/* =========================================================================
   T04: 课程网格 / 进度环 / 公开课（仿超星风格）
   全部使用 nc- 前缀变量与类，避免与既有 Tailwind/业务样式冲突。
   ========================================================================= */

:root {
    --nc-ring-color: #f97316;       /* 进度环主色（品牌橙） */
    --nc-ring-track: #e5e7eb;       /* 进度环底色 */
    --nc-ring-inner: #ffffff;       /* 进度环内圆 */
    --nc-card-bg: #ffffff;
    --nc-card-border: #f1f1f4;
    --nc-card-shadow: 0 1px 3px rgba(17, 24, 39, 0.06);
    --nc-card-radius: 16px;
    --nc-primary: #f97316;
    --nc-primary-600: #ea580c;
    --nc-text: #1f2937;
    --nc-text-soft: #6b7280;
}

[data-theme="dark"] {
    --nc-ring-color: #fb923c;
    --nc-ring-track: #374151;
    --nc-ring-inner: #1f2937;
    --nc-card-bg: #1f2430;
    --nc-card-border: #2c3340;
    --nc-card-shadow: 0 1px 3px rgba(0, 0, 0, 0.4);
    --nc-text: #e5e7eb;
    --nc-text-soft: #9ca3af;
}

/* ---------- 网格响应式：≤576 单列，≥992 三四列 ---------- */
.nc-course-grid {
    display: grid;
    gap: 1.25rem;
    grid-template-columns: repeat(1, minmax(0, 1fr));
}
@media (min-width: 576px) {
    .nc-course-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (min-width: 992px) {
    .nc-course-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}
@media (min-width: 1200px) {
    .nc-course-grid { grid-template-columns: repeat(4, minmax(0, 1fr)); }
}

/* ---------- 卡片 ---------- */
.nc-card {
    display: flex;
    flex-direction: column;
    background: var(--nc-card-bg);
    border: 1px solid var(--nc-card-border);
    border-radius: var(--nc-card-radius);
    box-shadow: var(--nc-card-shadow);
    overflow: hidden;
    transition: transform .2s ease, box-shadow .2s ease;
}
.nc-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 10px 24px rgba(17, 24, 39, 0.12);
}

/* 16:9 封面 */
.nc-card__cover {
    position: relative;
    width: 100%;
    aspect-ratio: 16 / 9;
    overflow: hidden;
    background: linear-gradient(135deg, #fff7ed, #ffedd5);
}
.nc-card__img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
}
.nc-card__cover-ph {
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
}
.nc-card__cover-ph .bi {
    font-size: 2.75rem;
    color: #fdba74;
    opacity: .6;
}

/* 进度环浮层 */
.nc-card__ring {
    position: absolute;
    right: 10px;
    bottom: 10px;
    line-height: 0;
    filter: drop-shadow(0 1px 2px rgba(0,0,0,.25));
}

/* 进度环（conic-gradient） */
.nc-ring {
    --nc-progress: 0;
    border-radius: 50%;
    background: conic-gradient(
        var(--nc-ring-color) calc(var(--nc-progress) * 1%),
        var(--nc-ring-track) 0
    );
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
}
.nc-ring::before {
    content: "";
    position: absolute;
    inset: 5px;
    border-radius: 50%;
    background: var(--nc-ring-inner);
}
.nc-ring__label {
    position: relative;
    font-size: 12px;
    font-weight: 700;
    color: var(--nc-ring-color);
    line-height: 1;
}

/* 卡片主体 */
.nc-card__body {
    display: flex;
    flex-direction: column;
    flex: 1;
    padding: 0.875rem 1rem 1rem;
}
.nc-card__title {
    font-size: 1rem;
    font-weight: 600;
    color: var(--nc-text);
    margin: 0 0 0.5rem;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
    line-height: 1.35;
    min-height: 2.7em;
}
.nc-card__meta {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 0.75rem;
    font-size: 0.75rem;
    color: var(--nc-text-soft);
}
.nc-badge {
    padding: 0.1rem 0.5rem;
    border-radius: 0.5rem;
    background: #fff7ed;
    color: #c2410c;
    font-weight: 600;
}
[data-theme="dark"] .nc-badge { background: rgba(249,115,22,.15); color: #fdba74; }
.nc-card__meta .bi { margin-right: 2px; }

/* 操作区 */
.nc-card__actions {
    margin-top: auto;
    display: flex;
    gap: 0.5rem;
    align-items: center;
}
.nc-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.3rem;
    padding: 0.5rem 0.9rem;
    border-radius: 0.6rem;
    font-size: 0.85rem;
    font-weight: 600;
    border: 1px solid transparent;
    cursor: pointer;
    text-decoration: none;
    transition: background .15s ease, color .15s ease, border-color .15s ease;
}
.nc-btn--primary {
    background: linear-gradient(135deg, var(--nc-primary), #f59e0b);
    color: #fff;
}
.nc-btn--primary:hover { background: linear-gradient(135deg, var(--nc-primary-600), #d97706); }
.nc-btn--ghost {
    background: transparent;
    border-color: var(--nc-card-border);
    color: var(--nc-text-soft);
}
.nc-btn--ghost:hover { border-color: #f87171; color: #ef4444; }
.nc-tag {
    font-size: 0.75rem;
    padding: 0.25rem 0.6rem;
    border-radius: 0.5rem;
    background: #f3f4f6;
    color: var(--nc-text-soft);
}
.nc-tag--lock { background: #fef3c7; color: #b45309; }

/* Tab 样式 */
.nc-tab {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.5rem 1rem;
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--nc-text-soft);
    text-decoration: none;
    border-bottom: 2px solid transparent;
    margin-bottom: -1px;
}
.nc-tab:hover { color: var(--nc-primary); }
.nc-tab--active {
    color: var(--nc-primary);
    border-bottom-color: var(--nc-primary);
}