/* ============================================
   组件:按钮/卡片/表单/代码块/提示框
   ============================================ */

/* ── 按钮 ── */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-sm);
    padding: 10px 24px;
    border-radius: var(--radius-md);
    font-size: 14px;
    font-weight: 600;
    font-family: var(--font-sans);
    border: none;
    cursor: pointer;
    transition: all var(--transition-fast);
    text-decoration: none;
}
.btn-primary {
    background: var(--gradient-brand);
    color: #fff;
    box-shadow: var(--shadow-brand);
}
.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 12px 28px rgba(30, 58, 138, 0.5);
    color: #fff;
}
.btn-secondary {
    background: var(--color-bg-surface);
    color: var(--color-text);
    border: 1px solid var(--color-border);
}
.btn-secondary:hover {
    border-color: var(--color-accent);
    color: var(--color-accent);
}
.btn-ghost {
    background: transparent;
    color: var(--color-text-secondary);
    border: 1px solid var(--color-border);
}
.btn-ghost:hover {
    color: var(--color-accent);
    border-color: var(--color-accent);
}
.btn-lg { padding: 14px 32px; font-size: 16px; }
.btn-block { width: 100%; }
.btn:disabled { opacity: 0.5; cursor: not-allowed; }

/* ── 卡片 ── */
.card {
    background: var(--color-bg-elevated);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-lg);
    transition: all var(--transition-base);
}
.card-hover:hover {
    transform: translateY(-4px);
    border-color: var(--color-accent);
    box-shadow: var(--shadow-lg);
}

/* 课程卡片 */
.course-card {
    background: var(--color-bg-elevated);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    overflow: hidden;
    transition: all var(--transition-base);
    display: flex;
    flex-direction: column;
    height: 100%;
}
.course-card:hover {
    transform: translateY(-6px);
    border-color: var(--color-accent);
    box-shadow: var(--shadow-lg), 0 0 0 1px rgba(6, 182, 212, 0.2);
}
/* Phase 8-F6:占位课程卡片(筹备中,不可点击) */
.course-card-placeholder {
    cursor: default;
    opacity: 0.7;
}
.course-card-placeholder:hover {
    transform: none;
    border-color: var(--color-border);
    box-shadow: none;
}
.course-cover {
    height: 140px;
    background: var(--gradient-card-cover);
    position: relative;
    overflow: hidden;
    display: flex;
    align-items: center;
    justify-content: center;
}
.course-cover::before {
    content: '';
    position: absolute;
    top: -50%; right: -20%;
    width: 200px; height: 200px;
    background: radial-gradient(circle, rgba(255,255,255,0.15) 0%, transparent 70%);
    border-radius: 50%;
}
.course-cover-icon {
    font-size: 48px;
    position: relative;
    z-index: 1;
    filter: drop-shadow(0 4px 8px rgba(0,0,0,0.3));
}
.course-cover-badge {
    position: absolute;
    top: var(--space-md);
    left: var(--space-md);
    background: rgba(0, 0, 0, 0.4);
    color: #fff;
    padding: 4px 10px;
    border-radius: var(--radius-full);
    font-size: 11px;
    font-weight: 600;
    backdrop-filter: blur(4px);
    z-index: 1;
}
.course-body {
    padding: var(--space-lg);
    flex-grow: 1;
    display: flex;
    flex-direction: column;
}
.course-title {
    font-size: 17px;
    font-weight: 700;
    color: var(--color-text);
    margin-bottom: var(--space-sm);
    line-height: 1.4;
}
.course-desc {
    color: var(--color-text-muted);
    font-size: 13px;
    line-height: 1.6;
    margin-bottom: var(--space-md);
    flex-grow: 1;
}
/* 课程学习进度条(复用青色品牌体系,与卡片圆角统一) */
.course-progress {
    margin-top: var(--space-sm);
    margin-bottom: var(--space-md);
}
.course-progress-head {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 6px;
    font-size: 12px;
}
.course-progress-label {
    color: var(--color-text-muted);
    letter-spacing: 0.5px;
}
.course-progress-pct {
    color: var(--color-accent);
    font-weight: 700;
    font-size: 13px;
}
.course-progress-bar {
    height: 6px;
    background: var(--color-bg-surface);
    border: 1px solid var(--color-border-light);
    border-radius: var(--radius-full);
    overflow: hidden;
}
.course-progress-fill {
    height: 100%;
    background: var(--gradient-brand);
    border-radius: var(--radius-full);
    transition: width 0.5s ease;
}
.course-progress-count {
    margin-top: 6px;
    font-size: 11px;
    color: var(--color-text-muted);
}
.course-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: var(--space-md);
    border-top: 1px solid var(--color-border-light);
}
.course-meta-item {
    color: var(--color-text-muted);
    font-size: 12px;
    display: flex;
    align-items: center;
    gap: 4px;
}
.course-meta-chapters {
    color: var(--color-accent);
    font-weight: 600;
}

/* ── 表单 ── */
.form-group { margin-bottom: var(--space-lg); }
.form-label {
    display: block;
    color: var(--color-text-secondary);
    font-size: 13px;
    font-weight: 500;
    margin-bottom: var(--space-sm);
}
.form-input, .form-select {
    width: 100%;
    background: var(--color-bg-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    padding: 12px 16px;
    color: var(--color-text);
    font-size: 14px;
    font-family: var(--font-sans);
    transition: all var(--transition-fast);
}
.form-input:focus, .form-select:focus {
    outline: none;
    border-color: var(--color-accent);
    box-shadow: 0 0 0 3px rgba(6, 182, 212, 0.15);
    background: var(--color-bg-elevated);
}
.form-input::placeholder { color: var(--color-text-muted); }

/* ── 提示/Toast ── */
.toast {
    position: fixed;
    top: calc(var(--nav-height) + var(--space-md));
    right: var(--space-lg);
    background: var(--color-bg-elevated);
    border: 1px solid var(--color-border);
    border-left: 4px solid var(--color-accent);
    border-radius: var(--radius-md);
    padding: var(--space-md) var(--space-lg);
    color: var(--color-text);
    font-size: 14px;
    box-shadow: var(--shadow-lg);
    z-index: 2000;
    min-width: 280px;
    animation: slideInRight 0.3s ease;
}
.toast.success { border-left-color: var(--color-success); }
.toast.error { border-left-color: var(--color-danger); }
.toast.warning { border-left-color: var(--color-warning); }
@keyframes slideInRight {
    from { transform: translateX(120%); opacity: 0; }
    to { transform: translateX(0); opacity: 1; }
}

/* ── 徽章/标签 ── */
.badge {
    display: inline-block;
    padding: 3px 10px;
    border-radius: var(--radius-full);
    font-size: 11px;
    font-weight: 600;
    letter-spacing: 0.3px;
}
.badge-primary { background: rgba(30, 58, 138, 0.2); color: var(--color-primary-light); border: 1px solid rgba(30, 58, 138, 0.3); }
.badge-accent { background: rgba(6, 182, 212, 0.15); color: var(--color-accent); border: 1px solid rgba(6, 182, 212, 0.3); }
.badge-success { background: rgba(16, 185, 129, 0.15); color: var(--color-success); border: 1px solid rgba(16, 185, 129, 0.3); }
.badge-warning { background: rgba(245, 158, 11, 0.15); color: var(--color-warning); border: 1px solid rgba(245, 158, 11, 0.3); }

/* ── 空状态 ── */
.empty-state {
    text-align: center;
    padding: var(--space-3xl) var(--space-lg);
    color: var(--color-text-muted);
}
.empty-state-icon { font-size: 64px; margin-bottom: var(--space-md); opacity: 0.6; }