/* Empira — Class Plan (Phase 2 rebuild)
   Design system: Inter font, #3B4CFF blue, #F4F5F9 paper.
   Matches Phase 1 topic page tokens. No gamification, no stars. */

:root {
  --blue-500: #3B4CFF;  --blue-600: #2F3DE0;  --blue-700: #2632C2;
  --blue-100: #D7DBFF;  --blue-50:  #EEF0FF;
  --amber-500: #FFB21E;
  --ink-900: #1A1D33;  --ink-700: #474C63;  --ink-500: #6B7191;  --ink-400: #8A90A6;
  --line: #ECEDF3;  --mist: #ECEEF4;  --paper: #F4F5F9;  --white: #FFFFFF;

  --font: 'Inter', system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;

  --s1: 4px; --s2: 8px; --s3: 12px; --s4: 16px; --s5: 20px; --s6: 24px;
  --s7: 32px; --s8: 48px;

  --r-s: 7px; --r-m: 12px; --r-l: 18px; --r-xl: 22px; --r-full: 999px;
  --ease: cubic-bezier(.2,.8,.2,1); --t-fast: 150ms;

  --page-gutter: 18px;
  --topbar-h: 62px;
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; min-height: 100vh;
  background: var(--paper); color: var(--ink-900);
  font-family: var(--font); font-size: 16px; line-height: 1.55;
  -webkit-font-smoothing: antialiased;
}
h1, h2, h3, p { margin: 0; font: inherit; }
ol, ul { margin: 0; padding: 0; list-style: none; }
a { color: inherit; text-decoration: none; }
button { font: inherit; color: inherit; background: none; border: 0; padding: 0; cursor: pointer; }
[hidden] { display: none !important; }

:focus-visible { outline: 2px solid var(--blue-500); outline-offset: 2px; }

.icon {
  width: 20px; height: 20px; flex: none;
  fill: none; stroke: currentColor; stroke-width: 1.75;
  stroke-linecap: round; stroke-linejoin: round;
}

/* ========== Top bar ========== */
.topbar {
  position: sticky; top: 0; z-index: 10;
  height: var(--topbar-h);
  background: var(--white);
  border-bottom: 1px solid var(--line);
}
.topbar__inner {
  height: 100%;
  max-width: calc(960px + 2 * var(--page-gutter));
  margin: 0 auto; padding: 0 var(--page-gutter);
  display: flex; align-items: center; gap: var(--s2);
}
.icon-btn {
  display: grid; place-items: center;
  width: 44px; height: 44px; margin-left: -10px;
  border-radius: var(--r-m); color: var(--ink-900);
  transition: background var(--t-fast) var(--ease);
}
.icon-btn .icon { width: 24px; height: 24px; }
.logo { display: inline-flex; align-items: center; height: 44px; border-radius: var(--r-s); }
.logo svg { height: 28px; width: auto; display: block; }
.logo .logo__full { display: none; }

.scan-btn {
  margin-left: auto;
  display: inline-flex; align-items: center; justify-content: center; gap: var(--s2);
  width: 44px; height: 44px;
  background: var(--white); color: var(--ink-900);
  border: 1px solid var(--line); border-radius: var(--r-m);
  font-size: 16px; font-weight: 600;
  transition: background var(--t-fast) var(--ease), border-color var(--t-fast) var(--ease), color var(--t-fast) var(--ease);
}
.scan-btn__label { display: none; }

/* ========== Page ========== */
.page {
  max-width: calc(960px + 2 * var(--page-gutter));
  margin: 0 auto;
  padding: var(--s6) var(--page-gutter) calc(var(--s8) + env(safe-area-inset-bottom));
}

/* ========== Class + subject ========== */
.eyebrow { font-size: 14px; line-height: 1.4; font-weight: 500; color: var(--ink-500); }
.plan-head__title {
  margin-top: var(--s1);
  font-size: 28px; line-height: 1.15; font-weight: 700; letter-spacing: -0.02em;
}
.subjects { margin-top: var(--s4); }
.subjects ul { display: flex; flex-wrap: wrap; gap: var(--s2); }
.subject {
  display: inline-flex; align-items: center;
  height: 44px; padding: 0 20px;
  background: var(--white);
  border: 1px solid var(--line); border-radius: var(--r-m);
  font-size: 16px; font-weight: 600; line-height: 1;
  transition: background var(--t-fast) var(--ease), border-color var(--t-fast) var(--ease), color var(--t-fast) var(--ease);
}
.subject[aria-current="true"] {
  background: var(--blue-50); color: var(--blue-500);
  border-color: var(--blue-500); box-shadow: inset 0 0 0 1px var(--blue-500);
}
.plan-head__summary {
  margin-top: var(--s3);
  font-size: 14px; line-height: 1.45; font-weight: 500; color: var(--ink-500);
}

/* This-week row */
.now-row {
  margin-top: var(--s5);
  display: grid;
  grid-template-columns: minmax(0, 1fr) 24px;
  grid-template-areas: "text go" "tag go";
  column-gap: var(--s4); row-gap: var(--s2);
  align-items: center;
  min-height: 64px;
  padding: var(--s3) var(--s4);
  background: var(--white);
  border: 1px solid var(--line); border-radius: var(--r-m);
  transition: background var(--t-fast) var(--ease), border-color var(--t-fast) var(--ease);
}
.now-row__text { grid-area: text; display: flex; flex-direction: column; gap: 2px; min-width: 0; }
.now-row__label { display: flex; align-items: center; gap: var(--s2); font-size: 14px; line-height: 1.4; font-weight: 500; color: var(--ink-500); }
.now-row__title { font-size: 17px; line-height: 1.3; font-weight: 600; letter-spacing: -0.01em; transition: color var(--t-fast) var(--ease); }
.now-row .tag { grid-area: tag; }
.now-row__go { grid-area: go; display: grid; place-items: center; color: var(--ink-500); transition: color var(--t-fast) var(--ease); }

/* ========== Plan ========== */
.plan { margin-top: var(--s7); }
.plan__bar { display: flex; flex-direction: column; align-items: flex-start; gap: var(--s2); }
.section-title { font-size: 20px; line-height: 1.25; font-weight: 700; letter-spacing: -0.015em; }
.hint { margin-top: var(--s1); font-size: 14px; line-height: 1.45; font-weight: 500; color: var(--ink-500); }

.text-btn {
  flex: none;
  height: 40px; padding: 0 var(--s3); margin-left: calc(-1 * var(--s3));
  border-radius: var(--r-m);
  font-size: 14px; font-weight: 600; color: var(--blue-500);
  transition: background var(--t-fast) var(--ease);
}

.chapters { margin-top: var(--s4); border-bottom: 1px solid var(--line); }

/* Chapter header */
.chapter { border-top: 1px solid var(--line); }
.chapter__h { margin: 0; }
.chapter__head {
  width: 100%;
  display: grid;
  grid-template-columns: minmax(0, 1fr) 24px;
  grid-template-areas: "text chev" "count chev";
  column-gap: var(--s4); row-gap: var(--s1);
  align-items: center;
  padding: var(--s4) 0;
  text-align: left;
  background: var(--paper);
  border-radius: 0;
}
.chapter__head[aria-expanded="true"] {
  position: sticky; top: var(--topbar-h); z-index: 2;
}
.chapter__text { grid-area: text; display: flex; flex-direction: column; gap: 2px; min-width: 0; }
.chapter__meta { font-size: 14px; line-height: 1.4; font-weight: 500; color: var(--ink-500); }
.chapter__title {
  font-size: 20px; line-height: 1.25; font-weight: 700; letter-spacing: -0.015em;
  transition: color var(--t-fast) var(--ease);
}
.chapter__count { grid-area: count; font-size: 14px; line-height: 1.4; font-weight: 500; color: var(--ink-500); }
.chapter__chevron {
  grid-area: chev; width: 24px; height: 24px; color: var(--ink-500);
  transition: transform var(--t-fast) var(--ease), color var(--t-fast) var(--ease);
}
.chapter__head[aria-expanded="true"] .chapter__chevron { transform: rotate(180deg); }

/* Topics panel */
.topics {
  margin: 0 0 var(--s5);
  padding: var(--s1);
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: var(--r-l);
}
.topics > li + li { border-top: 1px solid var(--mist); }

.topic {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) 24px;
  grid-template-areas: "title title go" "week tag go";
  column-gap: var(--s3); row-gap: var(--s2);
  align-items: center;
  min-height: 64px;
  padding: 14px var(--s3);
  border-radius: var(--r-m);
}
.topic__title {
  grid-area: title;
  font-size: 17px; line-height: 1.35; font-weight: 500; color: var(--ink-700);
  letter-spacing: -0.005em;
  transition: color var(--t-fast) var(--ease);
}
.topic__week {
  grid-area: week;
  display: flex; align-items: center; gap: var(--s3);
  font-size: 14px; line-height: 1.3; font-weight: 500; color: var(--ink-500);
  white-space: nowrap;
}
.now {
  display: inline-flex; align-items: center;
  height: 22px; padding: 0 8px; border-radius: var(--r-s);
  background: var(--mist); color: var(--ink-900);
  font-size: 13px; font-weight: 600;
}
.dot { width: 8px; height: 8px; border-radius: var(--r-full); background: var(--amber-500); flex: none; }
.tag {
  grid-area: tag; justify-self: start;
  display: inline-flex; align-items: center;
  height: 28px; padding: 0 10px;
  border-radius: var(--r-s);
  background: var(--blue-50); color: var(--blue-500);
  font-size: 13px; line-height: 1; font-weight: 600; letter-spacing: 0.01em;
  white-space: nowrap;
}
.topic__go { grid-area: go; display: grid; place-items: center; color: var(--ink-500); transition: color var(--t-fast) var(--ease); }

.topic--now { grid-template-areas: "title title go" "week week go" "tag tag go"; }
.topic--lab .topic__title { font-weight: 600; color: var(--ink-900); }
.topic--now .topic__title { color: var(--ink-900); }

/* ========== Interaction states ========== */
@media (hover: hover) {
  .now-row:hover { background: var(--blue-50); border-color: var(--blue-500); }
  .now-row:hover .now-row__title, .now-row:hover .now-row__go { color: var(--blue-500); }
  .topic:hover { background: var(--blue-50); box-shadow: inset 0 0 0 1px var(--blue-500); }
  .topic:hover .topic__title, .topic:hover .topic__go { color: var(--blue-500); }
  .chapter__head:hover .chapter__title, .chapter__head:hover .chapter__chevron { color: var(--blue-500); }
  .subject:not([aria-current="true"]):hover { background: var(--blue-50); border-color: var(--blue-500); color: var(--blue-500); }
  .scan-btn:hover { background: var(--blue-50); border-color: var(--blue-500); color: var(--blue-500); }
  .icon-btn:hover, .text-btn:hover { background: var(--blue-50); }
  .icon-btn:hover { color: var(--blue-500); }
}
.now-row:active { background: var(--blue-50); border-color: var(--blue-600); }
.topic:active { background: var(--blue-50); box-shadow: inset 0 0 0 1px var(--blue-600); }
.subject:active, .scan-btn:active { background: var(--blue-50); border-color: var(--blue-600); }
.icon-btn:active, .text-btn:active { background: var(--blue-50); }

/* ========== Empty state ========== */
.empty { margin-top: var(--s7); padding: var(--s6); background: var(--white); border: 1px solid var(--line); border-radius: var(--r-l); }
.empty__title { font-size: 18px; line-height: 1.4; font-weight: 600; }
.empty .btn { margin-top: var(--s4); }
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  height: 48px; padding: 0 20px; border-radius: var(--r-m);
  font-size: 16px; font-weight: 600; line-height: 1;
  transition: background var(--t-fast) var(--ease), border-color var(--t-fast) var(--ease), color var(--t-fast) var(--ease);
}
.btn--primary { background: var(--blue-500); color: var(--white); }
@media (hover: hover) { .btn--primary:hover { background: var(--blue-600); } }
.empty .btn + .btn { margin-left: var(--s2); }
@media (max-width: 639px) { .empty .btn { display: flex; width: 100%; } .empty .btn + .btn { margin-left: 0; margin-top: var(--s2); } }
.btn--secondary { background: var(--white); color: var(--ink-900); border: 1px solid var(--line); }
@media (hover: hover) { .btn--secondary:hover { background: var(--blue-50); border-color: var(--blue-500); color: var(--blue-500); } }
.btn--secondary:active { background: var(--blue-50); border-color: var(--blue-600); }

/* ========== Tablet >= 640px ========== */
@media (min-width: 640px) {
  :root { --page-gutter: 24px; }
  .page { padding-top: var(--s8); }
  .plan-head__title { font-size: 32px; }
  .plan { margin-top: var(--s8); }

  .logo .logo__full { display: block; }
  .logo .logo__symbol { display: none; }
  .plan__bar { flex-direction: row; align-items: flex-end; justify-content: space-between; gap: var(--s4); }
  .text-btn { margin-left: 0; margin-right: calc(-1 * var(--s3)); }
  .now-row { grid-template-columns: minmax(0, 1fr) auto 24px; grid-template-areas: "text tag go"; }

  .scan-btn { width: auto; height: 40px; padding: 0 var(--s4); }
  .scan-btn__label { display: inline; }

  .chapter__head {
    grid-template-columns: minmax(0, 1fr) auto 24px;
    grid-template-areas: "text count chev";
    padding: 20px 0;
  }
  .chapter__title { font-size: 22px; }

  .topic {
    grid-template-columns: 112px minmax(0, 1fr) auto 24px;
    grid-template-areas: "week title tag go";
    column-gap: var(--s4);
    padding: 14px var(--s4);
  }
  .topic__week { flex-direction: column; align-items: flex-start; gap: 2px; }
  .topic--now { grid-template-areas: "week title tag go"; }
  .topic__title { font-size: 18px; }
}

/* ========== Desktop >= 1024px ========== */
@media (min-width: 1024px) {
  :root { --page-gutter: 32px; --topbar-h: 64px; }
  .plan-head__title { font-size: 36px; }
}

@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; }
}