:root {
  --blue: #1d3fbf;
  --blue-d: #142c8a;
  --blue-l: #eef2ff;
  --ink: #1a1d27;
  --sub: #5d6375;
  --line: #e4e7ef;
  --bg: #f6f7fb;
  --ok: #18a058;
  --warm: #ffb547;
  --radius: 14px;
}
* { box-sizing: border-box; }
html, body { margin: 0; }
body {
  font-family: Pretendard, "Malgun Gothic", system-ui, sans-serif;
  background: var(--bg); color: var(--ink); line-height: 1.55;
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; text-decoration: none; }
button { font: inherit; cursor: pointer; }
[hidden] { display: none !important; }

/* 상단 */
.top {
  position: sticky; top: 0; z-index: 10;
  display: flex; align-items: center; justify-content: space-between;
  padding: 10px 20px; background: #fff; border-bottom: 1px solid var(--line);
}
.brand { display: flex; align-items: center; gap: 10px; font-weight: 800; color: var(--blue); font-size: 18px; letter-spacing: -0.3px; }
.brand img { width: 38px; height: 38px; border-radius: 50%; background: var(--blue-l); object-fit: cover; }
.who { display: flex; align-items: center; gap: 12px; color: var(--sub); font-size: 14px; }
.edu-link { color: var(--blue); font-weight: 700; padding: 5px 11px; border-radius: 999px; background: var(--blue-l); white-space: nowrap; }
.edu-link:hover { background: #dfe6ff; }
@media (max-width: 560px) { .edu-link span { display: none; } }
.link { background: none; border: 0; color: var(--sub); text-decoration: underline; padding: 4px; }

main { max-width: 1180px; margin: 0 auto; padding: 24px 16px 40px; min-height: 70vh; }
.loading { text-align: center; color: var(--sub); padding: 80px 0; }

/* 버튼 */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 6px;
  padding: 11px 18px; border-radius: 10px; border: 1px solid var(--line);
  background: #fff; color: var(--ink); font-weight: 600; font-size: 15px; transition: .15s;
}
.btn:hover { border-color: #c9cfdd; }
.btn.primary { background: var(--blue); border-color: var(--blue); color: #fff; }
.btn.primary:hover { background: var(--blue-d); }
.btn.on { background: #e8f7ef; border-color: #b9e6cc; color: var(--ok); }
.btn[aria-disabled="true"] { opacity: .35; pointer-events: none; }

/* 로그인 */
.login { max-width: 420px; margin: 10px auto 0; text-align: center; }
.login-logo { width: 210px; max-width: 70%; }
.login h1 { font-size: 26px; margin: 6px 0 4px; letter-spacing: -0.5px; }
.sub { color: var(--sub); margin: 0 0 20px; }
.card { background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 22px; text-align: left; box-shadow: 0 6px 24px rgba(20, 40, 120, .06); }
.card label { font-weight: 700; font-size: 14px; }
.card input {
  width: 100%; margin: 8px 0 14px; padding: 13px 14px; font-size: 16px;
  border: 1px solid var(--line); border-radius: 10px; outline: none; font-family: inherit;
}
.card input:focus { border-color: var(--blue); box-shadow: 0 0 0 3px rgba(29, 63, 191, .12); }
.card input.code { font-size: 28px; letter-spacing: 10px; text-align: center; font-weight: 800; }
.card .btn { width: 100%; }
.card .link { display: block; margin: 10px auto 0; }
.card input.code-in { font-size: 20px; letter-spacing: 2px; text-align: center; font-weight: 800; text-transform: uppercase; }
.card label small { font-weight: 400; color: var(--sub); }
.card label.agree { display: flex; gap: 8px; align-items: flex-start; font-weight: 400; font-size: 13px; color: var(--sub); margin: 0 0 14px; }
.card label.agree input { width: auto; margin: 3px 0 0; }
.first { display: block; margin: 16px 0 0; color: var(--sub); font-size: 14px; }
.first b { color: var(--blue); }
.hint { margin: 0 0 6px; font-size: 14px; color: var(--sub); }
.msg { min-height: 1.4em; margin: 12px 0 0; font-size: 14px; color: #d03b3b; }
.msg.ok { color: var(--ok); }
.notice { background: #fff8e8; border: 1px solid #ffe2a8; color: #7a5300; border-radius: 10px; padding: 10px 14px; font-size: 14px; text-align: left; margin: 16px 0; white-space: pre-line; }

.welcome { background: #eaf8f0; border: 1px solid #bfe8cf; color: #145c35; border-radius: var(--radius); padding: 14px 18px; margin-bottom: 16px; font-size: 15px; }
.welcome p { margin: 8px 0 0; color: #1f4a33; font-size: 14px; line-height: 1.6; }

/* 홈 */
.hello {
  display: flex; align-items: center; gap: 20px;
  background: linear-gradient(120deg, #fff 0%, var(--blue-l) 100%);
  border: 1px solid var(--line); border-radius: var(--radius); padding: 18px 24px; margin-bottom: 18px;
}
.hello-logo { width: 96px; flex: none; }
.hello > div { flex: 1; min-width: 0; }
.hello h1 { margin: 0; font-size: 22px; letter-spacing: -0.4px; }
.period { margin: 2px 0 10px; color: var(--sub); font-size: 14px; }
.bar { height: 8px; background: #dfe4f3; border-radius: 99px; overflow: hidden; max-width: 380px; }
.bar > div { height: 100%; background: var(--blue); border-radius: 99px; width: 0; transition: width .6s; }
.prog-text { margin: 6px 0 0; font-size: 13px; color: var(--sub); }
.resume { flex: none; }

.section { margin-top: 18px; }
.section h2 { font-size: 16px; color: var(--blue); margin: 0 0 8px 2px; }
.lessons { background: #fff; border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; }
.lesson {
  display: flex; align-items: center; gap: 14px; padding: 14px 18px;
  border-top: 1px solid var(--line); transition: background .12s;
}
.lesson:first-child { border-top: 0; }
.lesson:hover { background: #fafbff; }
.num {
  flex: none; width: 34px; height: 34px; border-radius: 50%;
  display: grid; place-items: center; font-weight: 800; font-size: 14px;
  background: var(--blue-l); color: var(--blue);
}
.lesson.seen .num { background: #fff1d6; color: #a66b00; }
.lesson.done .num { background: var(--ok); color: #fff; }
.lesson .t { flex: 1; min-width: 0; }
.lesson .t b { display: block; font-weight: 600; }
.lesson .t small { color: var(--sub); }
.lesson .meta { color: var(--sub); font-size: 13px; flex: none; }
.lesson.soon { opacity: .5; pointer-events: none; }

/* 시청 */
.watch { display: grid; grid-template-columns: minmax(0, 1fr) 320px; gap: 20px; align-items: start; }
.back { color: var(--sub); font-size: 14px; display: inline-block; margin-bottom: 10px; }
.player {
  position: relative; width: 100%; aspect-ratio: 16 / 9; background: #0d0f16;
  border-radius: var(--radius); overflow: hidden; user-select: none;
}
.player iframe { position: absolute; inset: 0; width: 100%; height: 100%; border: 0; }
.player .ph { position: absolute; inset: 0; display: grid; place-items: center; text-align: center; color: #c8cde0; padding: 20px; }
.player .ph img { width: 90px; opacity: .9; margin-bottom: 8px; }
.lesson-head { display: flex; justify-content: space-between; align-items: flex-start; gap: 16px; margin-top: 16px; }
.lesson-head h1 { margin: 0; font-size: 22px; letter-spacing: -0.4px; }
.lesson-head .sec { margin: 0 0 2px; color: var(--blue); font-weight: 700; font-size: 13px; }
.desc { color: var(--sub); white-space: pre-line; }
.nav { display: flex; justify-content: space-between; gap: 10px; margin-top: 18px; }
.side { background: #fff; border: 1px solid var(--line); border-radius: var(--radius); max-height: calc(100vh - 110px); overflow: auto; position: sticky; top: 76px; }
.side h3 { margin: 0; padding: 12px 16px 6px; font-size: 13px; color: var(--blue); }
.side .lesson { padding: 10px 14px; gap: 10px; }
.side .num { width: 28px; height: 28px; font-size: 12px; }
.side .lesson .t b { font-size: 14px; }
.side .lesson.cur { background: var(--blue-l); }

/* 오른쪽 탭: 수업노트 / 강의목록 */
.side { display: flex; flex-direction: column; }
.tabs { display: flex; border-bottom: 1px solid var(--line); flex: none; position: sticky; top: 0; background: #fff; z-index: 1; }
.tabs button { flex: 1; padding: 11px 6px; border: 0; background: none; font-weight: 600; color: var(--sub); border-bottom: 2px solid transparent; }
.tabs button.on { color: var(--blue); border-bottom-color: var(--blue); }
.pane { padding: 4px 0; }
.note-pane { padding: 12px; display: flex; flex-direction: column; gap: 8px; }
.note-tools { display: flex; align-items: center; justify-content: space-between; gap: 8px; }
.mini { padding: 6px 10px; border-radius: 8px; border: 1px solid var(--line); background: var(--blue-l); color: var(--blue); font-weight: 600; font-size: 13px; }
.mini:hover { border-color: #c9d3f5; }
.n-status { font-size: 12px; color: var(--sub); }
#n-text {
  width: 100%; min-height: 360px; resize: vertical; padding: 12px; border: 1px solid var(--line); border-radius: 10px;
  font: 14px/1.7 Pretendard, "Malgun Gothic", sans-serif; color: var(--ink); outline: none; background: #fffef8;
}
#n-text:focus { border-color: var(--blue); box-shadow: 0 0 0 3px rgba(29, 63, 191, .1); }
.stamps { display: flex; flex-wrap: wrap; gap: 6px; }
.stamps button { padding: 3px 9px; border-radius: 99px; border: 1px solid #ffd99a; background: #fff6e3; color: #8a5a00; font-size: 12px; font-weight: 600; }
.link.small { font-size: 12px; align-self: flex-start; }

/* 교안 */
.files { display: flex; flex-wrap: wrap; gap: 8px; margin: 12px 0 4px; }
.file {
  display: inline-flex; align-items: center; gap: 8px; padding: 9px 14px; border-radius: 10px;
  border: 1px solid var(--line); background: #fff; font-weight: 600; font-size: 14px;
}
.file:hover { border-color: var(--blue); color: var(--blue); }
.file .ic { font-size: 18px; }
.files-box { background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 14px 18px; margin-top: 6px; }
.files-box h2 { font-size: 16px; color: var(--blue); margin: 0; }

/* 이용 규정 */
.policy { max-width: 820px; }
.policy h1 { margin: 6px 0 2px; font-size: 26px; letter-spacing: -0.5px; }
.policy section { background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 6px 24px 18px; margin-top: 16px; scroll-margin-top: 76px; }
.policy h2 { font-size: 19px; color: var(--blue); margin: 16px 0 6px; }
.policy h3 { font-size: 15px; margin: 18px 0 6px; }
.policy ul { margin: 0; padding-left: 20px; }
.policy li { margin: 4px 0; font-size: 14.5px; }
.policy p { font-size: 14.5px; }
.policy .muted { color: var(--sub); font-size: 13px; }
.toc { display: flex; flex-wrap: wrap; gap: 6px; }
.toc a { padding: 6px 12px; border-radius: 99px; background: #fff; border: 1px solid var(--line); font-size: 13px; font-weight: 600; color: var(--sub); }
.toc a:hover { color: var(--blue); border-color: var(--blue); }
.ptbl { width: 100%; border-collapse: collapse; font-size: 14px; margin: 8px 0 10px; }
.ptbl th, .ptbl td { border: 1px solid var(--line); padding: 8px 10px; text-align: left; vertical-align: top; }
.ptbl thead th { background: var(--blue-l); color: var(--ink); font-weight: 700; }
.ptbl.kv th { width: 170px; background: #fafbfe; font-weight: 600; }
.foot-links { display: flex; justify-content: center; gap: 14px; margin-bottom: 8px !important; }
.foot-links a { color: var(--sub); font-weight: 600; }
.foot-links a:hover { color: var(--blue); }
.biz-line span + span::before { content: " · "; }
.agree a, .policy a.mail { color: var(--blue); text-decoration: underline; font-weight: 700; }

.foot { max-width: 1180px; margin: 0 auto; padding: 20px 16px 40px; color: #9aa0b2; font-size: 12px; text-align: center; }
.foot p { margin: 4px 0; }

@media (max-width: 860px) {
  .watch { grid-template-columns: 1fr; }
  .side { position: static; max-height: none; }
  .hello { flex-wrap: wrap; padding: 16px; }
  .hello-logo { width: 70px; }
  .resume { width: 100%; }
  .lesson-head { flex-direction: column; }
  .lesson-head .btn { width: 100%; }
  .lesson .meta { display: none; }
  .who #who-name { display: none; }
}