba(16,19,42,.24);
  --maxw: 1120px;
}
:root[data-theme="dark"] {
  --page: #0d0f16;
  --surface: #161922;
  --panel: #171a24;
  --panel-2: #1f2330;
  --ink: #f0f2fb;
  --ink-2: #b3bad0;
  --muted: #79809a;
  --line: #262b39;
  --line-strong: #363c4d;
  --primary: #6d8bff;
  --primary-ink: #9db2ff;
  --primary-soft: #1e2540;
  --accent-grad: linear-gradient(135deg, #4f6bf0 0%, #7f9dff 100%);
  --good: #2fbf6a;
  --good-ink: #45d07f;
  --warn: #e0a132;
  --bad: #ec6b67;
  --tier1: #5878ee;
  --tier2: #3e60c8;
  --tier3: #294a94;
  --shadow-sm: 0 1px 2px rgba(0,0,0,.35);
  --shadow: 0 2px 8px rgba(0,0,0,.35), 0 18px 40px -18px rgba(0,0,0,.6);
  --shadow-lg: 0 12px 48px -14px rgba(0,0,0,.7);
}
* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
html { -webkit-text-size-adjust: 100%; }
body {
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", sans-serif;
  background: var(--page);
  color: var(--ink);
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
a { color: var(--primary-ink); text-decoration: none; }
a:hover { text-decoration: underline; }
h1, h2, h3, h4 { line-height: 1.22; margin: 0 0 .4em; letter-spacing: -0.011em; }
p { margin: 0 0 .8em; }
small { color: var(--muted); }
::selection { background: color-mix(in srgb, var(--primary) 26%, transparent); }

/* ===== Topbar ===== */
.topbar {
  position: sticky; top: 0; z-index: 50;
  display: flex; align-items: center; gap: 14px;
  padding: 11px 22px;
  padding-top: calc(11px + env(safe-area-inset-top));
  background: color-mix(in srgb, var(--surface) 82%, transparent);
  backdrop-filter: saturate(1.6) blur(14px);
  -webkit-backdrop-filter: saturate(1.6) blur(14px);
  border-bottom: 1px solid var(--line);
}
.brand { display: flex; align-items: center; gap: 11px; cursor: pointer; flex: 0 0 auto; }
.brand-mark {
  display: grid; place-items: center;
  width: 40px; height: 40px; border-radius: 12px;
  background: var(--accent-grad);
  color: #fff; font-weight: 800; letter-spacing: .3px; font-size: 15px;
  box-shadow: 0 4px 14px -3px color-mix(in srgb, var(--primary) 55%, transparent);
}
.brand-text strong { display: block; font-size: 15px; letter-spacing: -0.01em; }
.brand-text small { font-size: 11px; color: var(--muted); }

.nav {
  display: flex; gap: 3px; margin-left: 6px; flex: 1;
  overflow-x: auto; flex-wrap: nowrap;
  scrollbar-width: none; -webkit-overflow-scrolling: touch;
  scroll-snap-type: x proximity;
}
.nav::-webkit-scrollbar { display: none; }
.nav a {
  flex: 0 0 auto; scroll-snap-align: start;
  padding: 8px 13px; border-radius: 999px; font-size: 13.5px; font-weight: 600;
  color: var(--ink-2); cursor: pointer; white-space: nowrap; transition: background .15s, color .15s;
}
.nav a:hover { background: var(--panel-2); color: var(--ink); }
.nav a.active { background: var(--primary-soft); color: var(--primary-ink); }

.topbar-actions { display: flex; align-items: center; gap: 8px; flex: 0 0 auto; }
.key-pill {
  font-size: 11.5px; font-weight: 700; padding: 6px 12px; border-radius: 999px;
  background: var(--panel-2); color: var(--muted); border: 1px solid transparent; white-space: nowrap;
  cursor: pointer; font-family: inherit; transition: background .15s;
}
.key-pill:hover { background: var(--line); }
.key-pill.on { background: color-mix(in srgb, var(--good) 15%, transparent); color: var(--good-ink); }
.key-pill.on:hover { background: color-mix(in srgb, var(--good) 22%, transparent); }
.icon-btn {
  width: 38px; height: 38px; border-radius: 11px; border: 1px solid var(--line-strong);
  background: var(--surface); color: var(--ink); cursor: pointer; font-size: 16px;
  display: inline-grid; place-items: center; transition: background .15s, border-color .15s;
}
.icon-btn:hover { background: var(--panel-2); border-color: var(--primary); }
.menu-btn { display: none; }

/* ===== Layout ===== */
.app { max-width: var(--maxw); margin: 0 auto; padding: 30px 22px 90px; }
.page-head { margin-bottom: 22px; }
.page-head h1 { font-size: 28px; letter-spacing: -0.02em; }
.page-head p { color: var(--ink-2); max-width: 72ch; font-size: 15px; }
.grid { display: grid; gap: 18px; }
.grid.cols-2 { grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); }
.grid.cols-3 { grid-template-columns: repeat(auto-fit, minmax(230px, 1fr)); }
.grid.cols-4 { grid-template-columns: repeat(auto-fit, minmax(168px, 1fr)); }

.card {
  background: var(--panel); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 20px 22px; box-shadow: var(--shadow-sm);
  transition: box-shadow .2s, border-color .2s, transform .2s;
}
.card.pad-lg { padding: 26px 28px; }
.card h3 { font-size: 16.5px; letter-spacing: -0.01em; }
.card .sub { color: var(--muted); font-size: 13px; margin-top: -2px; }

/* Stat tiles */
.stat {
  position: relative; overflow: hidden;
}
.stat .label { font-size: 11px; text-transform: uppercase; letter-spacing: .06em; color: var(--muted); margin-bottom: 6px; font-weight: 600; }
.stat .value { font-size: 30px; font-weight: 750; line-height: 1.05; letter-spacing: -0.02em; }
.stat .value.good { color: var(--good-ink); }
.stat .foot { font-size: 12.5px; color: var(--ink-2); margin-top: 4px; }

/* ===== Buttons ===== */
.btn {
  display: inline-flex; align-items: center; gap: 8px; justify-content: center;
  padding: 11px 17px; border-radius: 12px; font-weight: 650; font-size: 14px;
  border: 1px solid var(--line-strong); background: var(--surface); color: var(--ink);
  cursor: pointer; transition: transform .05s ease, background .15s, border-color .15s, box-shadow .15s;
  min-height: 42px;
}
.btn:hover { background: var(--panel-2); border-color: var(--primary); }
.btn:active { transform: translateY(1px); }
.btn.primary { background: var(--primary); border-color: transparent; color: #fff; box-shadow: 0 6px 16px -6px color-mix(in srgb, var(--primary) 70%, transparent); }
.btn.primary:hover { background: var(--primary-ink); }
.btn.ghost { background: transparent; border-color: transparent; color: var(--primary-ink); box-shadow: none; }
.btn.ghost:hover { background: var(--primary-soft); }
.btn.sm { padding: 7px 13px; font-size: 13px; min-height: 36px; border-radius: 10px; }
.btn.block { width: 100%; }
.btn:disabled { opacity: .5; cursor: not-allowed; }
.btn-row { display: flex; gap: 10px; flex-wrap: wrap; }

/* ===== Forms ===== */
label.field { display: block; margin-bottom: 16px; }
label.field .lab { font-size: 13px; font-weight: 600; margin-bottom: 6px; display: block; color: var(--ink); }
input[type=text], input[type=password], input[type=number], select, textarea {
  width: 100%; padding: 11px 13px; border-radius: 12px;
  border: 1px solid var(--line-strong); background: var(--surface); color: var(--ink);
  font-family: inherit; font-size: 15px; transition: border-color .15s, box-shadow .15s;
}
textarea { resize: vertical; min-height: 120px; line-height: 1.6; }
input:focus, select:focus, textarea:focus {
  outline: none; border-color: var(--primary);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--primary) 20%, transparent);
}
.chips { display: flex; flex-wrap: wrap; gap: 8px; }
.chip {
  padding: 8px 14px; border-radius: 999px; border: 1px solid var(--line-strong);
  background: var(--surface); cursor: pointer; font-size: 13px; font-weight: 600; color: var(--ink-2);
  transition: background .15s, border-color .15s, color .15s;
}
.chip:hover { background: var(--panel-2); border-color: var(--primary); }
.chip.active { background: var(--primary-soft); border-color: transparent; color: var(--primary-ink); }

/* ===== Weightage bars ===== */
.bar-row { display: flex; align-items: center; gap: 12px; margin: 10px 0; }
.bar-label { flex: 0 0 40%; font-size: 13.5px; }
.bar-track { flex: 1; background: var(--panel-2); border-radius: 999px; height: 22px; overflow: hidden; }
.bar-fill { height: 100%; border-radius: 999px; transition: width .5s cubic-bezier(.2,.8,.2,1); }
.bar-val { flex: 0 0 auto; font-size: 12.5px; font-weight: 700; color: var(--ink-2); }

/* ===== Tags / tiers ===== */
.tag { display: inline-block; padding: 3px 10px; border-radius: 999px; font-size: 11.5px; font-weight: 700; letter-spacing: .01em; }
.tag.t1 { background: color-mix(in srgb, var(--tier1) 16%, transparent); color: var(--tier1); }
.tag.t2 { background: color-mix(in srgb, var(--tier2) 20%, transparent); color: var(--tier2); }
.tag.t3 { background: color-mix(in srgb, var(--tier3) 32%, transparent); color: var(--ink); }
.tag.ok { background: color-mix(in srgb, var(--good) 15%, transparent); color: var(--good-ink); }
.tag.warn { background: color-mix(in srgb, var(--warn) 20%, transparent); color: var(--warn); }
.tag.bad { background: color-mix(in srgb, var(--bad) 16%, transparent); color: var(--bad); }

/* ===== Roadmap ===== */
.phase { position: relative; padding: 2px 0 4px 20px; margin: 0 0 20px; }
.phase::before { content: ""; position: absolute; left: 0; top: 6px; bottom: 6px; width: 3px; border-radius: 3px; background: var(--accent-grad); }
.phase h4 { font-size: 15.5px; margin-bottom: 3px; }
.phase .when { font-size: 11.5px; color: var(--primary-ink); font-weight: 700; text-transform: uppercase; letter-spacing: .05em; }
.phase ul { margin: 9px 0 0; padding-left: 18px; }
.phase li { margin-bottom: 5px; color: var(--ink-2); font-size: 14px; }

/* ===== Quiz ===== */
.quiz-meta { display: flex; align-items: center; justify-content: space-between; gap: 12px; flex-wrap: wrap; margin-bottom: 16px; }
.timer { font-variant-numeric: tabular-nums; font-weight: 800; font-size: 20px; letter-spacing: -0.01em; }
.q-text { font-size: 19px; font-weight: 620; margin: 8px 0 18px; letter-spacing: -0.01em; }
.q-tamil { font-size: 15px; color: var(--ink-2); font-weight: 500; margin-top: -10px; margin-bottom: 16px; }
.options { display: grid; gap: 11px; }
.option {
  text-align: left; padding: 14px 16px; border-radius: 13px;
  border: 1.5px solid var(--line-strong); background: var(--surface); color: var(--ink);
  cursor: pointer; font-size: 15px; display: flex; gap: 12px; align-items: flex-start;
  transition: border-color .15s, background .15s, transform .05s;
}
.option:hover { border-color: var(--primary); background: color-mix(in srgb, var(--primary) 4%, var(--surface)); }
.option:active { transform: scale(.995); }
.option .mark { font-weight: 800; color: var(--muted); flex: 0 0 auto; min-width: 16px; }
.option.selected { border-color: var(--primary); background: var(--primary-soft); }
.option.correct { border-color: var(--good); background: color-mix(in srgb, var(--good) 12%, transparent); }
.option.correct .mark { color: var(--good-ink); }
.option.wrong { border-color: var(--bad); background: color-mix(in srgb, var(--bad) 12%, transparent); }
.option.wrong .mark { color: var(--bad); }
.option[disabled] { cursor: default; }
.explain { margin-top: 16px; padding: 14px 16px; border-radius: 13px; background: var(--panel-2); border: 1px solid var(--line); font-size: 14px; }
.explain strong { color: var(--primary-ink); }

/* ===== Mock ===== */
.qnav { display: flex; flex-wrap: wrap; gap: 7px; }
.qnav button {
  width: 36px; height: 36px; border-radius: 9px; border: 1px solid var(--line-strong);
  background: var(--surface); cursor: pointer; font-size: 12.5px; font-weight: 700; color: var(--ink-2);
  transition: background .12s, border-color .12s;
}
.qnav button.answered { background: var(--primary-soft); color: var(--primary-ink); border-color: transparent; }
.qnav button.current { outline: 2px solid var(--primary); outline-offset: 1px; }
.progress { height: 9px; background: var(--panel-2); border-radius: 999px; overflow: hidden; }
.progress > div { height: 100%; background: var(--accent-grad); border-radius: 999px; transition: width .3s; }

/* ===== Chat ===== */
.chat { display: flex; flex-direction: column; height: calc(100vh - 280px); height: calc(100dvh - 280px); min-height: 380px; }
.chat-log { flex: 1; overflow-y: auto; padding: 6px 2px 12px; display: flex; flex-direction: column; gap: 12px; }
.msg { max-width: 86%; padding: 12px 15px; border-radius: 16px; font-size: 14.5px; white-space: pre-wrap; word-wrap: break-word; box-shadow: var(--shadow-sm); }
.msg.user { align-self: flex-end; background: var(--primary); color: #fff; border-bottom-right-radius: 5px; }
.msg.ai { align-self: flex-start; background: var(--surface); border: 1px solid var(--line); border-bottom-left-radius: 5px; }
.msg.ai h1,.msg.ai h2,.msg.ai h3 { font-size: 15px; margin: .5em 0 .2em; }
.msg.ai ul { margin: .3em 0; padding-left: 18px; }
.msg.ai code { background: var(--panel-2); padding: 1px 6px; border-radius: 6px; font-size: 13px; }
.chat-input { display: flex; gap: 10px; margin-top: 12px; }
.chat-input textarea { min-height: 48px; max-height: 150px; }

/* ===== AI markdown blocks ===== */
.ai-block h1,.ai-block h2,.ai-block h3 { font-size: 17px; margin: .9em 0 .3em; letter-spacing: -0.01em; }
.ai-block ul, .ai-block ol { padding-left: 20px; }
.ai-block li { margin-bottom: 5px; }
.ai-block strong { color: var(--ink); }
.ai-block p { color: var(--ink-2); }
.ai-block code { background: var(--panel-2); padding: 1px 6px; border-radius: 6px; font-size: 13px; }

/* ===== Misc ===== */
.spinner { width: 18px; height: 18px; border: 2.5px solid var(--line-strong); border-top-color: var(--primary); border-radius: 50%; animation: spin .7s linear infinite; display: inline-block; vertical-align: -3px; }
@keyframes spin { to { transform: rotate(360deg); } }
.empty { text-align: center; color: var(--muted); padding: 34px 20px; }
.divider { height: 1px; background: var(--line); margin: 20px 0; }
.notice { padding: 13px 16px; border-radius: 13px; font-size: 13.5px; border: 1px solid transparent; }
.notice.info { background: var(--primary-soft); color: var(--primary-ink); }
.notice.warn { background: color-mix(in srgb, var(--warn) 12%, var(--panel)); border-color: color-mix(in srgb, var(--warn) 38%, transparent); color: var(--ink); }
.row-between { display: flex; align-items: center; justify-content: space-between; gap: 12px; flex-wrap: wrap; }
.list-reset { list-style: none; padding: 0; margin: 0; }
.mock-item { display: flex; justify-content: space-between; align-items: center; gap: 12px; padding: 13px 0; border-bottom: 1px solid var(--line); }
.mock-item:last-child { border-bottom: none; }
.kv { display: flex; gap: 8px; font-size: 13px; align-items: baseline; }
.kv .k { color: var(--muted); }
table.res { width: 100%; border-collapse: collapse; font-size: 13.5px; }
table.res th, table.res td { text-align: left; padding: 8px 8px; border-bottom: 1px solid var(--line); }
table.res th { color: var(--muted); font-size: 11.5px; text-transform: uppercase; letter-spacing: .04em; font-weight: 600; }
table.res td { color: var(--ink-2); }

/* details (study) */
details.card > summary { cursor: pointer; list-style: none; display: flex; align-items: center; gap: 11px; }
details.card > summary::-webkit-details-marker { display: none; }
details.card { transition: box-shadow .2s; }
details.card[open] { box-shadow: var(--shadow); }

/* ===== Bottom tab bar (phones only) ===== */
.bottomnav { display: none; }
@media (max-width: 720px) {
  .bottomnav {
    display: flex; position: fixed; left: 0; right: 0; bottom: 0; z-index: 60;
    background: color-mix(in srgb, var(--surface) 92%, transparent);
    backdrop-filter: saturate(1.6) blur(14px); -webkit-backdrop-filter: saturate(1.6) blur(14px);
    border-top: 1px solid var(--line);
    padding: 6px 6px calc(6px + env(safe-area-inset-bottom));
  }
  .bottomnav a {
    flex: 1; display: flex; flex-direction: column; align-items: center; gap: 3px;
    padding: 6px 2px; border-radius: 12px; cursor: pointer;
    color: var(--muted); font-size: 10.5px; font-weight: 600; text-decoration: none;
    -webkit-tap-highlight-color: transparent;
  }
  .bottomnav a svg { width: 23px; height: 23px; fill: none; stroke: currentColor; stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; }
  .bottomnav a.active { color: var(--primary-ink); }
  .bottomnav a.active svg { stroke: var(--primary); }
  .bottomnav a:active { background: var(--panel-2); }
}

/* toast */
.toast {
  position: fixed; bottom: 24px; left: 50%; transform: translateX(-50%) translateY(20px);
  background: var(--ink); color: var(--surface); padding: 12px 20px; border-radius: 12px;
  font-size: 13.5px; font-weight: 600; opacity: 0; pointer-events: none; transition: all .25s; z-index: 200;
  box-shadow: var(--shadow-lg);
}
.toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }

/* ===== Tablet / iPad (portrait ~768, landscape ~1024) ===== */
@media (max-width: 1024px) {
  .app { padding: 26px 20px 90px; }
  .page-head h1 { font-size: 25px; }
}

/* ===== Touch devices — larger tap targets (covers iPad) ===== */
@media (pointer: coarse) {
  .btn { min-height: 46px; }
  .btn.sm { min-height: 38px; }
  .icon-btn { width: 42px; height: 42px; }
  .nav a { padding: 10px 15px; }
  .option { min-height: 54px; padding: 16px; }
  .chip { min-height: 40px; }
  .qnav button { width: 42px; height: 42px; font-size: 13px; }
  input, select, textarea { font-size: 16px; } /* avoid iOS zoom-on-focus */
}

/* ===== Phone ===== */
@media (max-width: 720px) {
  .topbar { padding: 10px 16px; gap: 10px; }
  .nav {
    display: none; position: absolute; top: 60px; left: 0; right: 0;
    flex-direction: column; overflow: visible;
    background: var(--surface); border-bottom: 1px solid var(--line); padding: 10px; gap: 3px;
    box-shadow: var(--shadow);
  }
  .nav.open { display: flex; }
  .nav a { padding: 12px 15px; border-radius: 12px; }
  .menu-btn { display: inline-grid; }
  .brand-text small { display: none; }
  .app { padding: 20px 15px calc(90px + env(safe-area-inset-bottom)); }
  .page-head h1 { font-size: 23px; }
  .card.pad-lg { padding: 20px 18px; }
  .bar-label { flex-basis: 48%; font-size: 12.5px; }
  .msg { max-width: 92%; }
  .chat { height: calc(100dvh - 300px); }
  .toast { bottom: calc(78px + env(safe-area-inset-bottom)); }
}