/* ===== Reset & Base ===== */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: 'Inter', 'Noto Sans KR', -apple-system, BlinkMacSystemFont, sans-serif;
  background: #0b0d10;
  color: #e7eaee;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; text-decoration: none; }
img { max-width: 100%; display: block; }

/* ===== Theme Variables ===== */
:root {
  --bg: #0b0d10;
  --bg-alt: #11151a;
  --bg-card: #161b22;
  --bg-card-hover: #1d242d;
  --border: #232a33;
  --border-strong: #2e3742;
  --text: #e7eaee;
  --text-mute: #9aa4b1;
  --text-soft: #c5cdd7;
  --accent: #d97757;        /* Claude orange-ish */
  --accent-glow: rgba(217, 119, 87, 0.18);
  --accent-strong: #e88a6c;
  --good: #6ee7b7;
}

/* ===== Layout ===== */
.container {
  max-width: 1120px;
  margin: 0 auto;
  padding: 0 24px;
}
.section {
  padding: 96px 0;
  border-top: 1px solid var(--border);
}
.section-alt {
  background: var(--bg-alt);
}
.section-head {
  text-align: center;
  margin-bottom: 56px;
}
.section-head h2 {
  font-size: 40px;
  margin: 8px 0 12px;
  letter-spacing: -0.02em;
  font-weight: 800;
}
.section-desc {
  color: var(--text-mute);
  max-width: 640px;
  margin: 0 auto;
  font-size: 17px;
}
.eyebrow {
  display: inline-block;
  padding: 4px 12px;
  background: var(--accent-glow);
  color: var(--accent-strong);
  border-radius: 999px;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

/* ===== Header ===== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(11, 13, 16, 0.85);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}
.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 800;
  font-size: 18px;
}
.brand-mark {
  color: var(--accent);
  font-size: 22px;
  filter: drop-shadow(0 0 8px var(--accent-glow));
}
.nav {
  display: flex;
  gap: 28px;
  font-size: 15px;
  color: var(--text-mute);
}
.nav a:hover { color: var(--text); }

/* ===== Hero ===== */
.hero {
  padding: 120px 0 96px;
  background:
    radial-gradient(circle at 20% 0%, rgba(217, 119, 87, 0.12), transparent 50%),
    radial-gradient(circle at 80% 100%, rgba(110, 130, 200, 0.10), transparent 50%),
    var(--bg);
  text-align: center;
}
.hero-tag {
  display: inline-block;
  padding: 6px 14px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 999px;
  font-size: 13px;
  color: var(--text-mute);
  margin-bottom: 28px;
}
.hero-title {
  font-size: clamp(48px, 8vw, 96px);
  font-weight: 800;
  letter-spacing: -0.04em;
  line-height: 1.05;
  margin: 0 0 24px;
}
.hero-title .accent {
  color: var(--accent);
  background: linear-gradient(180deg, var(--accent-strong), var(--accent));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}
.hero-sub {
  font-size: 19px;
  color: var(--text-soft);
  max-width: 580px;
  margin: 0 auto 48px;
}
.hero-meta {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
  max-width: 760px;
  margin: 0 auto 48px;
}
.meta-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 20px;
  text-align: left;
}
.meta-label {
  font-size: 12px;
  color: var(--text-mute);
  text-transform: uppercase;
  letter-spacing: 0.12em;
  margin-bottom: 6px;
}
.meta-value {
  font-size: 17px;
  font-weight: 700;
  color: var(--text);
}
.meta-sub {
  font-weight: 400;
  color: var(--text-mute);
  font-size: 13px;
}
.hero-cta {
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
}

/* ===== Buttons ===== */
.btn {
  display: inline-block;
  padding: 14px 26px;
  border-radius: 12px;
  font-weight: 600;
  font-size: 15px;
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform 0.15s ease, background 0.15s ease, box-shadow 0.15s ease;
}
.btn-primary {
  background: var(--accent);
  color: #1a0c05;
  box-shadow: 0 8px 24px var(--accent-glow);
}
.btn-primary:hover {
  background: var(--accent-strong);
  transform: translateY(-1px);
}
.btn-ghost {
  background: transparent;
  color: var(--text);
  border-color: var(--border-strong);
}
.btn-ghost:hover {
  background: var(--bg-card);
}
.btn-lg {
  padding: 18px 36px;
  font-size: 17px;
}

/* ===== Schedule ===== */
.schedule-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(190px, 1fr));
  gap: 16px;
}
.sched-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 24px;
  transition: border-color 0.2s ease, transform 0.2s ease;
}
.sched-card:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
}
.sched-week {
  font-size: 12px;
  color: var(--accent-strong);
  font-weight: 700;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}
.sched-date {
  font-size: 22px;
  font-weight: 700;
  margin-top: 8px;
}
.sched-time {
  color: var(--text-mute);
  font-size: 14px;
  margin-top: 2px;
}
.sched-topic {
  margin-top: 16px;
  padding-top: 16px;
  border-top: 1px solid var(--border);
  font-size: 15px;
  color: var(--text-soft);
  font-weight: 500;
}
.sched-extra {
  border-style: dashed;
}
.sched-extra .sched-week {
  color: var(--text-mute);
}

/* ===== Curriculum / Week Cards ===== */
.week-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 20px;
}
.week-card {
  display: block;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 28px;
  transition: transform 0.2s ease, border-color 0.2s ease, background 0.2s ease;
  position: relative;
  overflow: hidden;
}
.week-card::before {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at 100% 0%, var(--accent-glow), transparent 50%);
  opacity: 0;
  transition: opacity 0.3s ease;
}
.week-card:hover {
  border-color: var(--accent);
  transform: translateY(-4px);
  background: var(--bg-card-hover);
}
.week-card:hover::before { opacity: 1; }
.week-card > * { position: relative; }
.week-num {
  font-family: 'JetBrains Mono', monospace;
  font-size: 14px;
  color: var(--accent);
  font-weight: 700;
  letter-spacing: 0.16em;
}
.week-title {
  font-size: 22px;
  font-weight: 700;
  margin: 12px 0 10px;
  letter-spacing: -0.01em;
}
.week-desc {
  color: var(--text-mute);
  font-size: 14.5px;
  margin: 0 0 20px;
}
.week-bullets {
  list-style: none;
  padding: 0;
  margin: 0 0 20px;
}
.week-bullets li {
  font-size: 14px;
  color: var(--text-soft);
  padding: 6px 0 6px 20px;
  position: relative;
}
.week-bullets li::before {
  content: "—";
  color: var(--accent);
  position: absolute;
  left: 0;
  top: 6px;
  font-weight: 700;
}
.week-resource {
  font-size: 13px;
  color: var(--text-soft);
  padding: 10px 12px;
  background: rgba(217, 119, 87, 0.08);
  border: 1px solid rgba(217, 119, 87, 0.2);
  border-radius: 8px;
  margin-bottom: 16px;
}
.week-resource code {
  font-family: 'JetBrains Mono', monospace;
  color: var(--accent-strong);
  background: transparent;
  font-size: 13px;
  font-weight: 600;
}
.week-link {
  font-size: 14px;
  color: var(--accent);
  font-weight: 600;
}

/* ===== Prep ===== */
.prep-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 16px;
}
.prep-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 24px;
}
.prep-step {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: var(--accent-glow);
  color: var(--accent-strong);
  font-weight: 800;
  font-size: 14px;
  margin-bottom: 14px;
}
.prep-card h3 {
  font-size: 17px;
  margin: 0 0 8px;
}
.prep-card p {
  font-size: 14px;
  color: var(--text-mute);
  margin: 0 0 14px;
}
.prep-card a {
  color: var(--accent);
  font-weight: 600;
  font-size: 14px;
  margin-right: 12px;
}
.prep-card a:hover { color: var(--accent-strong); }
.prep-pending {
  font-size: 13px;
  color: var(--text-mute);
  font-style: italic;
}
.prep-card .copy-btn {
  display: inline-block;
  margin-top: 8px;
  padding: 6px 12px;
  font-size: 13px;
  font-weight: 600;
  color: var(--accent);
  background: transparent;
  border: 1px solid var(--accent);
  border-radius: 6px;
  cursor: pointer;
  font-family: inherit;
}
.prep-card .copy-btn:hover {
  background: var(--accent);
  color: #fff;
}
.prep-foot {
  margin-top: 32px;
  padding: 20px 24px;
  background: var(--bg-card);
  border-left: 4px solid var(--accent);
  border-radius: 8px;
  font-size: 15px;
  color: var(--text-soft);
}

/* ===== How it works ===== */
.how-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  margin-bottom: 32px;
}
.how-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 28px;
}
.how-step {
  font-family: 'JetBrains Mono', monospace;
  color: var(--accent);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.16em;
  margin-bottom: 10px;
}
.how-card h3 {
  font-size: 19px;
  margin: 0 0 12px;
  letter-spacing: -0.01em;
}
.how-card p {
  font-size: 14.5px;
  color: var(--text-mute);
  margin: 0;
}
.how-why {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-left: 4px solid var(--accent);
  border-radius: 12px;
  padding: 28px 32px;
}
.how-why h3 {
  font-size: 20px;
  margin: 0 0 12px;
}
.how-why p {
  color: var(--text-soft);
  font-size: 15px;
  margin: 0 0 18px;
}
.how-rules {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: 8px;
}
.how-rules li {
  font-size: 14.5px;
  color: var(--text-mute);
  padding-left: 16px;
  position: relative;
}
.how-rules li::before {
  content: "·";
  color: var(--accent);
  position: absolute;
  left: 0;
  font-weight: 700;
}
@media (max-width: 768px) {
  .how-grid { grid-template-columns: 1fr; }
}

/* ===== For Whom ===== */
.for-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 20px;
}
.for-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 28px;
  text-align: center;
}
.for-icon {
  font-size: 36px;
  margin-bottom: 12px;
}
.for-card h3 {
  font-size: 17px;
  margin: 0 0 8px;
}
.for-card p {
  font-size: 14.5px;
  color: var(--text-mute);
  margin: 0;
}

/* ===== FAQ ===== */
.faq-list {
  max-width: 760px;
  margin: 0 auto;
}
.faq {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 0 22px;
  margin-bottom: 12px;
  transition: border-color 0.2s ease;
}
.faq:hover { border-color: var(--border-strong); }
.faq summary {
  cursor: pointer;
  font-weight: 600;
  font-size: 16px;
  padding: 18px 0;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.faq summary::after {
  content: "+";
  color: var(--accent);
  font-size: 22px;
  font-weight: 400;
  transition: transform 0.2s ease;
}
.faq[open] summary::after {
  transform: rotate(45deg);
}
.faq summary::-webkit-details-marker { display: none; }
.faq p {
  color: var(--text-mute);
  font-size: 14.5px;
  margin: 0 0 18px;
  padding-bottom: 4px;
}

/* ===== CTA ===== */
.cta {
  padding: 96px 0;
  background:
    radial-gradient(circle at 50% 50%, rgba(217, 119, 87, 0.12), transparent 60%),
    var(--bg);
  text-align: center;
  border-top: 1px solid var(--border);
}
.cta-inner h2 {
  font-size: clamp(32px, 5vw, 48px);
  margin: 0 0 16px;
  letter-spacing: -0.02em;
  font-weight: 800;
}
.cta-inner p {
  color: var(--text-mute);
  font-size: 17px;
  margin: 0 0 32px;
}

/* ===== Footer ===== */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 32px 0;
  background: var(--bg-alt);
}
.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 16px;
  font-size: 14px;
  color: var(--text-mute);
}
.footer-meta {
  display: flex;
  gap: 8px;
}

/* ===== Week Detail Pages ===== */
.detail-hero {
  padding: 80px 0 48px;
  background:
    radial-gradient(circle at 30% 0%, var(--accent-glow), transparent 50%),
    var(--bg);
}
.detail-back {
  color: var(--text-mute);
  font-size: 14px;
  margin-bottom: 20px;
  display: inline-block;
}
.detail-back:hover { color: var(--accent); }
.detail-eyebrow {
  font-family: 'JetBrains Mono', monospace;
  color: var(--accent);
  font-size: 14px;
  font-weight: 700;
  letter-spacing: 0.16em;
  margin-bottom: 12px;
}
.detail-title {
  font-size: clamp(36px, 5vw, 56px);
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.1;
  margin: 0 0 16px;
}
.detail-sub {
  color: var(--text-mute);
  font-size: 18px;
  max-width: 680px;
}
.detail-meta {
  display: flex;
  gap: 24px;
  margin-top: 28px;
  flex-wrap: wrap;
}
.detail-meta-item {
  font-size: 14px;
  color: var(--text-mute);
}
.detail-meta-item strong {
  color: var(--text);
  display: block;
  margin-top: 2px;
}
.detail-section {
  padding: 48px 0;
  border-top: 1px solid var(--border);
}
.detail-section h2 {
  font-size: 28px;
  margin: 0 0 8px;
  letter-spacing: -0.01em;
}
.detail-section .sub {
  color: var(--text-mute);
  margin: 0 0 32px;
}
.session-list {
  display: grid;
  gap: 20px;
}
.session {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 28px;
}
.session-num {
  font-family: 'JetBrains Mono', monospace;
  font-size: 13px;
  color: var(--accent);
  font-weight: 700;
  letter-spacing: 0.14em;
}
.session h3 {
  font-size: 22px;
  margin: 8px 0 16px;
  letter-spacing: -0.01em;
}
.session ul {
  margin: 0;
  padding: 0;
  list-style: none;
}
.session li {
  padding: 8px 0 8px 24px;
  position: relative;
  color: var(--text-soft);
  font-size: 15px;
  border-bottom: 1px dashed var(--border);
}
.session li:last-child { border-bottom: none; }
.session li::before {
  content: "✓";
  position: absolute;
  left: 0;
  color: var(--accent);
  font-weight: 700;
}
.homework {
  background: var(--bg-card);
  border-left: 4px solid var(--accent);
  padding: 24px 28px;
  border-radius: 8px;
}
.homework h3 {
  margin: 0 0 12px;
  font-size: 18px;
}
.homework ul {
  margin: 0;
  padding-left: 20px;
  color: var(--text-soft);
}
.download-btn {
  display: inline-block;
  padding: 10px 18px;
  background: var(--accent);
  color: #fff;
  font-weight: 700;
  border-radius: 8px;
  text-decoration: none;
}
.download-btn:hover { background: var(--accent-strong); }
.download-note {
  margin: 8px 0 0;
  color: var(--text-mute);
  font-size: 14px;
}
.zip-contents {
  margin: 16px 0 0 12px;
  padding: 12px 16px;
  border: 1px dashed var(--border-strong);
  border-radius: 8px;
  font-size: 14px;
}
.zip-contents-label {
  margin-bottom: 6px;
  color: var(--text-mute);
  font-size: 13px;
}
.next-week {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 28px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 16px;
  margin-top: 24px;
}
.next-week-label {
  font-size: 12px;
  color: var(--text-mute);
  letter-spacing: 0.16em;
  text-transform: uppercase;
}
.next-week-title {
  font-size: 18px;
  font-weight: 700;
  margin-top: 4px;
}
.next-week-arrow {
  color: var(--accent);
  font-size: 24px;
  font-weight: 700;
}

/* ===== Responsive ===== */

/* Tablet (≤ 900px) */
@media (max-width: 900px) {
  .container { padding: 0 20px; }
  .section { padding: 72px 0; }
  .section-head { margin-bottom: 40px; }
  .section-head h2 { font-size: 32px; }
  .hero { padding: 96px 0 72px; }
  .hero-meta { grid-template-columns: 1fr 1fr; }
  .how-grid { grid-template-columns: 1fr; }
  .next-week { flex-direction: column; gap: 12px; align-items: flex-start; }
  .footer-inner { flex-direction: column; align-items: flex-start; gap: 8px; }
  .footer-meta { flex-wrap: wrap; }
}

/* Mobile (≤ 640px) */
@media (max-width: 640px) {
  .container { padding: 0 16px; }

  /* Header — nav becomes horizontal scroll */
  .site-header { height: auto; }
  .header-inner {
    flex-direction: column;
    height: auto;
    padding: 12px 0;
    gap: 8px;
  }
  .nav {
    width: 100%;
    overflow-x: auto;
    gap: 18px;
    font-size: 14px;
    padding: 4px 0 8px;
    justify-content: flex-start;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: none;
  }
  .nav::-webkit-scrollbar { display: none; }
  .nav a { white-space: nowrap; flex-shrink: 0; }
  .brand { font-size: 16px; }

  /* Hero */
  .hero { padding: 56px 0 56px; }
  .hero-tag { font-size: 12px; padding: 5px 12px; margin-bottom: 20px; }
  .hero-title { line-height: 1.1; margin-bottom: 18px; }
  .hero-sub { font-size: 16px; margin-bottom: 32px; }
  .hero-meta {
    grid-template-columns: 1fr;
    gap: 10px;
    margin-bottom: 32px;
  }
  .meta-card { padding: 16px; }
  .meta-value { font-size: 15px; }
  .hero-cta { flex-direction: column; align-items: stretch; gap: 10px; }
  .btn { width: 100%; padding: 14px 20px; }
  .btn-lg { padding: 16px 24px; font-size: 16px; }

  /* Sections */
  .section { padding: 56px 0; }
  .section-head { margin-bottom: 32px; }
  .section-head h2 { font-size: 26px; }
  .section-desc { font-size: 15px; }

  /* Schedule */
  .schedule-grid { grid-template-columns: 1fr; gap: 12px; }
  .sched-card { padding: 20px; }
  .sched-date { font-size: 19px; }

  /* Curriculum cards */
  .week-grid { grid-template-columns: 1fr; gap: 14px; }
  .week-card { padding: 22px; }
  .week-title { font-size: 19px; }

  /* Prep cards */
  .prep-grid { grid-template-columns: 1fr; gap: 12px; }

  /* For-whom */
  .for-grid { grid-template-columns: 1fr; gap: 14px; }
  .for-card { padding: 22px; }

  /* FAQ */
  .faq summary { font-size: 15px; padding: 16px 0; }

  /* CTA */
  .cta { padding: 64px 0; }
  .cta-inner h2 { font-size: 28px; }

  /* Detail (week pages) */
  .detail-hero { padding: 56px 0 32px; }
  .detail-title { font-size: 30px; }
  .detail-sub { font-size: 16px; }
  .detail-meta { gap: 14px; }
  .detail-meta-item { font-size: 13px; }
  .detail-section { padding: 36px 0; }
  .detail-section h2 { font-size: 24px; }

  /* Sessions */
  .session { padding: 22px; }
  .session h3 { font-size: 19px; }
  .session li { font-size: 14px; }

  /* Homework / Next-week */
  .homework { padding: 20px 22px; }
  .next-week { padding: 22px; }
  .next-week-title { font-size: 16px; }
}

/* Smallest (≤ 380px) — fine-tune for 320–380px */
@media (max-width: 380px) {
  .hero-title { font-size: 38px; }
  .section-head h2 { font-size: 22px; }
  .detail-title { font-size: 26px; }
  .week-card .week-title { font-size: 17px; }
}