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

/* Theme Variables */
:root {
    /* Light Theme (Default) */
    --bg-color: #fafafa;
    --text-color: #1a1a1a;
    --header-text-color: #666;
    --header-gradient-start: #667eea;
    --header-gradient-end: #764ba2;
    --card-bg: white;
    --border-color: #ddd;
    --input-bg: white;
    --input-border: #ddd;
    --primary-btn-start: #667eea;
    --primary-btn-end: #764ba2;
    --secondary-btn-bg: white;
    --secondary-btn-color: #333;
    --secondary-btn-border: #ddd;
    --spectrogram-bg: #000;
    --waveform-bg: #000;
    --progress-bar-bg: #ddd;
    --progress-fill-start: #667eea;
    --progress-fill-end: #764ba2;
    --upload-area-hover-bg: #f8f9ff;
    --upload-area-dragover-bg: #f0f4ff;
    --upload-area-border-hover: #667eea;
    --upload-content-svg: #999;
    --upload-content-p: #333;
    --upload-file-types: #666;
    --preview-heading-color: #333;
    --control-label-color: #333;
    --time-display-color: #666;
    --waveform-stroke: #667eea;
}

body.theme-dark {
    --bg-color: #1a1a1a;
    --text-color: #f0f0f0;
    --header-text-color: #ccc;
    --header-gradient-start: #7868e6;
    --header-gradient-end: #b67bff;
    --card-bg: #2d2d2d;
    --border-color: #444;
    --input-bg: #3c3c3c;
    --input-border: #555;
    --primary-btn-start: #7868e6;
    --primary-btn-end: #b67bff;
    --secondary-btn-bg: #3c3c3c;
    --secondary-btn-color: #f0f0f0;
    --secondary-btn-border: #555;
    --spectrogram-bg: #000;
    --waveform-bg: #000;
    --progress-bar-bg: #555;
    --progress-fill-start: #7868e6;
    --progress-fill-end: #b67bff;
    --upload-area-hover-bg: #3c3c3c;
    --upload-area-dragover-bg: #4c4c4c;
    --upload-area-border-hover: #7868e6;
    --upload-content-svg: #aaa;
    --upload-content-p: #f0f0f0;
    --upload-file-types: #ccc;
    --preview-heading-color: #f0f0f0;
    --control-label-color: #f0f0f0;
    --time-display-color: #ccc;
    --waveform-stroke: #b67bff;
}

body.theme-midnight {
    --bg-color: #0d0d1a;
    --text-color: #e0e0f0;
    --header-text-color: #b0b0d0;
    --header-gradient-start: #4a00e0;
    --header-gradient-end: #8e2de2;
    --card-bg: #1c1c2e;
    --border-color: #3a3a4c;
    --input-bg: #28283d;
    --input-border: #4a4a60;
    --primary-btn-start: #4a00e0;
    --primary-btn-end: #8e2de2;
    --secondary-btn-bg: #28283d;
    --secondary-btn-color: #e0e0f0;
    --secondary-btn-border: #4a4a60;
    --spectrogram-bg: #000;
    --waveform-bg: #000;
    --progress-bar-bg: #4a4a60;
    --progress-fill-start: #4a00e0;
    --progress-fill-end: #8e2de2;
    --upload-area-hover-bg: #28283d;
    --upload-area-dragover-bg: #3a3a4c;
    --upload-area-border-hover: #4a00e0;
    --upload-content-svg: #c0c0e0;
    --upload-content-p: #e0e0f0;
    --upload-file-types: #d0d0e0;
    --preview-heading-color: #e0e0f0;
    --control-label-color: #e0e0f0;
    --time-display-color: #d0d0e0;
    --waveform-stroke: #8e2de2;
}

body.theme-oceanic {
    --bg-color: #e0f2f7;
    --text-color: #0a2d3c;
    --header-text-color: #336677;
    --header-gradient-start: #2193b0;
    --header-gradient-end: #6dd5ed;
    --card-bg: #ffffff;
    --border-color: #a7d9eb;
    --input-bg: #eaf8fb;
    --input-border: #bfecf5;
    --primary-btn-start: #2193b0;
    --primary-btn-end: #6dd5ed;
    --secondary-btn-bg: #ffffff;
    --secondary-btn-color: #0a2d3c;
    --secondary-btn-border: #bfecf5;
    --spectrogram-bg: #000;
    --waveform-bg: #000;
    --progress-bar-bg: #a7d9eb;
    --progress-fill-start: #2193b0;
    --progress-fill-end: #6dd5ed;
    --upload-area-hover-bg: #eaf8fb;
    --upload-area-dragover-bg: #d7f1f7;
    --upload-area-border-hover: #2193b0;
    --upload-content-svg: #558899;
    --upload-content-p: #0a2d3c;
    --upload-file-types: #336677;
    --preview-heading-color: #0a2d3c;
    --control-label-color: #0a2d3c;
    --time-display-color: #336677;
    --waveform-stroke: #6dd5ed;
}

body {
    font-family: 'Cal Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    transition: background-color 0.3s ease, color 0.3s ease; /* Smooth theme transitions */
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
    position: relative; /* For absolute positioning of theme selector */
}

/* Theme Selector Styles */
.theme-selector {
    position: absolute;
    top: 2rem;
    right: 2rem;
    z-index: 10;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.theme-selector label {
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--text-color);
}

.theme-selector select {
    padding: 0.5rem 0.75rem;
    border-radius: 8px;
    border: 1px solid var(--border-color);
    background: var(--card-bg);
    color: var(--text-color);
    font-size: 0.9rem;
    appearance: none; /* Remove default arrow */
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='%23666' %3E%3Cpath d='M7 10l5 5 5-5z'/%3E%3C/svg%3E"); /* Custom arrow */
    background-repeat: no-repeat;
    background-position: right 0.75rem center;
    background-size: 16px;
    cursor: pointer;
    transition: background 0.3s ease, color 0.3s ease, border-color 0.3s ease;
}

.theme-selector select:hover {
    border-color: var(--primary-btn-start);
}

header {
    text-align: center;
    margin-bottom: 3rem;
}

header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    background: linear-gradient(135deg, var(--header-gradient-start) 0%, var(--header-gradient-end) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

header p {
    font-size: 1.1rem;
    color: var(--header-text-color);
    max-width: 600px;
    margin: 0 auto;
}

.upload-section {
    margin-bottom: 3rem;
}

.upload-area {
    border: 2px dashed var(--border-color);
    border-radius: 12px;
    padding: 3rem;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
    background: var(--card-bg);
    position: relative;
    overflow: hidden;
}

.upload-area:hover {
    border-color: var(--upload-area-border-hover);
    background: var(--upload-area-hover-bg);
    transform: translateY(-2px);
}

.upload-area.dragover {
    border-color: var(--upload-area-border-hover);
    background: var(--upload-area-dragover-bg);
    transform: scale(1.02);
}

.upload-content svg {
    color: var(--upload-content-svg);
    margin-bottom: 1rem;
}

.upload-content p {
    font-size: 1.2rem;
    color: var(--upload-content-p);
    margin-bottom: 0.5rem;
}

.file-types {
    color: var(--upload-file-types);
    font-size: 0.9rem;
}

.processing-section {
    display: grid;
    gap: 2rem;
    animation: fadeIn 0.5s ease-in-out;
}

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

.image-preview, .spectrogram-preview {
    background: var(--card-bg);
    padding: 1.5rem;
    border-radius: 12px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    transition: transform 0.3s ease;
}

.image-preview:hover, .spectrogram-preview:hover {
    transform: translateY(-2px);
}

#originalImage {
    max-width: 100%;
    max-height: 300px;
    border-radius: 8px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.15); /* Consider making shadow dynamic */
}

#spectrogramCanvas {
    max-width: 100%;
    border-radius: 8px;
    background: var(--spectrogram-bg);
}

.controls {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    background: var(--card-bg);
    padding: 1.5rem;
    border-radius: 12px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1); /* Consider making shadow dynamic */
}

.control-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    transition: all 0.3s ease;
}

.control-group:hover {
    transform: scale(1.02);
}

.range-inputs {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.range-inputs input {
    width: 80px;
    padding: 0.5rem;
    border: 1px solid var(--input-border);
    border-radius: 6px;
    font-size: 0.9rem;
    background: var(--input-bg);
    color: var(--text-color);
}

input[type="range"] {
    width: 100%;
    height: 6px;
    border-radius: 3px;
    background: var(--progress-bar-bg);
    outline: none;
    -webkit-appearance: none;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: var(--primary-btn-start);
    cursor: pointer;
}

input[type="range"]::-moz-range-thumb {
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: var(--primary-btn-start);
    cursor: pointer;
    border: none;
}

.action-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
    animation: slideUp 0.5s ease-in-out;
}

@keyframes slideUp {
    from { opacity: 0; transform: translateY(30px); }
    to { opacity: 1; transform: translateY(0); }
}

.primary-btn, .secondary-btn {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    min-width: 140px;
    position: relative;
    overflow: hidden;
}

.primary-btn {
    background: linear-gradient(135deg, var(--primary-btn-start) 0%, var(--primary-btn-end) 100%);
    color: white; /* Always white text on primary buttons */
}

.primary-btn:hover {
    transform: translateY(-2px);
    filter: brightness(1.1); /* Adjust brightness on hover */
}

.primary-btn:hover::before {
    left: 100%;
}

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

.secondary-btn:hover:not(:disabled) {
    background: #f5f5f5; /* Keep a light hover for secondary button, might need to vary */
    transform: translateY(-1px);
}

.secondary-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.audio-visualization {
    background: var(--card-bg);
    padding: 1.5rem;
    border-radius: 12px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1); /* Consider making shadow dynamic */
}

#waveformCanvas {
    width: 100%;
    height: 100px;
    background: var(--waveform-bg);
    border-radius: 8px;
    margin-bottom: 1rem;
}

.audio-controls {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.control-btn {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    transition: transform 0.2s ease;
    color: var(--text-color); /* Ensure control button icon color changes with theme */
}

.control-btn:hover {
    transform: scale(1.1);
}

.progress-bar {
    flex: 1;
    height: 6px;
    background: var(--progress-bar-bg);
    border-radius: 3px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(135deg, var(--progress-fill-start) 0%, var(--progress-fill-end) 100%);
    width: 0%;
    transition: width 0.1s ease;
}

#timeDisplay {
    font-size: 0.9rem;
    color: var(--time-display-color);
    min-width: 80px;
}

select {
    width: 100%;
    padding: 0.5rem;
    border: 1px solid var(--input-border);
    border-radius: 6px;
    font-size: 0.9rem;
    background: var(--input-bg);
    color: var(--text-color);
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='%23666' %3E%3Cpath d='M7 10l5 5 5-5z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 0.75rem center;
    background-size: 16px;
    cursor: pointer;
}

select:hover {
    border-color: var(--primary-btn-start);
}

/* Progress indicators */
.progress-indicator {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background: var(--card-bg);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 4px 20px rgba(0,0,0,0.2);
    z-index: 1000;
    display: none;
    text-align: center;
}

.spinner {
    width: 40px;
    height: 40px;
    border: 4px solid var(--border-color);
    border-top: 4px solid var(--primary-btn-start);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 0 auto 1rem;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* Pulse animation for active elements */
.pulse {
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0% { transform: scale(1); }
    50% { transform: scale(1.05); }
    100% { transform: scale(1); }
}

/* Custom Scrollbar Styling */
::-webkit-scrollbar {
    width: 12px;
    height: 12px;
}

::-webkit-scrollbar-track {
    background: var(--bg-color);
    border-radius: 10px;
}

::-webkit-scrollbar-thumb {
    background: linear-gradient(135deg, 
        var(--primary-btn-start) 0%, 
        var(--primary-btn-end) 100%);
    border-radius: 10px;
    border: 2px solid var(--bg-color);
    transition: all 0.3s ease;
}

::-webkit-scrollbar-thumb:hover {
    background: linear-gradient(135deg, 
        var(--primary-btn-end) 0%, 
        var(--primary-btn-start) 100%);
    transform: scale(1.05);
}

::-webkit-scrollbar-corner {
    background: var(--bg-color);
}

/* For Firefox */
* {
    scrollbar-width: thin;
    scrollbar-color: var(--primary-btn-start) var(--bg-color);
}

.preset-buttons {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
    gap: 0.5rem;
    margin-top: 0.5rem;
}

.preset-btn {
    padding: 0.75rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background: var(--card-bg);
    color: var(--text-color);
    font-size: 0.85rem;
    cursor: pointer;
    transition: all 0.3s ease;
    text-align: center;
}

.preset-btn:hover {
    background: var(--primary-btn-start);
    color: white;
    transform: translateY(-1px);
    box-shadow: 0 2px 8px rgba(0,0,0,0.15);
}

.preset-btn:active {
    transform: translateY(0);
}

/* Spectrogram layered canvases for playhead */
.spectrogram-stage {
    position: relative;
}

.spectrogram-stage canvas {
    display: block;
    max-width: 100%;
    border-radius: 8px;
}

#spectrogramOverlay {
    position: absolute;
    inset: 0;
    pointer-events: none;
}

/* Optional: sharper red line on dark backgrounds */
body.theme-dark #spectrogramOverlay,
body.theme-midnight #spectrogramOverlay {
    filter: none;
}

@media (max-width: 768px) {
    .container {
        padding: 1rem;
    }
    
    .theme-selector {
        position: static; /* Remove absolute positioning on smaller screens */
        margin-bottom: 1.5rem; /* Add space below theme selector */
        justify-content: center; /* Center align on small screens */
    }

    header {
        margin-top: 0; /* Adjust header margin if theme selector is static */
    }

    header h1 {
        font-size: 2rem;
    }
    
    .upload-area {
        padding: 2rem 1rem;
    }
    
    .controls {
        grid-template-columns: 1fr;
    }
    
    .action-buttons {
        flex-direction: column;
        align-items: center;
    }

    .preset-buttons {
        grid-template-columns: 1fr 1fr;
    }
}

@media (max-width: 480px) {
    .preset-buttons {
        grid-template-columns: 1fr;
    }
}