/* ============================================
   RD Summit 2025 - Modern Minimalist Styles
   Mobile-first responsive design
   ============================================ */

/* CSS Variables */
:root {
    /* Colors - Light Mode */
    --color-primary: #6366f1;
    --color-primary-dark: #4f46e5;
    --color-primary-light: #818cf8;
    --color-secondary: #8b5cf6;
    --color-success: #10b981;
    --color-danger: #ef4444;
    --color-warning: #f59e0b;

    --color-bg: #ffffff;
    --color-bg-secondary: #f9fafb;
    --color-bg-tertiary: #f3f4f6;
    --color-surface: #ffffff;
    --color-border: #e5e7eb;

    --color-text-primary: #111827;
    --color-text-secondary: #6b7280;
    --color-text-tertiary: #9ca3af;

    /* Typography */
    --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --font-mono: "SF Mono", Monaco, "Cascadia Code", "Roboto Mono", Consolas, monospace;

    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;

    /* Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-full: 9999px;

    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);

    /* Transitions */
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-base: 200ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 300ms cubic-bezier(0.4, 0, 0.2, 1);

    /* Z-index */
    --z-header: 100;
    --z-modal: 1000;
    --z-toast: 2000;
    --z-loading: 3000;
}

/* Dark Mode */
@media (prefers-color-scheme: dark) {
    :root {
        --color-bg: #0f172a;
        --color-bg-secondary: #1e293b;
        --color-bg-tertiary: #334155;
        --color-surface: #1e293b;
        --color-border: #334155;

        --color-text-primary: #f1f5f9;
        --color-text-secondary: #cbd5e1;
        --color-text-tertiary: #94a3b8;
    }
}

/* ============================================
   Reset & Base Styles
   ============================================ */

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

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-sans);
    font-size: 1rem;
    line-height: 1.5;
    color: var(--color-text-primary);
    background-color: var(--color-bg);
    min-height: 100vh;
    overflow-x: hidden;
}

/* ============================================
   Typography
   ============================================ */

h1, h2, h3, h4, h5, h6 {
    font-weight: 600;
    line-height: 1.2;
    color: var(--color-text-primary);
}

h1 { font-size: 2rem; }
h2 { font-size: 1.5rem; }
h3 { font-size: 1.25rem; }
h4 { font-size: 1.125rem; }

button, input, select, textarea {
    font-family: inherit;
    font-size: inherit;
    line-height: inherit;
}

/* ============================================
   Layout
   ============================================ */

.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

@media (min-width: 768px) {
    .container {
        padding: 0 var(--spacing-lg);
    }
}

/* ============================================
   Header
   ============================================ */

.header {
    position: sticky;
    top: 0;
    z-index: var(--z-header);
    background-color: var(--color-surface);
    border-bottom: 1px solid var(--color-border);
    padding: var(--spacing-md) 0;
    backdrop-filter: blur(8px);
    background-color: rgba(255, 255, 255, 0.95);
}

@media (prefers-color-scheme: dark) {
    .header {
        background-color: rgba(15, 23, 42, 0.95);
    }
}

.header .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--color-primary);
    margin: 0;
}

.btn-favorites {
    position: relative;
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-md);
    background: transparent;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-full);
    color: var(--color-text-primary);
    cursor: pointer;
    transition: all var(--transition-base);
    min-height: 44px;
}

.btn-favorites:hover {
    background-color: var(--color-bg-secondary);
    border-color: var(--color-primary);
    color: var(--color-primary);
}

.btn-favorites:focus {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

.favorites-count {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-width: 1.25rem;
    height: 1.25rem;
    padding: 0 var(--spacing-xs);
    background-color: var(--color-primary);
    color: white;
    font-size: 0.75rem;
    font-weight: 600;
    border-radius: var(--radius-full);
}

/* ============================================
   Main Content
   ============================================ */

.main {
    padding: var(--spacing-xl) 0;
    min-height: calc(100vh - 80px);
}

/* ============================================
   Search
   ============================================ */

.search-wrapper {
    margin-bottom: var(--spacing-xl);
}

.search-box {
    position: relative;
    display: flex;
    align-items: center;
}

.search-icon {
    position: absolute;
    left: var(--spacing-md);
    color: var(--color-text-tertiary);
    pointer-events: none;
}

.search-input {
    width: 100%;
    padding: var(--spacing-md) var(--spacing-md) var(--spacing-md) 3rem;
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    color: var(--color-text-primary);
    font-size: 1rem;
    transition: all var(--transition-base);
    min-height: 48px;
}

.search-input:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.search-input::placeholder {
    color: var(--color-text-tertiary);
}

.btn-clear-search {
    position: absolute;
    right: var(--spacing-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    width: 2rem;
    height: 2rem;
    background: transparent;
    border: none;
    border-radius: var(--radius-full);
    color: var(--color-text-tertiary);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.btn-clear-search:hover {
    background-color: var(--color-bg-tertiary);
    color: var(--color-text-secondary);
}

/* ============================================
   Dashboard
   ============================================ */

.dashboard {
    margin-bottom: var(--spacing-2xl);
}

.section-title {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: var(--spacing-lg);
    color: var(--color-text-primary);
}

/* Card Styles */
.card {
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-xl);
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-base);
}

.card-highlight {
    border-color: var(--color-primary);
    background: linear-gradient(135deg, rgba(99, 102, 241, 0.05) 0%, rgba(139, 92, 246, 0.05) 100%);
}

.card-header {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
}

.card-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin: 0;
}

/* Quick Access Grid */
.quick-access-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-md);
}

@media (min-width: 768px) {
    .quick-access-grid {
        grid-template-columns: repeat(4, 1fr);
    }
}

.quick-card {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-lg);
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    cursor: pointer;
    transition: all var(--transition-base);
    text-align: center;
    min-height: 140px;
}

.quick-card:hover {
    border-color: var(--color-primary);
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
}

.quick-card:focus {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

.quick-card-icon {
    font-size: 2rem;
    margin-bottom: var(--spacing-sm);
}

.quick-card-title {
    font-size: 1rem;
    font-weight: 600;
    margin: 0 0 var(--spacing-xs);
    color: var(--color-text-primary);
}

.quick-card-desc {
    font-size: 0.875rem;
    color: var(--color-text-secondary);
    margin: 0;
}

/* ============================================
   Badges
   ============================================ */

.badge {
    display: inline-flex;
    align-items: center;
    padding: 0.25rem 0.75rem;
    font-size: 0.75rem;
    font-weight: 600;
    border-radius: var(--radius-full);
    text-transform: uppercase;
    letter-spacing: 0.025em;
}

.badge-live {
    background-color: var(--color-danger);
    color: white;
    animation: pulse 2s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.7; }
}

.badge-theme {
    background-color: var(--color-bg-tertiary);
    color: var(--color-text-secondary);
    font-size: 0.75rem;
    padding: 0.25rem 0.5rem;
}

/* ============================================
   Filters
   ============================================ */

.filters-section {
    margin-bottom: var(--spacing-xl);
    padding: var(--spacing-lg);
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-xl);
}

.filters-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--spacing-lg);
}

.filters-grid {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.filter-group {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.filter-label {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--color-text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.025em;
}

.filter-chips {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
}

.chip {
    padding: var(--spacing-sm) var(--spacing-md);
    background-color: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-full);
    color: var(--color-text-primary);
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition-fast);
    white-space: nowrap;
    min-height: 36px;
}

.chip:hover {
    background-color: var(--color-bg-tertiary);
    border-color: var(--color-primary-light);
}

.chip:focus {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

.chip.active {
    background-color: var(--color-primary);
    border-color: var(--color-primary);
    color: white;
}

.filter-select {
    padding: var(--spacing-sm) var(--spacing-md);
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    color: var(--color-text-primary);
    font-size: 0.875rem;
    cursor: pointer;
    transition: all var(--transition-base);
    min-height: 40px;
}

.filter-select:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

/* Active Filters */
.active-filters {
    margin-top: var(--spacing-lg);
    padding-top: var(--spacing-lg);
    border-top: 1px solid var(--color-border);
}

.active-filters-label {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--color-text-secondary);
    margin-right: var(--spacing-sm);
}

.active-filters-list {
    display: inline-flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-sm);
}

.active-filter-tag {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-xs) var(--spacing-sm);
    background-color: var(--color-primary);
    color: white;
    font-size: 0.75rem;
    font-weight: 500;
    border-radius: var(--radius-md);
}

.active-filter-tag button {
    display: flex;
    align-items: center;
    background: transparent;
    border: none;
    color: white;
    cursor: pointer;
    padding: 0;
    margin: 0;
}

/* ============================================
   Sessions
   ============================================ */

.sessions-section {
    margin-bottom: var(--spacing-2xl);
}

.sessions-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--spacing-lg);
    flex-wrap: wrap;
    gap: var(--spacing-md);
}

.sessions-count {
    font-size: 0.875rem;
    color: var(--color-text-secondary);
    font-weight: 500;
}

.sessions-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

/* Session Card */
.session-card {
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    cursor: pointer;
    transition: all var(--transition-base);
}

.session-card:hover {
    box-shadow: var(--shadow-md);
    border-color: var(--color-primary-light);
    transform: translateY(-2px);
}

.session-card:focus {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

.session-card.is-live {
    border-color: var(--color-danger);
    border-width: 2px;
}

.session-card.is-favorite {
    border-color: var(--color-primary);
}

.session-header {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
}

.session-meta {
    flex: 1;
}

.session-time {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--color-primary);
    margin-bottom: var(--spacing-xs);
}

.session-stage {
    font-size: 0.75rem;
    color: var(--color-text-tertiary);
    text-transform: uppercase;
    letter-spacing: 0.025em;
    font-weight: 600;
}

.session-title {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--color-text-primary);
    margin: var(--spacing-sm) 0;
    line-height: 1.4;
}

.session-speaker {
    font-size: 0.875rem;
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-sm);
}

.session-themes {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
}

.btn-favorite {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 2.5rem;
    height: 2.5rem;
    background: transparent;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-full);
    color: var(--color-text-tertiary);
    cursor: pointer;
    transition: all var(--transition-fast);
    flex-shrink: 0;
}

.btn-favorite:hover {
    background-color: var(--color-bg-secondary);
    border-color: var(--color-primary);
    color: var(--color-danger);
}

.btn-favorite.is-favorite {
    background-color: var(--color-danger);
    border-color: var(--color-danger);
    color: white;
}

.btn-favorite.is-favorite svg {
    fill: currentColor;
}

/* ============================================
   Buttons
   ============================================ */

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: 0.875rem;
    font-weight: 600;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-base);
    border: none;
    min-height: 44px;
}

.btn-primary {
    background-color: var(--color-primary);
    color: white;
}

.btn-primary:hover {
    background-color: var(--color-primary-dark);
    box-shadow: var(--shadow-md);
}

.btn-primary:focus {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

.btn-secondary {
    background-color: var(--color-bg-secondary);
    color: var(--color-text-primary);
    border: 1px solid var(--color-border);
}

.btn-secondary:hover {
    background-color: var(--color-bg-tertiary);
    border-color: var(--color-primary);
}

.btn-text {
    background: transparent;
    color: var(--color-primary);
    padding: var(--spacing-sm);
    border: none;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.btn-text:hover {
    color: var(--color-primary-dark);
    text-decoration: underline;
}

/* ============================================
   Modal
   ============================================ */

.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: var(--z-modal);
    display: none;
}

.modal[aria-hidden="false"] {
    display: flex;
    align-items: center;
    justify-content: center;
    animation: fadeIn var(--transition-base);
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.modal-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(4px);
}

.modal-content {
    position: relative;
    width: 90%;
    max-width: 600px;
    max-height: 90vh;
    background-color: var(--color-surface);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-xl);
    display: flex;
    flex-direction: column;
    animation: slideUp var(--transition-slow);
    margin: var(--spacing-md);
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.modal-header {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    gap: var(--spacing-md);
    padding: var(--spacing-lg);
    border-bottom: 1px solid var(--color-border);
}

.modal-title {
    font-size: 1.25rem;
    font-weight: 700;
    margin: 0;
    flex: 1;
}

.modal-close {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 2rem;
    height: 2rem;
    background: transparent;
    border: none;
    border-radius: var(--radius-md);
    color: var(--color-text-tertiary);
    cursor: pointer;
    transition: all var(--transition-fast);
    flex-shrink: 0;
}

.modal-close:hover {
    background-color: var(--color-bg-secondary);
    color: var(--color-text-primary);
}

.modal-body {
    padding: var(--spacing-lg);
    overflow-y: auto;
    flex: 1;
}

.modal-body p {
    margin-bottom: var(--spacing-md);
    color: var(--color-text-secondary);
    line-height: 1.6;
}

.modal-footer {
    display: flex;
    gap: var(--spacing-md);
    padding: var(--spacing-lg);
    border-top: 1px solid var(--color-border);
}

.modal-footer .btn {
    flex: 1;
}

/* ============================================
   Toast Notifications
   ============================================ */

.toast-container {
    position: fixed;
    bottom: var(--spacing-lg);
    right: var(--spacing-lg);
    z-index: var(--z-toast);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
    pointer-events: none;
}

.toast {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-md) var(--spacing-lg);
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    min-width: 300px;
    pointer-events: all;
    animation: slideInRight var(--transition-base);
}

@keyframes slideInRight {
    from {
        opacity: 0;
        transform: translateX(100%);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

.toast-success {
    border-left: 4px solid var(--color-success);
}

.toast-error {
    border-left: 4px solid var(--color-danger);
}

.toast-icon {
    flex-shrink: 0;
}

.toast-content {
    flex: 1;
}

.toast-title {
    font-weight: 600;
    font-size: 0.875rem;
    margin-bottom: var(--spacing-xs);
}

.toast-message {
    font-size: 0.875rem;
    color: var(--color-text-secondary);
}

/* ============================================
   Empty State
   ============================================ */

.empty-state {
    text-align: center;
    padding: var(--spacing-2xl);
}

.empty-icon {
    font-size: 4rem;
    margin-bottom: var(--spacing-lg);
    opacity: 0.5;
}

.empty-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
}

.empty-text {
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-lg);
}

/* ============================================
   Loading
   ============================================ */

.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(4px);
    z-index: var(--z-loading);
    display: flex;
    align-items: center;
    justify-content: center;
}

@media (prefers-color-scheme: dark) {
    .loading-overlay {
        background-color: rgba(15, 23, 42, 0.9);
    }
}

.spinner {
    width: 3rem;
    height: 3rem;
    border: 4px solid var(--color-border);
    border-top-color: var(--color-primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

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

/* ============================================
   Utilities
   ============================================ */

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border-width: 0;
}

/* ============================================
   Responsive Breakpoints
   ============================================ */

@media (min-width: 768px) {
    .sessions-list {
        display: grid;
        grid-template-columns: repeat(2, 1fr);
        gap: var(--spacing-lg);
    }
}

@media (min-width: 1024px) {
    .filters-grid {
        display: grid;
        grid-template-columns: repeat(2, 1fr);
        gap: var(--spacing-lg);
    }
}

/* ============================================
   Print Styles
   ============================================ */

@media print {
    .header, .search-wrapper, .filters-section, .modal, .toast-container {
        display: none;
    }

    .session-card {
        page-break-inside: avoid;
        border: 1px solid #000;
        margin-bottom: 1rem;
    }
}