.panel{display:block!important;background:linear-gradient(180deg,rgba(255,255,255,.96),rgba(248,251,255,.94))!important;border:1px solid #e2eaf2!important;border-radius:22px!important;padding:28px 28px 24px!important;box-shadow:0 12px 28px rgba(148,163,184,.1)!important;position:relative!important;overflow:hidden!important}
.panel::before{content:""!important;position:absolute!important;inset:0 0 auto 0!important;height:5px!important;pointer-events:none!important;background:linear-gradient(90deg,#64b5f6 0%,#81c784 35%,#ffb74d 68%,#e57373 100%)!important}
.ex-card{background:#fff;border:1px solid #e2eaf2;border-radius:16px;padding:22px;margin:16px 0;box-shadow:0 6px 16px rgba(148,163,184,.08);position:relative}
.ex-num{position:absolute;top:16px;right:18px;font-size:11px;font-weight:800;color:#90a4ae;letter-spacing:.05em}
.ex-level{display:inline-block;padding:3px 10px;border-radius:999px;font-size:11px;font-weight:800;letter-spacing:.04em;margin-bottom:10px}
.ex-level.easy{background:#e8f5e9;color:#2e7d32}
.ex-level.medium{background:#fff3e0;color:#e65100}
.ex-level.hard{background:#fce4ec;color:#c62828}
.ex-title{font-size:17px;font-weight:800;color:#1f3552;margin-bottom:8px}
.ex-desc{font-size:14px;color:#33475d;line-height:1.8}
.ex-output{background:#1e1e2e;border-radius:10px;padding:12px 16px;margin:10px 0;font-family:"Consolas","Monaco",monospace;font-size:13px;color:#a6e3a1;line-height:1.7;border:1px solid #313244;white-space:pre}
.ex-output .inp{color:#89b4fa;text-decoration:underline}
.hint-btn{display:inline-block;padding:6px 14px;background:#eef3f8;border:1px solid #d5e0ea;border-radius:8px;font-size:12px;font-weight:700;color:#3a5a7c;cursor:pointer;margin:6px 4px 6px 0;transition:.2s;font-family:inherit}
.hint-btn:hover{background:#e3eefa;border-color:#90caf9}
.hint-content{display:none;margin:10px 0;padding:14px;background:#f8fbfe;border:1px solid #e2eaf2;border-radius:10px;font-size:13px;line-height:1.7;color:#33475d}
.hint-content.show{display:block}
.answer-code{display:none;margin:10px 0}
.answer-code.show{display:block}
.diff-filter{display:flex;gap:8px;flex-wrap:wrap;margin:12px 0}
.diff-btn{padding:8px 16px;border-radius:10px;border:2px solid #dce6ef;background:#fff;cursor:pointer;font-weight:700;font-size:13px;color:#5f6f82;transition:.2s;font-family:inherit}
.diff-btn:hover{border-color:#90caf9;color:#1565c0}
.diff-btn.active{background:linear-gradient(135deg,#4a8cc7,#64b5f6);color:#fff;border-color:#4a8cc7}