.main-container-app {
    position: relative;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: flex-start;
    padding: 48px 24px 60px;
    width: 100%;
    max-width: 900px;
    margin: 0 auto;
    box-sizing: border-box;
}

.converter-box {
    width: 100%;
    max-width: 640px;
    background: var(--card-bg, #fff);
    border: 1px solid color-mix(in srgb, var(--border, #e5e7eb) 100%, #e5e7eb);
    border-radius: calc(var(--radius, 10px) + 6px);
    padding: 40px 36px;
    box-shadow: 0 1px 4px rgba(0, 0, 0, 0.05);
    box-sizing: border-box;
}

.converter-header {
    text-align: center;
    margin-bottom: 28px;
}

.converter-header h1 {
    font-size: clamp(24px, 3vw, 32px);
    font-weight: 700;
    color: var(--text);
    margin: 0 0 8px;
}

.converter-header p {
    font-size: 14px;
    color: var(--muted-foreground);
    margin: 0;
}

.drop-zone {
    border: 2px dashed color-mix(in srgb, var(--border, #e5e7eb) 100%, #d1d5db);
    border-radius: calc(var(--radius, 10px) + 4px);
    padding: 48px 24px;
    text-align: center;
    cursor: pointer;
    transition: border-color 0.2s, background 0.2s;
    background: var(--bg-3, #f9fafb);
}

.drop-zone:hover,
.drop-zone.dragover {
    border-color: var(--primary);
    background: color-mix(in srgb, var(--primary) 4%, transparent);
}

.drop-zone-icon {
    width: 48px;
    height: 48px;
    margin: 0 auto 16px;
    color: var(--primary);
}

.drop-zone-title {
    font-size: 15px;
    font-weight: 600;
    color: var(--text);
    margin: 0 0 6px;
}

.drop-zone-hint {
    font-size: 13px;
    color: var(--muted-foreground);
    margin: 0;
}

.file-name-display {
    margin-top: 12px;
    font-size: 13px;
    color: var(--primary);
    font-weight: 500;
    word-break: break-all;
}

.convert-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    width: 100%;
    height: 44px;
    margin-top: 20px;
    border: none;
    border-radius: var(--radius, 10px);
    background: var(--grad);
    background-clip: border-box;
    -webkit-background-clip: border-box;
    color: var(--primary-foreground);
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    box-sizing: border-box;
    overflow: hidden;
    isolation: isolate;
    transition: opacity 0.2s, transform 0.2s;
}

.convert-btn:hover:not(:disabled) {
    opacity: 0.92;
    transform: translateY(-1px);
}

.convert-btn:disabled {
    opacity: 0.55;
    cursor: not-allowed;
}

.error-message {
    display: none;
    margin-top: 16px;
    padding: 12px 16px;
    border-radius: var(--radius, 10px);
    background: #fef2f2;
    border: 1px solid #fecaca;
    color: #dc2626;
    font-size: 13px;
    text-align: center;
}