:root{--secondary:#0f766e;--secondary-dark:#115e59;--glass-bg:#ffffffb3;--glass-border:#fff6;--bg-color:#faf8f5;--card-bg:#fff;--card-border:#1c19171f;--primary:#b45309;--primary-light:#b453091f;--primary-glow:#b4530933;--text-main:#1c1917;--text-muted:#78716c;--accent:#0d9488;--neutral-100:#f5f3ef;--neutral-200:#e7e2da;--radius-sm:6px;--radius-md:8px;--radius-lg:10px;--font-sans:"Inter", "Noto Sans JP", sans-serif}*{box-sizing:border-box;margin:0;padding:0}body{background-color:var(--bg-color);color:var(--text-main);font-family:var(--font-sans);line-height:1.6;overflow-x:hidden}#root{flex-direction:column;min-height:100vh;display:flex}.glass{background:var(--card-bg);border:1px solid var(--card-border);border-radius:var(--radius-md)}header{background:var(--bg-color);z-index:100;border-bottom:1px solid var(--card-border);justify-content:space-between;align-items:center;padding:.75rem 2rem;display:flex;position:sticky;top:0}.subtitle{color:var(--text-muted);font-size:.9rem;font-weight:500}.main-nav{gap:2rem;display:flex}.header-brand{text-align:right}.main-nav button{color:var(--text-muted);cursor:pointer;letter-spacing:.05em;background:0 0;border:none;padding:.5rem 0;font-size:.85rem;font-weight:800;transition:color .15s;position:relative}.main-nav button:hover,.main-nav button.active{color:var(--text-main)}.main-nav button.active:after{content:"";background:var(--primary);border-radius:1px;width:100%;height:3px;position:absolute;bottom:-2px;left:0}h1{letter-spacing:-.04em;color:var(--text-main);margin-bottom:0;font-size:1.8rem;font-weight:900}h1 .brand-accent{color:var(--primary)}.controls-row{align-items:center;gap:1.5rem;width:100%;margin:1.5rem 0 2.5rem;display:flex}.search-container{flex:1;align-items:center;display:flex;position:relative}.search-icon{color:var(--text-muted);pointer-events:none;z-index:2;font-size:1.1rem;position:absolute;left:1rem}.search-clear{background:var(--neutral-100);width:22px;height:22px;color:var(--text-muted);cursor:pointer;z-index:2;border:none;border-radius:50%;justify-content:center;align-items:center;font-size:.75rem;transition:background .15s,color .15s;display:flex;position:absolute;right:1rem}.search-clear:hover{background:var(--neutral-200);color:var(--text-main)}.search-input{border:1px solid var(--card-border);border-radius:var(--radius-lg);width:100%;color:var(--text-main);background:#fff;outline:none;padding:.9rem 2.75rem;font-size:1.05rem;transition:border-color .15s,box-shadow .15s}.search-input:focus{border-color:var(--primary);box-shadow:0 0 0 3px var(--primary-light)}.level-filter{border-radius:var(--radius-lg);border:1px solid var(--card-border);white-space:nowrap;background:#fff;align-items:center;gap:1rem;padding:.5rem 1.25rem;display:flex}.level-label{opacity:.7;font-size:1.1rem}@media (width<=950px){.controls-row{flex-direction:column;gap:1rem;margin-bottom:2rem}.level-filter{justify-content:center;width:100%}}.chip-group{flex-wrap:wrap;gap:.4rem;display:flex}.filter-chip{border-radius:var(--radius-sm);background:var(--neutral-100);cursor:pointer;color:var(--text-main);border:1px solid #0000;outline:none;padding:.4rem .8rem;font-size:.8rem;transition:background .15s,color .15s}.filter-chip:hover{background:var(--neutral-200)}.filter-chip.active{background:var(--primary);color:#fff}main{flex:1;width:100%;max-width:1400px;margin:0 auto;padding:1rem 1.5rem}.problem-grid{grid-template-columns:repeat(auto-fit,minmax(400px,1fr));gap:1.25rem;padding:.5rem 0;display:grid}.problem-card{border-left:3px solid var(--card-border);flex-direction:column;padding:1.5rem;transition:border-color .15s,box-shadow .15s;display:flex;position:relative;overflow:hidden}.problem-card:hover{border-color:var(--primary);border-left-color:var(--primary);box-shadow:0 2px 10px #1c191714}.problem-header{color:var(--text-muted);justify-content:space-between;align-items:center;margin-bottom:1rem;font-size:.85rem;display:flex}.problem-id{background:var(--neutral-100);border-radius:4px;padding:2px 8px;font-family:monospace}.problem-meta{flex-wrap:wrap;gap:.5rem;margin-bottom:1rem;display:flex}.tag{background:var(--primary-light);color:var(--primary);border-radius:10px;padding:2px 10px;font-size:.75rem}.level-tag{font-weight:700}.level-A{color:#10b981}.level-B{color:#3b82f6}.level-C{color:#f59e0b}.level-D{color:#ef4444}.problem-content{flex:1;min-height:100px;margin-bottom:1.5rem;font-size:1.05rem;overflow-x:auto}.problem-preview{border-radius:var(--radius-sm);border:1px solid var(--card-border);background:#fff;justify-content:center;align-items:center;margin-bottom:1.25rem;padding:1rem;display:flex}.problem-preview img{max-width:100%;height:auto;display:block}.problem-card-footer{border-top:1px solid var(--card-border);grid-template-columns:1fr 1fr;gap:.75rem;margin-top:auto;padding-top:1rem;display:grid}.card-btn{border-radius:var(--radius-sm);cursor:pointer;border:none;justify-content:center;align-items:center;gap:6px;padding:.6rem .5rem;font-size:.8rem;font-weight:700;transition:background .15s,color .15s;display:flex}.btn-icon{font-size:.9rem}.solution-btn.active{background:var(--secondary);color:#fff}.solution-btn.active:hover{background:var(--secondary-dark)}.solution-btn.disabled{background:var(--neutral-200);color:#a8a29e;cursor:not-allowed;opacity:.7}.copy-btn{border:1px solid var(--card-border);color:var(--text-main);background:#fff}.copy-btn:hover{background:var(--bg-color);border-color:var(--primary);color:var(--primary)}.modal-overlay{z-index:1000;background:#1c191799;justify-content:center;align-items:center;padding:2rem;display:flex;position:fixed;inset:0}.modal-container{border-radius:var(--radius-lg);background:#fff;flex-direction:column;width:100%;max-width:900px;max-height:90vh;display:flex;position:relative;overflow:hidden}.modal-header{border-bottom:1px solid var(--card-border);justify-content:space-between;align-items:center;padding:1.25rem 1.5rem;display:flex}.modal-title-group{flex-direction:column;display:flex}.modal-problem-id{color:var(--primary);font-size:1.1rem;font-weight:900}.modal-source{color:var(--text-muted);font-size:.8rem}.close-button{background:var(--neutral-100);cursor:pointer;width:36px;height:36px;color:var(--text-muted);border:none;border-radius:50%;justify-content:center;align-items:center;font-size:1.5rem;transition:background .15s,color .15s;display:flex}.close-button:hover{color:#fff;background:#ef4444}.modal-content{background:var(--bg-color);flex:1;justify-content:center;padding:1.5rem;display:flex;overflow-y:auto}.solution-image-container{border:1px solid var(--card-border);border-radius:var(--radius-sm);background:#fff;padding:1rem}.solution-image-container img{max-width:100%;height:auto;display:block}.modal-footer{border-top:1px solid var(--card-border);justify-content:space-between;align-items:center;padding:1rem 1.5rem;display:flex}.modal-hint{color:var(--text-muted);font-size:.8rem;font-style:italic}.modal-download-btn{background:var(--primary);color:#fff;border-radius:var(--radius-sm);cursor:pointer;border:none;padding:.5rem 1rem;font-size:.85rem;font-weight:700}.animate-fade-in{animation:.2s forwards fadeInModal}.animate-scale-up{animation:.2s forwards scaleUp}@keyframes fadeInModal{0%{opacity:0}to{opacity:1}}@keyframes scaleUp{0%{opacity:0;transform:translateY(10px)}to{opacity:1;transform:translateY(0)}}@media (width<=640px){.modal-overlay{padding:.5rem}.modal-container{border-radius:0;max-height:100vh}.problem-card-footer{grid-template-columns:1fr}}.copy-badge{color:#fff;z-index:20;border-radius:var(--radius-md);pointer-events:none;background:#0f766ed9;justify-content:center;align-items:center;font-size:1.5rem;font-weight:900;animation:.15s forwards badgeIn;display:flex;position:absolute;inset:0}@keyframes badgeIn{0%{opacity:0}to{opacity:1}}