/* Color Palette - Red Theme */
:root {
    --primary: #C41E3A;        /* Cardinal Red */
    --primary-dark: #8B0000;   /* Dark Red */
    --primary-light: #E74C3C;  /* Light Red */
    --accent: #FF6B6B;         /* Coral Red */
    --background: #1A1A2E;     /* Dark Navy */
    --surface: #16213E;        /* Darker Navy */
    --text-primary: #FFFFFF;
    --text-secondary: #B0B0B0;
    --border: #2D2D44;
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, var(--background) 0%, var(--surface) 100%);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    color: var(--text-primary);
}

.container {
    width: 100%;
    max-width: 500px;
    padding: 2rem;
}

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

header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--primary-light);
    margin-bottom: 0.5rem;
}

.subtitle {
    color: var(--text-secondary);
    font-size: 1rem;
}

.upload-area {
    background: var(--surface);
    border: 2px dashed var(--primary);
    border-radius: 16px;
    padding: 3rem 2rem;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
}

.upload-area:hover,
.upload-area.dragover {
    border-color: var(--accent);
    background: rgba(196, 30, 58, 0.1);
    transform: translateY(-2px);
}

.upload-icon {
    color: var(--primary);
    margin-bottom: 1rem;
}

.upload-text {
    font-size: 1.2rem;
    font-weight: 500;
    margin-bottom: 0.5rem;
}

.upload-subtext {
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.browse-btn {
    display: inline-block;
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    color: var(--text-primary);
    padding: 0.75rem 2rem;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
}

.browse-btn:hover {
    background: linear-gradient(135deg, var(--primary-light) 0%, var(--primary) 100%);
    transform: translateY(-2px);
    box-shadow: 0 4px 15px rgba(196, 30, 58, 0.4);
}

.file-info {
    display: none;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 1rem 1.5rem;
    margin-top: 1.5rem;
    align-items: center;
    justify-content: space-between;
}

.file-info.visible {
    display: flex;
}

.file-details {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
}

.file-name {
    font-weight: 500;
    color: var(--text-primary);
}

.file-size {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.remove-btn {
    background: transparent;
    border: none;
    color: var(--accent);
    font-size: 1.5rem;
    cursor: pointer;
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    transition: all 0.2s ease;
}

.remove-btn:hover {
    background: rgba(255, 107, 107, 0.2);
}

.convert-btn {
    width: 100%;
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    color: var(--text-primary);
    border: none;
    padding: 1rem;
    border-radius: 12px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    margin-top: 1.5rem;
    transition: all 0.3s ease;
}

.convert-btn:hover:not(:disabled) {
    background: linear-gradient(135deg, var(--primary-light) 0%, var(--primary) 100%);
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(196, 30, 58, 0.4);
}

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

footer {
    text-align: center;
    margin-top: 2rem;
    color: var(--text-secondary);
    font-size: 0.875rem;
}

/* Responsive Design */
@media (max-width: 600px) {
    .container {
        padding: 1rem;
    }
    
    header h1 {
        font-size: 2rem;
    }
    
    .upload-area {
        padding: 2rem 1rem;
    }
}