body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: #121212;
    color: #e0e0e0;
    margin: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
}

#app-container {
    display: flex;
    flex-direction: row;
    align-items: flex-start;
    justify-content: center;
    gap: 20px;
    width: 95%;
    max-width: 1600px;
    height: 95vh;
}

#main-content {
    flex-grow: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    max-width: 1200px;
}

#video-container {
    width: 100%;
    margin-bottom: 20px;
    background-color: #000;
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 8px 16px rgba(0,0,0,0.3);
    margin: 0;
    position: relative;
}

#video-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    background-color: rgba(0, 0, 0, 0.4);
    opacity: 0;
    transition: opacity 0.2s ease-in-out;
    pointer-events: none;
    gap: 20px;
}

.overlay-row {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 20px;
}

#video-container:hover #video-overlay,
#video-container.video-paused #video-overlay {
    opacity: 1;
    pointer-events: auto;
}

#video-overlay > * {
    pointer-events: auto; /* Make buttons clickable */
}

#play-pause-overlay-button {
    width: 100px;
    height: 100px;
    border: 3px solid white;
    background-color: rgba(0, 0, 0, 0.5);
    border-radius: 50%;
    cursor: pointer;
    padding: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 10;
}

#play-pause-overlay-button.play::after {
    content: "";
    display: block;
    width: 0;
    height: 0;
    border-top: 20px solid transparent;
    border-bottom: 20px solid transparent;
    border-left: 30px solid white;
    margin-left: 10px;
}

#play-pause-overlay-button.pause::after {
    content: "";
    display: block;
    width: 20px;
    height: 30px;
    border-left: 8px solid white;
    border-right: 8px solid white;
}

.overlay-control {
    width: 80px;
    height: 80px;
    border: 2px solid white;
    background-color: rgba(0, 0, 0, 0.5);
    border-radius: 50%;
    cursor: pointer;
    margin: 0 20px;
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
}

.overlay-control::after {
    content: '';
    display: block;
    color: white;
    font-size: 1.5rem;
    font-weight: bold;
}

#rewind-button::after {
    content: '« 15';
}

#forward-button::after {
    content: '15 »';
}

#prev-video-button::after {
    content: '';
    border-top: 15px solid transparent;
    border-bottom: 15px solid transparent;
    border-left: 20px solid white;
}

#next-video-button::after {
    content: '';
    border-top: 15px solid transparent;
    border-bottom: 15px solid transparent;
    border-left: 20px solid white;
}

.overlay-control:disabled {
    opacity: 0.3;
    cursor: not-allowed;
}

#exercise-video {
    width: 100%;
    height: auto;
    display: block;
}

#info-container {
    text-align: center;
    margin-bottom: 20px;
}

#info-container h1 {
    display: inline;
}

#countdown-display {
    font-size: 2.5rem;
    color: #28a745;
    font-weight: bold;
    margin-left: 15px;
    vertical-align: middle;
}

#exercise-title {
    font-size: 2.5rem;
    margin: 0 0 10px 0;
}

#exercise-details {
    font-size: 1.5rem;
    color: #b0b0b0;
    margin: 0 0 10px 0;
}

#section-title {
    font-size: 1.2rem;
    color: #888;
    margin: 0;
}

#progress-indicator {
    font-size: 1rem;
    color: #888;
    margin-top: 5px;
}

#controls-container button {
    background-color: #28a745;
    color: white;
    border: none;
    padding: 15px 30px;
    font-size: 1.2rem;
    border-radius: 8px;
    cursor: pointer;
    transition: background-color 0.3s ease;
    margin: 0 10px;
}

#mute-button, #fullscreen-button {
    font-size: 0; /* Hide text */
    position: relative;
    width: 60px; /* Make it squarer */
}

#mute-button::after, #fullscreen-button::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background-color: white;
}

/* Mute/Unmute Icon */
#mute-button::after {
    content: '';
    width: 24px;
    height: 24px;
    background-color: white;
    -webkit-mask: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cpath d='M16.5 12c0-1.77-1.02-3.29-2.5-4.03v2.21l2.45 2.45c.03-.2.05-.41.05-.63zm2.5 0c0 .94-.2 1.82-.54 2.64l1.51 1.51C20.63 14.91 21 13.5 21 12c0-4.28-2.99-7.86-7-8.77v2.06c2.89.86 5 3.54 5 6.71zM4.27 3L3 4.27 7.73 9H3v6h4l5 5v-6.73l4.25 4.25c-.67.52-1.42.93-2.25 1.18v2.06c1.38-.31 2.63-.95 3.69-1.81L19.73 21 21 19.73l-9-9L4.27 3zM12 4L9.91 6.09 12 8.18V4z'/%3E%3C/svg%3E") no-repeat center;
    mask: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cpath d='M16.5 12c0-1.77-1.02-3.29-2.5-4.03v2.21l2.45 2.45c.03-.2.05-.41.05-.63zm2.5 0c0 .94-.2 1.82-.54 2.64l1.51 1.51C20.63 14.91 21 13.5 21 12c0-4.28-2.99-7.86-7-8.77v2.06c2.89.86 5 3.54 5 6.71zM4.27 3L3 4.27 7.73 9H3v6h4l5 5v-6.73l4.25 4.25c-.67.52-1.42.93-2.25 1.18v2.06c1.38-.31 2.63-.95 3.69-1.81L19.73 21 21 19.73l-9-9L4.27 3zM12 4L9.91 6.09 12 8.18V4z'/%3E%3C/svg%3E") no-repeat center;
}

#mute-button.muted::after {
    -webkit-mask: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cpath d='M3.63 3.63c-.39.39-.39 1.02 0 1.41L7.29 8.7 7 9H4c-.55 0-1 .45-1 1v4c0 .55.45 1 1 1h3l5 5V17.7l4.29 4.29c.63.63 1.71.18 1.71-.71V7.95c0-.89-1.08-1.34-1.71-.71L16.2 8.04l-3.3-3.3-1.41-1.41-4.24-4.24c-.39-.39-1.02-.39-1.42 0zM19 12c0 .82-.15 1.61-.41 2.34l1.53 1.53c.63-1.02 1-2.21 1-3.53s-.37-2.51-1-3.53l-1.53 1.53c.26.73.41 1.52.41 2.34z'/%3E%3C/svg%3E") no-repeat center;
    mask: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cpath d='M3.63 3.63c-.39.39-.39 1.02 0 1.41L7.29 8.7 7 9H4c-.55 0-1 .45-1 1v4c0 .55.45 1 1 1h3l5 5V17.7l4.29 4.29c.63.63 1.71.18 1.71-.71V7.95c0-.89-1.08-1.34-1.71-.71L16.2 8.04l-3.3-3.3-1.41-1.41-4.24-4.24c-.39-.39-1.02-.39-1.42 0zM19 12c0 .82-.15 1.61-.41 2.34l1.53 1.53c.63-1.02 1-2.21 1-3.53s-.37-2.51-1-3.53l-1.53 1.53c.26.73.41 1.52.41 2.34z'/%3E%3C/svg%3E") no-repeat center;
}

/* Fullscreen Icon */
#fullscreen-button::after {
    content: '';
    width: 24px;
    height: 24px;
    background-color: white;
    -webkit-mask: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cpath d='M7 14H5v5h5v-2H7v-3zm-2-4h2V7h3V5H5v5zm12 7h-3v2h5v-5h-2v3zM14 5v2h3v3h2V5h-5z'/%3E%3C/svg%3E") no-repeat center;
    mask: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cpath d='M7 14H5v5h5v-2H7v-3zm-2-4h2V7h3V5H5v5zm12 7h-3v2h5v-5h-2v3zM14 5v2h3v3h2V5h-5z'/%3E%3C/svg%3E") no-repeat center;
}

#controls-container button:hover {
    background-color: #218838;
}

#controls-container button:disabled {
    background-color: #555;
    cursor: not-allowed;
}

#playlist-container {
    width: 350px;
    flex-shrink: 0;
    background-color: #1e1e1e;
    border-radius: 12px;
    padding: 10px;
    height: 100%;
    overflow-y: auto;
}

#playlist {
    list-style: none;
    padding: 0;
    margin: 0;
}

.playlist-chapter {
    padding: 10px 12px;
    font-size: 1rem;
    font-weight: bold;
    color: #e0e0e0;
    background-color: #2a2a2a;
    border-bottom: 1px solid #333;
    margin-top: 10px;
    cursor: default;
}

.playlist-chapter:first-child {
    margin-top: 0;
}

#playlist li {
    padding: 8px 12px;
    border-bottom: 1px solid #333;
    cursor: pointer;
    transition: background-color 0.2s ease;
    font-size: 0.9rem;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

#playlist li:last-child {
    border-bottom: none;
}

#playlist li:not(.playlist-chapter):hover {
    background-color: #2a2a2a;
}

#playlist li.active {
    background-color: #28a745;
    color: white;
}

#playlist li .playlist-item-name {
    font-size: 1rem;
    font-weight: bold;
}

#playlist li .playlist-item-details {
    font-size: 0.9rem;
    color: #b0b0b0;
}

#playlist li.active .playlist-item-details {
    color: #e0e0e0;
}