:root {
    --bg-color: #030303;
    --card-bg: #0a0a0a;
    --card-border: #1f1f1f;
    --text-main: #ffffff;
    --text-muted: #888888;
    --accent: #ffffff;
    --accent-hover: #e5e5e5;
    --date-bg: #111111;
    --date-text: #ffffff;
}

[data-theme="light"] {
    --bg-color: #f7f7f7;
    --card-bg: #ffffff;
    --card-border: #e0e0e0;
    --text-main: #111111;
    --text-muted: #666666;
    --accent: #111111;
    --accent-hover: #333333;
    --date-bg: #f0f0f0;
    --date-text: #111111;
}

/* Base element transitions for smooth theme switching */
body {
    transition: background-color 0.3s ease, color 0.3s ease;
}
.day-container, .day-header, .lesson-row, .lesson-time, .group-selector, .custom-options {
    transition: background-color 0.3s ease, border-color 0.3s ease, box-shadow 0.3s ease;
}

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

body {
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-main);
    line-height: 1.5;
    min-height: 100vh;
    /* Subtle dotted background pattern */
    background-image: radial-gradient(var(--card-border) 1px, transparent 1px);
    background-size: 24px 24px;
}

.top-blur {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: 300px;
    z-index: 80;
    pointer-events: none;
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    mask-image: linear-gradient(
        to bottom,
        rgba(0, 0, 0, 1) 0px,
        rgba(0, 0, 0, 1) 60px,
        rgba(0, 0, 0, 0.738) 90px,
        rgba(0, 0, 0, 0.541) 115px,
        rgba(0, 0, 0, 0.382) 140px,
        rgba(0, 0, 0, 0.278) 160px,
        rgba(0, 0, 0, 0.194) 180px,
        rgba(0, 0, 0, 0.09) 200px,
        rgba(0, 0, 0, 0) 220px,
        rgba(0, 0, 0, 0) 100%
    );
    -webkit-mask-image: linear-gradient(
        to bottom,
        rgba(0, 0, 0, 1) 0px,
        rgba(0, 0, 0, 1) 60px,
        rgba(0, 0, 0, 0.738) 90px,
        rgba(0, 0, 0, 0.541) 115px,
        rgba(0, 0, 0, 0.382) 140px,
        rgba(0, 0, 0, 0.278) 160px,
        rgba(0, 0, 0, 0.194) 180px,
        rgba(0, 0, 0, 0.09) 200px,
        rgba(0, 0, 0, 0) 220px,
        rgba(0, 0, 0, 0) 100%
    );
    opacity: 0;
    transition: opacity 0.3s ease;
}

.top-blur.active {
    opacity: 1;
}

.app-container {
    max-width: 900px;
    margin: 0 auto;
    padding: 3rem 1.5rem;
}

header {
    display: flex;
    flex-direction: column;
    align-items: center;
    margin-bottom: 1.5rem;
    gap: 1.5rem;
}

h1 {
    font-size: clamp(2rem, 4vw, 3rem);
    font-weight: 700;
    letter-spacing: -0.02em;
    text-align: center;
    color: var(--text-main);
    opacity: 0;
    animation: slideDown 0.6s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

.sticky-controls {
    position: -webkit-sticky;
    position: sticky;
    top: 1rem;
    z-index: 90;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 3rem;
}

.group-selector {
    display: flex;
    align-items: center;
    gap: 1rem;
    background: rgba(10, 10, 10, 0.85);
    padding: 0.5rem 0.5rem 0.5rem 1.25rem;
    border-radius: 12px;
    border: 1px solid var(--card-border);
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.5);
    transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
    transform-origin: top center;
}

.sticky-controls.stuck .group-selector {
    padding: 0.35rem 0.35rem 0.35rem 1rem;
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.8);
    background: rgba(10, 10, 10, 0.95);
    transform: scale(0.98);
}

.group-selector label {
    font-size: 0.875rem;
    color: var(--text-muted);
    font-weight: 500;
}

.custom-select-wrapper {
    position: relative;
    user-select: none;
    flex: 1;
}

.custom-select-trigger {
    background-color: var(--accent);
    color: #000;
    padding: 0.75rem 1.25rem;
    border-radius: 8px;
    font-weight: 600;
    font-size: 0.875rem;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: relative;
    transition: background-color 0.2s;
}

.custom-select-trigger:hover {
    background-color: var(--accent-hover);
}

.custom-select-trigger:active {
    transform: scale(0.98);
}

.custom-select-trigger .arrow {
    width: 20px;
    height: 20px;
    background-image: url("data:image/svg+xml;charset=US-ASCII,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%2224%22%20height%3D%2224%22%20viewBox%3D%220%200%2024%2024%22%20fill%3D%22none%22%20stroke%3D%22%23000000%22%20stroke-width%3D%222%22%20stroke-linecap%3D%22round%22%20stroke-linejoin%3D%22round%22%3E%3Cpolyline%20points%3D%226%209%2012%2015%2018%209%22%3E%3C%2Fpolyline%3E%3C%2Fsvg%3E");
    background-repeat: no-repeat;
    background-position: center;
    background-size: contain;
    transition: transform 0.3s ease;
    margin-left: 1rem;
}

.custom-select-wrapper.open .custom-select-trigger .arrow {
    transform: rotate(180deg);
}

.custom-options {
    position: absolute;
    top: calc(100% + 0.5rem);
    left: 0;
    right: 0;
    background-color: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 1rem;
    box-shadow: 0 10px 25px rgba(0,0,0,0.5);
    z-index: 100;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: all 0.2s cubic-bezier(0.16, 1, 0.3, 1);
    max-height: 300px;
    overflow-y: auto;
}

.custom-options::-webkit-scrollbar {
    width: 6px;
}
.custom-options::-webkit-scrollbar-thumb {
    background-color: #333;
    border-radius: 3px;
}

.custom-select-wrapper.open .custom-options {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.custom-option {
    padding: 0.75rem 1.25rem;
    color: var(--text-main);
    cursor: pointer;
    font-size: 0.875rem;
    transition: background-color 0.15s;
    border-bottom: 1px solid var(--card-border);
}

.custom-option:last-child {
    border-bottom: none;
}

.custom-option:hover {
    background-color: rgba(255, 255, 255, 0.05);
}

.custom-option.selected {
    background-color: rgba(255, 255, 255, 0.1);
    color: var(--accent);
    font-weight: 600;
}

.last-updated {
    font-size: 0.75rem;
    color: var(--text-muted);
    font-family: monospace;
    letter-spacing: 0.05em;
    text-transform: uppercase;
}

footer {
    text-align: center;
    margin-top: 4rem;
    padding-top: 2rem;
    border-top: 1px dashed var(--card-border);
    animation: fadeInUp 0.5s ease-out forwards;
    opacity: 0;
    animation-delay: 0.5s;
}

.loader {
    text-align: center;
    padding: 3rem;
    color: var(--text-muted);
    font-size: 1rem;
    letter-spacing: 0.05em;
    text-transform: uppercase;
}

.schedule-grid {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.day-container {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 12px;
    overflow: hidden;
    position: relative;
}

.day-container::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0; height: 1px;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.1), transparent);
}

.day-header {
    background: var(--date-bg);
    padding: 1.25rem 1.5rem;
    font-weight: 600;
    color: var(--date-text);
    border-bottom: 1px solid var(--card-border);
    text-transform: uppercase;
    font-size: 0.875rem;
    letter-spacing: 0.05em;
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.day-header::before {
    content: '';
    display: inline-block;
    width: 6px;
    height: 6px;
    background-color: var(--accent);
    border-radius: 50%;
}

.lesson-row {
    display: grid;
    grid-template-columns: 115px 1fr;
    border-bottom: 1px solid var(--card-border);
    transition: background-color 0.2s ease;
}

.lesson-row:hover {
    background-color: rgba(255, 255, 255, 0.03);
}

.lesson-time > *, .lesson-details > * {
    transition: transform 0.25s ease;
}

.lesson-row:hover .lesson-time > *, 
.lesson-row:hover .lesson-details > * {
    transform: translateX(4px);
}

.lesson-row:last-child {
    border-bottom: none;
}

.lesson-time {
    padding: 1.5rem 0.5rem;
    border-right: 1px solid var(--card-border);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    color: var(--text-muted);
    font-family: monospace;
    font-size: 0.8rem;
    letter-spacing: -0.03em;
    text-align: center;
    background: rgba(255, 255, 255, 0.02);
}

.lesson-number {
    font-family: 'Inter', sans-serif;
    font-weight: 800;
    font-size: 1.25rem;
    color: var(--bg-color);
    background: var(--text-main);
    width: 2.25rem;
    height: 2.25rem;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 8px;
    margin-bottom: 0.75rem;
    box-shadow: 0 4px 12px rgba(255, 255, 255, 0.1);
}

.lesson-details {
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.lesson-subject {
    font-weight: 500;
    font-size: 1.125rem;
    line-height: 1.4;
    padding-bottom: 0.75rem;
    margin-bottom: 0.75rem;
    border-bottom: 1px solid var(--card-border);
}

.lesson-meta-wrapper {
    display: flex;
}

.lesson-meta {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    font-size: 0.875rem;
    color: var(--text-muted);
}

.meta-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding-right: 1rem;
}

.meta-item:not(:first-child) {
    padding-left: 1rem;
    border-left: 1px solid var(--card-border);
}

/* Icons using SVG data URIs for a cleaner look */
.icon-location {
    width: 14px; height: 14px;
    background-color: currentColor;
    mask: url("data:image/svg+xml;charset=US-ASCII,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20viewBox%3D%220%200%2024%2024%22%20fill%3D%22none%22%20stroke%3D%22currentColor%22%20stroke-width%3D%222%22%20stroke-linecap%3D%22round%22%20stroke-linejoin%3D%22round%22%3E%3Cpath%20d%3D%22M21%2010c0%207-9%2013-9%2013s-9-6-9-13a9%209%200%200%201%2018%200z%22%3E%3C%2Fpath%3E%3Ccircle%20cx%3D%2212%22%20cy%3D%2210%22%20r%3D%223%22%3E%3C%2Fcircle%3E%3C%2Fsvg%3E") no-repeat center / contain;
    -webkit-mask: url("data:image/svg+xml;charset=US-ASCII,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20viewBox%3D%220%200%2024%2024%22%20fill%3D%22none%22%20stroke%3D%22currentColor%22%20stroke-width%3D%222%22%20stroke-linecap%3D%22round%22%20stroke-linejoin%3D%22round%22%3E%3Cpath%20d%3D%22M21%2010c0%207-9%2013-9%2013s-9-6-9-13a9%209%200%200%201%2018%200z%22%3E%3C%2Fpath%3E%3Ccircle%20cx%3D%2212%22%20cy%3D%2210%22%20r%3D%223%22%3E%3C%2Fcircle%3E%3C%2Fsvg%3E") no-repeat center / contain;
}

.icon-user {
    width: 14px; height: 14px;
    background-color: currentColor;
    mask: url("data:image/svg+xml;charset=US-ASCII,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20viewBox%3D%220%200%2024%2024%22%20fill%3D%22none%22%20stroke%3D%22currentColor%22%20stroke-width%3D%222%22%20stroke-linecap%3D%22round%22%20stroke-linejoin%3D%22round%22%3E%3Cpath%20d%3D%22M20%2021v-2a4%204%200%200%200-4-4H8a4%204%200%200%200-4%204v2%22%3E%3C%2Fpath%3E%3Ccircle%20cx%3D%2212%22%20cy%3D%227%22%20r%3D%224%22%3E%3C%2Fcircle%3E%3C%2Fsvg%3E") no-repeat center / contain;
    -webkit-mask: url("data:image/svg+xml;charset=US-ASCII,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20viewBox%3D%220%200%2024%2024%22%20fill%3D%22none%22%20stroke%3D%22currentColor%22%20stroke-width%3D%222%22%20stroke-linecap%3D%22round%22%20stroke-linejoin%3D%22round%22%3E%3Cpath%20d%3D%22M20%2021v-2a4%204%200%200%200-4-4H8a4%204%200%200%200-4%204v2%22%3E%3C%2Fpath%3E%3Ccircle%20cx%3D%2212%22%20cy%3D%227%22%20r%3D%224%22%3E%3C%2Fcircle%3E%3C%2Fsvg%3E") no-repeat center / contain;
}

.empty-state {
    text-align: center;
    padding: 4rem 2rem;
    color: var(--text-muted);
    border: 1px dashed var(--card-border);
    border-radius: 12px;
}

/* Animations */
@keyframes fadeInUp {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

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

.day-container {
    opacity: 0;
    animation: fadeInUp 0.5s ease-out forwards;
}

.week-separator {
    text-align: center;
    color: var(--text-muted);
    font-size: 0.875rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    margin: 1rem 0;
    opacity: 0;
    animation: fadeInUp 0.5s ease-out forwards;
    position: relative;
}

.week-separator::before,
.week-separator::after {
    content: '';
    position: absolute;
    top: 50%;
    width: calc(50% - 6rem);
    height: 1px;
    background: var(--card-border);
}

.week-separator::before { left: 0; }
.week-separator::after { right: 0; }

.end-of-schedule {
    text-align: center;
    color: var(--text-muted);
    font-size: 0.875rem;
    margin-top: 2rem;
    padding: 2rem;
    border: 1px dashed var(--card-border);
    border-radius: 12px;
    opacity: 0;
    animation: fadeInUp 0.5s ease-out forwards;
}

/* Mobile Responsive */
@media (max-width: 640px) {
    .app-container {
        padding: 2rem 1rem;
    }

    h1 {
        font-size: 2.5rem;
    }

    header {
        margin-bottom: 1.5rem;
    }

    .sticky-controls {
        top: 0.5rem;
    }

    .group-selector {
        width: 100%;
        justify-content: space-between;
        padding-left: 1rem;
    }

    select {
        flex: 1;
        text-align: right;
    }

    .lesson-row {
        grid-template-columns: 1fr;
    }

    .lesson-time {
        flex-direction: row;
        align-items: center;
        justify-content: flex-start;
        gap: 1rem;
        padding: 1rem 1.5rem;
        border-right: none;
        border-bottom: 1px solid var(--card-border);
    }
    
    .lesson-number {
        margin-bottom: 0;
        width: 2rem;
        height: 2rem;
        font-size: 1.125rem;
    }

/* Light Theme Component Overrides */
[data-theme="light"] .group-selector {
    background: rgba(255, 255, 255, 0.85);
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.05);
}
[data-theme="light"] .sticky-controls.stuck .group-selector {
    background: rgba(255, 255, 255, 0.95);
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.1);
}
[data-theme="light"] .custom-options {
    box-shadow: 0 10px 25px rgba(0,0,0,0.1);
}
[data-theme="light"] .custom-option:hover {
    background-color: rgba(0, 0, 0, 0.05);
}
[data-theme="light"] .custom-option.selected {
    background-color: rgba(0, 0, 0, 0.08);
}
[data-theme="light"] .day-container::before {
    background: linear-gradient(90deg, transparent, rgba(0,0,0,0.1), transparent);
}
[data-theme="light"] .lesson-row:hover {
    background-color: rgba(0, 0, 0, 0.02);
}
[data-theme="light"] .lesson-meta-wrapper {
    background: rgba(0, 0, 0, 0.02);
}
[data-theme="light"] .lesson-meta-wrapper:hover {
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
}

/* Theme Toggle Button */
.theme-toggle {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background-color: var(--card-bg);
    border: 1px solid var(--card-border);
    cursor: pointer;
    z-index: 100;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 4px 12px rgba(0,0,0,0.3);
    transition: transform 0.3s ease, background-color 0.3s ease, box-shadow 0.3s ease;
}

[data-theme="light"] .theme-toggle {
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

.theme-toggle:hover {
    transform: scale(1.1);
}

.theme-toggle svg {
    position: absolute;
    width: 22px;
    height: 22px;
    stroke: var(--text-main);
    transition: transform 0.5s cubic-bezier(0.4, 0, 0.2, 1), opacity 0.5s ease;
}

/* Dark mode (default): show sun, hide moon */
body[data-theme="dark"] .icon-sun {
    opacity: 1;
    transform: rotate(0) scale(1);
}
body[data-theme="dark"] .icon-moon {
    opacity: 0;
    transform: rotate(90deg) scale(0.5);
}

/* Light mode: show moon, hide sun */
body[data-theme="light"] .icon-sun {
    opacity: 0;
    transform: rotate(-90deg) scale(0.5);
}
body[data-theme="light"] .icon-moon {
    opacity: 1;
    transform: rotate(0) scale(1);
}

@media (max-width: 640px) {
    .theme-toggle {
        bottom: 1.5rem;
        right: 1.5rem;
        width: 44px;
        height: 44px;
    }
}

    .lesson-details {
        padding: 1.5rem;
    }

    .meta-item:not(:first-child) {
        border-left: none;
        padding-left: 0;
    }
    
    .meta-item {
        margin-bottom: 0.5rem;
    }
}