.ser-fc {
    max-width: 860px;
    margin: 0 auto 2rem;
    padding: 1rem 0 2rem;
    text-align: left;
    color: #243044;
}
.ser-fc-head {
    display: flex;
    flex-wrap: wrap;
    align-items: flex-end;
    justify-content: space-between;
    gap: 12px;
    margin-bottom: 12px;
}
.ser-fc-title {
    font-size: 1.35rem;
    font-weight: 700;
    margin: 0;
    color: #2a3a55;
}
.ser-fc-topic {
    display: flex;
    flex-direction: column;
    font-size: 12px;
    color: #5a6b84;
}
.ser-fc-topic-select {
    min-width: 180px;
    border: 1px solid #c9d7ee;
    border-radius: 10px;
    padding: 6px 10px;
    background: #f3f7fd;
}
.ser-fc-progress {
    height: 8px;
    background: #e8eef8;
    border-radius: 99px;
    overflow: hidden;
    margin-bottom: 8px;
}
.ser-fc-progress-bar {
    display: block;
    height: 100%;
    width: 0;
    background: linear-gradient(90deg, #8eb8f0, #f6b48a);
    transition: width 0.2s ease;
}
.ser-fc-count {
    margin: 0 0 12px;
    font-size: 0.95rem;
    color: #5a6b84;
}
.ser-fc-board {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-bottom: 12px;
    min-width: 0;
}
.ser-fc-stage {
    flex: 1 1 auto;
    min-width: 0;
    perspective: 1200px;
    overflow: hidden;
}
.ser-fc-card {
    position: relative;
    display: block;
    width: 100%;
    min-height: 320px;
    border: 0;
    padding: 0;
    background: transparent;
    cursor: pointer;
    outline: none;
}
.ser-fc-card:focus-visible {
    box-shadow: 0 0 0 3px rgba(91, 111, 214, 0.35);
    border-radius: 18px;
}
.ser-fc-flip-hint {
    position: absolute;
    right: 10px;
    bottom: 10px;
    z-index: 2;
    width: 28px;
    height: 28px;
    color: #7b8aa3;
    pointer-events: none;
    opacity: 0.72;
}
.ser-fc-flip-hint svg {
    display: block;
    width: 100%;
    height: 100%;
}
.ser-fc-inner {
    position: relative;
    min-height: 320px;
    transform-style: preserve-3d;
    transition: transform 0.45s ease;
}
.ser-fc.is-flipped .ser-fc-inner {
    transform: rotateY(180deg);
}
.ser-fc-face {
    position: absolute;
    inset: 0;
    backface-visibility: hidden;
    -webkit-backface-visibility: hidden;
    border-radius: 18px;
    box-shadow: 0 10px 28px rgba(60, 90, 130, 0.12);
    overflow: hidden;
}
.ser-fc-front {
    background: #eef5ff;
    border: 1px solid #d4e3f7;
}
.ser-fc-back {
    background: #fff4eb;
    border: 1px solid #f3d7c4;
    transform: rotateY(180deg);
}
.ser-fc-scroll {
    height: 100%;
    min-height: 320px;
    max-height: 62vh;
    overflow: auto;
    padding: 22px 22px 28px;
    text-align: left;
    font-size: 1.08rem;
    line-height: 1.55;
}
.ser-fc-scroll p {
    margin: 0 0 0.8em;
}
.ser-fc .ser-math {
    font-family: "Cambria Math", "Times New Roman", serif;
}
.ser-fc .ser-math-frac {
    display: inline-flex;
    flex-direction: column;
    align-items: center;
    vertical-align: middle;
    margin: 0 0.15em;
    line-height: 1.15;
}
.ser-fc .ser-math-num {
    padding: 0 0.3em 1px;
    border-bottom: 1px solid currentColor;
}
.ser-fc .ser-math-den {
    padding: 1px 0.3em 0;
}
.ser-fc .ser-math-radical {
    white-space: nowrap;
}
.ser-fc .ser-math-matrix {
    display: inline-flex;
    flex-direction: column;
    justify-content: center;
    vertical-align: middle;
    margin: 0 0.2em;
    padding: 0.15em 0.4em;
    border-left: 2px solid currentColor;
    border-right: 2px solid currentColor;
    line-height: 1.35;
}
.ser-fc .ser-math-matrix-row {
    display: flex;
    flex-direction: row;
    justify-content: center;
    gap: 0.7em;
}
.ser-fc-math {
    display: block;
    max-width: 100%;
    overflow-x: auto;
    overflow-y: hidden;
    padding: 0.15em 0;
}
.ser-fc-math mjx-container,
.ser-fc-math math {
    max-width: 100%;
}
.ser-fc-scroll img {
    display: block;
    max-width: 100%;
    height: auto;
    object-fit: contain;
    margin: 10px auto;
    background: #fff;
}
.ser-fc-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    min-width: 44px;
    min-height: 44px;
    padding: 0 8px;
    border: 1px solid transparent;
    border-radius: 10px;
    background: transparent;
    color: #2a3a55;
    cursor: pointer;
}
.ser-fc-icon svg {
    display: block;
    width: 22px;
    height: 22px;
}
.ser-fc-icon-label {
    font-size: 12px;
    font-weight: 600;
    color: currentColor;
}
.ser-fc-icon:hover {
    background: #f3f7fd;
}
.ser-fc-icon:focus-visible,
.ser-fc-nav:focus-visible {
    outline: 2px solid #5b6fd6;
    outline-offset: 2px;
}
.ser-fc-icon[aria-pressed="true"],
.ser-fc-icon.is-on {
    background: #eef2ff;
    border-color: #c9d3f5;
    box-shadow: inset 0 0 0 1px #5b6fd6;
}
.ser-fc-icon:disabled,
.ser-fc-nav:disabled {
    opacity: 0.35;
    cursor: default;
}
.ser-fc-nav {
    flex: 0 0 44px;
    color: #3d4e6b;
    background: #f7faff;
    border: 1px solid #d4e3f7;
}
.ser-fc-toolbar {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: center;
    gap: 4px 8px;
    min-height: 52px;
    margin: 0 0 14px;
}
.ser-fc-index {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 4px;
}
.ser-fc-index button {
    min-width: 32px;
    min-height: 32px;
    border: 1px solid #d4e3f7;
    background: #f7faff;
    border-radius: 8px;
    padding: 2px 6px;
    font-size: 12px;
}
.ser-fc-index button.is-active {
    background: #8eb8f0;
    color: #fff;
    border-color: #8eb8f0;
    font-weight: 700;
}
.ser-fc-index-gap {
    color: #8a97ad;
    padding: 0 2px;
    user-select: none;
}
.ser-fc-session {
    margin: -4px 0 12px;
    font-size: 0.9rem;
    color: #4b5d78;
}
.ser-fc-btn {
    border: 1px solid #c9d7ee;
    background: #fff;
    color: #2a3a55;
    border-radius: 999px;
    padding: 8px 14px;
    font-weight: 600;
}
.ser-fc-btn-accent {
    background: #f6b48a;
    border-color: #efc09a;
    color: #4a2d1b;
}
.ser-fc-admin-tools {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    align-items: center;
}
.ser-fc-admin-tools .form-control {
    max-width: 240px;
}
.ser-fc-admin-jump {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
    max-height: 7.5rem;
    overflow: auto;
}
.ser-fc-admin-jump-item {
    min-width: 32px;
    text-align: center;
    border: 1px solid #d4e3f7;
    background: #f7faff;
    border-radius: 8px;
    padding: 3px 7px;
    color: #2a3a55;
    text-decoration: none;
}
@media (max-width: 720px) {
    .ser-fc-board {
        position: relative;
        gap: 0;
    }
    .ser-fc-nav {
        position: absolute;
        z-index: 3;
        top: 50%;
        transform: translateY(-50%);
        background: rgba(255, 255, 255, 0.94);
        box-shadow: 0 2px 10px rgba(36, 48, 68, 0.12);
    }
    .ser-fc-nav-prev {
        left: 4px;
    }
    .ser-fc-nav-next {
        right: 4px;
    }
    .ser-fc-scroll {
        padding-left: 52px;
        padding-right: 52px;
    }
    .ser-fc-icon-label {
        display: none;
    }
    .ser-fc-card,
    .ser-fc-inner,
    .ser-fc-scroll {
        min-height: 260px;
    }
}