/* --- Basic Setup and Typography --- */
body {
    font-family: 'Inter', sans-serif;
    background-color: #ffffff;
    color: #1f2937; /* Corresponds to Tailwind's text-gray-800 */
    margin: 0;
}

/* --- Header --- */
.header {
    background-color: #2823B4; /* blue */
    padding: 1.5rem 0;
    box-shadow: 0 1px 2px 0 rgba(0, 0, 0, 0.05); /* shadow-sm */
}

.header-title {
    font-size: 1.875rem; /* text-3xl */
    font-weight: 700;
    text-align: center;
    color: #ffffff; /* white */
    margin: 0;
}

/* --- Main Content & Player Container --- */
.main-content {
    display: flex;
    justify-content: center;
    align-items: center;
    margin-top: 2.5rem; /* mt-10 */
    padding: 0 1rem; /* px-4 */
}

.player-container {
    width: 100%;
    max-width: 32rem; /* max-w-lg */
    background-color: #f9fafb; /* gray-50 */
    padding: 1.25rem; /* p-5 */
    border-radius: 0.75rem; /* rounded-xl */
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05); /* shadow-lg */
}

/* --- Topic Selector Dropdown --- */
.topic-selector {
    position: relative;
    margin-bottom: 1rem;
}

.topic-selector-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background-color: #2823B4;
    border: 1px solid #e5e7eb; /* border-gray-200 */
    padding: 0.75rem 1rem;
    border-radius: 0.5rem; /* rounded-lg */
    cursor: pointer;
    transition: border-color 150ms ease-in-out;
}

.topic-selector-header:hover {
    border-color: #d1d5db; /* hover:border-gray-300 */
}

.track-title {
    font-weight: 600; /* font-semibold */
    color: #ffffff; /* text-gray-700 */
}

.topic-dropdown-button {
    border: none;
    background: none;
    padding: 0;
    cursor: pointer;
}

.dropdown-arrow {
    width: 1.5rem;
    height: 1.5rem;
    background-color: #000000;
    color: #ffffff;
    border-radius: 9999px;
    padding: 0.25rem;
    transition: transform 300ms ease-in-out;
}

.dropdown-arrow.rotate-180 {
    transform: rotate(180deg);
}

.topic-list {
    display: none; /* Initially hidden */
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    margin-top: 0.25rem;
    background-color: #ffffff;
    border: 1px solid #e5e7eb;
    border-radius: 0.5rem;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    z-index: 10;
}

.topic-list.show {
    display: block;
}

.topic-list ul {
    list-style: none;
    padding: 0.25rem 0;
    margin: 0;
}

.topic-list li {
    padding: 0.5rem 1rem;
    cursor: pointer;
}

.topic-list li:hover {
    background-color: #f3f4f6; /* hover:bg-gray-100 */
}

/* --- Audio Controls --- */
.audio-controls {
    display: flex;
    align-items: center;
    gap: 0.75rem; /* space-x-3 */
}

.control-button {
    padding: 0.5rem;
    border: none;
    background: none;
    border-radius: 9999px;
    transition: background-color 150ms ease-in-out;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
}

.control-button:hover {
    background-color: #e5e7eb; /* hover:bg-gray-200 */
}

.icon {
    width: 1.5rem;
    height: 1.5rem;
    color: #4b5563; /* text-gray-600 */
}

#play-pause-btn .icon {
    color: #1f2937;
}

.time-display {
    font-size: 0.875rem; /* text-sm */
    color: #4b5563; /* text-gray-600 */
    width: 3rem; /* w-12 */
    text-align: center;
    flex-shrink: 0;
}

/* --- Seek Slider --- */
#seek-slider {
    flex-grow: 1;
    background: linear-gradient(to right, #374151 0%, #374151 0%, #d1d5db 0%, #d1d5db 100%);
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    height: 6px;
    border-radius: 9999px;
    outline: none;
    cursor: pointer;
}

#seek-slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 18px;
    height: 18px;
    background: #2823B4;
    border-radius: 50%;
    cursor: pointer;
    border: 2px solid white;
    box-shadow: 0 0 2px rgba(0,0,0,0.5);
}

#seek-slider::-moz-range-thumb {
    width: 18px;
    height: 18px;
    background: #374151;
    border-radius: 50%;
    cursor: pointer;
    border: 2px solid white;
    box-shadow: 0 0 2px rgba(0,0,0,0.5);
}

/* --- Utility Classes --- */
.hidden {
    display: none !important;
}

/* --- Responsive Design --- */
@media (min-width: 768px) {
    .header-title {
        font-size: 2.25rem; /* md:text-4xl */
    }
    .main-content {
        margin-top: 5rem; /* md:mt-20 */
    }
    .player-container {
        padding: 1.5rem; /* sm:p-6 */
    }
    .audio-controls {
        gap: 1rem; /* sm:space-x-4 */
    }
}