:root{
  --ink:#141B26; --slate:#4a545f; --line:#e6eaee; --bg:#f6f8fa; --card:#ffffff;
  --teal:#15C5BB; --teal-bright:#22D8CE; --teal-deep:#0B8F87;
  --ok:#12b886; --warn:#e8590c; --err:#e03131; --muted:#8a949e;
  --radius:14px; --shadow:0 1px 3px rgba(20,27,38,.06),0 8px 24px rgba(20,27,38,.05);
}
*{box-sizing:border-box}
html{overflow-x:hidden}
body{margin:0;font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Inter,Arial,sans-serif;
  color:var(--ink);background:var(--bg);line-height:1.5}
a{color:var(--teal-deep);text-decoration:none}
a:hover{text-decoration:underline}
.wrap{max-width:1040px;margin:0 auto;padding:26px 18px 60px}

/* nav */
.nav{position:sticky;top:0;z-index:20;display:flex;align-items:center;justify-content:space-between;
  gap:14px;padding:12px 20px;background:rgba(255,255,255,.9);backdrop-filter:blur(8px);
  border-bottom:1px solid var(--line)}
.brand{font-weight:800;font-size:18px;color:var(--ink)}
.brand:hover{text-decoration:none}
.nav-links{display:flex;align-items:center;gap:16px;flex-wrap:wrap}
.nav-links a{color:var(--slate);font-weight:600;font-size:14px}
.who{font-size:13px;color:var(--muted);display:inline-flex;align-items:center;gap:6px}
.dot{width:8px;height:8px;border-radius:50%;display:inline-block;background:var(--muted)}
.dot.ok{background:var(--ok)}
.ghost{color:var(--muted)!important;font-weight:600;font-size:14px}

/* buttons */
.btn{display:inline-block;background:linear-gradient(180deg,var(--teal-bright),var(--teal));
  color:#053b38;font-weight:800;border:none;border-radius:10px;padding:11px 18px;cursor:pointer;
  box-shadow:0 6px 16px rgba(21,197,187,.28);font-size:15px;text-align:center}
.btn:hover{filter:brightness(1.05);text-decoration:none}
.btn-sm{padding:7px 13px;font-size:13px;border-radius:9px}
.btn.lite{background:#eaf9f8;color:var(--teal-deep);box-shadow:none}
.btn.ghostbtn{background:transparent;color:var(--slate);box-shadow:none;border:1px solid var(--line)}
.btn.danger{background:#fff0f0;color:var(--err);box-shadow:none;border:1px solid #ffd6d6}
.btn:disabled{opacity:.5;cursor:not-allowed}

/* cards / panels */
.card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);
  box-shadow:var(--shadow);padding:18px}
.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:16px}
h1{font-size:30px;margin:.1em 0 .3em;letter-spacing:-.01em}
h2{font-size:21px;margin:.2em 0}
h3{font-size:17px;margin:.2em 0}
.muted{color:var(--muted)}
.sub{color:var(--slate);font-size:15px}
label{display:block;font-weight:600;font-size:13px;margin:10px 0 4px;color:var(--slate)}
input,textarea,select{width:100%;padding:10px 12px;border:1px solid var(--line);border-radius:10px;
  font-size:15px;font-family:inherit;background:#fff}
input:focus,textarea:focus,select:focus{outline:2px solid var(--teal-bright);border-color:transparent}
textarea{min-height:90px;resize:vertical}
.row{display:flex;gap:12px;flex-wrap:wrap}
.right{margin-left:auto}

/* flash */
.flash{padding:11px 14px;border-radius:10px;margin-bottom:14px;font-size:14px;font-weight:600}
.flash.ok{background:#e7f8f1;color:#0b7a53;border:1px solid #b6e8d4}
.flash.err{background:#fdecec;color:#b42318;border:1px solid #f6cccc}

/* auth */
.authbox{max-width:400px;margin:6vh auto;padding:26px}
.authbox h1{font-size:24px}

/* password show/hide */
.pw-wrap{position:relative}
.pw-wrap input{padding-right:46px}
.pw-toggle{position:absolute;right:6px;top:50%;transform:translateY(-50%);width:34px;height:34px;
  display:flex;align-items:center;justify-content:center;background:transparent;border:none;
  color:var(--muted);cursor:pointer;border-radius:8px;padding:0}
.pw-toggle:hover{color:var(--teal-deep);background:#eaf9f8}
.pw-toggle .eye-off{display:none}
.pw-toggle.on .eye{display:none}
.pw-toggle.on .eye-off{display:block}
.pw-toggle svg{width:20px;height:20px;display:block}

/* course/lesson */
.hero{padding:34px 0 10px}
.pill{display:inline-block;background:#eaf9f8;color:var(--teal-deep);font-weight:700;font-size:12px;
  padding:4px 11px;border-radius:999px}
.lock{filter:grayscale(.2);opacity:.85}
.locktag{display:inline-flex;align-items:center;gap:5px;background:#fff6e9;color:#a15c00;
  font-size:12px;font-weight:700;padding:3px 9px;border-radius:999px}
.progress{height:7px;background:#eef1f4;border-radius:99px;overflow:hidden;margin-top:10px}
.progress > i{display:block;height:100%;background:linear-gradient(90deg,var(--teal),var(--teal-bright))}
.course-card{display:flex;flex-direction:column;gap:8px;text-decoration:none;color:inherit}
.course-card:hover{text-decoration:none;transform:translateY(-2px);transition:.15s}
.mod{margin:18px 0}
.mod h3{margin-bottom:8px}
.lesson-row{display:flex;align-items:center;gap:12px;padding:12px 14px;border:1px solid var(--line);
  border-radius:11px;background:#fff;margin-bottom:8px}
.lesson-row:hover{border-color:var(--teal-bright)}
.lesson-row .chk{width:22px;height:22px;border-radius:50%;border:2px solid var(--line);flex:0 0 auto}
.lesson-row .chk.done{background:var(--ok);border-color:var(--ok)}
.lesson-row a{font-weight:700;color:var(--ink)}
.videoframe{position:relative;padding-bottom:56.25%;height:0;border-radius:14px;overflow:hidden;
  background:#000;margin:6px 0 18px}
.videoframe iframe{position:absolute;inset:0;width:100%;height:100%;border:0}
.assets a{display:flex;align-items:center;gap:10px;padding:10px 12px;border:1px solid var(--line);
  border-radius:10px;margin-bottom:8px;background:#fff;color:var(--ink);font-weight:600}
.assets a:hover{border-color:var(--teal);text-decoration:none}
.lessnav{display:flex;justify-content:space-between;gap:10px;margin-top:20px}

/* tables (admin) */
table{width:100%;border-collapse:collapse;font-size:14px}
th,td{text-align:left;padding:9px 10px;border-bottom:1px solid var(--line)}
th{color:var(--muted);font-size:12px;text-transform:uppercase;letter-spacing:.03em}
.tag{font-size:11px;font-weight:700;padding:2px 8px;border-radius:99px}
.tag.on{background:#e7f8f1;color:#0b7a53}.tag.off{background:#f1f3f5;color:#868e96}

/* foot */
.foot{max-width:1040px;margin:0 auto;padding:24px 18px;display:flex;justify-content:space-between;
  gap:12px;flex-wrap:wrap;color:var(--muted);font-size:13px;border-top:1px solid var(--line)}
@media(max-width:560px){.wrap{padding:18px 14px 40px}h1{font-size:24px}.nav{padding:10px 14px}}