:root{--primary-color:#ff6b00;--text-dark:#333;--text-gray:#666;--bg-gray-light:#f5f5f5;--bg-white:#fff;--shadow:0 2px 8px #00000014;--shadow-hover:0 4px 16px #0000001f}*{box-sizing:border-box;margin:0;padding:0}body{background-color:var(--bg-white);color:var(--text-dark);-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;padding-bottom:60px;font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica Neue,Arial,sans-serif;line-height:1.5}a{color:inherit;text-decoration:none}.header{background:var(--bg-white);z-index:100;border-bottom:1px solid #f0f0f0;justify-content:space-between;align-items:center;height:50px;padding:0 16px;display:flex;position:fixed;top:0;left:0;right:0}.logo{color:var(--primary-color);letter-spacing:-.5px;font-size:20px;font-weight:700}.header-icons{align-items:center;gap:20px;display:flex}.header-icon{width:22px;height:22px;color:var(--text-dark)}.main-content{background:var(--bg-white);min-height:100vh;padding-top:50px;padding-bottom:70px}.category-tabs{background:var(--bg-white);z-index:99;border-bottom:1px solid #f0f0f0;padding:12px 16px;position:fixed;top:50px;left:0;right:0}.tabs-scroll{scrollbar-width:none;-ms-overflow-style:none;gap:10px;display:flex;overflow-x:auto}.tabs-scroll::-webkit-scrollbar{display:none}.tab-item{background:var(--bg-gray-light);color:var(--text-gray);cursor:pointer;white-space:nowrap;border:none;border-radius:20px;flex-shrink:0;align-items:center;gap:6px;padding:8px 16px;font-size:14px;transition:all .2s;display:flex}.tab-item.active{background:var(--text-dark);color:var(--bg-white)}.tab-item:not(.active):hover{background:#e8e8e8}.difficulty-stars{letter-spacing:-1px;font-size:10px}.course-list{padding:80px 16px 20px}.course-grid{flex-direction:column;gap:16px;display:flex}.course-card{background:var(--bg-white);box-shadow:var(--shadow);cursor:pointer;border-radius:12px;transition:all .2s;display:block;overflow:hidden}.course-card:active{box-shadow:var(--shadow-hover);transform:scale(.98)}.course-cover{aspect-ratio:16/9;background:linear-gradient(135deg,#e8e8e8 0%,#d0d0d0 100%);justify-content:center;align-items:center;width:100%;display:flex;position:relative}.course-cover-placeholder{opacity:.3;width:60px;height:60px}.course-info{padding:12px}.course-title{color:var(--text-dark);margin-bottom:6px;font-size:16px;font-weight:600}.course-meta{color:var(--text-gray);align-items:center;gap:12px;font-size:12px;display:flex}.course-meta-item{align-items:center;gap:4px;display:flex}.difficulty-badge{border-radius:4px;padding:2px 6px;font-size:10px;font-weight:600;display:inline-block}.difficulty-k1{color:#4caf50;background:#e8f5e9}.difficulty-k2{color:#ff9800;background:#fff3e0}.difficulty-k3{color:#f44336;background:#ffebee}.tab-bar{background:var(--bg-white);z-index:100;border-top:1px solid #f0f0f0;justify-content:space-around;align-items:center;height:60px;display:flex;position:fixed;bottom:0;left:0;right:0}.tab-item-bar{cursor:pointer;flex-direction:column;justify-content:center;align-items:center;gap:4px;padding:8px 16px;transition:all .2s;display:flex}.tab-icon{color:#999;width:24px;height:24px;transition:color .2s}.tab-item-bar.active .tab-icon{color:var(--primary-color)}.tab-label{color:#999;font-size:10px;transition:color .2s}.tab-item-bar.active .tab-label{color:var(--primary-color);font-weight:500}@keyframes fadeIn{0%{opacity:0;transform:translateY(10px)}to{opacity:1;transform:translateY(0)}}.course-card{animation:.3s forwards fadeIn}.course-card:first-child{animation-delay:50ms}.course-card:nth-child(2){animation-delay:.1s}.course-card:nth-child(3){animation-delay:.15s}.course-card:nth-child(4){animation-delay:.2s}.course-card:nth-child(5){animation-delay:.25s}.course-card:nth-child(6){animation-delay:.3s}@supports (padding-bottom:env(safe-area-inset-bottom)){.tab-bar{padding-bottom:env(safe-area-inset-bottom);height:calc(60px + env(safe-area-inset-bottom))}body{padding-bottom:calc(60px + env(safe-area-inset-bottom))}}