/* Course cards: polished front-end card system. Business data and cover source remain unchanged. */
body.mathcourse-site .mathcourse-center__grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:22px;align-items:stretch}
body.mathcourse-site .mathcourse-card,body.mathcourse-site .mathcourse-center__card{position:relative;display:flex;flex-direction:column;overflow:hidden;border:1px solid #e3e9f1;border-radius:20px;background:#fff;box-shadow:0 8px 26px rgba(18,52,107,.065);transition:transform .22s ease,box-shadow .22s ease,border-color .22s ease}
body.mathcourse-site .mathcourse-card:hover,body.mathcourse-site .mathcourse-center__card:hover{transform:translateY(-4px);border-color:#d2deed;box-shadow:0 18px 42px rgba(18,52,107,.12)}
body.mathcourse-site .mathcourse-card a{color:inherit;text-decoration:none}
body.mathcourse-site .mathcourse-cover-wrap,body.mathcourse-site .mathcourse-center__cover{position:relative;aspect-ratio:16/9;overflow:hidden;background:#edf3f8}
body.mathcourse-site .mathcourse-cover-wrap:after,body.mathcourse-site .mathcourse-center__cover:after{content:"";position:absolute;inset:0;background:linear-gradient(180deg,transparent 55%,rgba(7,29,53,.13));pointer-events:none}
body.mathcourse-site .mathcourse-cover,body.mathcourse-site .mathcourse-center__cover img{display:block;width:100%;height:100%;object-fit:cover;transition:transform .35s ease}
body.mathcourse-site .mathcourse-card:hover .mathcourse-cover,body.mathcourse-site .mathcourse-center__card:hover .mathcourse-center__cover img{transform:scale(1.025)}
body.mathcourse-site .mathcourse-center__cover-placeholder{display:flex;align-items:center;justify-content:center;width:100%;height:100%;background:linear-gradient(135deg,#12346b,#2673ad);color:#fff;font-size:25px;font-weight:850}
body.mathcourse-site .mathcourse-center__cover-placeholder:before{content:"";position:absolute;width:150px;height:150px;border-radius:50%;background:rgba(255,255,255,.08);transform:translate(38px,-22px)}
body.mathcourse-site .mathcourse-center__body{display:flex;flex:1;flex-direction:column;box-sizing:border-box;padding:17px 19px 19px;min-height:194px}
body.mathcourse-site .mathcourse-card__body{padding:17px 19px 19px}
body.mathcourse-site .mathcourse-card__meta,body.mathcourse-site .mathcourse-center__meta{display:flex;align-items:center;gap:7px;flex-wrap:wrap;margin-bottom:10px}
body.mathcourse-site .mathcourse-card__meta span,body.mathcourse-site .mathcourse-center__meta span{display:inline-flex;align-items:center;min-height:24px;padding:4px 9px;border:1px solid #e4ebf3;border-radius:999px;background:#f6f8fb;color:#46617f;font-size:11px;font-weight:800;line-height:1}
body.mathcourse-site .mathcourse-card__meta span:first-child,body.mathcourse-site .mathcourse-center__meta span:first-child{border-color:#ffe2bf;background:#fff5e9;color:#c66d0a}
body.mathcourse-site .mathcourse-card__title,body.mathcourse-site .mathcourse-center__title{margin:0;color:#10264a;font-size:18px;line-height:1.48;font-weight:850;letter-spacing:-.01em}
body.mathcourse-site .mathcourse-center__title{min-height:54px}
body.mathcourse-site .mathcourse-center__description{display:-webkit-box;overflow:hidden;margin:8px 0 0;color:#7a8797;font-size:12px;line-height:1.65;-webkit-box-orient:vertical;-webkit-line-clamp:2}
body.mathcourse-site .mathcourse-card__info{display:flex;align-items:center;justify-content:space-between;gap:12px;margin-top:12px;padding-top:12px;border-top:1px solid #edf1f5;color:#7b8797;font-size:12px}
body.mathcourse-site .mathcourse-card__info strong{color:#51657c;font-weight:750}
body.mathcourse-site .mathcourse-center__info{display:flex;align-items:center;gap:14px;margin-top:13px;color:#7b8797;font-size:12px}
body.mathcourse-site .mathcourse-center__info span{display:inline-flex;align-items:center;gap:5px;white-space:nowrap}
body.mathcourse-site .mathcourse-center__info span:before{content:"";width:5px;height:5px;border-radius:50%;background:#b9c6d5}
body.mathcourse-site .mathcourse-card__button,body.mathcourse-site .mathcourse-center__button{display:flex;align-items:center;justify-content:space-between;gap:12px;margin-top:15px;padding:10px 12px;border:1px solid #e1e9f2;border-radius:11px;background:#f7f9fc;color:#173d68;font-size:13px;font-weight:800;text-decoration:none;transition:background .2s ease,color .2s ease,border-color .2s ease,transform .2s ease}
body.mathcourse-site .mathcourse-card:hover .mathcourse-card__button,body.mathcourse-site .mathcourse-center__card:hover .mathcourse-center__button{border-color:#d4e5f8;background:#edf5ff;color:#1768a8}
body.mathcourse-site .mathcourse-card__button span,body.mathcourse-site .mathcourse-center__button span{font-size:17px;line-height:1;transition:transform .2s ease}
body.mathcourse-site .mathcourse-card:hover .mathcourse-card__button span,body.mathcourse-site .mathcourse-center__card:hover .mathcourse-center__button span{transform:translateX(2px)}
body.mathcourse-site .mathcourse-center__button{margin-top:auto}
body.mathcourse-site .mathcourse-center__card:focus-within{border-color:#b9d3f3;box-shadow:0 0 0 3px rgba(23,105,224,.08),0 14px 35px rgba(18,52,107,.1)}
/* Course-center filter hierarchy: compact segmented type switch + quiet grade chips. */
body.mathcourse-site .mc-course-filter{align-items:center;margin-bottom:12px;box-shadow:0 5px 18px rgba(18,52,107,.045)}
body.mathcourse-site .mc-course-filter a{min-height:36px;display:inline-flex;align-items:center;justify-content:center;box-sizing:border-box;white-space:nowrap}
body.mathcourse-site .mc-course-filter a.is-active{box-shadow:0 2px 7px rgba(23,105,224,.08)}
body.mathcourse-site .mc-course-grade-filter{padding-bottom:2px;margin-bottom:24px;border-bottom:1px solid #e9eef4}
body.mathcourse-site .mc-course-grade-filter a{transition:background .15s ease,color .15s ease}
body.mathcourse-site .mc-course-grade-filter a.is-active{box-shadow:inset 0 0 0 1px #d9e2ec}
body.mathcourse-site .mathcourse-center__cover-placeholder{position:relative;overflow:hidden}
body.mathcourse-site .mathcourse-center__cover-placeholder span{position:relative;z-index:1}
@media(max-width:900px){body.mathcourse-site .mathcourse-center__grid{grid-template-columns:repeat(2,minmax(0,1fr));gap:17px}}
@media(max-width:600px){body.mathcourse-site .mathcourse-center__grid{grid-template-columns:1fr;gap:15px}body.mathcourse-site .mathcourse-center__body,body.mathcourse-site .mathcourse-card__body{padding:15px 16px 17px}.mathcourse-card__title,.mathcourse-center__title{font-size:17px!important}.mathcourse-center__title{min-height:auto}.mathcourse-center__description{font-size:12px}.mathcourse-center__info{margin-top:10px!important}body.mathcourse-site .mc-course-filter{max-width:100%;overflow-x:auto}body.mathcourse-site .mc-course-filter a{flex:0 0 auto}.mc-course-grade-filter{overflow-x:auto;flex-wrap:nowrap;padding-bottom:7px}.mc-course-grade-filter a{flex:0 0 auto}}
/* Video player visual polish only; existing custom controls remain in place. */
body.mathcourse-site .mc-video-shell,body.mathcourse-site .mathcourse-player{border-radius:16px;overflow:hidden}
body.mathcourse-site .video-js .vjs-control-bar{height:4.6em;background:linear-gradient(transparent,rgba(5,15,28,.94));padding:0 8px}
body.mathcourse-site .video-js .vjs-control{min-width:2.8em}
body.mathcourse-site .video-js .vjs-progress-control{position:absolute;left:10px;right:10px;top:-14px;width:auto;height:14px}
body.mathcourse-site .video-js .vjs-time-control{padding:0 4px;font-size:14px;font-weight:700}
body.mathcourse-site .video-js .vjs-playback-rate{display:none}
body.mathcourse-site .mc-player-skip-controls{bottom:68px!important;left:14px!important;gap:7px}
body.mathcourse-site .mc-player-skip-button{min-width:72px!important;min-height:42px!important;border-radius:11px!important;background:rgba(8,24,48,.9)!important;font-size:14px!important;box-shadow:0 3px 12px rgba(0,0,0,.18)}
@media(max-width:700px){body.mathcourse-site .mc-player-skip-controls{left:9px!important;bottom:62px!important}.mc-player-skip-button{min-width:64px!important;min-height:38px!important}}