:root {
  color-scheme: dark;
  --bg: #0a0b0d;
  --panel: #121419;
  --panel-2: #181b21;
  --line: #2a2e36;
  --text: #f7f7f8;
  --muted: #9ca3ad;
  --accent: #ff5a1f;
  --accent-soft: rgba(255, 90, 31, 0.14);
  font-family: Pretendard, "Noto Sans KR", system-ui, sans-serif;
}

* { box-sizing: border-box; }
body {
  margin: 0;
  min-width: 320px;
  color: var(--text);
  background:
    radial-gradient(circle at 82% 0%, rgba(255, 90, 31, 0.16), transparent 28rem),
    var(--bg);
}
a { color: inherit; }
button, input, select { font: inherit; }

.shell { width: min(1180px, calc(100% - 32px)); margin: 0 auto; }
.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 70px;
  border-bottom: 1px solid var(--line);
}
.brand { text-decoration: none; font-weight: 800; letter-spacing: .08em; }
.brand span { color: var(--accent); }
.topbar nav { display: flex; gap: 18px; color: var(--muted); font-size: 14px; }
.topbar nav a { text-decoration: none; }
.topbar nav a:hover { color: var(--text); }

.hero { padding: 86px 0 54px; }
.eyebrow {
  margin: 0 0 15px;
  color: var(--accent);
  font: 700 13px/1.2 ui-monospace, SFMono-Regular, monospace;
  letter-spacing: .14em;
}
h1 { max-width: 850px; margin: 0; font-size: clamp(38px, 7vw, 76px); line-height: .98; letter-spacing: -.055em; }
.hero-copy { max-width: 700px; margin: 25px 0 0; color: var(--muted); font-size: 17px; line-height: 1.75; }
.hero-meta { margin-top: 24px; color: var(--muted); font-size: 13px; }

.metrics {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
  margin-bottom: 38px;
}
.metric { padding: 22px; border: 1px solid var(--line); border-radius: 14px; background: rgba(18, 20, 25, .86); }
.metric span { color: var(--muted); font-size: 13px; }
.metric strong { display: block; margin-top: 8px; font: 700 30px/1 ui-monospace, SFMono-Regular, monospace; }

.toolbar {
  position: sticky;
  top: 10px;
  z-index: 10;
  display: grid;
  grid-template-columns: minmax(240px, 1fr) 220px 220px auto auto;
  gap: 10px;
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: rgba(10, 11, 13, .92);
  backdrop-filter: blur(18px);
}
.toolbar input, .toolbar select, .toolbar button {
  min-height: 44px;
  border: 1px solid var(--line);
  border-radius: 10px;
  color: var(--text);
  background: var(--panel-2);
  padding: 0 13px;
}
.toolbar button { cursor: pointer; font-weight: 700; }
.toolbar button:hover { border-color: var(--accent); }
.toolbar .primary { border-color: var(--accent); background: var(--accent); color: #fff; }

.result-head { display: flex; align-items: center; justify-content: space-between; margin: 32px 0 16px; }
.result-head h2 { margin: 0; font-size: 22px; }
#result-summary { color: var(--muted); font-size: 14px; }
.course-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 15px; }
.course-card {
  position: relative;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: var(--panel);
  transition: transform .2s ease, border-color .2s ease;
}
.course-card:hover { transform: translateY(-3px); border-color: rgba(255, 90, 31, .65); }
.thumb { aspect-ratio: 16 / 9; overflow: hidden; background: var(--panel-2); }
.thumb img { width: 100%; height: 100%; object-fit: cover; transition: transform .35s ease; }
.course-card:hover img { transform: scale(1.035); }
.card-body { padding: 17px; }
.card-meta { display: flex; justify-content: space-between; gap: 12px; color: var(--muted); font-size: 12px; }
.rank { color: var(--accent); font-family: ui-monospace, SFMono-Regular, monospace; font-weight: 700; }
.course-card h3 { min-height: 3em; margin: 11px 0 9px; font-size: 17px; line-height: 1.5; letter-spacing: -.02em; }
.creator { margin: 0; color: var(--muted); font-size: 14px; }
.tags { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 15px; }
.tags span { max-width: 100%; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; padding: 5px 8px; border-radius: 999px; color: #ffc2aa; background: var(--accent-soft); font-size: 11px; }
.stretched { position: absolute; inset: 0; }
.empty { padding: 80px 20px; text-align: center; color: var(--muted); }

.notice {
  margin: 56px 0 26px;
  padding: 20px;
  border-left: 3px solid var(--accent);
  color: var(--muted);
  background: var(--panel);
  font-size: 14px;
  line-height: 1.7;
}
footer { display: flex; justify-content: space-between; gap: 20px; padding: 30px 0 48px; color: var(--muted); font-size: 13px; border-top: 1px solid var(--line); }

@media (max-width: 900px) {
  .metrics { grid-template-columns: repeat(2, 1fr); }
  .toolbar { grid-template-columns: 1fr 1fr; }
  .toolbar input { grid-column: 1 / -1; }
  .course-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 620px) {
  .shell { width: min(100% - 22px, 1180px); }
  .topbar nav a:first-child { display: none; }
  .hero { padding-top: 58px; }
  .metrics, .toolbar, .course-grid { grid-template-columns: 1fr; }
  .toolbar input { grid-column: auto; }
  footer { flex-direction: column; }
}