:root {
    /* Color Palette - Premium Dark Theme */
    --bg-main: #0f172a; /* Slate 900 */
    --bg-secondary: #1e293b; /* Slate 800 */
    --bg-glass: rgba(30, 41, 59, 0.7);
    --border-color: rgba(255, 255, 255, 0.1);
    
    --text-primary: #f8fafc; /* Slate 50 */
    --text-secondary: #94a3b8; /* Slate 400 */
    --text-muted: #64748b; /* Slate 500 */
    
    --accent-blue: #3b82f6;
    --accent-blue-hover: #2563eb;
    --accent-purple: #8b5cf6;
    --accent-green: #10b981;
    --accent-green-hover: #059669;
    
    --shadow-sm: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 10px 15px -3px rgba(0, 0, 0, 0.3), 0 4px 6px -4px rgba(0, 0, 0, 0.2);
    --shadow-glass: 0 8px 32px 0 rgba(0, 0, 0, 0.37);
    
    --radius-md: 0.5rem;
    --radius-lg: 1rem;
    --radius-xl: 1.5rem;
    
    --transition: all 0.3s ease;
}

/* Light Theme overrides */
:root[data-theme="light"] {
    --bg-main: #f8fafc;
    --bg-secondary: #ffffff;
    --bg-glass: rgba(255, 255, 255, 0.85);
    --border-color: rgba(0, 0, 0, 0.1);
    
    --text-primary: #0f172a; 
    --text-secondary: #475569; 
    --text-muted: #64748b; 
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--bg-main);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    background-image: 
        radial-gradient(circle at 15% 50%, rgba(59, 130, 246, 0.15) 0%, transparent 50%),
        radial-gradient(circle at 85% 30%, rgba(139, 92, 246, 0.15) 0%, transparent 50%);
    background-attachment: fixed;
}

h1, h2, h3, h4, h5, h6 {
    font-weight: 600;
    line-height: 1.2;
}

/* Header */
.app-header {
    background-color: var(--bg-glass);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--border-color);
    padding: 1.5rem 2rem;
    position: relative;
    z-index: 100;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: var(--shadow-sm);
}
.header-container h1 {
    font-size: 1.75rem;
    background: linear-gradient(to right, var(--accent-blue), var(--accent-purple));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    margin-bottom: 0.25rem;
}
.header-container .subtitle {
    color: var(--text-secondary);
    font-size: 0.875rem;
}

/* Sync Indicator */
.sync-indicator {
    font-size: 0.8125rem;
    padding: 0.35rem 0.75rem;
    border-radius: var(--radius-xl);
    background: rgba(0, 0, 0, 0.2);
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    margin-right: 0.5rem;
    transition: var(--transition);
}
.sync-indicator.online {
    color: var(--accent-green);
    border-color: rgba(16, 185, 129, 0.3);
    background: rgba(16, 185, 129, 0.1);
}

/* Buttons */
.btn {
    background: rgba(255,255,255,0.05);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    padding: 0.5rem 1rem;
    border-radius: var(--radius-md);
    cursor: pointer;
    font-size: 0.875rem;
    font-weight: 500;
    transition: var(--transition);
}
.btn:hover {
    background: rgba(255,255,255,0.1);
}
.btn-primary {
    background: var(--accent-blue);
    color: white;
    border-color: var(--accent-blue);
}
.btn-primary:hover {
    background: var(--accent-blue-hover);
}

/* Main */
.app-main {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

/* Settings Panel */
.settings-panel {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    margin-bottom: 2rem;
    animation: fadeIn 0.3s ease;
}
.settings-content h3 {
    margin-bottom: 0.5rem;
}
.settings-content p {
    color: var(--text-secondary);
    font-size: 0.875rem;
    margin-bottom: 1rem;
}
.settings-actions {
    margin-top: 1rem;
    display: flex;
    gap: 1rem;
}

/* Loader */
.loader {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 4rem 0;
    color: var(--text-secondary);
}
.spinner {
    width: 40px;
    height: 40px;
    border: 3px solid rgba(59, 130, 246, 0.3);
    border-radius: 50%;
    border-top-color: var(--accent-blue);
    animation: spin 1s ease-in-out infinite;
    margin-bottom: 1rem;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* Controls Bar (Pinned) */
.controls-bar {
    position: sticky;
    top: 0;
    z-index: 90;
    background: var(--bg-glass);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 1rem;
    margin: 0 -1rem 2rem -1rem; /* push out to provide coverage across app-main padding */
    border-bottom: 1px solid var(--border-color);
    border-radius: var(--radius-md) var(--radius-md) 0 0;
    flex-wrap: wrap;
    gap: 1rem;
}

.tabs {
    display: flex;
    gap: 1rem;
}
.tab {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    font-size: 1.125rem;
    font-weight: 600;
    cursor: pointer;
    padding: 0.5rem 1rem;
    border-bottom: 2px solid transparent;
    transition: var(--transition);
}
.tab:hover { color: var(--text-primary); }
.tab.active {
    color: var(--accent-blue);
    border-bottom-color: var(--accent-blue);
}

.filters {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}
.filter-group {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}
.filter-group label {
    font-size: 0.875rem;
    color: var(--text-muted);
}
.form-control-inline {
    background: rgba(0,0,0,0.2);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 0.5rem;
    color: var(--text-primary);
    font-size: 0.875rem;
}
.form-control-inline:focus {
    outline: none;
    border-color: var(--accent-blue);
}
/* Ensure dropdown options respect theme backgrounds perfectly */
.form-control-inline option, .form-control option {
    background-color: var(--bg-secondary);
    color: var(--text-primary);
}

/* Group Container */
.day-group {
    margin-bottom: 3rem;
    animation: fadeIn 0.5s ease;
}
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}
.day-header {
    font-size: 1.75rem;
    margin-bottom: 0.5rem;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--border-color);
    color: var(--text-primary);
}
.time-header {
    font-size: 1.25rem;
    font-weight: 600;
    margin: 1.5rem 0 1rem 0;
    padding-left: 0.75rem;
    border-left: 4px solid var(--accent-purple);
    color: var(--text-secondary);
}

/* Sessions Table Layout */
.sessions-table {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.session-row-card {
    background: var(--bg-glass);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 0.75rem 1rem;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}
.session-row-card:hover {
    border-color: rgba(59, 130, 246, 0.4);
    box-shadow: var(--shadow-md);
}
.session-row-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 3px;
    height: 100%;
    background: linear-gradient(to bottom, var(--accent-blue), var(--accent-purple));
    opacity: 0.5;
}

.session-row-main {
    display: flex;
    align-items: flex-start;
    gap: 0.75rem;
}

.session-expand-btn {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    border-radius: 4px;
    width: 1.75rem;
    height: 1.75rem;
    cursor: pointer;
    flex: 0 0 auto;
}

.session-row-summary {
    flex: 1 1 auto;
    min-width: 180px;
}

.session-title.condensed {
    font-size: 1rem;
    margin-bottom: 0.25rem;
}

.session-meta.condensed {
    margin-bottom: 0;
}

.session-title {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}
.session-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 0.5rem;
    font-size: 0.8125rem;
    color: var(--text-secondary);
}
.meta-badge {
    background-color: rgba(255, 255, 255, 0.05);
    padding: 0.25rem 0.5rem;
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    gap: 0.25rem;
}
.session-speakers {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--accent-blue);
    margin-top: 0.5rem;
}
.session-description {
    font-size: 0.9375rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.session-row-details {
    margin-top: 0.75rem;
    border-top: 1px dashed var(--border-color);
    padding-top: 0.75rem;
}

/* Team Toggles */
.team-inline-controls {
    display: flex;
    flex-direction: column;
    gap: 0.4rem;
    margin-left: auto;
    min-width: 270px;
}
.member-inline-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 0.5rem;
}
.member-inline-name {
    font-size: 0.8125rem;
    color: var(--text-secondary);
    white-space: nowrap;
}
.toggle-group-inline {
    display: flex;
    gap: 0.35rem;
}
.btn-toggle-small {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    padding: 0.2rem 0.45rem;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.75rem;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 0.25rem;
    user-select: none;
}
.btn-toggle-small:hover { background: rgba(255,255,255,0.1); }
.btn-toggle-small.active.interesting {
    background: rgba(59, 130, 246, 0.2);
    color: var(--accent-blue);
    border-color: var(--accent-blue);
}
.btn-toggle-small.active.going {
    background: rgba(16, 185, 129, 0.2);
    color: var(--accent-green);
    border-color: var(--accent-green);
}

/* Form Controls */
.form-group {
    display: flex;
    flex-direction: column;
    gap: 0.375rem;
}
.form-group label {
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-muted);
    font-weight: 600;
}
.form-control {
    background: rgba(0, 0, 0, 0.2);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 0.625rem;
    color: var(--text-primary);
    font-family: inherit;
    font-size: 0.875rem;
    transition: var(--transition);
    width: 100%;
}
.form-control:focus {
    outline: none;
    border-color: var(--accent-blue);
    box-shadow: 0 0 0 2px rgba(59, 130, 246, 0.2);
}
textarea.form-control {
    resize: vertical;
    min-height: 2.5rem;
}

/* Schedule */
.schedule-container {
    animation: fadeIn 0.5s ease;
}
.schedule-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.5rem;
}
.day-col {
    background: var(--bg-glass);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    box-shadow: var(--shadow-md);
    display: flex;
    flex-direction: column;
    gap: 1rem;
}
.day-col h3 {
    text-align: center;
    color: var(--text-primary);
    padding-bottom: 1rem;
    border-bottom: 1px dashed var(--border-color);
    font-size: 1.125rem;
}
.time-slot {
    background: rgba(0, 0, 0, 0.2);
    border-radius: var(--radius-md);
    padding: 1rem;
    border-left: 3px solid var(--accent-blue);
}
.time-slot-header {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}
.schedule-item {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    padding: 0.75rem;
    margin-bottom: 0.5rem;
    cursor: pointer;
    position: relative;
    transition: var(--transition);
}
.schedule-item:hover {
    border-color: var(--accent-blue);
    background: rgba(255, 255, 255, 0.08);
}
.schedule-item-title {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.25rem;
}
.schedule-item-teams {
    font-size: 0.75rem;
    color: var(--text-secondary);
}

/* Tooltip */
.tooltip {
    display: none;
    position: absolute;
    top: 100%;
    left: 50%;
    transform: translateX(-50%);
    width: 280px;
    background: var(--bg-main);
    border: 1px solid var(--accent-blue);
    padding: 1rem;
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-md);
    z-index: 1000;
    margin-top: 8px;
    pointer-events: none;
}
.schedule-item:hover .tooltip {
    display: block;
}
.tooltip h4 {
    font-size: 0.875rem;
    margin-bottom: 0.5rem;
    color: var(--accent-blue);
}
.tooltip p {
    font-size: 0.75rem;
    color: var(--text-secondary);
    margin-bottom: 0.25rem;
    white-space: normal;
    word-break: break-word;
}
.tooltip p:last-child { margin-bottom: 0; }

/* Utils */
.hidden {
    display: none !important;
}

@media (max-width: 900px) {
    .schedule-grid { grid-template-columns: 1fr; }
}
@media (max-width: 768px) {
    .app-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 1rem;
        padding: 1rem;
    }
    .app-main {
        padding: 1rem;
    }
    .controls-bar {
        flex-direction: column;
        align-items: flex-start;
    }
    .session-row-main {
        flex-direction: column;
    }
    .team-inline-controls {
        width: 100%;
        min-width: 0;
        margin-left: 0;
    }
}