.spk-directory,
.spk-abstract {
    --spk-surface: #ffffff;
    --spk-text: #1f2933;
    --spk-muted: #64748b;
    --spk-line: #e2e8f0;
    --spk-accent: #006b8f;
    --spk-accent-dark: #004b66;
    --spk-accent-soft: #e6f4f8;
    --spk-gold: #c78b2a;
    --spk-shadow: 0 18px 44px rgba(15, 23, 42, 0.12);

    box-sizing: border-box;
    color: var(--spk-text);
    font-family: "Inter", "Segoe UI", Arial, Helvetica, sans-serif;
    line-height: 1.5;
}

.spk-directory *,
.spk-directory *::before,
.spk-directory *::after,
.spk-abstract *,
.spk-abstract *::before,
.spk-abstract *::after {
    box-sizing: border-box;
}

.spk-directory {
    width: 100%;
    margin: 0 auto;
}

.spk-header {
    position: relative;
    margin: 0 auto 42px;
    padding: 8px 0 18px;
    text-align: center;
}

.spk-header::after {
    display: block;
    width: 88px;
    height: 4px;
    margin: 18px auto 0;
    content: "";
    background: linear-gradient(90deg, var(--spk-accent), var(--spk-gold));
    border-radius: 999px;
}

.spk-eyebrow,
.spk-session-link,
.spk-session-badge {
    margin: 0 0 6px;
    color: var(--spk-accent);
    font-size: 0.82rem;
    font-weight: 700;
    letter-spacing: 0.08em;
    text-transform: uppercase;
}

.spk-header h2 {
    margin: 0;
    color: var(--spk-text);
    font-size: clamp(2.35rem, 5vw, 4.1rem);
    font-weight: 900;
    line-height: 1;
    text-transform: uppercase;
}

.spk-grid {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 28px;
}

.spk-plenary-section {
    display: flex;
    justify-content: center;
    margin: 0 0 38px;
}

.spk-plenary-grid {
    display: grid;
    grid-template-columns: minmax(280px, 380px);
    justify-content: center;
    width: 100%;
}

.spk-section-divider {
    width: min(760px, 100%);
    height: 1px;
    margin: 0 auto 42px;
    background: linear-gradient(90deg, rgba(0, 107, 143, 0), rgba(0, 107, 143, 0.34), rgba(199, 139, 42, 0.46), rgba(0, 107, 143, 0));
}

.spk-card {
    overflow: hidden;
    background: var(--spk-surface);
    border: 1px solid rgba(0, 107, 143, 0.14);
    border-radius: 14px;
    box-shadow: var(--spk-shadow);
    transition: transform 180ms ease, box-shadow 180ms ease, border-color 180ms ease;
}

.spk-card-plenary {
    border: 2px solid rgba(199, 139, 42, 0.58);
    box-shadow: 0 24px 60px rgba(0, 75, 102, 0.18);
}

.spk-card-plenary .spk-info {
    background: linear-gradient(180deg, #ffffff 0%, #fffaf0 100%);
}

.spk-card-plenary .spk-info::before {
    width: 56px;
    height: 4px;
    background: linear-gradient(90deg, var(--spk-gold), var(--spk-accent));
}

.spk-card-plenary .spk-session-badge {
    background: #fff3d8;
    color: #7a4c0b;
}

.spk-card-plenary h3 {
    font-size: clamp(1.36rem, 1.9vw, 1.62rem);
}

.spk-card:hover {
    border-color: rgba(0, 107, 143, 0.32);
    box-shadow: 0 24px 54px rgba(15, 23, 42, 0.18);
    transform: translateY(-4px);
}

.spk-photo-link {
    position: relative;
    display: block;
    aspect-ratio: 4 / 5;
    background: #d8e3df;
    overflow: hidden;
}

.spk-photo-link img {
    display: block;
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 240ms ease;
}

.spk-card:hover .spk-photo-link img {
    transform: scale(1.035);
}

.spk-photo-link::after {
    position: absolute;
    right: 0;
    bottom: 0;
    left: 0;
    height: 38%;
    content: "";
    background: linear-gradient(to top, rgba(0, 33, 48, 0.28), rgba(0, 33, 48, 0));
    pointer-events: none;
}

.spk-info {
    position: relative;
    padding: 20px 20px 22px;
}

.spk-info::before {
    display: block;
    width: 46px;
    height: 3px;
    margin: 0 0 14px;
    content: "";
    background: var(--spk-gold);
    border-radius: 999px;
}

.spk-info .spk-session-badge {
    display: inline-block;
    margin-bottom: 10px;
    padding: 5px 10px;
    background: var(--spk-accent-soft);
    border-radius: 999px;
    color: var(--spk-accent-dark);
    font-size: 0.9rem;
    line-height: 1.2;
    text-decoration: none;
}

.spk-session-invited-speaker {
    background: #e6f4f8;
    color: #004b66;
}

.spk-session-plenary {
    background: #fff3d8;
    color: #7a4c0b;
}

.spk-session-asean {
    background: #ecfdf3;
    color: #146c43;
}

.spk-session-foreign-professors-living-in-th {
    background: #f0e8ff;
    color: #5b2e91;
}

.spk-name-link {
    color: var(--spk-text);
    text-decoration: none;
    transition: color 160ms ease, text-decoration-color 160ms ease;
}

.spk-name-link:hover,
.spk-name-link:focus,
.spk-back-link:hover,
.spk-back-link:focus {
    color: var(--spk-accent-dark);
    text-decoration: underline;
    text-decoration-thickness: 2px;
    text-underline-offset: 4px;
}

.spk-info h3 {
    margin: 0 0 10px;
    color: var(--spk-text);
    font-size: clamp(1.22rem, 1.6vw, 1.42rem);
    font-weight: 800;
    line-height: 1.22;
}

.spk-info p {
    margin: 0;
    color: var(--spk-muted);
    font-size: 1.03rem;
    line-height: 1.45;
}

.spk-back-link {
    display: inline-block;
    margin-bottom: 22px;
    color: var(--spk-accent);
    font-weight: 800;
    text-decoration: none;
}

.spk-panel {
    background: var(--spk-surface);
    border: 1px solid var(--spk-line);
    border-radius: 8px;
    box-shadow: var(--spk-shadow);
    padding: 32px;
}

.spk-panel h2 {
    margin: 0;
    color: var(--spk-text);
    font-size: clamp(2rem, 5vw, 3rem);
    line-height: 1.1;
}

.spk-panel .spk-org {
    margin: 12px 0 0;
    color: var(--spk-muted);
}

.spk-panel hr {
    margin: 28px 0;
    border: 0;
    border-top: 1px solid var(--spk-line);
}

.spk-panel h3 {
    margin: 0 0 12px;
    color: var(--spk-text);
    font-size: 1.25rem;
}

.spk-muted,
.spk-empty {
    color: var(--spk-muted);
}

@media (max-width: 980px) {
    .spk-grid {
        grid-template-columns: repeat(3, minmax(0, 1fr));
    }
}

@media (max-width: 720px) {
    .spk-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
        gap: 16px;
    }

    .spk-info {
        padding: 18px;
    }
}

@media (max-width: 460px) {
    .spk-grid {
        grid-template-columns: 1fr;
    }

    .spk-panel {
        padding: 24px;
    }
}