:root{--primary:#2C3E50;--bg-color:#F0F2F5;--card-bg:#FFFFFF;--accent-blue:#3498DB;--accent-orange:#FF8C66;--text-main:#333333;--text-sub:#666666}body{font-family:poppins,sans-serif;background-color:var(--bg-color);color:var(--text-main);margin:0;padding:0;line-height:1.6}.navbar{background-color:var(--card-bg);padding:15px 30px;display:flex;justify-content:space-between;align-items:center;box-shadow:0 2px 10px rgba(0,0,0,5%);position:sticky;top:0;z-index:100}.logo{font-weight:700;font-size:1.4rem;color:#000;letter-spacing:-.5px}.logo span{color:var(--accent-blue)}.back-btn{text-decoration:none;color:var(--text-sub);font-weight:500;font-size:.9rem;transition:color .3s}.back-btn:hover{color:var(--primary)}.container{max-width:1e3px;margin:40px auto;padding:0 20px}.lesson-header{text-align:center;margin-bottom:30px}.lesson-header h1{font-size:2.2rem;margin-bottom:10px;color:var(--primary)}.lesson-header p{color:var(--text-sub);font-size:1.1rem}.video-wrapper{background:#000;border-radius:20px;overflow:hidden;box-shadow:0 10px 30px rgba(0,0,0,.15);margin-bottom:50px;aspect-ratio:16/9;position:relative}.video-placeholder{width:100%;height:100%;display:flex;align-items:center;justify-content:center;color:#fff;flex-direction:column;background:linear-gradient(135deg,#2c3e50,#3498db)}.resources-grid{display:grid;grid-template-columns:1fr 1fr;gap:30px;margin-bottom:60px}.card{background:var(--card-bg);border-radius:16px;padding:30px;text-align:center;transition:transform .3s ease,box-shadow .3s ease;box-shadow:0 4px 6px rgba(0,0,0,4%);border:1px solid rgba(0,0,0,3%);position:relative;overflow:hidden}.card.study{border-top:6px solid var(--accent-blue)}.card.practice{border-top:6px solid var(--accent-orange)}.card:hover{transform:translateY(-8px);box-shadow:0 15px 30px rgba(0,0,0,.1)}.icon-circle{width:70px;height:70px;border-radius:50%;display:flex;align-items:center;justify-content:center;margin:0 auto 20px;font-size:1.8rem}.study .icon-circle{background:#ebf5fb;color:var(--accent-blue)}.practice .icon-circle{background:#fff3e0;color:var(--accent-orange)}.card h3{margin:0 0 10px;font-size:1.4rem;color:var(--primary)}.card p{color:var(--text-sub);margin-bottom:25px;font-size:.95rem}.btn{display:inline-block;padding:12px 28px;border-radius:50px;text-decoration:none;font-weight:600;transition:all .2s;border:none;cursor:pointer}.btn-study{background-color:var(--accent-blue);color:#fff}.btn-study:hover{background-color:#2980b9}.btn-practice{background-color:var(--accent-orange);color:#fff}.btn-practice:hover{background-color:#e67e22}.completion-zone{text-align:center;margin-top:60px;padding:40px;background:#fff;border-radius:20px}@media(max-width:768px){.resources-grid{grid-template-columns:1fr}.lesson-header h1{font-size:1.8rem}}