/* Simple modern styles */
:root{--bg:#f7f8fb;--card:#fff;--accent:#0b5ed7;--danger:#E22D33;--muted:#6b7280}
*{box-sizing:border-box}
body{font-family:Inter, system-ui, -apple-system,Segoe UI, Roboto; margin:0; background:var(--bg); color:#111}
.topbar{display:flex;align-items:center;justify-content:space-between;padding:12px 18px;background:#fff;border-bottom:1px solid #e6e9ef}
.brand{display:flex;align-items:center;gap:12px}
.brand h1{font-size:20px;margin:0}
.logo{width:44px;height:44px;border-radius:6px}
.view-toggle button{padding:6px 10px;margin-left:6px;border:1px solid #ddd;background:#fff;border-radius:6px;cursor:pointer}
.view-toggle .active{background:var(--accent);color:#fff;border-color:var(--accent)}
main{max-width:980px;margin:20px auto;padding:0 12px}
.card{background:var(--card);padding:14px;border-radius:10px;box-shadow:0 6px 18px rgba(15,23,42,0.06);margin-bottom:14px}
.loading{position:fixed;left:0;top:40%;width:100%;text-align:center;color:var(--danger);font-size:20px;font-weight:700}
.hidden{display:none}
#loginSection input, #lessonForm input, #lessonForm select{display:block;width:100%;padding:8px;margin:6px 0 12px;border:1px solid #e2e8f0;border-radius:6px}
.role-select{display:flex;gap:8px;margin-bottom:8px}
.role{flex:1;padding:8px;border-radius:8px;border:1px solid #ddd;background:#fff;cursor:pointer}
.role.active{background:#eef2ff;border-color:var(--accent);color:var(--accent)}
.actions{display:flex;justify-content:flex-end}
.actions button, #lessonForm button, #logoutBtn{background:var(--accent);color:#fff;padding:8px 12px;border:none;border-radius:8px;cursor:pointer}
.toolbar{display:flex;justify-content:space-between;align-items:center;margin-bottom:10px}
#scheduleTableWrap{overflow:auto}
table{width:100%;border-collapse:collapse}
th,td{border:1px solid #eef2f5;padding:8px;text-align:center}
td .lesson{display:block;padding:6px;border-radius:6px;background:#f1f5f9}
.lesson .enroll{display:inline-block;margin-top:6px;padding:4px 6px;border-radius:6px;background:#0b5ed7;color:#fff;cursor:pointer;font-size:13px}
.lesson .remove{background:#E22D33;margin-left:6px;padding:4px 6px}
.footer{font-size:13px;color:var(--muted)}
.small-note{font-size:12px;color:var(--muted)}