:root {
    /* Palette */
    --color-dust-grey: #d6d6d6;
    --color-bright-lemon: #ffee32;
    --color-bright-amber: #ffd100;
    --color-carbon-black: #202020;
    --color-graphite: #333533;

    /* Defaults (Dark Mode) - The "Premium" Look */
    --bg-primary: var(--color-carbon-black);
    --bg-secondary: #2a2a2a;
    --bg-header: rgba(32, 32, 32, 0.95);
    --text-primary: var(--color-dust-grey);
    --text-secondary: rgba(214, 214, 214, 0.6);
    --accent: var(--color-bright-amber);
    --accent-hover: var(--color-bright-lemon);
    --accent-ring: rgba(255, 213, 0, 0.1);
    --card-bg: var(--color-graphite);
    --card-hover-bg: #404240;
    --border-color: rgba(255, 255, 255, 0.08);

    /* Typography */
    --font-family: 'Inter', system-ui, sans-serif;

    /* Transitions */
    --transition-fast: 0.2s;
    --transition-normal: 0.3s;

    /* Shadows */
    --shadow-sm: 0 4px 6px rgba(0, 0, 0, 0.2);
    --shadow-md: 0 10px 15px rgba(0, 0, 0, 0.3);

    /* Border Radius */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 20px;
    --radius-full: 50%;
}

[data-theme="light"] {
    --bg-primary: #f0f0f0;
    --bg-secondary: #e5e5e5;
    --bg-header: rgba(240, 240, 240, 0.95);
    --text-primary: #1a1a1a;
    --text-secondary: #555555;
    --accent: #d4af37;
    /* Darker gold for light mode text readability */
    --accent-hover: var(--color-bright-amber);
    --accent-ring: rgba(212, 175, 55, 0.1);
    --card-bg: #ffffff;
    --card-hover-bg: #f9f9f9;
    --border-color: rgba(0, 0, 0, 0.1);
    --shadow-sm: 0 4px 6px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 10px 15px rgba(0, 0, 0, 0.1);
}

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

body {
    font-family: var(--font-family);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    transition: background-color var(--transition-normal), color var(--transition-normal);
    line-height: 1.5;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header */
.header {
    background: var(--bg-header);
    -webkit-backdrop-filter: blur(10px);
    backdrop-filter: blur(10px);
    position: sticky;
    top: 0;
    z-index: 100;
    border-bottom: 1px solid var(--border-color);
    padding: 1.5rem 0;
}

.header-content {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    letter-spacing: -0.5px;
    background: linear-gradient(135deg, var(--color-dust-grey), var(--accent));
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

[data-theme="light"] .logo {
    background: none;
    -webkit-text-fill-color: var(--color-carbon-black);
}

/* Controls */
.container {
    max-width: 1400px;
    margin: 2rem auto;
    padding: 0 2rem;
    flex: 1;
    width: 100%;
}

.controls {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 3rem;
    gap: 1rem;
    flex-wrap: wrap;
}

.footer {
    margin-top: 3rem;
    padding: 2rem 0;
    text-align: center;
    color: var(--text-secondary);
    border-top: 1px solid var(--border-color);
}

.search-wrapper {
    position: relative;
    flex: 1;
    max-width: 500px;
}

.search-icon {
    position: absolute;
    left: 1rem;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-secondary);
    pointer-events: none;
}

#search-input {
    width: 100%;
    background-color: var(--bg-secondary);
    border: 1px solid transparent;
    border-radius: var(--radius-md);
    padding: 1rem 1rem 1rem 3rem;
    color: var(--text-primary);
    font-family: inherit;
    font-size: 1rem;
    transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

#search-input:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 3px var(--accent-ring);
}

.sort-wrapper {
    display: flex;
    gap: 0.75rem;
    background: var(--bg-secondary);
    padding: 0.25rem;
    border-radius: var(--radius-md);
}

.btn-sort {
    background: none;
    border: none;
    padding: 0.6rem 1.25rem;
    color: var(--text-secondary);
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-family: inherit;
    font-weight: 500;
    font-size: 0.9rem;
    transition: color var(--transition-fast), background-color var(--transition-fast);
}

.btn-sort:hover {
    color: var(--text-primary);
}

.btn-sort:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 2px;
}

.btn-sort.active {
    background-color: var(--accent);
    color: var(--color-carbon-black);
    font-weight: 600;
}

/* Grid & Cards */
.sessions-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1.5rem;
}

.session-card {
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 2rem;
    cursor: pointer;
    transition: transform var(--transition-normal) cubic-bezier(0.25, 0.8, 0.25, 1),
        box-shadow var(--transition-normal),
        background-color var(--transition-normal);
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    height: 100%;
    position: relative;
    overflow: hidden;
}

.session-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 100%;
    background: var(--accent);
    opacity: 0;
    transition: opacity var(--transition-normal);
}

.session-card:hover,
.session-card:focus-visible {
    transform: translateY(-5px);
    box-shadow: var(--shadow-md);
    background-color: var(--card-hover-bg);
}

.session-card:hover::before,
.session-card:focus-visible::before {
    opacity: 1;
}

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

.session-id {
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--accent);
    margin-bottom: 1rem;
    font-weight: 600;
}

.session-title {
    font-size: 1.25rem;
    font-weight: 600;
    line-height: 1.4;
    color: var(--text-primary);
    margin-bottom: 1rem;
}

.card-cta {
    font-size: 0.85rem;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-top: auto;
    opacity: 0;
    transform: translateY(10px);
    transition: opacity var(--transition-normal), transform var(--transition-normal);
}

.session-card:hover .card-cta,
.session-card:focus-visible .card-cta {
    opacity: 1;
    transform: translateY(0);
}

/* Modal */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.8);
    -webkit-backdrop-filter: blur(5px);
    backdrop-filter: blur(5px);
    z-index: 1000;
    display: flex;
    justify-content: center;
    align-items: center;
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transition: opacity var(--transition-normal),
        visibility 0s linear var(--transition-normal);
}

.modal-overlay.modal-active {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
    transition: opacity var(--transition-normal),
        visibility 0s linear 0s;
}

.modal-content {
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    width: 90%;
    max-width: 600px;
    border-radius: var(--radius-xl);
    padding: 3rem;
    position: relative;
    transform: translateY(20px) scale(0.95);
    transition: transform var(--transition-normal) cubic-bezier(0.34, 1.56, 0.64, 1);
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
}

.modal-overlay.modal-active .modal-content {
    transform: translateY(0) scale(1);
}

.modal-close {
    position: absolute;
    top: 1.5rem;
    right: 1.5rem;
    background: none;
    border: none;
    font-size: 2rem;
    color: var(--text-secondary);
    cursor: pointer;
    line-height: 1;
}

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

.modal-close:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 2px;
}

.modal-header {
    margin-bottom: 2.5rem;
}

.modal-id {
    display: block;
    color: var(--accent);
    font-size: 0.85rem;
    font-weight: 600;
    letter-spacing: 1px;
    margin-bottom: 0.5rem;
    text-transform: uppercase;
}

.modal-title {
    font-size: 2rem;
    line-height: 1.2;
}

.modal-actions {
    display: flex;
    gap: 1rem;
    margin-bottom: 2.5rem;
    flex-wrap: wrap;
}

.modal-resources-heading {
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: 1rem;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius-sm);
    font-weight: 600;
    text-decoration: none;
    transition: transform var(--transition-fast), background-color var(--transition-fast);
}

.btn:active {
    transform: scale(0.98);
}

.btn-primary {
    background-color: var(--accent);
    color: var(--color-carbon-black);
}

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

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

.btn-secondary:hover {
    background-color: var(--card-hover-bg);
}

.modal-resources {
    border-top: 1px solid var(--border-color);
    padding-top: 2rem;
}

.resource-item {
    margin-bottom: 0.75rem;
}

.resource-item a {
    color: var(--text-secondary);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    transition: color var(--transition-fast);
}

.resource-item a:hover {
    color: var(--accent);
}

.resource-item a::before {
    content: '\2192';
}

/* Toggle Icons */
.btn-icon {
    background: none;
    border: none;
    cursor: pointer;
    color: var(--text-primary);
    padding: 0.5rem;
    border-radius: var(--radius-full);
}

.icon-sun {
    display: none;
}

.icon-moon {
    display: block;
}

[data-theme="light"] .icon-sun {
    display: block;
}

[data-theme="light"] .icon-moon {
    display: none;
}

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

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

/* Reduced Motion */
@media (prefers-reduced-motion: reduce) {

    *,
    *::before,
    *::after {
        transition-duration: 0.01ms !important;
        animation-duration: 0.01ms !important;
    }
}

/* Tablet */
@media (max-width: 900px) {

    .header-content,
    .container {
        padding: 0 1.5rem;
    }

    .sessions-grid {
        grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
    }
}

/* Mobile */
@media (max-width: 600px) {

    .header-content,
    .container {
        padding: 0 1rem;
    }

    .controls {
        flex-direction: column;
        align-items: stretch;
        margin-bottom: 2rem;
    }

    .search-wrapper {
        max-width: 100%;
    }

    .sort-wrapper {
        justify-content: flex-start;
    }

    .modal-content {
        width: 95%;
        padding: 2rem;
    }

    .modal-title {
        font-size: 1.5rem;
    }

    .modal-actions {
        flex-direction: column;
    }

    .btn {
        width: 100%;
        justify-content: center;
    }
}