:root {
    --bg-main: #121212;
    --bg-sidebar: #000000;
    --bg-player: #181818;
    --bg-card: #181818;
    --bg-card-hover: #282828;
    --text-primary: #ffffff;
    --text-secondary: #b3b3b3;
    --accent: #1db954;
    --accent-hover: #1ed760;
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--bg-main);
    color: var(--text-primary);
    display: flex;
    flex-direction: column;
    height: 100vh;
    overflow: hidden;
}

/* --- Layout --- */
.app-container {
    display: flex;
    flex: 1;
    overflow: hidden;
    height: calc(100vh - 90px);
}

/* --- Sidebar --- */
.sidebar {
    width: 240px;
    background-color: var(--bg-sidebar);
    display: flex;
    flex-direction: column;
    padding-top: 24px;
}

.logo {
    padding: 0 24px;
    font-size: 24px;
    font-weight: bold;
    margin-bottom: 30px;
    display: flex;
    align-items: center;
    gap: 10px;
}

.logo i {
    font-size: 28px;
}

.nav-links {
    list-style: none;
    padding: 0 8px;
}

.nav-links li {
    padding: 12px 16px;
    display: flex;
    align-items: center;
    gap: 16px;
    color: var(--text-secondary);
    font-weight: 600;
    font-size: 14px;
    cursor: pointer;
    border-radius: 4px;
    transition: color 0.2s;
}

.nav-links li:hover {
    color: var(--text-primary);
}

.nav-links li.active {
    color: var(--text-primary);
}

.nav-links i {
    font-size: 20px;
}

.playlists {
    margin-top: 24px;
    padding: 0 24px;
    flex: 1;
    overflow-y: auto;
}

.playlist-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    color: var(--text-secondary);
    font-size: 12px;
    font-weight: 700;
    letter-spacing: 1px;
    margin-bottom: 16px;
}

.playlist-header i {
    cursor: pointer;
    font-size: 14px;
}

.playlist-header i:hover {
    color: var(--text-primary);
}

.playlist-list {
    list-style: none;
}

.playlist-list li {
    color: var(--text-secondary);
    font-size: 14px;
    padding: 8px 0;
    cursor: pointer;
}

.playlist-list li:hover {
    color: var(--text-primary);
}

/* Scrollbar styling */
::-webkit-scrollbar {
    width: 8px;
}
::-webkit-scrollbar-track {
    background: transparent;
}
::-webkit-scrollbar-thumb {
    background: #555;
    border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover {
    background: #888;
}

/* --- Main Content --- */
.main-content {
    flex: 1;
    background: linear-gradient(to bottom, #1f1f1f 0%, var(--bg-main) 100%);
    overflow-y: auto;
    display: flex;
    flex-direction: column;
}

.top-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 16px 32px;
    background-color: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(10px);
    position: sticky;
    top: 0;
    z-index: 10;
}

.nav-arrows {
    display: flex;
    gap: 16px;
    align-items: center;
}

.search-box {
    display: flex;
    align-items: center;
    background-color: #242424;
    border-radius: 500px;
    padding: 0 12px;
    height: 48px;
    width: 364px;
    margin-left: 8px;
    border: 2px solid transparent;
    transition: all 0.3s ease;
}

.search-box:hover, .search-box:focus-within {
    border-color: #333;
    background-color: #2a2a2a;
}

.search-box i {
    color: var(--text-secondary);
    font-size: 20px;
    margin-right: 12px;
}

.search-box input {
    background: transparent;
    border: none;
    color: white;
    font-size: 14px;
    width: 100%;
}

.search-box input:focus {
    outline: none;
}

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

.arrow-btn {
    background-color: rgba(0, 0, 0, 0.7);
    color: var(--text-primary);
    border: none;
    width: 32px;
    height: 32px;
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    cursor: pointer;
}

.user-profile {
    display: flex;
    align-items: center;
    gap: 10px;
    background-color: rgba(0, 0, 0, 0.7);
    padding: 2px 12px 2px 2px;
    border-radius: 20px;
    font-size: 14px;
    font-weight: bold;
    cursor: pointer;
}

.user-profile:hover {
    background-color: #282828;
}

.profile-avatar {
    background-color: #535353;
    width: 28px;
    height: 28px;
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
}

.content-padding {
    padding: 24px 32px;
}

.greeting {
    font-size: 32px;
    font-weight: bold;
    margin-bottom: 24px;
}

.section-title {
    font-size: 24px;
    font-weight: bold;
    margin-bottom: 20px;
}

.song-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    gap: 24px;
}

.song-card {
    background-color: var(--bg-card);
    padding: 16px;
    border-radius: 8px;
    cursor: pointer;
    transition: background-color 0.3s;
    position: relative;
}

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

.card-img-container {
    width: 100%;
    aspect-ratio: 1;
    margin-bottom: 16px;
    position: relative;
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.5);
    border-radius: 4px;
    overflow: hidden;
}

.card-img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.card-play-btn {
    position: absolute;
    bottom: 8px;
    right: 8px;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background-color: var(--accent);
    color: #000;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 20px;
    opacity: 0;
    transform: translateY(8px);
    transition: all 0.3s ease;
    box-shadow: 0 8px 8px rgba(0, 0, 0, 0.3);
}

.song-card:hover .card-play-btn {
    opacity: 1;
    transform: translateY(0);
}

.card-play-btn:hover {
    background-color: var(--accent-hover);
    transform: translateY(0) scale(1.05);
}

.card-title {
    font-size: 16px;
    font-weight: bold;
    margin-bottom: 8px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.card-artist {
    font-size: 14px;
    color: var(--text-secondary);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

/* Active track styling */
.song-card.playing .card-title {
    color: var(--accent);
}

/* --- Player Bar --- */
.player-bar {
    height: 90px;
    background-color: var(--bg-player);
    border-top: 1px solid #282828;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 16px;
    z-index: 100;
}

/* Now Playing Info */
.now-playing {
    display: flex;
    align-items: center;
    width: 30%;
    min-width: 180px;
}

.np-cover {
    width: 56px;
    height: 56px;
    border-radius: 4px;
    margin-right: 14px;
    box-shadow: 0 0 10px rgba(0,0,0,0.3);
}

.np-info {
    display: flex;
    flex-direction: column;
    justify-content: center;
}

.np-title {
    font-size: 14px;
    font-weight: 600;
    margin-bottom: 4px;
    cursor: pointer;
}

.np-title:hover {
    text-decoration: underline;
}

.np-artist {
    font-size: 12px;
    color: var(--text-secondary);
    cursor: pointer;
}

.np-artist:hover {
    color: var(--text-primary);
    text-decoration: underline;
}

.np-heart {
    color: var(--text-secondary);
    margin-left: 16px;
    cursor: pointer;
}

.np-heart:hover {
    color: var(--text-primary);
}

/* Player Controls */
.player-controls {
    display: flex;
    flex-direction: column;
    align-items: center;
    width: 40%;
    max-width: 722px;
}

.control-buttons {
    display: flex;
    align-items: center;
    gap: 24px;
    margin-bottom: 8px;
}

.ctrl-btn {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    font-size: 16px;
    cursor: pointer;
    transition: color 0.2s;
}

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

.play-pause-btn {
    width: 32px;
    height: 32px;
    border-radius: 50%;
    background-color: var(--text-primary);
    color: #000;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 14px;
    transition: transform 0.1s;
}

.play-pause-btn:hover {
    transform: scale(1.05);
    color: #000;
}

.play-pause-btn:active {
    transform: scale(0.95);
}

.progress-container {
    display: flex;
    align-items: center;
    width: 100%;
    gap: 8px;
}

.time {
    font-size: 12px;
    color: var(--text-secondary);
    min-width: 40px;
}

#currentTime {
    text-align: right;
}

/* Range Slider Styling */
input[type=range] {
    -webkit-appearance: none;
    width: 100%;
    background: transparent;
    height: 12px;
    cursor: pointer;
}

input[type=range]:focus {
    outline: none;
}

/* WebKit Track */
input[type=range]::-webkit-slider-runnable-track {
    width: 100%;
    height: 4px;
    cursor: pointer;
    background: #535353;
    border-radius: 2px;
}

/* WebKit Thumb */
input[type=range]::-webkit-slider-thumb {
    height: 12px;
    width: 12px;
    border-radius: 50%;
    background: var(--text-primary);
    cursor: pointer;
    -webkit-appearance: none;
    margin-top: -4px;
    opacity: 0;
    box-shadow: 0 2px 4px 0 rgba(0, 0, 0, 0.5);
    transition: opacity 0.2s;
}

/* Hover styles for slider container to show thumb and change track color */
.progress-container:hover input[type=range]::-webkit-slider-thumb,
.volume-controls:hover input[type=range]::-webkit-slider-thumb {
    opacity: 1;
}

.progress-container:hover input[type=range]::-webkit-slider-runnable-track,
.volume-controls:hover input[type=range]::-webkit-slider-runnable-track {
    background: var(--accent);
}

/* Firefox styling omitted for brevity, focusing on WebKit which handles Chrome/Edge/Safari well for this demo */

/* Volume Controls */
.volume-controls {
    display: flex;
    align-items: center;
    width: 30%;
    min-width: 180px;
    justify-content: flex-end;
    gap: 8px;
}

.volume-controls i {
    color: var(--text-secondary);
    font-size: 14px;
    cursor: pointer;
}

.volume-controls i:hover {
    color: var(--text-primary);
}

.volume-slider {
    width: 100px !important;
}

/* Mobile Navigation Bar */
.mobile-nav {
    display: none;
    position: fixed;
    bottom: 0;
    left: 0;
    width: 100%;
    background-color: rgba(18, 18, 18, 0.95);
    backdrop-filter: blur(10px);
    border-top: 1px solid #282828;
    z-index: 200;
    justify-content: space-around;
    padding: 12px 0 16px 0;
}

.mobile-nav-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    color: var(--text-secondary);
    font-size: 10px;
    gap: 4px;
    cursor: pointer;
    transition: color 0.2s ease;
}

.mobile-nav-item.active {
    color: var(--text-primary);
}

.mobile-nav-item:hover {
    color: var(--text-primary);
}

.mobile-nav-item i {
    font-size: 20px;
}

/* Responsive adjustments */
@media (max-width: 768px) {
    .app-container {
        height: calc(100vh - 140px); /* Account for player + mobile nav */
    }

    .sidebar {
        display: none;
    }
    
    .mobile-nav {
        display: flex;
    }

    .player-bar {
        bottom: 60px; /* Above mobile nav */
        position: fixed;
        width: 100%;
        height: 70px;
        padding: 0 8px;
    }
    
    .now-playing {
        width: 45%;
        min-width: 0;
    }

    .np-cover {
        width: 48px;
        height: 48px;
        margin-right: 8px;
    }

    .np-title {
        font-size: 12px;
    }

    .np-artist {
        font-size: 11px;
    }
    
    .volume-controls {
        display: none;
    }
    
    .player-controls {
        width: 55%;
    }

    .control-buttons {
        gap: 12px;
        margin-bottom: 0;
    }

    .progress-container {
        display: none; /* Hide progress bar on very small screens for clean UI */
    }

    .top-bar {
        padding: 12px 16px;
    }

    .search-box {
        width: 100%;
        margin-left: 0;
        margin-right: 8px;
    }

    .nav-arrows {
        display: none;
    }

    .content-padding {
        padding: 16px;
    }

    .song-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 12px;
    }
    
    .greeting {
        font-size: 24px;
        margin-bottom: 16px;
    }
    
    .section-title {
        font-size: 20px;
    }
}