:root {
    --bg-primary: #000000;
    --bg-secondary: #0a0a0a;
    --bg-tertiary: #111111;
    --border-color: #333333;
    --text-primary: #ededed;
    --text-secondary: #a1a1a1;
    --accent: #0070f3;
    --accent-hover: #0761d1;
    --success: #0dda6e;
    --error: #e00;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 2rem;
    width: 100%;
}

header {
    text-align: center;
    margin-bottom: 3rem;
    padding-top: 2rem;
}

h1 {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    background: linear-gradient(135deg, var(--accent) 0%, #00d4ff 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.subtitle {
    color: var(--text-secondary);
    font-size: 1.1rem;
}

.upload-zone {
    border: 2px dashed var(--border-color);
    border-radius: 12px;
    padding: 4rem 2rem;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
    background: var(--bg-secondary);
}

.upload-zone:hover {
    border-color: var(--accent);
    background: var(--bg-tertiary);
}

.upload-zone.dragover {
    border-color: var(--accent);
    background: var(--bg-tertiary);
    transform: scale(1.02);
}

.upload-icon {
    width: 64px;
    height: 64px;
    margin: 0 auto 1rem;
    stroke-width: 1.5;
    color: var(--text-secondary);
}

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

.upload-hint {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.converter-panel {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 2rem;
}

.hidden {
    display: none !important;
}

.file-info {
    margin-bottom: 1.5rem;
    padding-bottom: 1.5rem;
    border-bottom: 1px solid var(--border-color);
}

.file-name {
    font-size: 1.1rem;
    font-weight: 500;
    margin-bottom: 0.5rem;
    word-break: break-all;
}

.file-size {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.format-selector {
    margin-bottom: 1.5rem;
}

.format-selector label {
    display: block;
    margin-bottom: 0.5rem;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.format-selector select {
    width: 100%;
    padding: 0.75rem;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    color: var(--text-primary);
    font-size: 1rem;
    cursor: pointer;
}

.format-selector select:focus {
    outline: none;
    border-color: var(--accent);
}

.convert-btn, .download-btn, .reset-btn, .cancel-btn {
    width: 100%;
    padding: 0.875rem;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
}

.convert-btn, .download-btn {
    background: var(--accent);
    color: white;
}

.convert-btn:hover, .download-btn:hover {
    background: var(--accent-hover);
}

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

.cancel-btn {
    background: transparent;
    color: var(--text-secondary);
    border: 1px solid var(--border-color);
    margin-top: 0.75rem;
}

.cancel-btn:hover {
    background: var(--bg-tertiary);
}

.reset-btn {
    background: transparent;
    color: var(--text-primary);
    border: 1px solid var(--border-color);
    margin-top: 0.75rem;
}

.reset-btn:hover {
    background: var(--bg-tertiary);
}

.progress-panel {
    margin-top: 1.5rem;
}

.progress-bar {
    width: 100%;
    height: 8px;
    background: var(--bg-tertiary);
    border-radius: 4px;
    overflow: hidden;
    margin-bottom: 0.75rem;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--accent) 0%, #00d4ff 100%);
    width: 0%;
    transition: width 0.3s ease;
}

.progress-text {
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.result-panel {
    text-align: center;
    margin-top: 1.5rem;
}

.success-icon {
    width: 64px;
    height: 64px;
    margin: 0 auto 1rem;
    background: var(--success);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    color: white;
}

.result-text {
    font-size: 1.1rem;
    margin-bottom: 1.5rem;
}

footer {
    text-align: center;
    margin-top: auto;
    padding: 2rem 0;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

footer a {
    color: var(--accent);
    text-decoration: none;
}

footer a:hover {
    text-decoration: underline;
}

@media (max-width: 640px) {
    .container {
        padding: 1rem;
    }

    h1 {
        font-size: 2rem;
    }

    .upload-zone {
        padding: 2rem 1rem;
    }
}