:root{
  --bg:#f6f8fb;
  --card:#ffffff;
  --accent:#6c5ce7;
  --text:#222;
  --shadow: 0 6px 18px rgba(0,0,0,0.08);
  --radius:14px;
}

*{box-sizing:border-box;font-family: 'Segoe UI', Tahoma, Arial, sans-serif}
html,body,#app{height:100%;margin:0;background:linear-gradient(180deg,#fefefe,#f6f8fb)}
.app-header{display:flex;align-items:center;justify-content:space-between;padding:12px 16px}
.app-header h1{margin:0;font-size:20px;color:var(--text)}
.icon-btn{background:transparent;border:none;font-size:18px;padding:8px;cursor:pointer}
.grid{display:grid;grid-template-columns:repeat(3,1fr);gap:12px;padding:16px}
.subject-tile{height:110px;border-radius:12px;color:#fff;display:flex;align-items:center;justify-content:center;font-weight:600;box-shadow:var(--shadow);cursor:pointer}
.screen{padding-bottom:80px}
.hidden{display:none}
.subject-topbar{display:flex;align-items:center;justify-content:space-between;padding:10px 12px;background:transparent}
.subject-topbar h2{margin:0;font-size:18px}
.tabs{display:flex;gap:8px;padding:10px 12px}
.tab{flex:1;padding:10px;border-radius:10px;color:#fff;border:none;cursor:pointer;font-weight:700}
.tab.active{outline:3px solid rgba(0,0,0,0.06)}
.tab-content{padding:12px}
.tab-panel{min-height:300px}
.fab{position:fixed;right:18px;bottom:18px;background:#111;color:#fff;border:none;width:58px;height:58px;border-radius:50%;font-size:28px;box-shadow:var(--shadow);cursor:pointer}

.note-card{width:120px;height:120px;background:var(--card);border-radius:10px;padding:10px;box-shadow:var(--shadow);overflow:hidden;word-break:break-word;cursor:pointer}
.notes-grid, .pdfs-grid, .images-grid, .audio-list{display:flex;flex-wrap:wrap;gap:12px}

.pdf-card{width:260px;height:90px;border-radius:8px;padding:12px;display:flex;align-items:center;gap:12px;box-shadow:var(--shadow);cursor:pointer}
.pdf-title{font-weight:700}

.field-tile{width:120px;height:120px;border-radius:10px;display:flex;align-items:center;justify-content:center;color:#fff;font-weight:700;cursor:pointer}
.images-grid .img-thumb{width:120px;height:120px;border-radius:8px;object-fit:cover;cursor:pointer}
.modal{position:fixed;inset:0;background:rgba(0,0,0,0.45);display:flex;align-items:center;justify-content:center;padding:12px;z-index:40}
.modal-content{background:#fff;border-radius:10px;padding:12px;max-width:960px;width:100%;max-height:90vh;overflow:auto;position:relative}
.audio-card{display:flex;align-items:center;gap:12px;padding:12px;border-radius:8px;min-width:280px;max-width:100%;box-shadow:var(--shadow)}
.progress{height:6px;background:#eee;border-radius:6px;overflow:hidden;width:100%}
.progress > i{display:block;height:100%;background:#3498db;width:0%}

.small-muted{color:#666;font-size:12px}
.edit-input{padding:8px;border-radius:8px;border:1px solid #ddd;width:200px}