.board-wrapper{position:relative;width:100%;max-width:500px;margin:0 auto}.board-columns{display:grid;grid-template-columns:repeat(7,1fr);gap:6px;position:absolute;top:12px;left:12px;right:12px;bottom:12px;z-index:2}.board-column-zone{position:relative;cursor:default;transition:background-color .15s ease}.board-column-zone.active{cursor:pointer}.board-column-zone.active:hover{background:#ffffff1f;border-radius:8px}.column-indicator{position:absolute;top:-28px;left:50%;transform:translate(-50%);font-size:1.2rem;color:#e74c3c;animation:bounce .6s ease infinite}@keyframes bounce{0%,to{transform:translate(-50%) translateY(0)}50%{transform:translate(-50%) translateY(4px)}}.board{background:linear-gradient(145deg,#1a5ab8,#1e6fd9);border-radius:0 0 16px 16px;padding:12px;border:1px solid rgba(255,255,255,.15);border-top:none;box-shadow:0 8px 32px #1a5ab866,inset 0 2px 4px 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.cell-inner{background:radial-gradient(circle at 35% 35%,#e74c3c59,#c0392b40);box-shadow:inset 0 3px 6px #ffffff1a,inset 0 -3px 6px #0000001a}.cell-drop .cell-inner{animation:dropIn .35s cubic-bezier(.25,.46,.45,.94)}@keyframes dropIn{0%{transform:translateY(-400%);opacity:.7}60%{transform:translateY(5%);opacity:1}80%{transform:translateY(-3%)}to{transform:translateY(0);opacity:1}}.cell-win .cell-inner{animation:winPulse .8s ease-in-out infinite alternate}@keyframes winPulse{0%{filter:brightness(1);transform:scale(1)}to{filter:brightness(1.3);transform:scale(1.04)}}.cell-hint .cell-inner{background:radial-gradient(circle at 35% 35%,#2ecc7180,#27ae6059);box-shadow:inset 0 3px 6px #ffffff26,inset 0 -3px 6px #0000001a;animation:hintPulse .8s ease-in-out infinite alternate}@keyframes hintPulse{0%{opacity:.6}to{opacity:1}}.hint-indicator{color:#27ae60!important;animation:hintBounce .6s ease infinite!important}@keyframes hintBounce{0%,to{transform:translate(-50%) 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both}.modal-title{font-size:1.8rem;font-weight:800;margin:0 0 .4rem;color:#2c3e50}.modal-win .modal-title{color:#27ae60}.modal-lose .modal-title{color:#e74c3c}.modal-subtitle{font-size:.95rem;color:#666;margin:0 0 1.5rem;line-height:1.4}.modal-buttons{display:flex;gap:.75rem;justify-content:center}.modal-btn{padding:.65rem 1.3rem;border:none;border-radius:10px;font-size:.9rem;font-weight:600;cursor:pointer;transition:transform .15s,box-shadow .15s}.modal-btn:hover{transform:translateY(-1px)}.modal-btn:active{transform:translateY(0)}.modal-btn-primary{background:linear-gradient(135deg,#1a5ab8,#1e6fd9);color:#fff;box-shadow:0 2px 8px #1a5ab84d}.modal-btn-primary:hover{box-shadow:0 4px 12px #1a5ab866}.modal-btn-secondary{background:#f0f0f0;color:#555}.modal-btn-secondary:hover{background:#e4e4e4}@keyframes fadeIn{0%{opacity:0}to{opacity:1}}@keyframes slideUp{0%{opacity:0;transform:translateY(30px) scale(.95)}to{opacity:1;transform:translateY(0) scale(1)}}@keyframes 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cubic-bezier(.16,1,.3,1)}.htp-close{position:absolute;top:1rem;right:1rem;background:none;border:none;font-size:1.5rem;color:#999;cursor:pointer;width:32px;height:32px;display:flex;align-items:center;justify-content:center;border-radius:8px;transition:background .15s,color .15s}.htp-close:hover{background:#f0f0f0;color:#333}.htp-title{font-size:1.5rem;font-weight:800;color:#1a1a2e;margin-bottom:1.25rem}.htp-section{margin-bottom:1.25rem}.htp-section h3{font-size:.95rem;font-weight:700;color:#1a5ab8;margin-bottom:.5rem;text-transform:uppercase;letter-spacing:.5px}.htp-section ul{list-style:none;padding:0}.htp-section li{position:relative;padding-left:1.25rem;margin-bottom:.5rem;font-size:.9rem;line-height:1.5;color:#444}.htp-section li:before{content:"";position:absolute;left:0;top:.55em;width:6px;height:6px;border-radius:50%;background:#d0d5dd}.htp-section p{font-size:.9rem;line-height:1.6;color:#444;margin-bottom:.5rem}.htp-section strong{color:#1a1a2e}@keyframes htpFadeIn{0%{opacity:0}to{opacity:1}}@keyframes htpSlideUp{0%{opacity:0;transform:translateY(20px) scale(.97)}to{opacity:1;transform:translateY(0) scale(1)}}@media(max-width:480px){.htp-panel{padding:1.5rem 1.25rem 1.25rem;border-radius:12px}.htp-title{font-size:1.3rem}}.app{display:flex;flex-direction:column;align-items:center;padding-bottom:2rem}.app-header{display:flex;align-items:center;justify-content:space-between;width:100%;max-width:500px;margin-bottom:1rem}.title{font-size:1.8rem;font-weight:800;color:#1a1a2e;letter-spacing:-.5px;margin:0;white-space:nowrap}.header-right{display:flex;align-items:center;gap:.75rem}.difficulty-select{-moz-appearance:none;appearance:none;-webkit-appearance:none;padding:.35rem 1.8rem .35rem .6rem;border:1.5px solid #d0d5dd;border-radius:8px;background:#fff url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='10' height='6'%3E%3Cpath d='M0 0l5 6 5-6z' fill='%23666'/%3E%3C/svg%3E") no-repeat right .6rem center;color:#344054;font-size:.8rem;font-weight:600;cursor:pointer;min-height:32px;transition:border-color .15s}.difficulty-select:hover{border-color:#98a2b3}.difficulty-select:focus{outline:2px solid #1a5ab8;outline-offset:2px}.controls-actions{display:flex;gap:.5rem;margin-bottom:.75rem;justify-content:center}.new-game-btn{padding:.5rem 1.2rem;border:none;border-radius:8px;background:linear-gradient(135deg,#1a5ab8,#1e6fd9);color:#fff;font-size:.875rem;font-weight:600;cursor:pointer;transition:transform .15s,box-shadow .15s;box-shadow:0 2px 8px #1a5ab84d;min-height:38px}.new-game-btn:hover{transform:translateY(-1px);box-shadow:0 4px 12px #1a5ab866}.new-game-btn:active{transform:translateY(0)}.new-game-btn:focus-visible{outline:2px solid #1a5ab8;outline-offset:2px}.secondary-btn{padding:.5rem 1.2rem;border:1.5px solid #d0d5dd;border-radius:8px;background:#fff;color:#344054;font-size:.875rem;font-weight:600;cursor:pointer;transition:all .15s;min-height:38px;min-width:64px;display:flex;align-items:center;justify-content:center}.secondary-btn:hover:not(:disabled){background:#f9fafb;border-color:#98a2b3;transform:translateY(-1px);box-shadow:0 2px 8px #00000014}.secondary-btn:active:not(:disabled){transform:translateY(0)}.secondary-btn:disabled{opacity:.35;cursor:not-allowed}.secondary-btn:focus-visible{outline:2px solid #1a5ab8;outline-offset:2px}.hint-spinner{display:inline-block;width:16px;height:16px;border:2.5px solid rgba(52,64,84,.2);border-top-color:#344054;border-radius:50%;animation:spin .6s linear infinite}@keyframes spin{to{transform:rotate(360deg)}}.game-area{width:100%;max-width:500px;display:flex;flex-direction:column;gap:0}.status-bar{display:flex;align-items:center;gap:.5rem;padding:.6rem 1rem;border-radius:10px 10px 0 0;font-weight:600;font-size:.875rem;transition:background-color .3s,color .3s;justify-content:center}.status-indicator{width:12px;height:12px;border-radius:50%;flex-shrink:0}.status-playing{background:#e8f4e8;color:#27ae60}.status-playing .status-indicator{background:#27ae60;box-shadow:0 0 0 3px #27ae6033;animation:pulse 1.5s ease infinite}.status-thinking{background:#fff8e1;color:#b8860b}.status-thinking .status-indicator{background:#f1c40f;box-shadow:0 0 0 3px #f1c40f33;animation:pulse .8s ease infinite}.status-win{background:#e8f8e8;color:#27ae60}.status-win .status-indicator{background:#27ae60;box-shadow:0 0 0 3px #27ae6033}.status-lose{background:#fde8e8;color:#c0392b}.status-lose .status-indicator{background:#e74c3c;box-shadow:0 0 0 3px #e74c3c33}.status-draw{background:#f0f0f0;color:#666}.status-draw .status-indicator{background:#999}@keyframes pulse{0%,to{opacity:1}50%{opacity:.4}}.legend{display:flex;gap:1.5rem;margin-top:.75rem}.legend-item{display:flex;align-items:center;gap:.4rem;font-size:.875rem;color:#666}.legend-dot{width:16px;height:16px;border-radius:50%}.legend-player{background:radial-gradient(circle at 35% 35%,#ff6b6b,#e74c3c)}.legend-ai{background:radial-gradient(circle at 35% 35%,#ffe066,#f1c40f)}@media(max-width:480px){.app-header{flex-direction:column;align-items:flex-start;gap:.5rem}.title{font-size:1.5rem}.header-right{width:100%;justify-content:space-between}.controls-actions{width:100%}.new-game-btn,.secondary-btn{flex:1;min-height:44px}.difficulty-select{min-height:36px}.status-bar{padding:.5rem 1rem}}:root{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica Neue,sans-serif;line-height:1.5;font-weight:400;color:#1a1a2e;background-color:#f5f5f7;font-synthesis:none;text-rendering:optimizeLegibility;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale}*{margin:0;padding:0;box-sizing:border-box}body{min-height:100vh;display:flex;justify-content:center;align-items:flex-start;padding-top:2rem}#root{width:100%;max-width:600px;padding:0 1rem}@media(max-width:480px){body{padding-top:1.5rem}}