:root {
    --primary: #1a73e8;
    --text: #202124;
    --secondary-text: #5f6368;
    --bg: #ffffff;
    --surface: #f8f9fa;
    --border: #dadce0;
    --link: #1a73e8;
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: "Roboto", "Helvetica Neue", Arial, sans-serif;
    color: var(--text);
    background: var(--bg);
    line-height: 1.6;
}

a {
    color: var(--link);
    text-decoration: none;
}

a:hover {
    text-decoration: underline;
}

.portrait-placeholder {
    align-items: center;
    background: #e8eaed;
    color: var(--secondary-text);
    display: flex;
    font-size: 14px;
    height: 150px;
    justify-content: center;
    margin: 0 auto 12px;
    width: 120px;
}

/* Navigation */
nav {
    background: var(--bg);
    border-bottom: 1px solid var(--border);
    padding: 0 20px;
    position: sticky;
    top: 0;
    z-index: 100;
}

nav ul {
    list-style: none;
    margin: 0;
    padding: 0;
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 8px;
}

nav li {
    margin: 0;
}

nav a {
    display: block;
    padding: 14px 12px;
    color: var(--text);
    font-weight: 500;
    font-size: 14px;
}

nav a:hover {
    background: var(--surface);
    text-decoration: none;
}

/* Header */
header {
    background: var(--surface);
    padding: 48px 20px;
    text-align: center;
    border-bottom: 1px solid var(--border);
}

header h1 {
    margin: 0 0 12px;
    font-size: 32px;
    font-weight: 400;
    line-height: 1.3;
}

header p {
    margin: 0;
    color: var(--secondary-text);
    font-size: 18px;
}

/* Main content */
main {
    max-width: 960px;
    margin: 0 auto;
    padding: 24px 20px 64px;
}

section {
    margin-bottom: 40px;
}

section h2 {
    font-size: 24px;
    font-weight: 400;
    margin: 0 0 16px;
    padding-bottom: 8px;
    border-bottom: 1px solid var(--border);
}

section h3 {
    font-size: 18px;
    font-weight: 500;
    margin: 24px 0 8px;
}

ul {
    margin: 8px 0;
    padding-left: 24px;
}

li {
    margin-bottom: 6px;
}

.card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
    gap: 20px;
    margin-top: 16px;
}

.card-grid.speakers-grid {
    grid-template-columns: repeat(2, 1fr);
}

.card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 16px;
    text-align: center;
}

.card img {
    width: 120px;
    height: 150px;
    border-radius: 12px;
    object-fit: cover;
    margin: 0 auto 12px;
    display: block;
}

.card .name {
    font-weight: 500;
    font-size: 16px;
    margin-bottom: 4px;
}

.card .affiliation {
    color: var(--secondary-text);
    font-size: 14px;
    margin-bottom: 8px;
}

.card .talk-title {
    font-size: 14px;
    font-style: italic;
    color: var(--secondary-text);
}

.card .speaker-bio {
    border-top: 1px solid var(--border);
    font-size: 14px;
    margin: 14px 0 0;
    padding-top: 14px;
    text-align: left;
}

.info-box {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 16px 20px;
}

.info-box p {
    margin: 4px 0;
}

.table-wrapper {
    width: 100%;
    overflow-x: auto;
    border: 1px solid var(--border);
    border-radius: 8px;
}

.schedule-table {
    width: 100%;
    min-width: 680px;
    border-collapse: collapse;
    background: var(--bg);
}

.schedule-table caption {
    padding: 14px 16px;
    background: var(--surface);
    font-size: 18px;
    font-weight: 500;
    text-align: left;
}

.schedule-table th,
.schedule-table td {
    padding: 12px 14px;
    border-top: 1px solid var(--border);
    text-align: left;
    vertical-align: top;
}

.schedule-table th {
    background: var(--surface);
    font-weight: 500;
}

.schedule-table th:first-child,
.schedule-table td:first-child {
    width: 160px;
    white-space: nowrap;
}

.schedule-table th:last-child,
.schedule-table td:last-child {
    width: 30%;
}

.schedule-table tbody tr:nth-child(even) {
    background: #fcfcfc;
}

footer {
    text-align: center;
    padding: 24px 20px;
    color: var(--secondary-text);
    font-size: 14px;
    border-top: 1px solid var(--border);
}

@media (max-width: 600px) {
    header h1 {
        font-size: 24px;
    }

    .card-grid.speakers-grid {
        grid-template-columns: 1fr;
    }

    nav ul {
        gap: 0;
    }

    nav a {
        padding: 12px 8px;
        font-size: 13px;
    }
}