/* ==========================================================================
   YES Investing Course — Shared Styles
   ========================================================================== */

:root {
  --navy:       #0F1C2E;
  --navy-mid:   #1B2A4A;
  --gold:       #C9A84C;
  --gold-muted: #8A6F30;
  --slate:      #8A99AC;
  --white:      #F5F4F0;
  --white-dim:  #BFC8D4;
  --surface:    #162032;
  --green:      #3DAA78;
  --red:        #D95C5C;

  --sidebar-width: 260px;
  --content-max: 720px;
  --font-serif: 'DM Serif Display', Georgia, serif;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: 'Courier New', Courier, monospace;
}

* , *::before, *::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  padding: 0;
  background: var(--navy);
  color: var(--white);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--gold);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

img { max-width: 100%; }

h1, h2, h3, h4 {
  font-family: var(--font-serif);
  font-weight: 400;
  color: var(--white);
  line-height: 1.25;
  margin: 0 0 0.6em;
}

h1 { font-size: 2.4rem; letter-spacing: 0.01em; }
h2 { font-size: 1.75rem; margin-top: 2.2em; }
h3 { font-size: 1.3rem; margin-top: 1.8em; color: var(--gold); }

p { margin: 0 0 1.3em; color: var(--white-dim); }

ul, ol {
  color: var(--white-dim);
  margin: 0 0 1.3em;
  padding-left: 1.4em;
}
li { margin-bottom: 0.5em; }

strong { color: var(--white); font-weight: 600; }

.eyebrow {
  font-family: var(--font-sans);
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  font-weight: 500;
  color: var(--gold);
  display: block;
  margin-bottom: 0.8em;
}

.formula, pre, code {
  font-family: var(--font-mono);
}

.formula {
  background: var(--navy-mid);
  border: 1px solid rgba(201, 168, 76, 0.25);
  border-left: 3px solid var(--gold);
  border-radius: 4px;
  padding: 1em 1.3em;
  margin: 1.5em 0;
  color: var(--white);
  font-size: 0.95rem;
  overflow-x: auto;
}

code {
  background: var(--navy-mid);
  padding: 0.15em 0.4em;
  border-radius: 3px;
  font-size: 0.9em;
  color: var(--gold);
}

/* ==========================================================================
   Skip link
   ========================================================================== */
.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--gold);
  color: var(--navy);
  padding: 0.6em 1em;
  z-index: 999;
}
.skip-link:focus {
  left: 1em;
  top: 1em;
}

/* ==========================================================================
   App shell: sidebar + main
   ========================================================================== */
.app {
  display: flex;
  min-height: 100vh;
}

/* ---- Sidebar ---- */
.sidebar {
  width: var(--sidebar-width);
  flex-shrink: 0;
  background: var(--navy-mid);
  border-right: 1px solid rgba(201, 168, 76, 0.12);
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  overflow-y: auto;
  z-index: 100;
  transition: transform 0.25s ease;
}

.sidebar-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1.6em 1.4em 1.2em;
  border-bottom: 1px solid rgba(201, 168, 76, 0.12);
}

.sidebar-logo {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  color: var(--white);
  letter-spacing: 0.02em;
}
.sidebar-logo span { color: var(--gold); }
.sidebar-logo:hover { text-decoration: none; }

.sidebar-close {
  display: none;
  background: none;
  border: none;
  color: var(--white-dim);
  font-size: 1.6rem;
  line-height: 1;
  cursor: pointer;
}

.sidebar-progress {
  padding: 1em 1.4em;
  border-bottom: 1px solid rgba(201, 168, 76, 0.12);
}
.sidebar-progress-label {
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--slate);
  margin-bottom: 0.5em;
  display: block;
}
.progress-track {
  background: rgba(255,255,255,0.06);
  border-radius: 99px;
  height: 6px;
  overflow: hidden;
}
.progress-fill {
  background: var(--green);
  height: 100%;
  width: 0%;
  border-radius: 99px;
  transition: width 0.4s ease;
}
.progress-text {
  font-size: 12px;
  color: var(--slate);
  margin-top: 0.5em;
  display: block;
}

.sidebar-nav {
  padding: 0.6em 0 2em;
}

.unit-group {
  border-bottom: 1px solid rgba(201, 168, 76, 0.08);
}

.unit-summary {
  list-style: none;
  cursor: pointer;
  padding: 0.9em 1.4em;
  font-size: 13px;
  font-weight: 500;
  color: var(--white-dim);
  display: flex;
  align-items: baseline;
  gap: 0.6em;
  user-select: none;
}
.unit-summary::-webkit-details-marker { display: none; }
.unit-summary::before {
  content: '\25B8';
  color: var(--gold-muted);
  font-size: 10px;
  transition: transform 0.15s ease;
  flex-shrink: 0;
}
details[open] > .unit-summary::before {
  transform: rotate(90deg);
}
.unit-summary:hover { color: var(--white); }

.unit-num-tag {
  font-family: var(--font-mono);
  color: var(--gold-muted);
  font-size: 11px;
}

.lesson-list {
  list-style: none;
  margin: 0;
  padding: 0 0 0.6em;
}

.lesson-list li {
  margin: 0;
}

.lesson-list a {
  display: block;
  padding: 0.5em 1.4em 0.5em 2.4em;
  font-size: 13.5px;
  color: var(--slate);
  border-left: 3px solid transparent;
  position: relative;
}

.lesson-list a:hover {
  color: var(--white);
  text-decoration: none;
  background: rgba(255,255,255,0.02);
}

.lesson-list a.active {
  color: var(--gold);
  border-left-color: var(--gold);
  background: rgba(201, 168, 76, 0.06);
  font-weight: 500;
}

.lesson-check {
  display: inline-block;
  width: 14px;
  color: var(--green);
  margin-right: 0.3em;
  opacity: 0;
}
.lesson-list li.is-complete .lesson-check {
  opacity: 1;
}

.sidebar-footer {
  padding: 1.2em 1.4em 2em;
}
.sidebar-footer a {
  font-size: 12.5px;
  color: var(--slate);
}

/* ---- Mobile menu button ---- */
.menu-toggle {
  display: none;
  position: fixed;
  top: 1em;
  left: 1em;
  z-index: 90;
  background: var(--navy-mid);
  border: 1px solid rgba(201,168,76,0.25);
  color: var(--white);
  border-radius: 6px;
  padding: 0.5em 0.7em;
  font-size: 1rem;
  cursor: pointer;
}

.sidebar-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.55);
  z-index: 95;
}

/* ---- Main content ---- */
.main {
  margin-left: var(--sidebar-width);
  flex: 1;
  min-width: 0;
  padding: 3em 2em 6em;
  display: flex;
  justify-content: center;
}

.content {
  width: 100%;
  max-width: var(--content-max);
}

/* ==========================================================================
   Breadcrumb / lesson meta
   ========================================================================== */
.breadcrumb {
  font-size: 13px;
  color: var(--slate);
  margin-bottom: 1.2em;
}
.breadcrumb a { color: var(--slate); }
.breadcrumb a:hover { color: var(--gold); }

.lesson-meta {
  display: flex;
  align-items: center;
  gap: 1em;
  color: var(--slate);
  font-size: 13px;
  margin-bottom: 2em;
  padding-bottom: 1.6em;
  border-bottom: 1px solid rgba(201,168,76,0.12);
}
.lesson-meta .dot::before { content: '\00B7'; margin-right: 1em; }

/* ==========================================================================
   Self-check
   ========================================================================== */
.self-check {
  margin: 3em 0 2em;
  background: var(--surface);
  border: 1px solid rgba(201,168,76,0.2);
  border-radius: 8px;
  padding: 1.6em 1.8em;
}
.self-check-label {
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--gold);
  font-weight: 500;
  display: block;
  margin-bottom: 0.8em;
}
.self-check p.question {
  color: var(--white);
  font-weight: 500;
  margin-bottom: 1em;
}
.self-check details {
  border-top: 1px solid rgba(201,168,76,0.15);
  padding-top: 1em;
}
.self-check summary {
  cursor: pointer;
  color: var(--gold);
  font-size: 14px;
  font-weight: 500;
  list-style: none;
}
.self-check summary::-webkit-details-marker { display: none; }
.self-check summary::before {
  content: '\25B8 ';
}
.self-check details[open] summary::before {
  content: '\25BE ';
}
.self-check .answer {
  margin-top: 1em;
  padding-top: 1em;
  border-top: 1px dashed rgba(255,255,255,0.1);
  color: var(--white-dim);
}
.self-check .answer p:last-child { margin-bottom: 0; }

/* ==========================================================================
   Mark complete + lesson nav
   ========================================================================== */
.mark-complete {
  margin: 2.5em 0;
  text-align: center;
}

.btn {
  display: inline-block;
  font-family: var(--font-sans);
  font-size: 13px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  padding: 0.9em 1.8em;
  border-radius: 6px;
  border: 1px solid var(--gold);
  color: var(--gold);
  background: transparent;
  cursor: pointer;
  transition: background 0.15s ease, color 0.15s ease;
}
.btn:hover {
  background: var(--gold);
  color: var(--navy);
  text-decoration: none;
}
.btn-solid {
  background: var(--gold);
  color: var(--navy);
}
.btn-solid:hover {
  background: var(--gold-muted);
  border-color: var(--gold-muted);
  color: var(--white);
}
.btn[data-complete-state="done"] {
  background: var(--green);
  border-color: var(--green);
  color: var(--navy);
}

.lesson-pager {
  display: flex;
  justify-content: space-between;
  gap: 1em;
  margin-top: 3em;
  padding-top: 2em;
  border-top: 1px solid rgba(201,168,76,0.12);
}
.pager-link {
  flex: 1;
  padding: 1em 1.2em;
  background: var(--navy-mid);
  border-radius: 8px;
  border: 1px solid rgba(201,168,76,0.12);
  color: var(--white-dim);
}
.pager-link:hover {
  border-color: var(--gold);
  text-decoration: none;
}
.pager-link.next { text-align: right; }
.pager-label {
  display: block;
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--slate);
  margin-bottom: 0.4em;
}
.pager-title {
  display: block;
  color: var(--gold);
  font-size: 14.5px;
  font-weight: 500;
}

.back-to-overview {
  display: block;
  text-align: center;
  margin-top: 2em;
  font-size: 13.5px;
  color: var(--slate);
}

/* ==========================================================================
   Tables
   ========================================================================== */
table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.6em 0;
  font-size: 14.5px;
}
th, td {
  text-align: left;
  padding: 0.7em 0.9em;
  border-bottom: 1px solid rgba(255,255,255,0.08);
  color: var(--white-dim);
}
th {
  color: var(--gold);
  font-weight: 500;
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  border-bottom: 1px solid rgba(201,168,76,0.3);
}
tr:last-child td { border-bottom: none; }

/* ==========================================================================
   Landing page
   ========================================================================== */
.hero {
  padding: 5em 2em 4em;
  text-align: center;
  max-width: 780px;
  margin: 0 auto;
}
.hero .eyebrow { justify-content: center; text-align: center; }
.hero h1 {
  font-size: 3rem;
  letter-spacing: 0.01em;
  margin-bottom: 0.5em;
}
.hero p.lead {
  font-size: 1.15rem;
  color: var(--white-dim);
  max-width: 600px;
  margin: 0 auto 2em;
}

.home-progress {
  max-width: 480px;
  margin: 0 auto 2.5em;
  background: var(--surface);
  border: 1px solid rgba(201,168,76,0.2);
  border-radius: 8px;
  padding: 1.4em 1.6em;
  display: none;
}
.home-progress.visible { display: block; }
.home-progress .progress-text { color: var(--white-dim); font-size: 13.5px; }

.unit-grid {
  max-width: 1080px;
  margin: 0 auto;
  padding: 0 2em 5em;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 1.4em;
}

.unit-card {
  background: var(--navy-mid);
  border: 1px solid rgba(201,168,76,0.15);
  border-radius: 10px;
  padding: 1.8em;
  position: relative;
  overflow: hidden;
  display: block;
  color: inherit;
}
.unit-card:hover {
  border-color: var(--gold);
  text-decoration: none;
}
.unit-card-num {
  position: absolute;
  top: -0.3em;
  right: 0.2em;
  font-family: var(--font-serif);
  font-size: 5.5rem;
  color: var(--gold);
  opacity: 0.08;
  line-height: 1;
  pointer-events: none;
}
.unit-card-eyebrow {
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--gold-muted);
  margin-bottom: 0.6em;
  display: block;
}
.unit-card h3 {
  font-family: var(--font-serif);
  font-size: 1.3rem;
  color: var(--white);
  margin: 0 0 0.5em;
}
.unit-card p {
  font-size: 14px;
  color: var(--slate);
  margin: 0 0 1em;
  position: relative;
  z-index: 1;
}
.unit-card-count {
  font-size: 12px;
  color: var(--slate);
}

footer.site-footer {
  text-align: center;
  padding: 3em 2em 4em;
  color: var(--slate);
  font-size: 13px;
}

/* ==========================================================================
   Unit overview signature element (used within lesson/unit intro contexts)
   ========================================================================== */
.unit-hero {
  position: relative;
  padding: 1em 0 1.5em;
  margin-bottom: 1em;
}
.unit-hero-num {
  position: absolute;
  top: -0.6em;
  left: -0.1em;
  font-family: var(--font-serif);
  font-size: 7rem;
  color: var(--gold);
  opacity: 0.12;
  z-index: 0;
  line-height: 1;
}
.unit-hero-title {
  position: relative;
  z-index: 1;
}

/* ==========================================================================
   Responsive
   ========================================================================== */
@media (max-width: 900px) {
  .sidebar {
    transform: translateX(-100%);
    width: 280px;
  }
  .sidebar.open {
    transform: translateX(0);
    box-shadow: 8px 0 24px rgba(0,0,0,0.4);
  }
  .sidebar-close { display: block; }
  .menu-toggle { display: block; }
  .sidebar-overlay.open { display: block; }
  .main {
    margin-left: 0;
    padding: 5em 1.2em 4em;
  }
  .hero { padding: 4em 1.2em 3em; }
  .hero h1 { font-size: 2.2rem; }
  .unit-grid { padding: 0 1.2em 4em; }
  .lesson-pager { flex-direction: column; }
  .pager-link.next { text-align: left; }
}

@media (max-width: 480px) {
  h1 { font-size: 1.9rem; }
  .hero h1 { font-size: 1.8rem; }
  .unit-hero-num { font-size: 5rem; }
}