:root {
    /* Light Theme Colors */
    --light-bg: #f5f5f5;
    --light-surface: #ffffff;
    --light-text: #333333;
    --light-text-secondary: #666666;
    --light-border: #e0e0e0;
    --light-accent: #4285f4;
    --light-accent-hover: #3367d6;
    --light-danger: #ea4335;
    --light-success: #34a853;
    --light-input-bg: #f8f8f8;
    
    /* Dark Theme Colors */
    --dark-bg: #121212;
    --dark-surface: #1e1e1e;
    --dark-text: #f5f5f5;
    --dark-text-secondary: #b0b0b0;
    --dark-border: #333333;
    --dark-accent: #4285f4;
    --dark-accent-hover: #5c9aff;
    --dark-danger: #ff6b6b;
    --dark-success: #4cd964;
    --dark-input-bg: #2a2a2a;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Poppins', sans-serif;
    transition: background-color 0.3s, color 0.3s, border-color 0.3s, box-shadow 0.3s;
}

body {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.light-theme {
    background-color: var(--light-bg);
    color: var(--light-text);
}

.dark-theme {
    background-color: var(--dark-bg);
    color: var(--dark-text);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
    width: 100%;
    flex: 1;
    display: flex;
    flex-direction: column;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 30px;
    padding-bottom: 15px;
    border-bottom: 1px solid;
}

.light-theme header {
    border-color: var(--light-border);
}

.dark-theme header {
    border-color: var(--dark-border);
}

h1 {
    font-size: 28px;
    font-weight: 600;
    background: linear-gradient(90deg, var(--light-accent), var(--light-success));
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
}

.dark-theme h1 {
    background: linear-gradient(90deg, var(--dark-accent), var(--dark-success));
    -webkit-background-clip: text;
    background-clip: text;
}

.theme-toggle {
    display: flex;
    align-items: center;
}

.theme-icon-btn {
    background: none;
    border: none;
    cursor: pointer;
    font-size: 24px;
    color: var(--light-accent);
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s ease;
}

.theme-icon-btn:hover {
    background-color: rgba(66, 133, 244, 0.1);
}

.dark-theme .theme-icon-btn {
    color: var(--dark-accent);
}

.dark-theme .theme-icon-btn:hover {
    background-color: rgba(92, 154, 255, 0.1);
}

.light-theme .dark-icon {
    display: none;
}

.dark-theme .light-icon {
    display: none;
}

main {
    display: flex;
    flex-direction: column;
    gap: 30px;
    flex: 1;
}

.card {
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
}

.light-theme .card {
    background-color: var(--light-surface);
    border: 1px solid var(--light-border);
}

.dark-theme .card {
    background-color: var(--dark-surface);
    border: 1px solid var(--dark-border);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.2);
}

.upload-container {
    display: flex;
    flex-direction: column;
    gap: 0;
}

.upload-area {
    border: 2px dashed;
    border-radius: 10px;
    padding: 40px 20px;
    text-align: center;
    cursor: pointer;
    margin: 20px;
    transition: all 0.3s ease;
}

.light-theme .upload-area {
    border-color: var(--light-border);
    background-color: var(--light-input-bg);
}

.dark-theme .upload-area {
    border-color: var(--dark-border);
    background-color: var(--dark-input-bg);
}

.upload-area.highlight {
    border-color: var(--light-accent);
    transform: scale(1.02);
}

.dark-theme .upload-area.highlight {
    border-color: var(--dark-accent);
}

.upload-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 15px;
}

.upload-content i {
    font-size: 48px;
    color: var(--light-accent);
}

.dark-theme .upload-content i {
    color: var(--dark-accent);
}

.btn {
    padding: 10px 20px;
    border: none;
    border-radius: 8px;
    font-weight: 500;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    transition: all 0.3s;
}

.upload-btn {
    background-color: var(--light-accent);
    color: white;
    padding: 12px 24px;
    font-size: 16px;
}

.dark-theme .upload-btn {
    background-color: var(--dark-accent);
}

.upload-btn:hover {
    background-color: var(--light-accent-hover);
    transform: translateY(-2px);
    box-shadow: 0 4px 10px rgba(66, 133, 244, 0.2);
}

.dark-theme .upload-btn:hover {
    background-color: var(--dark-accent-hover);
    box-shadow: 0 4px 10px rgba(92, 154, 255, 0.2);
}

.selected-files-container {
    padding: 20px;
    max-height: 300px;
    border-top: 1px solid;
}

.light-theme .selected-files-container {
    border-color: var(--light-border);
}

.dark-theme .selected-files-container {
    border-color: var(--dark-border);
}

.selected-files-container h3 {
    margin-bottom: 15px;
    font-size: 18px;
    color: var(--light-accent);
}

.dark-theme .selected-files-container h3 {
    color: var(--dark-accent);
}

.selected-files {
    display: flex;
    flex-direction: column;
    gap: 10px;
    max-height: 220px;
    overflow-y: auto;
    padding-right: 5px;
}

.file-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 12px;
    border-radius: 8px;
    transition: transform 0.2s;
}

.file-item:hover {
    transform: translateX(5px);
}

.light-theme .file-item {
    background-color: var(--light-input-bg);
}

.dark-theme .file-item {
    background-color: var(--dark-input-bg);
}

.file-info {
    display: flex;
    align-items: center;
    gap: 12px;
}

.file-thumbnail {
    width: 48px;
    height: 48px;
    border-radius: 8px;
    object-fit: cover;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
}

.dark-theme .file-thumbnail {
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.3);
}

.file-details {
    display: flex;
    flex-direction: column;
}

.file-name {
    font-size: 15px;
    font-weight: 500;
}

.file-size {
    font-size: 13px;
    color: var(--light-text-secondary);
}

.dark-theme .file-size {
    color: var(--dark-text-secondary);
}

.delete-file {
    background: none;
    border: none;
    color: var(--light-danger);
    cursor: pointer;
    font-size: 18px;
    width: 36px;
    height: 36px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s;
}

.delete-file:hover {
    background-color: rgba(234, 67, 53, 0.1);
}

.dark-theme .delete-file {
    color: var(--dark-danger);
}

.dark-theme .delete-file:hover {
    background-color: rgba(255, 107, 107, 0.1);
}

.conversion-options {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 25px;
}

.format-selection {
    display: flex;
    align-items: center;
    gap: 15px;
}

.format-selection h3 {
    font-size: 16px;
    font-weight: 500;
}

select {
    padding: 12px 20px;
    border-radius: 8px;
    font-size: 15px;
    outline: none;
    border: 1px solid;
    appearance: none;
    background-image: url("data:image/svg+xml;charset=UTF-8,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='currentColor' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3e%3cpolyline points='6 9 12 15 18 9'%3e%3c/polyline%3e%3c/svg%3e");
    background-repeat: no-repeat;
    background-position: right 12px center;
    background-size: 16px;
    padding-right: 40px;
}

.light-theme select {
    background-color: var(--light-input-bg);
    border-color: var(--light-border);
    color: var(--light-text);
}

.dark-theme select {
    background-color: var(--dark-input-bg);
    border-color: var(--dark-border);
    color: var(--dark-text);
}

.action-buttons {
    display: flex;
    gap: 15px;
}

.convert-btn {
    background-color: var(--light-accent);
    color: white;
    min-width: 120px;
}

.dark-theme .convert-btn {
    background-color: var(--dark-accent);
}

.convert-btn:hover:not(:disabled) {
    background-color: var(--light-accent-hover);
    transform: translateY(-2px);
    box-shadow: 0 4px 10px rgba(66, 133, 244, 0.2);
}

.dark-theme .convert-btn:hover:not(:disabled) {
    background-color: var(--dark-accent-hover);
    box-shadow: 0 4px 10px rgba(92, 154, 255, 0.2);
}

.reset-btn {
    background-color: transparent;
    border: 1px solid;
    min-width: 120px;
}

.light-theme .reset-btn {
    color: var(--light-text);
    border-color: var(--light-border);
}

.dark-theme .reset-btn {
    color: var(--dark-text);
    border-color: var(--dark-border);
}

.reset-btn:hover:not(:disabled) {
    transform: translateY(-2px);
}

.light-theme .reset-btn:hover:not(:disabled) {
    background-color: rgba(0, 0, 0, 0.05);
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.05);
}

.dark-theme .reset-btn:hover:not(:disabled) {
    background-color: rgba(255, 255, 255, 0.05);
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
}

.btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none !important;
    box-shadow: none !important;
}

.conversion-progress {
    padding: 25px;
    text-align: center;
}

.progress-bar {
    height: 10px;
    background-color: var(--light-border);
    border-radius: 5px;
    overflow: hidden;
    margin-bottom: 15px;
}

.dark-theme .progress-bar {
    background-color: var(--dark-border);
}

.progress {
    height: 100%;
    background-color: var(--light-accent);
    width: 0%;
    transition: width 0.3s;
}

.dark-theme .progress {
    background-color: var(--dark-accent);
}

.result-container {
    padding: 25px;
    text-align: center;
}

.result-container h3 {
    margin-bottom: 15px;
    font-size: 20px;
    color: var(--light-success);
}

.dark-theme .result-container h3 {
    color: var(--dark-success);
}

.download-info {
    margin-bottom: 20px;
    font-size: 15px;
    line-height: 1.6;
}

.download-btn {
    background-color: var(--light-success);
    color: white;
    margin: 10px auto;
    padding: 12px 24px;
    font-size: 16px;
}

.dark-theme .download-btn {
    background-color: var(--dark-success);
}

.download-btn:hover {
    opacity: 0.9;
    transform: translateY(-2px);
    box-shadow: 0 4px 10px rgba(52, 168, 83, 0.2);
}

footer {
    margin-top: 40px;
    text-align: center;
    padding: 20px 0;
    font-size: 14px;
    color: var(--light-text-secondary);
}

.dark-theme footer {
    color: var(--dark-text-secondary);
}

/* Responsive styles */
@media (max-width: 768px) {
    header {
        flex-direction: column;
        gap: 15px;
        align-items: flex-start;
    }
    
    .theme-toggle {
        align-self: flex-end;
        margin-top: -40px;
    }
    
    .conversion-options {
        flex-direction: column;
        gap: 20px;
        align-items: stretch;
    }
    
    .format-selection {
        flex-direction: column;
        align-items: flex-start;
    }
    
    select {
        width: 100%;
    }
    
    .action-buttons {
        justify-content: space-between;
    }
}

@media (max-width: 480px) {
    h1 {
        font-size: 24px;
    }
    
    .upload-content i {
        font-size: 36px;
    }
    
    .action-buttons {
        flex-direction: column;
        gap: 10px;
    }
    
    .btn {
        width: 100%;
    }
    
    .upload-area {
        padding: 30px 15px;
    }
    
    .file-thumbnail {
        width: 40px;
        height: 40px;
    }
}

/* Scrollbar styling */
::-webkit-scrollbar {
    width: 8px;
}

.light-theme ::-webkit-scrollbar-track {
    background: var(--light-input-bg);
    border-radius: 4px;
}

.dark-theme ::-webkit-scrollbar-track {
    background: var(--dark-input-bg);
    border-radius: 4px;
}

.light-theme ::-webkit-scrollbar-thumb {
    background: var(--light-border);
    border-radius: 4px;
}

.dark-theme ::-webkit-scrollbar-thumb {
    background: var(--dark-border);
    border-radius: 4px;
}

.light-theme ::-webkit-scrollbar-thumb:hover {
    background: var(--light-text-secondary);
}

.dark-theme ::-webkit-scrollbar-thumb:hover {
    background: var(--dark-text-secondary);
}