:root {
    --primary-hue: 210;
    --primary-color: hsl(var(--primary-hue), 89%, 60%);
    --primary-color-dark: hsl(var(--primary-hue), 80%, 50%);
    --success-color: hsl(150, 60%, 50%);
    --error-color: hsl(0, 80%, 60%);
    --bg-light: #f6f9fc;
    --bg-dark: #eef2f7;
    --card-bg: #ffffff;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --border-color: #e2e8f0;
    --font-family: 'Inter', sans-serif;
}

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

body {
    font-family: var(--font-family);
    background-color: var(--bg-light);
    color: var(--text-primary);
    display: flex;
    justify-content: center;
    padding: 40px 20px;
    min-height: 100vh;
}

.hidden { display: none !important; }

.converter-wrapper {
    width: 100%;
    max-width: 700px;
}

.app-header {
    text-align: center;
    margin-bottom: 30px;
}
.app-icon {
    width: 64px;
    height: 64px;
    margin-bottom: 1rem;
    object-fit: contain;
}
.app-header h1 {
    font-size: 2.25rem;
    font-weight: 700;
    background: linear-gradient(45deg, var(--primary-color), var(--primary-color-dark));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}
.app-header p {
    font-size: 1rem;
    color: var(--text-secondary);
    margin-top: 5px;
}

.converter-body {
    background-color: var(--card-bg);
    border-radius: 16px;
    box-shadow: 0 20px 50px rgba(0, 0, 0, 0.08);
    padding: 30px;
}

/* Upload Area */
.upload-area {
    border: 2px dashed var(--border-color);
    border-radius: 12px;
    padding: 40px;
    text-align: center;
    cursor: pointer;
    transition: background-color 0.2s ease, border-color 0.2s ease;
}
.upload-area:hover, .upload-area.drag-over {
    background-color: var(--bg-light);
    border-color: var(--primary-color);
}

/* ========== পরিবর্তনটি এখানে করা হয়েছে ========== */
.upload-icon-img {
    width: 48px;
    height: 48px;
    margin-bottom: 16px;
    transition: transform 0.3s ease;
    object-fit: contain;
}
.upload-area:hover .upload-icon-img {
    transform: translateY(-5px) scale(1.1);
}

.upload-title {
    font-size: 1rem;
    font-weight: 500;
}
.upload-subtitle {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-top: 4px;
}
#file-input { display: none; }

/* Controls Area */
.controls-area {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 20px;
    padding: 15px;
    background-color: var(--bg-dark);
    border-radius: 10px;
}
.format-control label {
    font-weight: 500;
    color: var(--text-secondary);
    margin-right: 10px;
}
.select-wrapper {
    position: relative;
    display: inline-block;
}
.select-wrapper::after {
    content: '▼';
    font-size: 12px;
    position: absolute;
    right: 12px;
    top: 50%;
    transform: translateY(-50%);
    pointer-events: none;
    color: var(--text-secondary);
}
#format-select {
    appearance: none;
    -webkit-appearance: none;
    padding: 8px 30px 8px 12px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background-color: var(--card-bg);
    font-family: var(--font-family);
    font-size: 0.9rem;
    cursor: pointer;
}

/* Action Buttons */
.action-button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 10px 18px;
    border: none;
    border-radius: 8px;
    font-family: var(--font-family);
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
}
.action-button:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}
.action-button:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}
.convert-btn {
    background: linear-gradient(45deg, var(--primary-color), var(--primary-color-dark));
    color: white;
}
.download-zip-btn {
    background: var(--success-color);
    color: white;
}
.clear-btn {
    background-color: var(--border-color);
    color: var(--text-secondary);
}
.clear-btn:hover {
    background-color: #d1d9e6;
}

/* File List */
.file-list-area { margin-top: 20px; }
.file-item {
    display: flex;
    align-items: center;
    gap: 15px;
    padding: 15px;
    border: 1px solid var(--border-color);
    border-radius: 10px;
    margin-bottom: 10px;
    animation: slideInUp 0.5s ease-out;
}
@keyframes slideInUp { from { opacity: 0; transform: translateY(20px); } to { opacity: 1; transform: translateY(0); } }
.thumbnail {
    width: 48px;
    height: 48px;
    border-radius: 8px;
    object-fit: cover;
    flex-shrink: 0;
}
.file-info {
    flex-grow: 1;
    overflow: hidden;
}
.file-name {
    font-weight: 600;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}
.file-meta {
    font-size: 0.8rem;
    color: var(--text-secondary);
    margin-top: 2px;
}
.progress-bar-container {
    height: 6px;
    width: 100%;
    background-color: var(--bg-dark);
    border-radius: 3px;
    margin-top: 8px;
    overflow: hidden;
    display: none;
}
.progress-bar-fill {
    height: 100%;
    width: 0;
    background: linear-gradient(90deg, var(--primary-color), var(--success-color));
    border-radius: 3px;
    transition: width 0.4s ease;
}
.file-action {
    width: 40px;
    height: 40px;
    display: flex;
    justify-content: center;
    align-items: center;
    flex-shrink: 0;
}
.download-icon-btn {
    display: flex;
    justify-content: center;
    align-items: center;
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background-color: var(--success-color);
    color: white;
    text-decoration: none;
    transition: transform 0.2s;
}
.download-icon-btn:hover { transform: scale(1.1); }
.status-icon {
    width: 24px;
    height: 24px;
}
.error-icon { color: var(--error-color); }

/* Footer */
.footer-actions {
    display: flex;
    gap: 15px;
    margin-top: 20px;
    border-top: 1px solid var(--border-color);
    padding-top: 20px;
}
.footer-actions .download-zip-btn,
.footer-actions .clear-btn {
    flex: 1; /* Makes both buttons take up equal space */
}


@media (max-width: 600px) {
    body { padding: 20px 10px; }
    .converter-body { padding: 20px; }
    .controls-area { flex-direction: column; gap: 15px; align-items: stretch; }
}